Edinburgh Research Explorer · 2015, Vol. 16(4) Supplement 104 ... KS Deacon, JL Mitchell and LG Mould ... 30R Computational modelling of oxygen delivery in acute respiratory distress

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Using serum hepcidin to identify iron deficiency in previouslycritically ill patients at time of hospital discharge

Citation for published version:Shah, A, K, W, McKechnie, S, Stanworth, SJ, Griffith, D, Walsh, T, Drakesmith, H & Roy, N 2015, 'Usingserum hepcidin to identify iron deficiency in previously critically ill patients at time of hospital discharge'Journal of the Intensive Care Society, vol. 16, no. 4 (supp), pp. 104-128. DOI: 10.1177/1751143715615287

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Abstracts

Intensive Care Foundation ResearchPoster Presentations

Wednesday 9 December 2015

1R Out-of-hospital cardiac arrest and PCI – A single-site study from the South West ofEnglandN Williams and R Appelboam

2R Abstract not available

3R Oesophageal sealing and aspiration via a novel nasogastric tube to prevent gastrooesophageal reflux in critically ill patients: Results from a feasibility studyB Lane, MT Gwinnutt, BD Murray and N Scawn

4R Prokinetic agents in intensive care – Where are we now?BA Summers, BA McGrath and M Dean

5R The DAISY project: Identifying dysphagia in acute cervical spinal cord injuryJ McRae

6R Using serum hepcidin to identify iron deficiency in previously critically ill patients attime of hospital dischargeA Shah, K Wray, S McKechnie, S Stanworth, R Kirkbride, D Griffith, T Walsh, H Drakesmith and N Roy


8R Necrotising soft tissue infection: A retrospective case studySH Chia and G Dempsey

9R Endotracheal tube colonisation and ventilator-associated pneumonia in cardiacsurgery patientsE Senanayake, R Giri, S Gopal, A Nevill and H Luckraz

10R Cytochrome c oxidase: Evaluating the metabolic impact of impaired cerebralautoregulationD Highton, C Elwell and M Smit

11R The moon, the madness, the myth? Lunar cycle and the incidence of delirium onthe intensive care unitS Berhane, C Arrowsmith, C Peters and SC Robert

12R Clinical sedation monitoring using a novel technology (Responsiveness Index):Clinical experience of patients enrolled in the DESIST clinical trialEC Phillips, J Antonelli, K Kydonaki, T Quasim, J Ruddy, A Davidson, J Rutherford, P Peltola, MOK Sarkela, K Uutela and TS Walsh; for theDevelopment and Evaluation of Strategies to Improve Sedation practice in inTensive care (DESIST) study investigators

13R User experience of three interventions developed to improve sedationmanagement in intensive care units: Concurrent qualitative study within the DESISTstudyK Kydonaki, J Hanley, J Antonelli and TS Walsh; for the Development and Evaluation of Strategies to Improve Sedation practice in inTensive care(DESIST) study investigators

Journal of the Intensive Care Society

2015, Vol. 16(4) Supplement 104–128

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14R SoundEar devices passively reduce ambient sound in critical careNR Plummer, J Baldwin and S Laha

15R Noises in the intensive care unitJulie L Darbyshire, Emma Jeffs, Sarah Vollam, Lisa Hinton and J Duncan Young

16R An improved classifier for mortality prediction in adult critical care admissionsA Shenfield, M Rodrigues, D Valentine, D Liu and J Moreno-Cuesta

17R A study of the impact of alcohol on admissions to a large Welsh intensive care unitCeri Battle, Morgan Pengelly, Karen James, Abigail Clayton and Craig Jerwood

18R Visiting in intensive care: A survey of UK unitsKS Deacon, JL Mitchell and LG Mould

19R Team perceptions of risk and safety: A qualitative study of ICU staffingD D’Lima, E Murray and S Brett


21R A case note analysis of the reasons for early unplanned acute hospital re-admissionsamong adult ICU survivors

D Nassif, N Jones, E Donaghy, L Salisbury, P Ramsay, N Lone and T Walsh


23R Direct monitoring of physical activity in critical care: Feasibility, tolerability andvalidity of the ActivPAL accelerometerG Atkins, D McWilliams and C Snelson

24R Mapping physical activity in critically ill patients in a UK intensive care unit: Aprospective observational service studyJ Mortimore, J Rose, N Hart, S Berney and B Connolly

25R Can verbal encouragement and self-reported patient motivation predict activeparticipation in physiotherapy on critical care?CA Lawrence, F Lorencatto and JJ Francis



28R The effect of bed percussion vibration therapy on airflow in mechanically ventilatedpatients with severe respiratory failureK Morris, L Osman, A Wilson and E Main

29R Mortality in critically ill non-surgical patients with pre-existing pulmonaryhypertensionKB Bauchmuller, Y Arunan, R Condliffe, C Billings and GH Mills

30R Computational modelling of oxygen delivery in acute respiratory distresssyndrome: Optimising positive end-expiratory pressureM Chikhani, A Das, M Haque, W Wang, O Cole, DG Bates and JG Hardman

Research Poster Presentations 105



1R Out-of-hospital cardiac arrest andPCI – A single-site study from the SouthWest of England

N Williams and R Appelboam

Royal Devon and Exeter NHS Trust, Exeter, UK

AbstractThere is a substantial body of evidence which supports theuse of immediate percutaneous coronary intervention(PCI) for patients presenting with out-of-hospital cardiacarrest (OOHCA) with return of spontaneous circulationwithout obvious extra cardiac cause.1–3 The evidence alsodemonstrates neurological status on presentation shouldnot be used for prognostication and thus refusal of PCI onthose grounds.4 Despite this, we know there is significantvariation in practice with few centres mandating PCI for allcomers, with lack of ST elevation on the electrocardio-gram (ECG) or low Glasgow Coma Scale (GCS) com-monly cited reasons for not taking patients immediatelyfor PCI. This study looks at practice at a large districtgeneral hospital in the South West of England.

Between January 2010 and December 2014, 159patients were referred to the intensive care unit havingsuffered an OOHCA and resuscitated to achieve returnof spontaneous circulation. Of these patients, 17 had aclear non-cardiac cause for their arrest, and they wereexcluded from the remainder of the analysis. Of theremaining group, 76 (48%) had PCI on the day of pre-sentation, with a further 22 (14%) having PCI on a sub-sequent day. For patients having PCI on presentation,48% had ST elevation and 52% without. Of all patientshaving PCI, 47 (29%) had ‘successful’ PCI with resolutionof flow past an occlusive lesion.

The in-hospital survival rate was 46% overall, with 80%of survivors discharged from hospital with a CerebralPerformance Score of 1 or 2 (capable of independentliving). For patients having PCI on presentation, 55% sur-vived, as compared with 25% who did not have PCI.

The data from our centre demonstrate a low overallrate of PCI for patients presenting with OOHCA andwould seem to suggest a survival benefit for PCI onthe day of presentation. We plan to use these data as abasis for further engagement of cardiology colleagues toconsider PCI for all comers where there is no clear extracardiac cause for OOHCA, irrespective of GCS or ECGon presentation.

References

1. Dumas F, Cariou A, Manzo-Silberman S, et al.Immediate percutaneous coronary intervention is asso-ciated with better survival after out of hospital cardiacarrest – insights from the PROCAT registry. CircCardiovasc Interv 2010; 3: 200–207.

2. Spaulding C, Joly LM, and Rosenburg A. Immediatecoronary angiography in survivors of out of hospitalcardiac arrest. N Engl J Med 1997; 336: 1629–1633.

3. Kern KB. Optimal treatment of patients surviving out-of-hospital cardiac arrest. JACC Cardiovasc Interv2012; 5: 597–605.

4. Sandroni C, Cariou A, Cavallaro F, et al.Prognositcation in comatose survivors of cardiac arrest:an advisory statement from the European ResuscitationCouncil and the European Society of Intensive CareMedicine. Intensive Care Med 2014; 40: 1816–1831.


3R Oesophageal sealing and aspirationvia a novel nasogastric tube to preventgastro oesophageal reflux in critically illpatients: Results from a feasibility study

B Lane, MT Gwinnutt, BD Murray and N Scawn

Liverpool Heart and Chest Hospital, Liverpool, UK

AbstractVentilator-associated pneumonia (VAP) is one of themost common nosocomial infections in intensive careaffecting up to 28% of patients.1 Gastro oesophagealreflux plays a major role in its pathogenesis as supinepositioning, nasogastric feeding and the presence of tra-cheal pepsin have all been demonstrated to be indepen-dent risk factors for VAP.2,3

We present the first use of a commercially available,novel nasogastric aspiration tube (Nutriseal, Israel) whichaims to reduce the risk of gastro oesophageal reflux. Thetube incorporates six small channels arranged in its outerwall which exit in the distal and mid oesophagus. Low-pressure suction is applied to these channels, drawing theoesophagus against the tube to create a sealing effect. Inaddition, any accumulated reflux contents in the oeso-phagus are actively aspirated from the suction ports.

Local ethics board approval was obtained. Informedconsent was gained from patients, prior to cardiac andthoracic aortic surgery. The device was inserted post-operatively in 16 adult patients when nasogastric tubeinsertion was indicated on clinical grounds. Correct posi-tioning of the tube was confirmed radiographically usingintegrated radiopaque markers. Oropharyngeal sampleswere obtained for pepsin assay, as a marker for reflux,3,4

prior to tube insertion and at 12 hourly intervals for thenext 60 h. The Mann–Whitney U test was used to com-pare pepsin levels during tube use with baseline samples.Clinician and nurse questionnaires were administered toassess ease of use.

Nutriseal nasogastric aspiration tubes were inserted in16 patients. The median length of time patients had a trialtube in situ was 5.5 days [IQR 2.7–9.4]. Sixty-five oro-pharyngeal aspirates were sent for assay. Insertion of thenasogastric aspiration tube resulted in a statistically sig-nificant reduction in pharyngeal pepsin levels from

106 Journal of the Intensive Care Society 16(4) State of the Art Abstracts Supplement



baseline with median values of 14 6 ng/ml [IQR 28–214]vs. 27.5 ng/ml [IQR 0–74] (p¼ 0.036) (Figure 1). Nursingstaff and clinicians found the tubes easy to use. Therewere no unexpected adverse incidents attributed to useof the device.

This proof of concept study shows the device is safeand easy to use in a cardiac intensive care setting. Thetube significantly reduced gastro oesophageal refluxwhich may decrease the risk of ventilator associatedpneumonia as well as offsetting the risk of enteral feedingin mechanically ventilated patients.

Funding

The authors disclosed receipt of the following financial sup-port for the research, authorship, and/or publication of thisarticle: Funding and support to carry out this study wasprovided by Swing Medical, Tel Aviv, Israel.

References

1. Richards M, Edwards J, Culver D, et al. Nosocomialinfections in medical intensive care units in the UnitedStates. National Nosocomial Infections SurveillanceSystem. Crit Care Med 1999; 27: 887–892.

2. Drakulovic M, Torres A, Bauer T, et al. Supine bodyposition as a risk factor for nosocomial pneumonia inmechanically ventilated patients: a randomised trial.Lancet 1999; 354: 1851–1858.

3. Metheny N, Clouse R, Chang Y, et al.Tracheobronchial aspiration of gastric contents in criti-cally ill tube-fed patients: frequency, outcomes, and riskfactors. Crit Care Med 2006; 34: 1007–1015.

4. Nseir S, Zerimech F, Fournier C, et al. Continuouscontrol of tracheal cuff pressure and microaspirationof gastric contents in critically ill patients. Am JRespir Crit Care Med 2011; 184: 1041–1047.

4R Prokinetic agents in intensive care –Where are we now?

BA Summers, BA McGrath and M Dean

University of Salford, Salford, UK

AbstractIntolerance to enteral feeding in intensive care iscommon and can contribute to direct or indirect mor-bidity and mortality. The use of prokinetic agents mayimprove the success and tolerance of enteral feedingbut practice varies widely regarding the choice ofagent, route of administration and optimum co-deliveryof enteral nutrition. We therefore performed a systema-tic review examining available evidence regarding the useof prokinetic agents to promote enteral feeding in theintensive care unit.

A search of Medline (1946–2013), Embase (1980–2013), The Cochrane Library (1898–2013) and GoogleScholar was performed. Key search terms included‘intensive care’, ‘critical care’, ‘Erythromycin’, ‘metoclo-pramide’, ‘prokinetic’, ‘enteral nutrition’, ‘gastrointestinalmotility’ and ‘gastric emptying’. Abstracts from all clinicaltrials, review articles and case reports examining theeffects of prokinetics on enteral feeding were reviewed.The following exclusion criteria were applied: age <16,trials using currently unavailable prokinetic agents andtrials exclusively examining the placement of feedingtubes, Twenty-three remaining clinical trials were indivi-dually critically analysed in detail against an a priorichecklist of defined criteria concerning study design,power and reliability of results.

Metoclopramide and erythromycin are the mainagents being compared in the 13 trials prior to 2007which concentrate on single-agent therapy. Overall,these trials conclude that prokinetics could be beneficialin patients with intolerance to enteral feeding, increasinggastric motility as shown by increased levels of parace-tamol absorption or reduced gastric residual volumes.

Since 2007, four trials have examined combinationtherapy as well as single-agent therapy. As a singleagent, erythromycin was significantly more efficaciousshowing reduction in gastric residual volumes whereasthe greatest overall benefit was seen using combina-tion.1–4 The issue of tachyphylaxis is evident with signifi-cant reduction in benefit after approximately 48 h oftherapy. However, overall evidence is limited; studieswith the strongest design lack power, and, conversely,well-powered studies lack reliability in their design suchas lack of blinding. Due to the heterogeneity of the meth-ods and outcomes, meta-analysis is not feasible. The lackof clinical outcomes such as mortality or length of stay isanother limitation when interpreting the benefit of pro-kinetics in intensive care.

Despite limitations, available evidence suggests intra-venous metoclopramide and erythromycin both individu-ally increase tolerance to enteral feed. The greatesteffect is seen when these agents are used synergistically

Figure 1. Box plot showing median oropharyngeal pepsinlevels at baseline and at 12 hourly intervals from nasogastrictube insertion. Baseline in red. Post-nasogastric tube insertionin blue boxes. Circles represent outliers.




for up to 48 h, after which tachyphylaxis reduces theirefficacy. Further studies into clinically relevant outcomessuch as mortality and length of stay are required beforestronger recommendations can be made.

References

1. Dickerson RN, Mitchell JN, Morgan LM, et al.Disparate response to metoclopramide therapy for gas-tric feeding intolerance in trauma patients with andwithout traumatic brain injury. JPEN 2009; 33:646–655.

2. Lu NF, Zheng RQ, Lin H, et al. Study of erythromycinand metoclopramide in treatment of feeding intoleranceof critically ill patients in intensive care unit. Chin CritCare Med 2010; 22: 36–39.

3. Nguyen NQ, Chapman MJ, Fraser RJ, et al.Erythromycin is more effective than metoclopramidein the treatment of feed intolerance in critical illness.Crit Care Med 2007; 35: 483–489.

4. Nguyen NQ, Chapman M, Fraser RJ, et al. Prokinetictherapy for feed intolerance in critical illness: one drugor two? Crit Care Med 2007; 35: 2561–2567.

5R The DAISY project: Identifying dysphagiain acute cervical spinal cord injury

J McRae

London and London Spinal Cord Injury Centre, UniversityCollege, Stanmore, UK

AbstractAcute cervical spinal cord injury patients (CSCI) are pri-marily admitted to major trauma centres (MTC) whilstawaiting transfer to specialist spinal injury units (SIU).Delays identified by the Spinal Injuries Association1 aredue to limited respiratory beds, leaving admitting inten-sive care units (ICU) to commence ventilatory supportand plan cervical spine surgery, known to cause laryngealimpairment. Dysphagia incidence is around 40%2 withsilent aspiration impacting on respiratory function andassociated with increased mortality and morbidity.3

Allied Heath Professionals (AHP) are often involved tomanage ventilator weaning, feeding and resolve swallow-ing problems.

The aim of this study is to investigate the clinical deci-sions made by team members in different ICU settingsthat admit CSCI patients.

An online survey comprising of 35 multiple-choicequestions covering five topics: tracheostomy and ventila-tor weaning, nutrition, swallowing, mouthcare and com-munication was distributed through critical carenetworks and professional bodies to doctors, nurses,dietitians, physiotherapist and speech and language thera-pists (SLT). Biographical information was collected onprofession, type and size of hospital ICU.

Responses were received from 219 professionals from87 UK hospitals. Nearly a third were doctors, anotherthird were nurses with AHP responses from phy-siotherapists (16.3%), SLTs (13.9%) and dietitians (4.8%).

Respondents were based in MTC (32.9%), DistrictGeneral Hospitals (DGH) (26.9%), Teaching Hospitals(14.2%) and 7.8% worked in a MTC with a SIU on-site.The majority (69.4%) worked in large hospitals withover 500 beds and 60.6% in ICU’s with over 10beds. 85.4% reported that their unit admitted SCIpatients.

National ventilator weaning protocols were devel-oped4 to ensure a safe and effective weaning transitionfor those with CSCI; however, 42.1% reported using alocally agreed protocol. Measures of vital capacity wereused more by SIU staff (90.5%) than MTC staff (49.3%)and SIU routinely capped off the tracheostomy (76.2%)compared to MTC (16.4%) and DGH (21.9%).

With regard to tracheostomy care, 57.7% of respon-dents considered a cuff prevented aspiration of secre-tions and 12.1% thought that this allowed safe oralintake. Eating with the cuff up happened ‘sometimes’ by52.9% of staff at MTC, compared to 40% SIU and 60%DGH.

Enteral feeding commenced only after failure to takeadequate oral intake (82.6%) or prolonged intubation(50.7%). Gastrostomy tube was considered after ongoingswallowing problems (75%) or recommendation by SLT(63.2%). SLT (86.8%) and nurses (54.2%) most commonlyscreened for swallowing problems and 41.5% of staffused a blue dye test.

Coughing (95.1%) was almost universally accepted as asign of dysphagia, followed by food from tracheostomy(91.5%) and aspiration pneumonia (89.4%). With 90.4%using bedside swallow assessment and only 37.8% usingflexible nasendoscopy, this may explain why silent aspira-tion is missed.

In summary, a wide range of clinical decisions aremade by staff in the respiratory and feeding manage-ment of CSCI patients. This affects length of stayresulting in complications. A structured protocol isproposed, ensuring consistent screening and interven-tions, with education and support from SpinalOutreach Teams.

References

1. Spinal Injuries Association. A paralysed system? http://www.spinal.co.uk/userfiles/images/uploaded/pdf/382-783205.pdf (2015, accessed 4 August 2015).

2. Shem K, Castillo K, Wong SL, et al. Dysphagia andrespiratory care in individuals with tetraplegia: inci-dence, associated factors, and preventable complica-tions. Top Spinal Cord Inj Rehabil 2012; 18: 15–22.

3. Roquilly A, Seguin P, Mimoz O, et al. Risk factors forprolonged duration of mechanical ventilation in acutetraumatic tetraplegic patients—a retrospective cohortstudy. J Crit Care 2014; 29: 313 e7–313 e13.




4. Respiratory Information for Spinal Cord Injury.Weaning guidelines for spinal cord injury patients incritical care units, http://www.risci.org.uk/NSCISB%20RISCI%20final.doc (2012, accessed 4August 2015).

6R Using serum hepcidin to identify irondeficiency in previously critically illpatients at time of hospital discharge

A Shah1, K Wray2, S McKechnie1, S Stanworth3, R Kirkbride4,D Griffith5,6, T Walsh5,6, H Drakesmith2 and N Roy2

1Nuffield Department of Clinical Neurosciences, John RadcliffeHospital, Oxford, UK2Weatherall Institute of Molecular Medicine, John RadcliffeHospital, Oxford, UK3NHS Blood & Transplant, Oxford, UK4Royal Infirmary of Edinburgh, NHS Lothian, Edinburgh, UK5Centre for Inflammation Research, University of Edinburgh,Edinburgh, UK

6Department of Anaesthesia, Critical Care and Pain Medicine,University of Edinburgh, Edinburgh, UK

AbstractAnaemia during critical illness is multifactorial and well stu-died. There is less data on anaemia during the recoveryphase of critical illness and its relation to long-term out-comes.1 Iron deficiency is the largest and treatable cause ofanaemia worldwide, but in intensive care (ICU), diagnosis ofiron depletion is complicated by concomitant inflammation,which raises serum ferritin, the commonest estimate foriron status. Hepcidin has emerged as a key regulator of ironmetabolism. Its expression is increased in states of inflam-mation and iron overload and repressed in iron deficiency,hypoxia and erythroid expansion.2,3

Our aims were:

(i) To identify the proportion of patients discharged from ICUwho remain anaemic at, or close to, hospital discharge;

(ii) To identify the proportion of anaemic patients with irondeficiency anaemia (IDA), anaemia of inflammation (AID)and combined anaemia of inflammation and iron deficiency(IDI); and

Study popula!on (N = 117)M = 75 F = 42

AnaemicM (Hb<130 g.L-1) = 71/75 F (Hb<120 g.L-1) = 39/42

Presence of inflamma!onCRP >8 mg.L-1

No M: 6/71 F: 4/39

Iron Deficiency Anaemia (IDA)

M: 0/6 F: 0/4

YesM: 65/71 F: 35/39

Anaemia of inflamma!on (AID)

M: 59/65 F: 30/35

Iron Deficiency & inflamma!on (IDA)

M: 6/65 F: 5/35

Ferri!n≤150 ug.L-1Ferri!n>150 ug.L-1Ferri!n<20 ug.L-1

Yes

Figure 1. Flow of classification of different types of anaemia classified by haemoglobin, CRP and ferritin cut-offs.




(iii) To investigate if serum hepcidin values are significantlylower in the IDI group compared to the AID group.

Anaemia was defined according to World HealthOrganization guidelines: males <130 g"L#1 and females<120 g"L#1. In the presence of inflammation (C-reactiveprotein (CRP) >8 mg"L#1), a ferritin cut-off of 150mg"L#1

was used to differentiate between IDI (<150) and AID(>150).3 Serum samples collected as part of RECOVER,a multicenter randomised controlled trial assessing theeffects of a complex rehabilitation intervention after ICUdischarge on patient outcomes, were analysed.4 Weassayed serum hepcidin, soluble transferrin receptor,CRP, ferritin and other markers of iron status. Statisticalsignificance was defined as p< 0.05.

In sum, 117 patient samples were analysed. Proportionsof different types of anaemia are shown in Figure 1. Mean(SD) sample collection day was 4.6 (6.08) days prior tohospital discharge and 18.5 (18.5) days post-ICU discharge;110/117 (94%) patients were anaemic prior to hospitaldischarge. Overall, 89/117 (76%) had an AID and 11/117(9%) had IDI based on our pre-defined criteria. Geometricmean (95% CI) hepcidin levels were significantly lower inthe IDI group compared to the AID group: 9.13 (3.57–23.3) ng mL#1 vs. 28.6 (24.8–33.1) ng mL#1 (p< 0.05).Using area under the curve for receiver operator charac-teristic (AUCROC) curves for our diagnosis of IDI, hepcidin<8 ng mL#1 had a sensitivity of 36.3% and a specificity of95.8%, while hepcidin of <19 ng mL#1 had a sensitivity of72.7% and a specificity of 71.7% with an AUCROC of 0.722.

The majority of patients discharged from ICU, and sub-sequently hospital, have an AID and a small proportiondevelop IDI based on current available tests. We haveshown that serum hepcidin is a promising diagnostic testof iron deficiency in the context of inflammation. However,the hepcidin levels are elevated to a point where, based onprevious studies, patients would not be expected torespond to oral iron.2,5 Prospective studies are thereforeneeded to further understand hepcidin regulation duringthe acute and recovery phases of critical illness, to assess ifintravenous iron may be beneficial in treating anaemicpatients recovering from critical illness, and determine ifserum hepcidin levels could identify those most likely torespond to this therapy.

Author Note

H Drakesmith and N Roy contributed equally to this work.

References

1. Walsh TS, Wyncoll DA, and Stanworth SJ. Managinganaemia in critically ill adults. Br Med J 2010; 341:547–551.

2. Pasricha S, Atkinson SA, Armitage AE, et al.Expression of the iron hormone hepcidin distinguishesdifferent types of anemia in African children. Sci TranslMed 2014; 6: 235re3.

3. Lee EJ, Oh EJ, Park YT, et al. Soluble transferrinreceptor (sTfR), ferritin and sTfR/Log ferritin indexin anaemic patients with nonhematological malignancy

and chronic inflammation. Clin Chem 2002; 48:1119–1121.

4. Walsh TS, Salisbury LG, Merriweather J, et al. Theeffectiveness of increased hospital-based rehabilitationand information provision after intensive care unit dis-charge: the RECOVER randomised clinical trial.JAMA Intern Med 2015; 175: 901–910.

5. Bregman DB, Morris D, Koch TA, et al. Hepcidinlevels predict nonresponsiveness to oral iron therapyin patients with iron deficient anaemia. Am JHaematol 2013; 88: 97–101.


8R Necrotising soft tissue infection: Aretrospective case study

SH Chia and G Dempsey

Intensive Care Unit, Aintree University Hospital, Liverpool, UK

AbstractIntroduction: Necrotising soft tissue infection (NSTI) isa rare but potentially fatal disease requiring early aggres-sive surgical debridement if treatment is to be successful.A number of prognostic indicators, including theLaboratory Risk Indicator for Necrotising Fasciitis(LRINEC) score and Acute Physiology and ChronicHealth Evaluation (APACHE) II score, have beendescribed to assist diagnosis and predict outcome.1–3

Objective: To identify physiological factors predictive ofsurvival to hospital discharge present within the first 24 hof admission to critical care.Method: We have performed a retrospective case notereview of patients admitted to the intensive care unit inAintree University Hospital between 2002 and 2014 witha diagnosis of NSTI. Notes were reviewed for demo-graphic, baseline physiological and survival data. In thisstudy, we have used the LRINEC score to help withdiagnosis. The APACHE II and the Sequential OrganFailure Assessment (SOFA) score have been used asprognostic tools. The Functional Co-morbidity scorewas used to quantify chronic health status.Results: Twenty-eight patients with a diagnosis of NSTIwere identified. Twenty patients survived to hospital dis-charge. Demographic and physiological data are pre-sented in Table 1.

In this cohort, the serum lactate in non survivors washigher and found to be statistically significant at 2.97(p¼ 0.048, Mann–Whitney U test).Conclusion: Patients surviving to hospital dischargetend to be younger with a lesser degree of physiologicalinsult. The LRINEC, SOFA, Functional Co-morbidityscore and the APACHE II score did not appear to reliablypredict outcome in this cohort.




References

1. Wang JM, and Lim HK. Necrotizing fasciitis: eight-year experience and literature review. Braz J InfectDis 2014; 18: 137–143.

2. Das D, Baker M, and Venugopal K. Necrotizing fascii-tis in New Zealand – risk factors, microbiological find-ings and outcomes in a large case series. Int J Infect Dis2012; 16: e343.

3. Wong C-H, Khin L-W, Heng K-S, et al. The LRINEC(Laboratory Risk Indicator for Necrotizing Fasciitis)score: a tool for distinguishing necrotizing fasciitisfrom other soft tissue infections. Crit Care Med 2004;32: 1535–1541. http://www.ncbi.nlm.nih.gov/pubmed/15241098.20/07/2015.

9R Endotracheal tube colonisation andventilator-associated pneumonia incardiac surgery patients

E Senanayake1, R Giri2, S Gopal3, A Nevill4 and H Luckraz1

1Cardiothoracic Surgery, Heart & Lung Centre,Wolverhampton, UK2Cardiothoracic Anaesthesiology, Heart & Lung Centre,Wolverhampton, UK3Intensive Care, Heart & Lung Centre, Wolverhampton, UK4University of Wolverhampton, UK

AbstractIntroduction and aim: Ventilator-associated pneumo-nia (VAP) is estimated to develop in 25% of patients aftercardiac surgery.1 Aspiration of microbes in pooled sub-glottic secretions into the lower respiratory tract is thecommon cause of VAP.2 Endotracheal (ET) tube colonisa-tion contributes to the late onset of VAP. The PneuXendotracheal tube (ETT) has been shown to halve VAP

in high-risk patients undergoing cardiac surgery.3 Potentialmechanisms include the aspiration of subglottic secretions,a low-volume low-pressure-monitored and airtight endo-tracheal cuff and an ETT non-stick inner lining (parylenecoating). This study assessed ETT colonisation of PneuXETT against standard ETT and the development of VAP.Methods: This was a single-institution, prospective, ran-domised control trial. Patients were categorised as eitherGroup A (PneuX ET tube, n¼ 120) or Group B(Standard ET tube, n¼ 120). Inclusion criteria includedpatients over the age of 70 years and/or impaired leftventricular function (LVEF< 50%) undergoing cardiacsurgery. Patients were monitored for VAP for up to48 h post-extubation, VAP being defined as per theCenters for Disease Control and Prevention definitionand diagnosed on the Hospitals in Europe Link forInfection Control through Surveillance criteria.Following extubation, the inner surface of the distal

Table 1. Patient characteristics: Survivors to hospital discharge versus non-survivors.

Survivors (n¼ 20) Non-survivors (n¼ 8)

Age in years (SD) 48.2 (15.89) 58.5 (15.57)

Number of males (%) 11 (55) 3 (37.5)

APACHE II score (IQR) 13 (9–14) 14.5 (10.5–15.68)

Number with diabetes (%) 8 (40) 2 (25)

Functional Co-morbidity score (IQR) 1.5 (1–3.5) 3 (2–4)

LRINEC score (IQR) 7.5 (5.25–9) 9 (6.5–9)

Haemoglobin g/L (SD) 85.375 (39.68) 105 (35.82)

White cell count $ 109/L (SD) 19.22 (8.32) 13.55 (8.00)

C-reactive protein, mg/L (SD) 203.65 (158.93) 272.75 (216.53)

Serum creatinine, mmol/L (IQR) 96.5 (78.5–167.05) 133.5 (87–215.625)

Arterial pH (SD) 7.36 (0.08) 7.31 (0.08)

Serum lactate, mmol/L (IQR) 1.2 (0.875–1.5) 2.97(1.65–3.73)

SOFA score (IQR) 11 (8–12.5) 10 (10–12.5)

Values expressed as mean (SD) for normally distributed data and median (IQR) for non-parametric data.

118106N =

ET tube group

LoVAP tubestandard ET

95%

CI E

TBU

GN

O500000000

400000000

300000000

200000000

100000000

0

-100000000

Figure 1. Mean (95%CI) bacterial colony forming units (CFU)cultured from distal inner lumen of endotracheal tubes.




ETT tube was swabbed and sent for microbial culture(n¼ 234).Results: There were no significant differences in thepatients’ demographics. The mean EuroScore was 6.39(2.2) for Group A and 6.48 (2.6) for Group B (p¼ 0.9).The median intubation times were 14.7 (7.3, 2927.2) hand 13 (2.5, 528.7) h, respectively. VAP incidence wassignificantly lower in the PneuX ET group being 10.8%(13/120) as compared to 21% (25/120) in the standardET group (p¼ 0.03). Overall, ETT colonisation was asso-ciated with VAP in only 9% (11/120) for the PneuX ETTas compared to 16% (19/120) of patients with standardETT (p¼ 0.08). There was no significant differencebetween the two ETTs in terms of types of bacterialcolonisation (p¼ 0.5) or the mean value of the colonyforming units being 4.35$ 107 (1.18$ 108) and2.16$ 108 (1.24$ 109) (p¼ 0.8, Figure 1). Colonisationof the ETT (in VAP confirmed cases) was lower with thePneuX tube as the duration of intubation increases over48 h (43% vs. 71%).Conclusion: Colonisation of the ETT does not seem toplay an important role in early VAP. This may be due tothe short intubation time. There is a tendency forreduced ETT colonisation in the PneuX tube as durationof intubation increases. This may have an impact on redu-cing the incidence of late-onset VAP.

References

1. Chastre J, and Fagon JY. Ventilator associated pneu-monia. Am J Resp Crit Care Med 2002; 165: 867–903.

2. Mietto C, Pinciroli R, Patel N, et al. Ventilator asso-ciated pneumonia: evolving definitions and preventivemeasures. Respir Care 2013; 58: 990–1003.

3. Gopal S, Luckraz H, Giri H, et al. Significant reductionin ventilator-associated pneumonia with the Venner-PneuX System in high-risk patients undergoing cardiacsurgery: the LoVAP (Low Ventilator-Associated-Pneumonia) study. Eur J Cardiothorac Surg 2015; 47:e92–e96.

10R Cytochrome c oxidase: Evaluatingthe metabolic impact of impairedcerebral autoregulation

D Highton1, C Elwell2 and M Smit1,2

1Neurocritical Care, National Hospital for Neurology andNeurosurgery, London, UK2Department of Medical Physics & Bioengineering, UniversityCollege London, London, UK

AbstractAcute brain injury is associated with impaired cerebralautoregulation (CA). Continuous beside CA indices havebeen proposed as an adjunct to therapy. The mean velo-city index (Mx) is an extensively validated index derivedfrom correlation between transcranial Doppler flowvelocity in the middle cerebral artery (TCD) and arterialblood pressure (ABP).1 Near-infrared spectroscopy(NIRS) is a non-invasive optical technique which can mea-sure cerebral oxy/deoxy-haemoglobin and form the basisof Mx-style indices. Using a highly optimised in-housespectroscopy system a metabolic marker, the oxidationstatus of cytochrome c oxidase (oxCCO) – the terminal

Figure 1. Blood pressure thresholds for cytochrome c oxidation status (error bars, standard error mean).




electron acceptor in the mitochondrial respiratory chaincan be measured.2 The aim of this work is to measurethe impact of impaired CA on [oxCCO]. We hypothesisethat failure of CA will render [oxCCO] pressure passivepotentially indicating flow-limited metabolism.

Following ethical approval and consent, patients withacute brain injury were recruited. Monitoring includedTCD and broadband NIRS.2 CA indices were derivedas previously described1 using a moving Pearson correla-tion coefficient: Mx (TCD, ABP), TOx (NIRS tissueoxygen saturation, ABP) and THx (NIRS total haemoglo-bin, ABP). A value >0.3 suggests impaired CA. [oxCCO]was analysed with respect to ABP using a wavelet mea-sure of phase (semblance) between 0.1 Hz and 0.01 Hz.The Mx was compared using Pearson correlation.

Thirty-six patients were recruited (subarachnoid hae-morrhage 21, traumatic brain injury 1 and intracranial hae-morrhage 14). Mx correlated with [oxCCO]/ABP phaser¼ 0.34 p¼ 0.04, TOx r¼ 0.45 p< 0.01 and THx 0.40p¼ 0.02. The figure illustrates the relationship betweenmean ABP and [oxCCO]/ABP phase. This suggests thatABPoutside awell-defined ‘plateau’region affects [oxCCO].

Our data suggest that impaired autoregulation is asso-ciated with pressure passive changes in [oxCCO]. Thismight reflect changes in mitochondrial oxygen deliveryor its utilisation. Although further work is required toconfirm these findings, [oxCCO] has considerable theo-retical advantages over other methods of investigatingthe effects of CA as it reflects a metabolic endpoint.

Funding

The authors disclosed receipt of the following financial sup-port for the research, authorship, and/or publication of thisarticle: EPSRC Grant (EP/K020315/1).

References

1. Czosnyka M, and Smielewski P. Continuous assessmentof the cerebral vasomotor reactivity in head injury.Neurosurgery 1997; 41: 11–17.

2. Kolyva C, and Ghosh A. Cytochrome c oxidaseresponse to changes in cerebral oxygen delivery in theadult brain shows higher brain-specificity than haemo-globin. NeuroImage 2014; 85: 234–244.

11R The moon, the madness, the myth?Lunar cycle and the incidence of deliriumon the intensive care unit

S Berhane1, C Arrowsmith2, C Peters3 and SC Robert4

1Homerton University Hospital, London, England2Emergency Medicine, Homerton University Hospital, London,England3Intensive Care Medicine and Anaesthesia, HomertonUniversity Hospital, London, England

4Intensive Care and Acute Medicine, Homerton UniversityHospital, London, England

AbstractMany health professionals believe that the lunar cycle hasan effect on the incidence of psychiatric presentations tohospitals.1,2 Research has shown that the circalunar cyclecan influence the subjective and objective quality ofsleep3 and the incidence of psychiatric symptoms.4

However, more robust research largely involving emer-gency psychiatric presentations have failed to find anycorrelation.5 Thus far there has been no consistent asso-ciation between lunar cycle and psychopathology. Therehave been no studies investigating whether circalunarrhythm has any effect on delirium (or psychiatric mor-bidity in general) in intensive care patients. The aim ofthis study was to examine whether there was any corre-lation between the incidence of delirium and the fullmoon.

The study was conducted over six months (January–June 2015) in an 11-bedded general intensive care unit.Data were collected using the three-day model, meaningthat data were collected on the day of the full moon andnew moon of each month and 24 h before and after thatdate (three days in total). In total, data over four newmoon and four full moon cycles were collected. Deliriumwas assessed twice a day using the validated ConfusionAssessment Method – Intensive Care (CAM-ICU).Patients who were too sedated to be assessed byCAM-ICU were excluded (65 patients in total) as werepatients whose CAM-ICU score was not clearly docu-mented (7).

Overall, 92 patients were included (54 during newmoon and 38 during full moon). Background character-istics and interventions known to increase the risk ofdelirium were also collected. There was no significantdifference in the baseline characteristics including meanage between the new moon and full moon group (58.6 vs.58.8, respectively), gender (70% male vs. 71% male),Acute Physiology and Chronic Health Evaluation(APACHE) II scores (11 vs. 9) and pre-existing psychia-tric history (31% vs. 26%). Sedative and psychotropicdrugs used in the two groups were similar apart fromthe fact that patients in the full moon group receivedmore benzodiazepines (0% vs. 10%) and more haloper-idol (0% vs. 12%); however, there was no independentassociation between full moon and increased sedationoverall.

There was no statistically significant independent asso-ciation between the incidence of delirium during the newmoon (CAM-ICU positive 20%) and the full moon group(CAM-ICU positive 14%). However, this was a relativelysmall study that was powered to detect only a largedifference between the incidence of delirium at differentstages of the lunar cycle. Our results are in keeping withlarger studies outside of the intensive care settingreporting no association between the full moon andincreased psychopathology.




In conclusion, our study found no association betweenthe incidence of delirium and the full moon in intensivecare patients. We hypothesise that the reason for thepersistence of the belief that the full moon is associatedwith increased psychiatric morbidity is confirmation bias.This may explain why our patients received more seda-tive drugs during the full moon when compared to thenew moon nights. Larger studies would be required toconfirm these results.

References

1. Wilson JE, and Tobacyk JJ. Lunar phases and crisiscenter telephone calls. J Soc Psychol 1990; 130:47–51.

2. Raison CL, Klein HM, and Steckler M. The moon andmadness reconsidered. J Affect Disord 1999; 53:99–106.

3. Turanyi CZ, Ronai KZ, and Zoller R. Associationbetween lunar phase and sleep characteristics. SleepMed 2014; 15: 1411–1416.

4. Barr W. Lunacy revisited: the influence of the moon onmental health and quality of life. J Psychosoc NursMental Health Serv 2000; 38: 28–35.

5. Parmar VS, Talikowska-Szymczak E, Downs E, et al.Effects of full-moon definition on psychiatric emer-gency department presentations. ISRN Emerg Med2014; 2014: 1–6.

12R Clinical sedation monitoring using anovel technology (Responsiveness Index):Clinical experience of patients enrolled inthe DESIST clinical trial

EC Phillips1, J Antonelli1, K Kydonaki1, T Quasim2, J Ruddy3,A Davidson4, J Rutherford5, P Peltola6, MOK Sarkela6,K Uutela6, TS and and Walsh1; for the Development andEvaluation of Strategies to Improve Sedation practice ininTensive care (DESIST) study investigators

1Anaesthetics, Critical Care and Pain Medicine, University ofEdinburgh, Edinburgh, Scotland2University Department of Anaesthetics, Glasgow University,Glasgow Royal Infirmary, Glasgow, Scotland3Department of Anaesthetics, Monklands Hospital, NHSLanarkshire, Scotland4Department of Anaesthetics, Victoria Infirmary, NHS GGC,Glasgow, Scotland5Department of Anaesthetics, Dumfries Hospital, NHSDumfries and Galloway, Scotland6GE Healthcare Finland Oy, Helsinki, Finland

AbstractSedation strategies primarily aim to avoid over-sedationin intensive care units (ICUs), which is associated withadverse outcomes.1 We recently described a novel

technology for continuously alerting bedside staff thatdeep sedation may be present – the ResponsivenessIndex (RI).2,3 RI uses facial electromyography to trackpatient arousals and was one of the quality improvementinterventions used in the recently completed DESISTclinical trial (ClinicalTrials.gov NCT016344514). Wedescribe the use of RI monitoring observed in the trial;this was the first use in routine clinical practice.

Four ICUs used RI monitoring, which was started fol-lowing consent. Monitoring use was encouraged untilpatients were awake and/or extubated. Continuous RIdata were presented as numeric values and traffic lightcolours: RI score 0–20, RED (high risk of deep sedation);21–40, amber (intermediate risk); and 41–100, green(low risk). Following training, nurses were encouragedto reduce sedation in response to a red RI and aim forgreen RI values, but this was not linked to strictprotocols.

Two-hundred and six patients received RI monitoring(range 26–90 across ICUs). RI data were not analysed fornine patients (six received neuromuscular paralysis, twoadvanced ventilator modes and one no data recorded);197 patients’ data were analysed. The median (1st, 3rdquartile; min–max) time between intubation and startingmonitoring was 21 h (11, 34; 0–103) and median durationof monitoring was 66 h (27, 139; 1–925). Monitoringcontinued until extubation in 32% of ICU survivors.The first RI recorded was red 59% (range 50–66%across ICUs), amber 12% (range 4–17%) and green28% (range 25–38%). Among patients whose first RIwas red, 16% never had a green RI; 68% of these wereICU non-survivors. For patients whose RI values didincrease to the green range, the median time to firstgreen RI was 9 h (4, 23; 1–103). Among all patients, theRI value was red for 35% of monitoring time (range 23–48% across ICUs), amber for 13% (range 11–13%) andgreen for 35% (range 30–42%). No RI data wererecorded for a median 17% of monitoring time (range8–29% across ICUs). The median longest recorded timewith continuous red RI values was 7 h (3, 14; 0–69) and70% of patients had 51 period of 54 h of sequential redRI values; sedatives were administered for 93% of theseepisodes. Among the patients in whom monitoring con-tinued until extubation, the last recorded RI was red10%, amber 17%, and green 74%. ICU non-survivorstended to have a higher prevalence of red RI values.

In this first description of RI monitoring during routinecritical care, we found a high prevalence of red RI valuesconsistent with deep sedation, despite encouragingnurses to adjust sedation to achieve higher RI values.The reasons for this are uncertain but could indicate afailure to fully use the RI technology as intended despitetraining and education. Our data suggest the technologyhas potential to reduce deep sedation, but further train-ing and possibly a protocolised approach may be neededto maximise impact on clinical outcomes.




References

1. Shehabi Y, Bellomo R, Reade MC, et al. Early intensivecare sedation predicts long-term mortality in ventilatedcritically ill patients. Am J Respir Crit Care Med 2012;186: 724–731.

2. Walsh TS, Lapinlampi TP, Ramsay P, et al.Responsiveness of the frontal EMG for monitoringthe sedation state of critically ill patients. Br JAnaesth 2011; 107: 710–718.

3. Walsh TS, Everingham K, Frame F, et al. An evalua-tion of the validity and potential utility of facial electro-myelogram Responsiveness Index for sedationmonitoring in critically ill patients. J Crit Care 2014;29: 886.e1–886.e7.

4. Development and Evaluation of Strategies to ImproveSedation Quality in InTensive Care (DESIST), www.cli-nicaltrials.gov (reference number: NCT01634451;accessed 28 July 7 2015).

13R User experience of threeinterventions developed to improvesedation management in intensive careunits: Concurrent qualitative studywithin the DESIST study

K Kydonaki1, J Hanley2, J Antonelli1 and TS Walsh1; for theDevelopment and Evaluation of Strategies to Improve Sedationpractice in inTensive care (DESIST) study investigators

1Anaesthetics, Critical Care and Pain Medicine, University ofEdinburgh, Edinburgh, UK2Research and Development Management, NHS Lothian, TheQueens Medical Research Institute, Edinburgh, UK

AbstractOptimising sedation practice is part of patient-safety carebundles but is difficult to implement.1 Sub-optimum inten-sive care unit (ICU) sedation-analgesia management wor-sens patient outcomes and safety.2,3 The DESIST studydeveloped novel ICU sedation-quality indicators and intro-duced and evaluated three interventions designed toimprove sedation practice (ClinicalTrials.govNCT01634451).3 In a cluster-randomised design, we ran-domised pairs of eight Scottish ICUs to four differentcombinations of these interventions, namely (a) enhancededucation alone (2 ICUs), (b) education plus regular seda-tion quality feedback using process control methodology(2 ICUs), (c) education plus a novel sedation monitoringtechnology (Responsiveness Index (RI); (2 ICUs))4,5 and(d) all three interventions (2 ICUs). We collected pre-and post-intervention sedation-quality data for 90 weeksin all ICUs (45 weeks for each phase). We used actionresearch for process evaluation of the intervention phase.We report here the experiences of ICU staff on the imple-mentation and use of the three interventions.

An action research design was used. During implemen-tation and intervention phases, one trained researcher(KK) used participant observation in each ICU in threedistinct timelines to understand the uptake of interven-tions and subsequent changes in practice: beginning ofintervention phase, midway of intervention phase andthe end of intervention phase. We also conductedmulti-professional focus groups in the final month ofthe intervention phase, in which participants reflectedon intervention(s) uptake and the resultant changes tosedation practice. Field notes and transcripts were ver-batim transcribed and entered in NVivo 10 software forqualitative analysis (QSR International, Ltd). An inductivecomparative thematic analysis was conducted without apre-defined theoretical framework to allow the in-depthexploration and understanding of the impact of interven-tions on sedation management. Data were compared bycombination of interventions.

Among the three interventions, clinicians showedmore preference towards the education package andthe RI monitor and less towards the process feedbackmeasures. The education package was informative andraised awareness of the various aspects of sedation man-agement but was time consuming. The RI monitor wasused as a prompt tool to consider deep sedation, butthere was lack of understanding of the philosophy of thedevice (despite a training programme). The process mea-sures stimulated some discussion about sedation practicebut were considered difficult to understand and unreli-able to stimulate a change of practice. At individual clin-ician level, raising awareness increased nurses’ autonomyin decision making. Changes in clinical practice that staffconsidered were the introduction or replacement of newassessment tools for pain, delirium and sedation level;reviewing the timing of the sedation hold; consideringsleep promotion and pain management initiatives; intro-ducing algorithms for delirium and agitation. Changes inthe routine staff communication processes were takeninto account to maintain consistency and provide clearguidance in decision making.

In conclusion, clinicians in all eight ICUs showed pre-ference to interventions that were more approachableand meaningful to their daily clinical practice. The impactof the education and RI monitoring interventions seemedmost relevant to the needs and current gaps in sedationpractice.

Funding

The authors disclosed receipt of the following financial sup-port for the research, authorship, and/or publication of thisarticle: The study was funded by the Chief Scientist Office(CSO grant ref number: CSO/3/3), Scotland. The study wasco-supported by GE Healthcare as part of the originalapplication. GE Healthcare provided "200K of unrestrictedsupport (through Edinburgh University) and also suppliedthe Responsiveness monitors and associated disposablesused in the study.




References

1. Gill KV, Voils SA, Chenault GA, et al. Perceived versusactual sedation practices in adult intensive care unitpatients receiving mechanical ventilation. AnnPharmacother 2012; 46: 1331–1339.

2. Jackson DL, Proudfoot CW, Cann KF, et al. The inci-dence of sub-optimal sedation in the ICU: a systematicreview. Crit Care 2009; 13: R204.

3. Development and Evaluation of Strategies to ImproveSedation Quality in InTensive Care (DESIST), www.clinicaltrials.gov (reference number: NCT01634451;accessed 28 July 2015).

4. Lapinlampi TP, Viertio-Oja HE, Helin M, et al.Algorithm for quantifying frontal EMG responsivenessfor sedation monitoring. Can J Neurol Sci 2014; 41:611–619.

5. Walsh TS, Everingham K, Frame F, et al. An evalua-tion of the validity and potential utility of facial electro-myogram Responsiveness Index for sedationmonitoring in critically ill patients. J Crit Care 2014;29: 886, e881–e887.

14R SoundEar devices passively reduceambient sound in critical care

NR Plummer, J Baldwin and S Laha

Critical Care Unit, Lancashire Teaching Hospitals NHSFoundation Trust, Preston, UK

AbstractIntroduction: Critical care environments are noisy andsubject patients to constant disturbance by healthcare

providers.1 Patients frequently complain of poor sleep,with growing evidence that sleep deprivation and delir-ium are intrinsically linked, leading to increased length ofstay, higher morbidity and increased mortality.2 Welocally trialled a multi-component bundle of measuresto reduce overnight environmental noise and light andlimit iatrogenic sleep disturbance.3 Whilst the bundleimproved sleep, halved delirium rates, and reduced ambi-ent sound by 6.9 dB within the controlled conditions of atrial, the adoption of these measures to sustain improve-ments for patients outside of research conditions is thenext challenge. SoundEar visual noise warning deviceshave been used to reduce noise levels in the neonatalenvironment,4 so we aimed to evaluate their ability toreduce ambient sound overnight in the adult critical careenvironment.Methods: A SoundEar III device was deployed over thenurses station in the centre of a seven-bed adult criticalcare area, visible from all bed spaces. dB(A) slow(ambient sound) and dB(C) fast (peak sound) levelswere recorded every second overnight (11 pm to 7 am)for eight days before the device was revealing trialed andvisual sound warnings activated. Data were thenrecorded for a subsequent eight days.Results: Mean ambient sound was reduced from56.1% 5.1 dB to 54.3% 4.4 dB, a reduction of 1.77 dB(95%CI 1.73–1.79, p< 0.001). Mean peak sound wasreduced from 66.2% 2.4 dB to 65.5% 1.8 dB, a reductionof 0.73 dB (95%CI 0.72–0.74, p< 0.001). Ambient soundlevels overnight appear to follow a bimodal distribution(Figure 1), with introduction of the SoundEar

Figure 1. Histogram of background sound levels before (blue) and after (green) the SoundEar III device’s visual sound warnings wereturned on.




corresponding to a reduction of proportion of timespent in the ‘loud’ distribution.Conclusion: Without implementation of any education,the SoundEar device still significantly reduced ambientsound levels overnight. Although not as substantial areduction as in the initial trial, the devices were able topassively affect behavioural change to make the unit qui-eter, as reflected by the change in relative sizes of thebimodal distribution. The SoundEar had less of an effecton peak noise levels, reflecting the environmental natureof theses (bins, alarms and doors), which are relativelymore resistant to behavioural change. Further research isnow necessary to see whether this translates into sus-tained improvement in sleep quality and reduction indelirium rates, and whether the SoundEar devices willact synergistically with the introduction of a more per-sistent bundle of sleep improvement measures.

Acknowledgements

Registered with Lancashire Teaching Hospitals NHSFoundation Trust Department of Research andInnovation. Ethical approval was waived. SoundEar IIIdevices were provided free of charge by SoundEar A/S(Birkerød, Denmark), with explicit agreement to publishresults regardless of positive or negative findings.

References

1. Boyko Y, et al. Sleep disturbances in critically illpatients in ICU: how much do we know? ActaAnaesthesiol Scand 2012; 56: 950–958.

2. Kamdar BB, et al. Sleep deprivation in critical illness:its role in physical and psychological recovery. JIntensive Care Med 2012; 27: 97–111.

3. Patel J, et al. The effect of a multicomponent multidis-ciplinary bundle of interventions on sleep and deliriumin medical and surgical intensive care patients.Anaesthesia 2014; 69: 540–549.

4. Wang D, et al. Reduction of noise in the neonatal inten-sive care unit using sound-activated noise meters. ArchDis Child Fetal Neonatal Ed 2014; 99: 515–516.

15R Noises in the intensive care unit

Julie L Darbyshire1, Emma Jeffs1, Sarah Vollam1, Lisa Hinton2

and J Duncan Young1,2

1Nuffield Department of Clinical Neurosciences, University ofOxford University, Oxford, UK2Health Experiences Research Group, University of Oxford,Oxford, UK3Adult Intensive Care Unit, Oxford University Hospitals NHSTrust, Oxford, UK

AbstractNoise levels in intensive care units (ICUs) are about asloud as the dining room of a busy restaurant.1 This highbackground noise is likely to contribute to abnormalsleep and increase the incidence of ICU-acquired delir-ium. Patients who suffer from delirium in hospital havelonger stays and more health problems after they return

home.2 Disrupted sleep is common in the ICU and maybe associated with delirium.3

The SILENCE portfolio of studies aims to identify themajor sources of noise in the intensive care unit, confirmviable measures for sleep and delirium and implement afeasible noise reduction strategy that can be formallytested in a future large-scale randomised controlled trial.

For this noise identification study, two qualitativeresearchers independently conducted observations infour ICUs in the Oxford University Hospital NHSTrust. Observation sessions lasted from 2 to 12 h andwere completed during the day and overnight, bothduring the week and at weekends. Sound pressurelevels (SPL) were recorded using portable sound levelmonitors which were calibrated before and after use.

A total of 35 h of observations were completed in thetwo general adult ICUs with shorter comparison ses-sions in the neonatal unit (6 h) and adult neuro-ICU(3 h). Activity, particularly at staff handover periods andwhen preparing patients for transfer, and alarms wereidentified as the primary sources of noise. Several occur-rences of ‘alarm blindness’ were witnessed. Supportiveinfrastructure in the neonatal unit has been introduced asa response to the potentially damaging effects of noise.Illuminated signs are in use and privacy screens encou-rage foot traffic away from the patient cots.

Where lighting levels were higher overnight, it wasalso noticeably louder. Most visitors were quiet butsome seemed to have poor health literacy and weredisruptive. Staff chat was predominantly focused onpatient care but not exclusively. Where staff hadformed friendships, it was more likely that colleagueswould silence alarms for patients other than their own.

Concurrent SPL monitoring confirmed that levels arestill much higher than the World Health Organizationrecommended limit of 30 dBA. Subjective reflection onthe environmental noise levels at times contradicted theobjective SPL measure.

Noise levels in the ICU remain elevated. Much of thenoise is generated from alarms which are not silenced, andgeneral activity. Alerting signs raise awareness of noise butdo not achieve a lower SPL. Post-observation discussionwith staff and patients has led to the development of analarms management policy and the introduction of simpleenvironmental changes such as switching metal bins forplastic. We are also developing new teaching materialsdesigned to raise awareness of the effects of noise.Additional suggestions for future work included re-assess-ment of night-time illumination practices, integrated alarmsystems, noise cancellation and concentrated care areas.

Funding

The authors disclosed receipt of the following financial sup-port for the research, authorship, and/or publication of thisarticle: The National Institute for Health Research‘Research for Patient Benefit’ programme funds theSILENCE research project at the University of Oxfordand Oxford University Hospitals NHS Trust.




References

1. Darbyshire JL, and Young JD. An investigation ofsound levels on intensive care units with reference tothe WHO guidelines. Crit Care 2013; 17: R187.

2. Salluh JI, Soares M, Teles JM, et al. Delirium epide-miology in critical care (Decca): an international study.Crit Care 2010; 14: R210.

3. Aaron JN, Carlisle CC, Carskadon MA, et al.Environmental noise as a cause of sleep disruption inan intermediate respiratory care unit. Sleep 1996; 19:707–710.

16R An improved classifier for mortalityprediction in adult critical careadmissions

A Shenfield1, M Rodrigues1, D Valentine2, D Liu2 and J Moreno-Cuesta2

1Sheffield Hallam University, Sheffield, UK2North Middlesex University Hospital, London, UK

AbstractIntroduction: Over the last 25 years, there has beensignificant work carried out in producing risk predictionmodels for patients admitted to critical care units. Themost recent of these models is the Intensive CareNational Audit and Research Centre (ICNARC) modeldeveloped in 2007,1 which uses data from 231,930 admis-sions to 163 critical care units to develop and validate aUK-based model outperforming other approaches (withan average c index of 0.863).Aims: This research aims to present an artificial neuralnetwork based model for critical care admissions thatimproves over the ICNARC model in terms of the dis-crimination across the dataset used in this study.Results: Figure 1 shows a comparison between thereceiver operator characteristics (ROC) curve for ourartificial neural network (ANN) model and theICNARC model presented in Harrison et al.1 Figure 1also shows the ROC curve and point-wise confidence

intervals for the true-positive values of both our model(in blue) and the ICNARC model (in red). In comparison,our artificial neural network classification model pro-duces an average c value of 0.8983 in 10-fold cross vali-dation of our data compared to a c value of 0.8306 forthe ICNARC model using the same dataset (consisting of642 patients admitted to North Middlesex Hospital cri-tical care unit over a 28-month period. Data exclude 432patients where data were incomplete).

Conclusion: Our classification model provides a per-centage risk score that outperforms the ICNARC model.This classification model does suffer from some of sameissues surrounding the ICNARC model – for instance,the influence of some of the parameters within bothmodels can be unclear to clinicians trying to predictthe survival of individual patients. However, furtherwork is ongoing to improve the transparency of thismodel.

Reference

1. Harrison DA, Parry GJ, Carpenter JR, et al. A new riskprediction model for critical care: the Intensive CareNational Audit & Research Centre (ICNARC) model.Crit Care Med 2007; 35: 1091–1098.

17R A study of the impact of alcohol onadmissions to a large Welsh intensivecare unit

Ceri Battle1, Morgan Pengelly2, Karen James1, Abigail Clayton1

and Craig Jerwood1

1Critical Care Unit, Morriston Hospital, Swansea, UK2College of Medicine, University of Otago, Otago, NewZealand

AbstractThe harmful use of alcohol has led to 3.3 million deathseach year worldwide, which represents 5.9% of alldeaths.1 Alcohol-related deaths rates were significantlyhigher in Wales than in England in 2012, with 18.0 com-pared to 14.7 per 100,000, respectively.2 Social depriva-tion is reported to influence alcohol-related mortality.The alcohol-related mortality rate in the most deprivedcommunities of Wales was 22.0 per 100,000 in 2002–2006, more than three times higher than the leastdeprived areas.3 We undertook a prospective evaluationof the impact of alcohol-attributable admissions to anintensive care unit (ICU) in a major tertiary centre inWales.

Data collection was completed from 20 November2014 until 31 December 2014. Re-admissions to ICUduring the same hospital stay were excluded. Ethicalapproval was not required (Wales REC 6). Each conse-cutive admission was prospectively screened for director indirect alcohol associations (defined as alcohol-attri-butable admissions) according to pre-determined defini-tions based on the ICD-10 criteria, outlined in a similarFigure 1. ROC Curves with Pointwise Confidence Bounds.




study.4 The Ward-Watcher database (Critical Care AuditLimited, Ilkley, UK) was used to obtain patient outcomes.

Using the patient’s postcode, a deprivation code wasassigned using the Welsh Index of Multiple Deprivation(2011).5 Eight domains of deprivation are included andeach domain is made up of a number of indicators. Theincome domain indicator was used as a marker of depri-vation in this study as it is an absolute score which pro-vides the percentage of those living in the area receivingincome related benefits and has an extremely high cor-relation with the overall deprivation index.5

A total of 124 were included, with two exclusions dueto re-presentation; 23 (18.5%) admissions were attribu-table to alcohol with chronic alcohol-related diseaserecorded in 18 (15%) patients. A significantly higherlevel of deprivation in the alcohol-attributable admissionsgroup (p<0.05) was reported. Patients’ characteristicsand outcomes are shown in Table 1.

In this study, we identified that almost a fifth of admis-sions were due to alcohol-attributable conditions. ICUmortality for alcohol-attributable admissions in our studywas 13%, compared to a similar result of 18% in a recentScottish study.4 Previous research has reported alcohol-related admissions are more likely to be male patientsand younger compared with those without alcohol-related disease.4 The results of this study supportedthese findings. This study demonstrated that patientsadmitted to the ICU of a Welsh tertiary centre withalcohol-attributable conditions are significantly morelikely to live in an area with higher social deprivation.

References

1. World Health Organization. Alcohol factsheet, http://www.who.int/mediacentre/factsheets/fs349/en/ (2014,accessed 10 February 2015).

2. Office for National Statistics. Alcohol-related deaths inthe United Kingdom, registered in 2012, http://www.ons.gov.uk/ons/rel/subnational-health4/alcohol-

related-deaths-in-the-united-kingdom/2012/index.html(2014, accessed 10 February 2015).

3. Public Health Wales Observatory. Alcohol and healthin Wales 2014. Wales profile, http://www.wales.nhs.uk/sitesplus/922/page/75229 (2014, accessed 10 February2015).

4. Geary T, O’Brien P, Ramsay S, , et alon behalf ofScottish Intensive Care Trainees’ Audit Share Group.A national service evaluation of the impact of alcoholon admissions to Scottish intensive care units.Anaesthesia 2012; 67: 1132–1137.

5. Welsh Government Statistical Directorate. Welsh indexof multiple deprivation 2011: summary report, http://wales.gov.uk/docs/statistics/2011/110831wimd11sum-maryen.pdf (2011, accessed 10 February 2015).

18R Visiting in intensive care: A survey ofUK units

KS Deacon, JL Mitchell and LG Mould

University of Wolverhampton, UK

AbstractIntensive care units (ICUs) are stressful for both patientsand relatives and when visiting is restricted relatives anxi-ety levels are increased.1 Relatives can experience feel-ings of helplessness and a lack of control, and these arereduced if allowed to visit more and help care for thepatient.2 Patients have reported remembering theirfamilies visiting them in the ICU and that this helpedthem to feel secure, less alone and gave them the cour-age to fight.3 One previous survey of UK ICU visitingpractices has been carried out which established that80% of units had some level of restriction on visitinghours; within this, 80% of units allowed 4 h or moreper day1. The current survey aimed to build on thisdata to establish what the range and average visitingtime allowed is within UK ICUs, along with further ques-tions on visiting policy and the influencing factors.

Table 1. Patients’ characteristics for admission to ICU, attributable and non-attributable to alcohol.

All patients Alcohol-attributableNon-alcohol-attributable p

Number 124 23 (18.5%) 101 (81.5%)

Male 65 (52%) 17 (74%) 48 (48%) 0.036

APACHE II 14 (10–20) 14 (10–21) 14 (10–20) 0.888

Age 65 (54–74) 60 (52–68) 66 (54–75) 0.033

Income domain indicator 15 (8–26) 22 (15–31) 13 (8–24) 0.001

ICU mortality 23 (19%) 3 (13%) 20 (20%) 0.563

Hospital mortality 31 (25%) 7 (30%) 24 (24%) 0.594

Ventilator days 2 (0–7) 2 (0–7) 1 (0–6) 0.605

ICU length of stay (days) 5 (3–11) 5 (3–10) 5 (3–11) 0.575

Hospital length of stay (days) 15 (5–30) 20 (5–38) 13 (5–28) 0.221

Median (25th–75th IQR) or n (%). APACHE: Acute Physiology and Chronic Health Evaluation.




A survey was designed to provide answers on fourspecific questions: whether the unit has a written visitingpolicy, what the permitted visiting times are, the numberof visitors allowed at one time and whether children areallowed to visit. Following each of these set questions, afree text box was provided to enable respondents to alsocomment on the factors that had influenced the deci-sions in each area. A final box was provided at the endof the survey for writing any further comments relatingto visiting in their units.

The survey was posted to the lead nurse at 341 UKICUs, which included 34 paediatric or neonatal units. Alist of UK ICUs was obtained from the Intensive CareSociety (ICS) and cross-referenced with a second listprovided by the Intensive Care National Audit andResearch Centre (ICNARC). Completed surveys werereceived from 166 units (48.7%). Analysis of these datawill provide descriptive statistics to summarise responsesto the set questions. Separate analysis of paediatric andneonatal unit data will allow for comparison with adultunits. Alongside this a narrative summary of the influen-cing factors described and the further comments will beprovided with illustrative quotes.

Having obtained data on visiting practices from justunder half of UK ICUs the results of this survey willallow for an informed discussion of what current visitingpractices are within UK ICUs and the factors the influ-ence these practices.

References

1. Hunter JD, Goddard C, Rothwell M, et al. A survey ofintensive care unit visiting policies in the UnitedKingdom. Anaesthesia 2010; 65: 1101–1105.

2. Roland P, Russel J, Richards KC, et al. Visitation inCritical care: processes and outcomes of a performanceimprovement initiative.JNursCareQual2001; 15: 18–26.

3. Eriksson T, Bergbom I, and Lindahl B. The experiencesof patients and their families of visiting whilst in anintensive care unit – a hermeneutic interview study.Intensive Crit Care Nurs 2011; 27: 60–66.

19R Team perceptions of risk and safety:A qualitative study of ICU staffing

D D’Lima, E Murray and S Brett

Imperial College Healthcare NHS Trust, London, UK

AbstractSafety concerns have prompted an increasingly regula-tory focus on intensive care unit (ICU) staffing, yetthere is limited literature on the factors that ICUteams perceive to be relevant to safe team workingand minimising staffing risks.

The aim of our qualitative interview study was to (i)examine the human factors that teams perceive to be

relevant to safe staffing and (ii) identify practice improve-ments based on the factors to minimise risk and improvesafety.

Forty-five semi-structured interviews were conductedwith three core professional groups (nurses, doctors andphysiotherapists) across three adult ICU units within oneNHS trust. The qualitative interview data were analysedby a research psychologist. An initial framework of highlevel themes was developed based on the experiences ofinterviewers, discussion with clinical leads, the relevantliterature and outcomes of initial coding exercises. Thisframework was then applied deductively across the data-set. In parallel to this approach, additional themes andsub-themes were identified inductively throughout theprocess of analysis. The framework was continuouslydiscussed and iterated with input from clinical teammembers as the analysis progressed.

An overarching finding was the importance of achiev-ing a dynamic balance within and across teams, patientsand the hospital. Individuals and teams identified theneed to exercise judgement and work resiliently inorder to manage this balance, rather than relying onregulation and quotas (i.e. simply matching a certainamount or type of patients to a certain amount ortype of staff). A set of related findings were identified.Interviewees’ views of the clinical status of patients didnot necessarily fit established staff/patient ratios. Forexample, a Level 3 patient may need more physical sup-port, but a Level 2 patient may need more combinedpsychological and physical support. Individuals had theirown personalised perception of how to categorise theacuity of their patients and this developed with experi-ence. A further finding was that interviewees’ views onwhat makes a good team were not necessarily objective.It seemed that people who are realistic (i.e. persevere todeliver ‘good enough’ care despite difficulties) werefavoured as optimal team members over optimists (i.e.those people who tried to consistently perform at a highstandard based on a value driven approach). We foundthat differing perspectives and priorities were identifiedacross the professional groups, possibly reflecting profes-sional roles and training. For example, where theaccountability of the individual/team ends (i.e. at theunit or beyond) varied according to professional rolesand seniority. Coping mechanisms were demonstratedwhere (particularly junior) staff focused in on the unitor individual patient and chose not to take on theresponsibility of critically ill patients beyond the unit.This was demonstrated through both physical andmental separation from additional patient workload.

The results suggest the importance of team and unitdynamics, over regulation, to achieve a well-functioningunit. Resilience skills, such as working flexibly and opti-mal team utilisation, could be achieved through scenario-based team training, to encourage different professionalgroups to create and work towards shared priorities.





21R A case note analysis of the reasonsfor early unplanned acute hospital re-admissions among adult ICU survivors

D Nassif1, N Jones1, E Donaghy2, L Salisbury3, P Ramsay3,N Lone1,3 and T Walsh1,3

1Department of Critical Care, Royal Infirmary Edinburgh,Edinburgh, Scotland2Centre of Population Health Sciences, University of Edinburgh,Edinburgh, Scotland3Critical Care Medicine, University of Edinburgh, Edinburgh,Scotland

AbstractIncreasing numbers of adult intensive care unit (ICU)patients survive to hospital discharge. Recent researchdemonstrated a 23% re-admission rate to acute hospitalbeds within 90 days of discharge.1 The reasons forunplanned re-admission are uncertain but could indicatea system failure; it has been shown, for example, that fewpatients receive structured rehabilitation despite theircomplex physical and psychological needs.2 We under-took a case note review informed by a literature reviewof known drivers of unplanned hospital admission. Weincluded patients who participated in a recently publishedrandomised controlled trial of hospital-based rehabilita-tion, where local records indicated unplanned hospital re-admission within 90 days of hospital discharge.3

Our literature review was used to develop a prelimin-ary explanatory matrix. In addition to medical indications(e.g. clinical deterioration), other factors included multi-

morbidity, polypharmacy, social deprivation, socio-demo-graphics, rurality, social support and substance misuse.We used this matrix to conduct a medical case noteanalysis, extracting data onto the different fields to cate-gorise contributory factors.

In total, we examined medical case notes of 18patients re-admitted to hospital within 90 days(Table 1). Thirteen required more than one unplannedre-admission within that period. Using a process of inde-pendent review and multi-disciplinary staff consensus, wedivided the re-admitted patients into two categories:appropriate admissions for medical reasons (15/18,83%) or for significant social problems impacting ontheir health and ability to manage in the community (3/18, 17%).

We found that most patients (15/18, 83%) had threeor more documented physical co-morbidities and nine(50%) had documented psychological co-morbidities.Polypharmacy was highly prevalent (14/18, 78%), with10 patients (55%) on high-risk medication (e.g. warfarin,insulin, immunosuppressants).

The Scottish Index of Multiple Deprivation (SIMD)score indicated that 10 patients (55%) were resident inthe most deprived areas of the region (quintiles 1–2).Almost half lived alone with no social support, and athird had significant alcohol or substance misuse.

Our case note review demonstrates that a significantproportion of ICU survivors requiring unplanned acutehospital re-admission have significant pre-existing physi-cal and psychological morbidity, and complex socialissues including social deprivation, social isolation andalcohol and substance abuse. These data suggest thatmultiple factors other than the medical condition leadingto ICU admission are relevant to unplanned re-admis-sion, and by inference the recovery process towards

Table 1. Presence of known drivers of hospital re-admission.

Case

Medical

reason Multimorbidity

Social

deprivation Polypharmacy Frailty

Poor

nutritional

status

Substance

misuse Unemployment

Social

isolation

1 Y N N N N N N Y N

2 Y Y N Y Y Y N Y N

3 N Y N Y Y Y Y Y Y

4 Y Y Y Y N N N Y N

5 Y Y Y Y N Y N # N

6 Y Y Y Y N Y Y Y N

7 Y Y N Y N N Y N N

8 Y Y Y Y N Y N N N

9 Y Y Y Y Y N N Y N

10 Y Y Y Y Y Y N Y Y

11 Y Y N Y Y Y N N N

12 Y Y Y Y N N Y Y N

13 N Y Y Y N N N N N

14 Y N N N Y Y Y # N

15 Y Y Y Y N Y Y Y N

16 N Y Y Y Y N N N Y

17 Y Y N N N N N N N

18 Y Y Y N N Y N N N

Note. Y: yes; N: no; #: data not available.




independence. Our findings support the development oftargeted interventions across health and social care thatmight anticipate need and be implemented both beforeand after hospital discharge.

Author Note

D Nassif and N Jones are Joint first authors.

References

1. Lone NI. J Intensive Care Soc 2013; 14: 68–69.2. Connolly B, Douiri A, Steier J, et al. A UK survey of

rehabilitation following critical illness: implementationof NICE Clinical Guidance 83 (CG83) following hospi-tal discharge. BMJ Open 2014; 4: e004963.

3. Walsh TS, Salisbury LG, Merriweather JL, et al.Increased hospital-based physical rehabilitation andinformation provision after intensive care unit dis-charge: the RECOVER randomized clinical trial.JAMA Intern Med 2015; 175: 901–910.


23R Direct monitoring of physical activityin critical care: Feasibility, tolerabilityand validity of the ActivPALaccelerometer

G Atkins, D McWilliams and C Snelson

University Hospitals Birmingham NHS Foundation Trust,Queen Elizabeth Hospital Birmingham, Birmingham, UK

AbstractIntroduction: There is a growing body of evidenceregarding rehabilitation within critical care. In healthcaresystems that have physiotherapy as a standard of care, ithas been recognised that there is a need to define ‘usual

care’ before being able to access the impact of enhancedrehabilitation. The ActivPAL is a small activity monitorworn on the thigh which has been demonstrated as validfor measuring activity in healthy older adults,1–3 cancerpatients4 and children.5 If found to be feasible and accuratefor ICU patients, it could be utilised to assess differentactivity levels and rehabilitation strategies in future studies.Aim: To access the feasibility, validity and tolerability ofthe ActivPAL monitor within the ICU in measuring sit-ting/lying, standing, walking time and step counts duringphysiotherapy treatments for patients on critical care.Method: Twenty patients admitted to critical care at theQueen Elizabeth Hospital Birmingham (QEHB), assessedas ready to commence rehabilitation were consecutivelyrecruited to the study. Patients were fitted with AcitvPALmonitors for a 24-h period. During this period, any phy-siotherapy rehabilitation sessions were video recorded.The ActivPAL transitions and duration of lying/sitting, sitto stand, stepping and number of steps were comparedto video data.Results: The ActivPAL monitor demonstrated a highlevel of correlation with transitions between all positions(see Tables 1 and 2), with the highest level of sensitivityseen for moving into a standing position (96%). Despitethis, overall agreement levels were low regarding dura-tion of activity, with only a 25% correlation seen whencomparing the ActivPAL and video recording regardingthe duration of the stand. Accuracy was also low forboth lie/sit and stepping (35% and 40% accordingly),with similarly poor correlation between the number ofsteps taken (35%).Conclusion: The ActivPAL monitor was well toleratedby patients and demonstrated a high degree of accuracyin measuring positional transitions. Unfortunately, thiscorrelation was not seen when assessing the exact dura-tion spent in each position, or with regard to measuringthe number of steps taken by patients within critical care.This would limit its overall usefulness as a method ofcapturing levels of activity for patients within critical care.

Table 2. Percentage agreement between ActivPAL and video observation.

Predictive value

Agreement Sensitivity Lie/Sit Stand Step Step no

All samples 34% 34% 35% 25% 40% 35%

Table 1. Transitions between positions.

Predictive value

Agreement Sensitivity Sit to stand Stand to sit Step

All samples 84% 84% 96% 74% 75%




References

1. Chastin S, Ferriolli E, Stephens N, et al. Relationshipbetween sedentary behaviour, physical activity, musclequality and body composition in healthy older adults.Age Ageing 2012; 41: 111–114.

2. Grant P, Dall P, Mitchell S, et al. Activity-monitoraccuracy in measuring step number and cadence incommunity dwelling older adults. J Ageing Phys Act2008; 16: 201–214.

3. Grant P, Ryan C, Tigbe W, et al. The validation of anovel activity monitor in the measurement of postureand motion during everyday activites. Br J Sports Med2006; 40: 992–997.

4. Ferriolli E, Skipworth R, Hendry P, et al. Physicalactivity monitoring: a responsive and meaningfulpatient-centered outcome for surgery, chemotherapyor radiotherapy? J Pain Symptom Manage 2012; 43:1025–1035.

5. Aminian S, and Hinckson E. Examining the validity ofthe ActivPAL monitor in measuring posture and ambu-latory movement in children. Int J Behav Nutr PhysActiv 2012; 9: 119.

24R Mapping physical activity in criticallyill patients in a UK intensive care unit: Aprospective observational service study

J Mortimore1,2, J Rose3, N Hart1,4,5, S Berney3,6,7

and B Connolly1,4,5

1Lane Fox Clinical Respiratory Physiology Research Unit, St.Thomas’ Hospital, Guy’s & St. Thomas’ NHS Foundation Trust,London, UK2Department of Physiotherapy, King’s College London, London,UK3Physiotherapy Department, Austin Health, Melbourne,Australia4Guy’s & St. Thomas’ NHS Foundation Trust and King’s CollegeLondon NIHR Biomedical Research Centre, London, UK5Division of Asthma, Allergy and Lung Biology, King’s CollegeLondon, London, UK6Institute of Breathing and Sleep, Austin Health, Melbourne,Australia7Physiotherapy Department, University of Melbourne, Australia

AbstractEarly mobilisation (EM) of critically ill patients in theintensive care unit (ICU) is advocated to mitigate againstperipheral skeletal muscle wasting and weakness occur-ring during the illness course. Improvements in patient-

Table 1. Summary of location, activity level and people present for the whole cohort and according to ventilation and sedationstatus.

All (n¼42) (%)

Mechanicallyventilated(n¼31) (%)

Non-mechanicallyventilated(n¼11) (%)

RASSa #1, #2,0,þ1,þ2 (n¼24) (%)

RASSa

#5,#4,#3,þ3,þ4(n¼18) (%)

Location

In the bed 100 (96–100) 100 (92–100) 100 (98–100) 100 (97–100) 100 (92–100)

In the bedspace 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 0

Out of bedspace 0 (0–0) 0 0 0 0

Off ward 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–8)

Activity level

No/minimal intensity 99 (92–100) 100 (92–100) 98 (92–100) 100 (91–100) 98 (92–100)

Low intensity 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 0

Moderate intensity 0 (0–0) 0 0 (0–0) 0 (0–0) 0

High intensity 0 (0–0) 0 0 0 0

Not observed 0 (0–3) 0 (0–3) 0 (0–3) 0 (0–0) 2 (0–8)

People present

Alone 64 (41–83) 67 (46–83) 41 (35–73) 54 (39–73) 78 (61–89)

Nursing Staff 13 (6–33) 11 (5–24) 32 (19–43) 25 (13–38) 10 (3–12)

Medical Staff 2 (0–3) 2 (0–3) 2 (0–6) 2 (0–5) 0 (0–3)

Physiotherapist 2 (0–5) 2 (0–5) 5 (0–5) 3 (0–5) 0 (0–3)

AHP 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0) 0 (0–0)

Family/Visitors 3 (0–30) 2 (0–25) 11 (0–37) 11 (0–37) 2 (0–20)

Other 0 (0–0) 0 (0–0) 0 0 0 (0–0)

Not observed 0 (0–3) 0 (0–3) 0 (0–3) 0 (0–3) 2 (0–8)

Data are expressed as median (IQR) percentage of aggregate percentages of observations. Where no range is indicated (0), no observations were madein this category to report. AHP: allied health professional; RASS: Richmond Agitation Sedation Scale.aRASS: (#5) Unrousable; (#4) Deep sedation; (#3) Moderate sedation; (#2) Light sedation; (#1) Drowsy; (0) Alert and Calm; (þ1) Restless; (þ2)Agitated; (þ3) Very agitated; (þ4) Combative.




and clinical-centred outcomes have been demonstratedwith this approach. However, recent international data-sets have highlighted poor implementation of EM intoroutine practice,1–3 with patients spending significantproportions of the day in bed, alone and participatingin little or no physical activity.4 To date, there are fewpublished data regarding EM practice and physical activitylevels of patients in UK ICUs.

The aim of the current study was therefore to pro-spectively characterise the profile of physical activityundertaken by critically ill patients in a UK ICU.

A single-centre, prospective observational study (HRAclassification ‘service evaluation’, www.hra-decisiontool-s.org.uk/research/uk) utilising the technique of behaviouralmapping was conducted in the 30-bedded adult tertiaryreferral ICU of a large, university teaching hospitalbetween June and July 2015. Patients who had been inva-sively mechanically ventilated for more than 48 h and whowere likely to remain in the ICU for a further 24-h periodwere included. Throughout the course of a full day (0830–2000), patients were observed for 1 out of every 10 min.During each observation, data on the location of thepatient, persons present at the bedside and highest levelof physical activity performed were recorded.

Forty-two patients were included: M:F 22:20, mean (SD)age 59.4 (15.0) years, SOFA at ICU admission 13.1 (3.5),medical admission diagnosis 32/42 (76.2%) in whom 2646observations were collected over eight non-consecutivedays (6 weekdays, 2 weekend days). On the day of observa-tion, at a median (IQR) ICU length of stay of 7.9 (4.3–12.7)days, 31 patients were invasively mechanicallyventilated with endotracheal tubes in situ, 4 were inreceipt of extracorporeal membrane oxygenation therapy,12 had inotropic support in situ and 18 were heavilysedated.

Patients spent 100% (96–100%) of the day (10.5 (10.1–10.5) h) located in bed, with no or minimal activity for99% (96–100%) of the day (10.4 (9.7–10.5) h). Table 1reports data for the whole cohort and classified accord-ing to ventilatory and sedation status. Mechanically ven-tilated patients spent proportionately more time alonethan non-mechanically ventilated patients (67 (46–83)%vs. 41 (35–73)%). Similarly, increasing sedation statusresulted in proportionately more time spent alone(‘heavy’ sedation, 54 (39–73)% vs. ‘light’ sedation, 78(61–89)%). Nursing staff were most frequently observedat the bedside irrespective of ventilatory or sedationstatus. There was no difference between proportion oftime spent in each location, activity level or personspresent across week- or week-end days. Ten patientsparticipated in exercise therapy during their observationday, with the most frequent activity sitting-over-the-edge-of-the-bed. Patients exercising had lower illnessacuity (SOFA score, 8.0 (2.1) vs. 11.3 (4.0), p¼ 0.02)and less sedation (RASS, #0.5 (#2.0–0.0) vs. #3.0(#4.0–#1.3), p¼ 0.0006) than those who did not.

These low physical activity levels in the majority of thiscohort of ICU patients, who spent up to two-thirds of

the day alone, highlight the potential for greater integra-tion of physical activity into clinical management.

References

1. Investigators TTS. Early mobilization and recovery inmechanically ventilated patients in the ICU: a bi-national, multi-centre, prospective cohort study. CritCare 2015; 19: 81.

2. Nydahl P, Ruhl AP, Bartoszek G, et al. Early mobiliza-tion of mechanically ventilated patients: a 1-day point-prevalence study in Germany. Crit Care Med 2014; 42:1178–1186.

3. Strizich L, Caldwell ES, Spece LJ, et al. Mechanicalventilation is an important barrier to mobilization ofstable ICU patients. Am J Respir Crit Care Med 2015;191: A2275.

4. Berney SC, Rose JW, Bernhardt J, et al. Prospectiveobservation of physical activity in critically ill patientswho were intubated for more than 48 hours. J Crit Care2015; 30: 658–663.

25R Can verbal encouragement and self-reported patient motivation predictactive participation in physiotherapy oncritical care?

CA Lawrence1,2, F Lorencatto2 and JJ Francis2

1Barts Health NHS Trust, London, UK2School of Health Sciences, City University London, London,UK

AbstractCritical illness is systemic in nature and subsequent com-plications include global deconditioning, muscle wastingand decreased health-related quality of life.1 The preva-lence and magnitude of these complications mean thatrehabilitation is essential throughout the critical carecontinuum.1 ‘Rehabilitation’ refers to early movement,exercise and mobility. The ideal duration of each rehabi-litation session remains undetermined and patient toler-ability of treatment is under-researched.

The wider literature suggests patient motivation, self-efficacy and health beliefs can impact on participation inrehabilitation in outpatient physiotherapy settings.2–4

However, it is unclear whether this translates to an inpa-tient environment. Routine physiotherapy in this settingis based on assumptions that patient motivation andverbal encouragement from physiotherapists may influ-ence patients’ persistence during rehabilitation sessions.Therefore, the aim of this study was to identify whetherself-reported patient motivation and extent of verbalencouragement given by physiotherapists during rehabi-litation are predictors of duration of patients’ active par-ticipation in physiotherapy on critical care.




Patients were recruited at three hospitals. BetweenMay and July 2015, all patients requiring critical care for>48 h, receiving physiotherapy, were invited to partici-pate. A total of 31 patients participated (meanage¼ 60.61, range: 18-88 years), 15 males (48%) and16 females (52%). The lead author observed a rehabilita-tion session and measured the length of time (minutes/seconds) of active patient participation in physiotherapy.Criteria for judging the start and end of active participa-tion were decided following a small validation study.Participants were asked to complete a structured inter-view, conducted using four sub-scales from the intrinsicmotivation inventory (IMI)5 and they indicated theiragreement with statements about the session using aLikert scale (1¼ not at all true, 7¼ very true).Coefficient alpha (a) was computed to assess internalconsistency reliability of the subscales. The physiothera-pist and participant were also asked to report theamount of verbal encouragement given (1¼ no encour-agement, 7¼ extreme encouragement).

The IMI subscale of interest/enjoyment (a¼0.85)demonstrated good internal consistency in this patientgroup. It is considered to be the self-report measure ofintrinsic motivation5 (median [IQR]¼ 5.71 [6–7]). Thevalue/usefulness subscale suggested that patients felt phy-siotherapy was important to their recovery (median[IQR]¼ 7 [7–7]); however, limited variance meant itwas not appropriate to use in subsequent analyses.There was also limited variation in amount of verbalencouragement as reported by the patient (median[IQR]¼ 7 [6–7]) compared with the physiotherapist(median [IQR]¼ 5 [3–6]).

Preliminary analysis was conducted using Spearman’sRho correlation. There was no significant relationshipbetween length of active participation and the followingvariables: mean score for interest/enjoyment(r(31)¼#0.06, p¼ 0.74), verbal encouragement(patient) (r(31)¼#0.17, p¼ 0.36) or verbal encourage-ment (physiotherapist) (r(31)¼ 0.29, p¼ 0.11).

In this relatively small cohort of patients, results sug-gest that preconceptions about motivation, encourage-ment and participation in physiotherapy may not beapplicable in the critical care setting. However, thestudy highlighted difficulties with the measurement ofconstructs such as verbal encouragement and value/use-fulness in this setting. Therefore, further research isneeded to explore other potential patient barriers toparticipating in rehabilitation on critical care.

Funding

The authors disclosed receipt of the following financial sup-port for the research, authorship, and/or publication of thisarticle: This study was conducted in part fulfilment of aMaster of Research Clinical Research award, which wasfunded by the National Institute of Health Research.

References

1. Gosselink R, Bott J, Johnson M, et al. Physiotherapyfor adult patients with critical illness: recommendationsof the European Respiratory Society and EuropeanSociety of Intensive Care Medicine Task Force on phy-siotherapy for critically ill patients. Intensive Care Med2008; 34: 1188–1199.

2. Cleary K, LaPier T, and Beadle C. Adherence issues,behavior change readiness, and self-motivation in hos-pitalized patients with coronary heart disease. JACPT2011; 2: 55–63.

3. Slovinec D’Angelo ME, Pelletier LG, Reid RD, et al.The roles of self-efficacy and motivation in the predic-tion of short- and long-term adherence to exerciseamong patients with coronary heart disease. HealthPsychol 2014; 33: 1344–1353.

4. Chan DK, Lonsdale C, Ho P, et al. Patient motivationand adherence to post surgery rehabilitation exerciserecommendations: the influence of physiotherapists’autonomy-supportive behaviors. Arch Phys MedRehabil 2009; 90: 1977–1982.

5. Ryan RM, Mims V, and Koestner R. Relation ofreward contingency and interpersonal context to intrin-sic motivation: a review and test using cognitive evalua-tion theory. J Pers Soc Psychol 1983; 45: 736.



28R The effect of bed percussionvibration therapy on airflow inmechanically ventilated patients withsevere respiratory failure

K Morris1,2, L Osman1,2, A Wilson2 and E Main2

1Department of Physiotherapy, Guy’s and St Thomas’ NHSFoundation Trust, London, UK2Institute of Child Heath, University College London, London,UK

AbstractPatients with severe respiratory failure (SRF) requiremechanical ventilation which is associated with impairedmucociliary clearance.1 Airway clearance techniques(ACTs), including manual chest wall vibration (CWV)and hyperinflation are interventions which aim to expelsecretions by increasing airway expiratory airflow bias.2

Critical thresholds of peak inspiratory flow to peakexpiratory flow ratio (PIF:PEF) of <0.9 or an absolutedifference in PIF-PEF of >17 l/min are reported to pro-mote cephalad expulsion of mucus.3,4 Bed percussionvibration therapy (BPVT) is a modality, whereby apatient’s mattress delivers percussion and vibration.




Manufacturers promote this modality as aiding secretionclearance; however, its effectiveness is yet to be deter-mined. This study aimed to investigate the effectivenessof BPVTas an ACT by measuring airflow bias in mechani-cally ventilated patients with SRF.

This is a prospective, observational study. Patientsadmitted to a large inner-city hospital critical care unitwere screened for eligibility. Patients included were onan SRF pathway, mechanically ventilated and nursed onthe Total Care Bed! (Hill-Rom, IN, USA). Patient con-sent/consultee declaration was obtained, and ethicalapproval was granted by the local ethics committee(14/EE/0106). Primary outcomes were PIF:PEF and PIF-PEF difference, measured over three time periods:before, during and after BPVT. BPVT was applied for15 min: 5 min percussion at 5 Hz followed by 10 minvibration at 13 Hz. Airflow was measured via a flowmeterinserted in to patients’ ventilator circuits. Physiological

variables were recorded in parallel. Differences in pri-mary outcomes were assessed using Wilcoxon signed-rank tests, significance reported at p< 0.05.

Ten participants were recruited Table 1. Participantsunderlying conditions were heterogeneous, including pneu-monia, asthma and overdose. No statistically significant dif-ferences in either PIF:PEF or PIF-PEF difference were foundbetween any of the three measurement periods.Physiological parameters remained unchanged throughout.

In this small heterogeneous group of patients with SRF,PIF:PEF and PIF-PEF differences did not meet criticalthresholds to promote mucus expulsion during BPVT.Unlike physiotherapy CWV techniques, BPVT is appliedwithout the presence of an opposing force. Manual CWVapply compressive forces downwards through the chestwall with the patient against a surface. The absence ofany opposing force during BPVT may result in reducedtransfer of chest wall forces to changes in airflow withinthe airways. The role of BPVT as an ACT in those withSRF has yet to be determined, further research isrequired in larger, defined populations, including evalua-tion of the forces applied and their effects on airflowwithin the airways.

References

1. Ntoumenopoulos G, Shannon H, and Main E. Do com-monly used ventilator settings for mechanically venti-lated adults have the potential to embed secretions orpromote clearance? Resp Care 2011; 56: 1887–1892.

2. Gosselink R, Bott J, Johnson M, et al. Physiotherapyfor adult patients with critical illness: recommendationsof the European Respiratory Society and EuropeanSociety of Intensive Care Medicine Task Force onPhysiotherapy for Critically Ill Patients. Intensive CareMed 2008; 34: 1188–1199.

3. Kim C, Iglesias A, and Sackner M. Mucus clearance bytwo phase gas-liquid flow mechanism: asymmetric per-iodic flow model. J App Phys 1987; 62: 959–971.

4. Volpe M, Adams A, Amato M, et al. Ventilation pat-terns influence airway secretion movement. Resp Care2008; 53: 1287–1294.

29R Mortality in critically ill non-surgicalpatients with pre-existing pulmonaryhypertension

KB Bauchmuller1, Y Arunan1, R Condliffe2, C Billings2

and GH Mills1

1Department of Anaesthesia and Critical Care, SheffieldTeaching Hospitals NHS Foundation Trust, Sheffield, UK2National Pulmonary Hypertension Service, PulmonaryVascular Disease Unit, Royal Hallamshire Hospital, SheffieldTeaching Hospitals NHS Foundation Trust, Sheffield, UK

AbstractPulmonary hypertension (PH) is an uncommon yet life-limiting condition that has been associated with a poorprognosis. Recent changes in our understanding of itspathophysiology have led to novel therapeutic

Table 1. Group characteristics and primary variables.

Characteristic Group data (n¼10)

Age (years) 44 (36–56)

Gender M:F 5:5

Murray score 3.3 (0.29)

P/F (kPa) 16 (6.56)

Mandatory ventilation days 5.5 (3.25–8.5)

Ventilation mode

BiPAP/ASB 1

APRV 4

CPAP/PS 3

PAC 1

PRVC 1

PIF (l/min)

Before 50.24 (13.04)

During 51.97 (13.64)

After 47.64 (13.61)

PEF (l/min)

Before 45.66 (17.54)

During 46.62 (16.39)

After 45.46 (18.06)

PIF:PEF

Before BPVT 1.49 (0.71)

During BPVT 1.36 (0.55)

After BPVT 1.46 (0.66)

PIF-PEF difference

Before BPVT 5.25 (22.75)

During BPVT 5.31 (22.52)

After BPVT 5.25 (24.60)

Data shown as mean (SD) or median (IQR). P/F: partial pressure ofoxygen/fraction of inspired oxygen ratio; PIF:PEF: peak inspiratory flowto peak expiratory flow ratio; PIF-PEF: absolute difference betweenpeak inspiratory and expiratory flow; BiPAP/ASB: bilevel positiveairway pressure/assisted spontaneous breathing; APRV: airway pressurerelease ventilation; CPAP/PS: continuous positive airway pressure/pres-sure support; PAC: pressure assist control; PRVC: pressure regulatedvolume control; BPVT: bed percussion vibration therapy.




strategies.1 However, there is limited data on outcome ofpatients with PH requiring admission to an intensive careunit (ICU).2

We conducted a retrospective observational study ofpatients with PH admitted to the ICU in a UK nationalpulmonary hypertension referral centre for non-surgicalconditions between April 2000 and July 2014. Data onpatient characteristics, admission details, physiologicaland biochemical parameters as well as treatment mod-alities throughout the ICU stay were collected from ourcritical care electronic patient record system(Metavision) and the PH unit clinical database. ICU-spe-cific therapies and their association with hospital survivalwere assessed using logistic regression analysis usingSPSS. Results are expressed as median (range) andodds ratios (OR) with 95% confidence intervals (CI).

One hundred thirty-three consecutive patientsadmitted were included in the study. The patients’median age was 52 (18–83) and 63% were female.Different types of PH were represented in the followingproportions: 65% in group 1 (pulmonary arterial hyper-tension), 6% each in groups 2 (left heart disease) and 3(lung disease), 16% in group 4 (chronic thromboembolichypertension) and 7% in group 5 (miscellaneous).Thirteen, 60 and 27% of patients fell into WHO functionalclass groups 2, 3 and 4. The leading reasons for ICUadmission were heart failure (35%), chest sepsis (23%),renal failure (9%), sepsis of non-pulmonary origin (8%)and arrhythmias (8%). Overall, 72% of patients survivedto ICU discharge and 65% left hospital alive. Thirty-sixpercent of patients received CPAP, 11% bi-level NIV, 7%invasive ventilation, 15% CVVH, 24% vasopressors and22% inotropes. These therapeutic modalities were asso-ciated with a hospital survival of 52, 43, 11, 60, 34 and 31,respectively. Several interventions were identified as pre-dictors of hospital mortality at uni- and multivariate logis-tic regression analysis, most notably CPAP, IPPV andvasopressor and inotrope use (see Table 1).

Overall, roughly two-thirds of patients with pre-existingPH admitted to ICU survived to hospital discharge.Invasive ventilation was associated with a dismal survivalrate. The need for CPAP as well as haemodynamic sup-port represented independent predictors of hospital

mortality whereas renal replacement therapy did not.This may reflect the ability to tightly regulate fluid statusthereby optimising preload of a compromised rightventricle.

References

1. Kiely DG, Elliott CA, Sabroe I, et al. Pulmonary hyper-tension: diagnosis and management. BMJ 2013; 346:f2028.

2. Sztrymf B, Souza R, Bertoletti L, et al. Prognostic fac-tors of acute heart failure in patients with pulmonaryarterial hypertension. Eur Respir J 2010; 35: 1286–1293.

30R Computational modelling of oxygendelivery in acute respiratory distresssyndrome: Optimising positive end-expiratory pressure

M Chikhani1, A Das2, M Haque1, W Wang2, O Cole1,DG Bates2 and JG Hardman1

1Anaesthesia and Critical Care, Division of ClinicalNeuroscience, University of Nottingham, UK2School of Engineering, University of Warwick, UK

AbstractDuring mechanical ventilation, positive end-expiratorypressure (PEEP) is applied to the lungs of patients withacute respiratory distress syndrome (ARDS) to preventcollapse of open but unstable alveoli and to recruit col-lapsed alveoli.1 PEEP has the potential to impair cardiacoutput. Despite finding a consistent improvement in oxy-genation and lung compliance, few studies have demon-strated a survival benefit associated with the applicationof high PEEP (i.e. >10 cm H2O) in ARDS.2 The reductionin cardiac output may outweigh the benefit of improvedarterial oxygenation and alveolar mechanics by causing anoverall reduction in oxygen delivery (DO2). Disease andpatient heterogeneity makes the issue difficult to study

Table 1. Therapeutic modalities associated with hospital survival.

Univariate Multivariate

OR 95% CI p OR 95% CI p

CPAP 2.338 1.119–4.888 0.024 2.539 1.045–6.168 0.04

NPPV 2.807 0.910–8.661 0.073

IPPV 17.436 2.107–144.267 0.008 13.334 1.260–141.109 0.031

RRT 1.265 0.477–3.354 0.637

Vasopressors 5.507 2.342–12.950 <0.001 3.059 1.044–8.959 0.041

Inotropes 6.337 2.575–15.597 <0.001 3.793 1.318–10.912 0.013

IV Iloprost 0.995 0.465–2.142 0.995

OR: odds ratio; CI: confidence interval; CPAP: continuous positive pressure ventilation; NPPV: non-invasive positive pressure ventilation; IPPV: invasivepositive pressure ventilation; RRT: renal replacement therapy.




in vivo, making this an ideal opportunity for high-fidelitymodelling studies investigating the effects of PEEP inARDS.

The Interdisciplinary Collaboration in SystemsMedicine (ICSM)-integrated pulmonary and cardiovas-cular model was developed as a bespoke multi-organ,multi-scalar pathophysiological model. It is based onthe widely validated Nottingham PhysiologySimulator.3 The modelling includes a multi-chambercontractile cardiac model, dynamic alveolar behaviourand pulsatile blood flow. The model was matched tohistorical data to create nine virtual patients with var-ious cardiovascular states and ARDS severity. Thesevirtual patients underwent pulmonary ventilation usinglung-protective techniques and were subjected to anincremental PEEP trial (10 min at each value of PEEP:0, 5, 10, 15, 20 cm H2O), before returning to zeroPEEP at the final setting.

In silico data describing alveolar gas exchange, cardiacoutput and alveolar dynamics were recorded. Cardiacoutput reduced and while oxygenation improved inevery modelled patient at every increment in PEEP,although the rate of change in each of these variedbetween patients and between PEEP levels. Figure 1 illus-trates the relationship between PEEP, mean airway pres-sure and DO2.

Using high-fidelity simulation, we have demonstratedthe potential for oxygen delivery to reduce in responseto the incremental increase in PEEP even in the context

of an apparent improvement in gas exchange. The reduc-tion in DO2 was most apparent in simulated patientswith less severe gas exchange defect.

The observed fall in DO2 is of particular importance inthe context of routine monitoring of oxygenation butnot cardiac output – potentially leading to a misleadingimpression of clinical therapeutic benefit with increasingairway pressure. We hypothesise that the clinicallyobserved improvement in oxygenation during PEEP maybe offset by a reduction in organ perfusion, and that thismight account for the failure to demonstrate any survivalbenefit of high-PEEP ventilation strategies in patients withARDS.

References

1. Slutsky AS, and Hudson LD. PEEP or no PEEP-lungrecruitment may be the solution. New Engl J Med 2006;354: 1839–1841.

2. Briel M, Meade M, Mercat A, et al. Higher vs lowerpositive end-expiratory pressure in patients with acutelung injury and acute respiratory distress syndrome:systematic review and meta-analysis. JAMA 2010;303: 865–873.

3. McCahon R, Columb M, Mahajan R, et al. Validationand application of a high-fidelity, computational modelof acute respiratory distress syndrome to the examin-ation of the indices of oxygenation at constant lung-state. Br J Anaes 2008; 101: 358–365.

Figure 1. Graph showing modelled oxygen delivery in millilitres per minute (left hand axis) with PEEP (dark bars) and mean airwaypressure (light bars) in cmH2O (right hand axis) during a time-based PEEP trial. Each line corresponds to a virtual patient.




Documents

Edinburgh Research Explorer · 2015, Vol. 16(4) Supplement 104 ... KS Deacon, JL Mitchell and LG Mould ... 30R Computational modelling of oxygen delivery in acute respiratory distress