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WTM0205/1September 2011
Learning portfolio
the management of fluids
learning@lunch flexsolutions for national hospital pharmacy learning needs
Learning portfolio
Learning with CPPE
The Centre for Pharmacy Postgraduate Education (CPPE) offers a wide range of learningopportunities for the pharmacy workforce. We are based in the University of Manchester’sSchool of Pharmacy and Pharmaceutical Sciences and are funded by the Department ofHealth to provide continuing education for practising pharmacists and pharmacy techniciansproviding NHS services in England. For further information about our portfolio, visithttp://www.cppe.ac.uk.
Acknowledgements
CPPE programme managerMaria Bell, CPPE regional manager, Yorkshire and Humber
AuthorCharlie Walker, surgical pharmacist, St James's University Hospital, Leeds Teaching HospitalsNHS Trust
ReviewersAnne Noott, CPPE tutor, Walsall and WolverhamptonJoe Quinn, CPPE regional manager, North EastKeith Addie, critical care pharmacist, Victoria Infirmary, NHS Greater Glasgow and ClydeRachel Westwood, lead clinical pharmacist for surgery, Northampton General Hospital NHSTrust
SubeditorNeil Condron, CPPE subeditor
ThanksThis programme was piloted at Poole Hospital NHS Foundation Trust by Robert Harvey,senior pharmacist, and at Watford General Hospital, West Hertfordshire Hospitals NHSTrust, by Sital Sanghvi, pharmacy team leader for clinical care. We appreciate their feedbackand that of the participants in the pilot sessions.
ProductionPeacock Design & Print Limited.
Published in September 2011 by the Centre for Pharmacy Postgraduate Education, Schoolof Pharmacy and Pharmaceutical Sciences, University of Manchester, Oxford Road,Manchester M13 9PT. http://www.cppe.ac.uk
the management of fluids
learning@lunch flex
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About this learning@lunch flex programme
The overall aim of this learning@lunch flex programme is to support pharmacistsand pharmacy technicians in advancing their knowledge and skills in relation tothe management of fluid balance. The case studies you will work through at thissession cover the possible causes of and the management of fluid overload anddehydration in secondary care. In addition, we will look at management of fluidloss via stomas.
After your learning@lunch flex session, you can assess your learning by workingthrough the e-assessment on our website at http://www.cppe.ac.uk/assessment.
Learning objectives
On completion of this learning programme, you should be able to:
This learning programme will provide you with evidence of learning for thefollowing dimensions of the NHS Knowledge and Skills Framework:
• understand the homeostatic mechanisms which maintain fluid balance• recognise the signs and symptoms of dehydration and fluid overload• understand the main conditions which can predispose patients to fluid overload• understand how to interpret urea and electrolyte results in determining fluid
overload or dehydration• understand how the pharmacy team can contribute to the medicines used in fluid
overload• demonstrate an understanding of the considerations when choosing fluids for the
dehydrated patient • explain the management of fluid loss in patients with a stoma.
Health and wellbeing HWB6
Health and wellbeing HWB7
Knowledge and information resourcesIK3
Assessment and treatment planning - Level 3
Interventions and treatment - Level 3
Organise resources and provide information - Level 3
Learning portfolio
It will also provide you with evidence for the following General Level Frameworkcompetency clusters:
About this learning portfolio
We have developed this learning portfolio as part of the learning@lunch flexprogramme on the management of fluids. The learning and activities in thelearning@lunch flex series will help you to think about changing your practice anddemonstrate your continued fitness to practise.
This booklet also contains our suggested answers to the reflective questions inthe pre-session tasks, the answers to the case studies in this portfolio and somesuggestions for practice-based activities that you can work through after thesession that will help to extend your learning.
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the management of fluids
Delivery of patient care
Selection of drug
Monitoring drug therapy
Personal
Team work
Problem solving
Knowledge
Gathering information
Analysing information
Management and organisation
Clinical governance
Drug-patient selectionDrug-disease interactions
Use of guidelines
Pharmacy team
Pathophysiology
Accesses information
Appraises options
Risk management
learning@lunch flex
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Case studies
When you are on the ward reviewing patients you have access to lots of different sourcesof information about the patient and their clinical condition. In the case studies that follow,we give you the key points about each patient and you should make a decision based onthese points alone.
The cases are designed to illustrate some of the difficult decisions involved in dealing withdehydration and fluid overload in patients with complex medical and surgical needs, and toallow you to discuss solutions with your colleagues.
CASE STUDY 1 – DEREK
Derek McCulloch is a 45-year-old gentleman who has been admitted to your surgical wardimmediately following an oesophagectomy. Derek’s condition is stable; however, he is nil bymouth in order to allow the surgical wound to heal. Given that he weighs 120 kg, what arehis basic fluid and electrolyte requirements for 24 hours?
What are the main mechanisms of fluid output in the body?
Learning portfolio
What hormones regulate fluid balance?
The following day, Derek’s fluid balance sheet shows that 1 L of gastric juice is beingaspirated by his nasogastric tube. Assuming his other parameters are within normal limits,what are the changes to his fluid and electrolyte requirements and how can these be met?
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the management of fluids
learning@lunch flex
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CASE STUDY 2 – PAMELA
Pamela Zawadzka is admitted to the high dependency unit (HDU) following surgery oninjuries sustained in a road traffic accident. Pamela is currently diagnosed as being in‘circulatory shock’.
While attending the HDU ward round you are asked by a junior doctor how to prescribeappropriate fluids to replace Pamela’s circulatory volume.
What is the definition of ‘circulatory shock’ and how might this be recognised?
State at least one advantage and one disadvantage of crystalloids and colloids in this clinicalsituation.
You advise that Pamela requires 2 L of sodium chloride 0.9 percent intravenous infusion andtell the doctor to prescribe the first 1 L bag to be administered rapidly over 15 minutes (viaa pump), with the second bag more slowly, according to response.
What effect will this have on expansion of body fluid compartments in the longer-term?
Learning portfoliothe management of fluids
6
Why has a crystalloid been chosen over a colloid preparation for Pamela in this instance?
If Pamela had received 2 L of colloid, how would the expansion of compartments havediffered?
What physical signs or biochemical parameters would need to be monitored in Pamela andhow frequently?
learning@lunch flex
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CASE STUDY 3 – PRIYA
Priya Wagle is a 74-year-old lady who recently suffered a stroke. Following her dischargehome she has not been eating and drinking normally and, over the past week, has beenincreasingly confused. Priya is admitted to your medical assessment ward with a suspectedurinary tract infection.
On examination Priya appears dehydrated and, on investigation, she is found to have lowsodium and potassium:• Sodium: 120 mmol/L (normal range: 135 mmol/L to 144 mmol/L)• Potassium: 3.0 mmol/L (normal range: 3.5 mmol/L to 5.5 mmol/L)
Her weight is 68 kg.
You carry out medicines reconciliation on Priya’s medicines:• Bendroflumethiazide 2.5 mg each morning• Furosemide 40 mg each morning and 20 mg at lunchtime• Ramipril 1.25 mg each morning• Aspirin 75 mg each morning• Simvastatin 40 mg at night• Lansoprazole 15 mg each morning
The patient is intolerant of calcium-channel blockers.
Which medicines may be contributing to the dehydration and deranged electrolyte levels?
Learning portfolio
Following a mid-stream urine test the presence of a urinary tract infection is confirmed, andPriya is still confused. On the ward round the medical team decide that the derangedelectrolytes and dehydration need resolving as soon as possible. On questioning, you findher creatinine clearance is 25 mL/min.
Why is it important to ensure renal function is not impaired with regard to fluid therapy?
What recommendations would you make to the medical team regarding treatment ofPriya’s hyponatraemia, hypokalaemia and dehydration?
What are the potential problems with replacing electrolytes intravenously?
What further treatment does Priya require at this stage?
As the medical admissions ward pharmacist, what other medication related factors mustyou take into consideration for Priya given that she has recently experienced a stroke?
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the management of fluids
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CASE STUDY 4 – BEN
Following a motorbike accident, Ben Flanagan is admitted to an orthopaedic ward with afractured femur and pelvis. Following extensive surgery he is now stable and in traction.
However, Ben has a raised temperature and a raised white cell count, indicating a probableinfection. The medical team diagnose osteomyelitis and wish to prescribe intravenousantibiotics. Your current trust policy in this situation is to prescribe vancomycin andflucloxacillin.
Ben’s biochemistry results are:
Ben is prescribed vancomycin 1.5 g twice daily in 500 mL sodium chloride 0.9 percent, andflucloxacillin 2 g four times a day in 100 mL sodium chloride 0.9 percent.
How much sodium will Ben receive during each 24-hour period as a result of hisintravenous antibiotics?
Creatinine
Urea
Sodium
Potassium
87
3.7
139 mmol/L
3.8 mmol/L
(normal range 80-110)
(normal range 3-6)
(normal range 135 mmol/L to 144 mmol/L)
(normal range 3.5 mmol/L to 5.5 mmol/L)
Learning portfolio
After seven days’ treatment with these intravenous antibiotics, Ben shows no sign ofimprovement – the area remains swollen, red and painful. Ben is still exhibiting a raisedtemperature, a raised white cell count and raised C-reactive protein. The medical team areplanning to surgically debride his wound area.
Which three physiological responses will affect fluid and electrolyte balance post-operatively, and what effects will they have?
On post-operative day 5, the patient becomes acutely unwell, showing signs of acidosis: the arterial blood gas sample shows pH below 7.35 and a bicarbonate level of under 24 mmol/L.
What may be the cause of this acidosis?
What is the mechanism of this process?
Why might this problem have been prevented if compound sodium lactate solution(Hartmann’s solution) had been prescribed rather than sodium chloride with glucose?
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the management of fluids
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CASE STUDY 5 – REBECCA
Rebecca Altman has been undergoing treatment for ovarian cancer for several months. Dueto the severe side-effects that she experienced with her previous cycles of chemotherapy,Rebecca has been admitted to an oncology ward for the final cycle of cisplatinchemotherapy.
Due to the potential nephrotoxicity of this drug, Rebecca is given the following fluid regime:
Following the above, post-hydration, Rebecca appears short of breath and has puffy ankles– symptoms of heart failure.
Have Rebecca’s body fluids caused these symptoms? How?
How should Rebecca’s symptoms be managed?
Infusion fluid and additives
Sodium chloride 0.9%
Sodium chloride 0.9%
Mannitol 20%
Cisplatin 106 mg
Mannitol 20%
Sodium chloride 0.9% + 2 g magnesium sulphate + 20 mmol potassium chloride
Ensure urine output > 100 mL/hour prior to giving cisplatin.
Volume
1000 mL
500 mL
100 mL
1000 mL
100 mL
1000 mL
Infusion time
1 hour
30 minutes
10 minutes
2 hours
10 minutes
2 hours
Learning portfolio
Rebecca remains in hospital for a further 24 hours for monitoring and to ensure symptomsresolve. She is then discharged home.
A couple of weeks later she attends the ward complaining of symptoms similar to thoseexperienced post-chemotherapy; her weight has increased by 10 kg and she is sufferingfrom shortness of breath, with reduced exercise tolerance and swollen ankles.
A blood sample is taken with a request for albumin levels to be measured. Why would thisbe done?
The patient has a normal albumin level (37 g/dL) and is admitted to cardiology with adiagnosis of heart failure.
What drug treatment should be commenced?
By what mechanism do these drugs improve the signs and symptoms of heart failure?
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the management of fluids
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After your learning@lunch flex sessionYou have now reached the end of your learning programme on the management of fluids.
At this point you should have:• completed the reflective questions• accessed the British Consensus Guidelines on Intravenous Fluid Therapy for Adult
Surgical Patients document • discussed the differences between national and local trust guidelines on the
prescribing of medical fluids• considered your own role in supporting effective prescribing of medical fluids• applied the knowledge gained via the pre-session tasks to our case studies• reflected on how the national guidelines may apply to the patients you see on
your wards.
Next stepsNow it is time to record your learning and to plan how you will put your knowledgeinto practice.
There are three steps that you should undertake to achieve this, listed in the tablebelow. Use the table to plan and record your actions.
Next step
Complete your ownCPD records for thesedifferent elements.
Develop your ownaction plan for whatyou’re going to donext.
Put together adepartment action planto make sure thateveryone knows howfluid managementguidelines are appliedon their wards.
Action required When will you do this? Datecompleted
Learning portfolio
Learning checklist
Use this checklist to highlight key areas of learning and how you may wish toextend your knowledge.
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the management of fluids
Activity
Read the two ClinicalFocus articles from ClinicalPharmacist
Complete the pre-sessionreading of two articlesfrom Clinical Pharmacist
Read the British ConsensusGuidelines on IntravenousFluid Therapy for AdultSurgical Patients document
Find your trust’spolicy/policies onprescribing medical fluids
Compare local trust policyon prescribing medicalfluids with the Britishconsensus guidelines
Read the National PatientSafety Agency alert onsafer use of injectablemedicines
Consider your role in theprescribing of fluids
Complete the case studies
Tick if completedas part oflearning@lunchflex session
If not undertaken as pre-session or sessionlearning, how do you plan to refresh yourknowledge?
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Suggested answers to:Reflective questionsCase studies
In this section of the learning portfolio, we offer some suitable answers to thereflective questions and case studies. Points stimulating debate are provided, andthe answers encourage you to apply your learning to practice.
Learning portfolio
Reflective questions before workshop
By this stage, you will have completed this learning@lunch flex programme on themanagement of fluids. On the pre-session handout, we asked you to consider somereflective questions. Here are some suggested answers.
1. Why do patients require intravenous fluid prescriptions?
2. What physical and biochemical parameters/markers can be used to assess fluid balance?
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the management of fluids
Suggested answer
• Intravenous fluids are prescribed to replace losses incurred during surgery or via astoma.
• For maintenance while a patient is nil by mouth or their enteral intake is insufficient.
Suggested answer
• A fluid balance chart is essential as it not only shows the input and output, but alsothe route of any fluid loss and therefore what electrolytes may also need replacing.
• Physical symptoms of fluid overload may include oedema, pale urine and ‘wetbreathing’ (where the breathing sounds crackly) in extreme cases.
• Physical symptoms of dehydration may include thirst, poor skin elasticity, darkcircles under eyes, dark concentrated urine and a low urine output. The patient mayexhibit signs of fatigue, altered levels of consciousness and confusion.
• Biochemical markers of fluid overload may include low serum electrolytes (ie, belownormal range due to dilution).
• Biochemical markers of dehydration include raised urea, raised urea:creatinine ratio(a ratio of 10:1 indicates dehydration), high serum electrolytes due to increasedconcentration, and haemoglobin and haematocrit may appear to be increased.
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3. Can you state the major active components of a colloid and a crystalloid?
4. Can you complete the following table to describe the electrolyte composition (in mmol/L) of the body’s major fluid compartments?
Suggested answer
• Crystalloids are solutions of small molecules in water (eg, sodium, glucose). • Colloids are dispersions of large organic molecules such as hydroxyethyl starches
(HESs) or modified gelatins.1
Electrolyte
Sodium
Potassium
Chloride
Bicarbonate
Blood plasma
142
4
103
25
Interstitial fluid
145
4.1
113
27
Intracellular fluid
12
150
4
12
Gastric1
20-60
14
140
0-15
Suggested answer
Learning portfolio
5. What would be the options for hydration if the patient was nil by mouth and had no intravenous access?
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the management of fluids
Suggested answer
Hypodermoclysis (interstitial infusion) is the process of giving fluids subcutaneously. Thiswould normally be either saline or glucose. This provides a slow rate of fluid uptake andis usually limited to 1 mL per minute but more than one site may be used to increase therate.
Subcutaneous fluid administration can also be helpful if patients are being dischargedhome but still require fluids.
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Case studies
The case studies, along with our suggested answers and any discussion points, are listed onthe pages that follow. You may, or may not, have worked through all of these case studiesat your session.
Learning portfolio
CASE STUDY 1 – DEREK
Derek McCulloch is a 45-year-old gentleman who has been admitted to your surgical wardimmediately following an oesophagectomy. Derek’s condition is stable; however, he is nil bymouth in order to allow the surgical wound to heal. Given that he weighs 120 kg, what arehis basic fluid and electrolyte requirements for 24 hours?
Discussion pointsThe key point is that as long as you get near to approximate requirements, using full bags thatare commercially available, you are highly unlikely to cause any harm to the patient.4 Furtherprescriptions of fluids may need to change following subsequent urea and electrolyte results andfluid balance charts. Consensus guidelines suggest that there is more evidence to support theuse of compound sodium lactate solution, usually given 1 L over 6 to 8 hours depending on howmany are required in the 24-hour period.5
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the management of fluids
Suggested answer
120 kg x 25-35 mL ≈ 3000-4000 mL (3-4 L).
You should normally aim for lower end volume as patients are usually in positive fluidbalance post-operatively due to fluids and blood administered during the surgery.
Advice on the electrolyte requirements can vary, so we have used ranges based on therecommended reading.
• Sodium requirements may be between 1-2 mmol/kg.• Potassium requirements may be between 0.5-1.0 mmol/kg.
Therefore the amounts for Derek would be in the region of:• 120 kg x 1.5 mmol for sodium requirements ≈ 180 mmol of sodium.• 120 kg x 0.8 mmol for potassium requirements ≈ 100 mmol of potassium.2,3
Using the commercially available bags, the possible prescriptions could be:• 1 L sodium chloride 0.9 percent + 40 mmol potassium + 1 L glucose 4 percent /
sodium chloride 0.18 percent + 40 mmol potassium + 1 L glucose 5 percent + 40 mmol potassium, or
• 2 L sodium chloride 0.45 percent + 40 mmol potassium + 1 L glucose 4 percent / sodium chloride 0.18 percent + 20 mmol potassium, or
• 1 L compound sodium lactate solution + 1 L glucose 4 percent / sodium chloride 0.18 percent + 40 mmol potassium + 1 L glucose 5 percent + 40 mmol potassium, or
• 1 L compound sodium lactate solution + 2 L glucose 5 percent + 40 mmol potassium.
NB: the National Institute for Health and Clinical Excellence and the National Patient SafetyAgency recommend that Hartmann’s solution is referred to as compound sodium lactatesolution.4
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What are the main mechanisms of fluid output in the body?
What hormones regulate fluid balance?
The following day, Derek’s fluid balance sheet shows that 1 L of gastric juice is beingaspirated via his nasogastric tube. Assuming his other parameters are within normal limits,what are the changes to his fluid and electrolyte requirements and how can these be met?
Suggested answer
The main mechanisms are:2
• urine – approximately 1500 mL/day• perspiration / expired air (insensible losses) – approximately 500 mL/day• faeces – approximately 100 mL/day• other secretions – 50 mL/day
Suggested answer
Antidiuretic hormone (vasopressin) and aldosterone.3
Suggested answer
Derek will require an additional litre of fluid, plus replacement sodium and potassiumover a 24-hour period.
There are sometimes small differences in what is recommended in different guidelines.Consensus guidelines suggest there are levels of 20 mmol/L to 60 mmol/L sodium and 14 mmol/L potassium in gastric juice;5 however, they state that gastric contents ‘representa mixture of parietal and oxyntic secretions, saliva and bile, therefore secretions are seldompure’ so, in this situation, we would recommend using 20 mmol potassium in a 1L bag ofsodium chloride 0.9 percent (150 mmol sodium) and adding this to the prescriptionabove for Derek. As stated before, using a ready prepared bag with the potassiumalready added reduces the risks involved in adding potassium chloride to a bag.4
Learning portfolio
CASE STUDY 2 – PAMELA
Pamela Zawadzka is admitted to the HDU following surgery on injuries sustained in a roadtraffic accident. Pamela is currently diagnosed as being in ‘circulatory shock’.
While attending the HDU ward round you are asked by a junior doctor how to prescribeappropriate fluids to replace Pamela’s circulatory volume.
What is the definition of ‘circulatory shock’ and how might this be recognised?
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the management of fluids
Suggested answer
Circulatory shock – often termed simply ‘shock’ – is a failure of the circulatory system tosupply sufficient oxygen and nutrients to meet the metabolic needs of organs andperipheral tissues. In addition, the poor circulation leads to incomplete removal of wasteproducts from the affected tissues. Circulatory shock is serious and an often life-threatening condition, commonly resulting from haemorrhage or infection. Symptomsmay include weak rapid pulse, low blood pressure and cold, sweaty skin as the bodyattempts to maintain perfusion of vital organs. Increased capillary filling time, oliguria oranuria may also be present.
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State at least one advantage and one disadvantage of crystalloids and colloids in this clinicalsituation.
Discussion pointsAccording to the SAFE study, there is no proven difference in outcomes for patients when usingcrystalloids or colloids in critically unwell patients.6 The important thing is to restoreintravascular volume and this can be done with both products.
Suggested answer
Crystalloids advantages
Cystalloids disadvantages
Colloids advantages
Colloids disadvantages
InexpensiveThe evidence of outcomes is at least as good as with colloids inmost patients
Larger volumes needed compared to colloidsUsually exert their effects over less time (could be an advantage insome patients)
Remain within intravascular compartment (advantageous becausethey will not cause massive oedema as crystalloids do once theystart leaking out into interstitial compartments)Less volume requiredMaintain their effect over a longer period of time (eg, up to 6hours compared to 30 to 60 minutes for crystalloids)
May contain large quantities of sodiumSignificantly more expensive than crystalloidsMay impair renal functionAssociated risks of pulmonary oedema and anaphylaxis
Learning portfolio
You advise that Pamela requires 2 L of sodium chloride 0.9 percent intravenous infusion andtell the doctor to prescribe the first 1 L bag to be administered rapidly over 15 minutes (viaa pump), with the second bag more slowly, according to response.
What effect will this have on expansion of body fluid compartments in the longer-term?
Why has a crystalloid been chosen over a colloid preparation for Pamela in this instance?
If Pamela had received 2 L of colloid, how would the expansion of compartments havediffered?
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the management of fluids
Suggested answer
Approximately 75 percent of the fluid (1.5 L) will leave intravascular space and settle inthe interstitial fluid compartment.
Suggested answer
There is no definitive benefit of a colloid or a crystalloid in these circumstances, and thechoice will depend on weighing up the risks and benefits of each preparation. Crystalloidwill be less expensive, therefore, all else being equal, it will be more cost effective.1
Suggested answer
All fluid would have stayed in the intravascular space and, as a result of its osmoticpotential, fluid from other compartments would have entered the intravascular space –causing a potential increase in intravascular volume of greater than 2 L (probably anoverall increase of approximately 2.5 L to 3 L).
Fluid resuscitation with colloids, therefore, usually requires smaller volumes (such as 500 mL).
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What physical signs or biochemical parameters would need to be monitored in Pamela andhow frequently?
Suggested answer
Blood pressure and heart rate should be rechecked during and after the infusion. A lowblood pressure and high heart rate indicates that the patient may require more fluid.
Hourly urine output should be monitored – the target urine output is 0.5 mL/kg/hr.
Glasgow Coma Scale (GCS) should be checked during and after the infusion.
If the patient’s blood pressure, heart rate and GCS have not improved following the 15-minute infusion, further intravenous fluids will need to be prescribed.
Central venous pressure is usually monitored in critical care patients, which allowsconstant monitoring of fluid status and allows for fine adjustments in fluids administered.
Learning portfolio
CASE STUDY 3 – PRIYA
Priya Wagle is a 74-year-old lady who recently suffered a stroke. Following her dischargehome she has not been eating and drinking normally and, over the past week, has beenincreasingly confused. Priya is admitted to your medical assessment ward with a suspectedurinary tract infection.
On examination Priya appears dehydrated and, on investigation, she is found to have lowsodium and potassium:• Sodium: 120 mmol/L (normal range: 135 mmol/L to 144 mmol/L)• Potassium: 3.0 mmol/L (normal range: 3.5 mmol/L to 5.5 mmol/L)
Her weight is 68 kg.
You carry out medicines reconciliation on Priya’s medicines:• Bendroflumethiazide 2.5 mg each morning• Furosemide 40 mg each morning and 20 mg at lunchtime• Ramipril 1.25 mg each morning• Aspirin 75 mg each morning• Simvastatin 40 mg at night• Lansoprazole 15 mg each morning
The patient is intolerant of calcium-channel blockers.
Which medicines may be contributing to the dehydration and deranged electrolyte levels?
Discussion pointsAngiotensin-converting enzyme (ACE) inhibitors may reduce renal perfusion and therefore causea renal impairment, which may act to raise serum potassium levels.
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the management of fluids
Suggested answer
Bendroflumethiazide may lower potassium and sodium levels, thus contributing to thedehydration.
Ramipril may affect serum electrolytes, in particular raising the potassium level.
Furosemide is likely to cause substantial fluid loss. When this is combined with potentialpotassium and sodium loss, dehydration is likely to result.
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Following a mid-stream urine (MSU) test the presence of a urinary tract infection isconfirmed, and Priya is still confused. On the ward round the medical team decide that thederanged electrolytes and dehydration need resolving as soon as possible. On questioning,you find her creatinine clearance is 25 mL/min.
Why is it important to ensure renal function is not impaired with regard to fluid therapy?
What recommendations would you make to the medical team regarding treatment ofPriya’s hyponatraemia, hypokalaemia and dehydration?
Suggested answer
Patients with renal impairment may not be able to excrete electrolytes and fluidsappropriately and will therefore require less in their replacement.
Suggested answer
All diuretics should be stopped temporarily until the situation resolves. Intravenous fluidsshould be prescribed immediately, preferably 1 L of sodium chloride 0.9 percent with20 mmol of potassium over 8 hours. It may be wise to stop the ramipril until renalfunction improves.
When her fluid balance returns to normal, her diuretics should be reintroduced cautiouslyin a step-wise manner with monitoring of blood pressure and fluid balance.
The combination of the diuretics is appropriate in this case as the patient is intolerant ofcalcium-channel blockers.
Learning portfolio
What are the potential problems with replacing electrolytes intravenously?
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the management of fluids
Suggested answer
Extravasation is classed as a discharge or escape from a vessel into the tissues. This couldbe a problem in Priya’s case.3
Potassium chloride at concentrations of greater than 40 mmol/L is classed as a vesicant,meaning that it has potential to cause tissue damage if it extravasates. It is usuallyinadvisable to give more than 40 mmol/L potassium peripherally (trust policies may varyslightly, but 40 mmol is generally accepted as the maximum peripheral concentration).
Potassium cannot be replaced too quickly as this can cause arrhythmias or even stop theheart completely. The usual rate would be 10 mmol/hour to 15 mmol/hour in wardsother than the intensive care unit. However, local trust guidelines may vary.
Inappropriate administration of potassium chloride concentrate has caused patient deaths.Please refer to your local trust policy and the National Patient Safety Agency website forthe latest advice on control of potassium chloride.4
You should use ready made solutions containing potassium whenever possible to avoidproblems due to miscalculation of dose or inadequate mixing when potassium is added toa bag of another intravenous fluid.
If given too quickly, sodium can cause central pontine myelinolysis – a syndrome causedby rapid shrinking of brain cells as a result of increased extracellular osmolality. You wouldtherefore aim to increase serum sodium by approximately 10 mmol/L/day.
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What further treatment does Priya require at this stage?
As the medical admissions ward pharmacist, what other medication related factors mustyou take into consideration for Priya given that she has recently experienced a stroke?
Suggested answer
Empirical treatment with antibiotics should be initiated immediately in line with your trustpolicy on prescribing in urinary tract infections. When the sensitivities are returned fromthe MSU, these should be checked against the antibiotic being used to ensure theorganism present is not resistant to your chosen antibiotic. The level of renal impairmentshould also be considered and may affect the choice of antibiotic and the dose.
Suggested answer
A patient who has suffered a stroke may have difficulty swallowing, so a speech andlanguage therapy (SALT) assessment should be performed to identify the patient’s needs.If a SALT assessment is not in the notes, then one should be obtained immediately.
Priya’s ability to eat and drink may have contributed to her dehydration and it isimportant that she and her family understand her requirements. You need to ensure thatthe antibiotic and any other medication is in a form which she can take (ie, some strokepatients require liquid formulations of all their medication).
Priya’s weight should be checked – if she has lost weight, consider involving the dietitianteam to prescribe some nutritional supplements.
Thromboprophylaxis risk needs to be assessed and appropriate medicines prescribedaccording to local trust policy.
Learning portfolio
CASE STUDY 4 – BEN
Following a motorbike accident, Ben Flanagan is admitted to an orthopaedic ward with afractured femur and pelvis. Following extensive surgery he is now stable and in traction.
However, Ben has a raised temperature and a raised white cell count, indicating a probableinfection. The medical team diagnose osteomyelitis and wish to prescribe intravenousantibiotics. Your current trust policy in this situation is to prescribe vancomycin andflucloxacillin.
Ben’s biochemistry results are:
Ben is prescribed vancomycin 1.5 g twice daily in 500 mL sodium chloride 0.9 percent, andflucloxacillin 2 g four times a day in 100 mL sodium chloride 0.9 percent.
How much sodium will Ben receive during each 24-hour period as a result of hisintravenous antibiotics?
Discussion pointsThe flucloxacillin vial has 2.2 mmol per 1 g of drug, which we have not accounted for in thecalculations as the worrying amount of sodium comes from the fluids.
Vancomycin can also be given in glucose five percent, which will greatly reduce sodium burden fromantibiotic regime.3 In many centres, however, the default position is to infuse in glucose – again,this is just an example of how administration of intravenous antibiotics can affect sodium input.
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the management of fluids
Creatinine
Urea
Sodium
Potassium
87
3.7
139 mmol/L
3.8 mmol/L
(normal range 80-110)
(normal range 3-6)
(normal range 135 mmol/L to 144 mmol/L)
(normal range 3.5 mmol/L to 5.5 mmol/L)
Suggested answer
500 mL x 2 = 1 L sodium chloride 0.9 percent = 154 mmol/day from vancomycin100 mL x 4 = 0.4 L sodium chloride 0.9 percent = 62 mmol/day from flucloxacillin
Total from antibiotic infusions = 216 mmol/day.
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After seven days’ treatment with these intravenous antibiotics, Ben shows no sign ofimprovement – the area remains swollen, red and painful. Ben is still exhibiting a raisedtemperature, a raised white cell count and raised C-reactive protein. The medical team areplanning to surgically debride his wound area.
Which three physiological responses will affect fluid and electrolyte balance post-operatively, and what effects will they have?
Discussion pointsConsensus guidelines recommend that administering glucose 4 percent plus saline 0.18 percentis not appropriate for resuscitation or replacement therapy, except in situations where there issignificant free water deficit – for example, in diabetes insipidus, or if there is a significant risk of hyponatraemia, especially in children and the elderly.1
Suggested answer
Vascular leakage – plasma proteins and electrolytes leak through capillary walls intointerstitial space.
Antidiuretic hormone activation – this causes retention of sodium and reduces urineoutput.
Transient hyperkalaemia – this may occur post-operatively or post-trauma due totissue damage, causing intracellular potassium to escape and a potential rise in serumpotassium levels.
The antibiotics above are continued post-operatively and the patient receives glucose 4 percent, plus sodium chloride 0.18 percent 2 L/day for the first two post-operativedays to maintain post-operative tissue perfusion.
Learning portfolio
On post-operative day 5, the patient becomes acutely unwell, showing signs of acidosis: the arterial blood gas sample shows pH below 7.35 and a bicarbonate level of under 24 mmol/L.
What may be the cause of this acidosis?
What is the mechanism of this process?
Why might this problem have been prevented if compound sodium lactate solution(Hartmann’s solution) had been prescribed rather than sodium chloride with glucose?
Discussion pointsHartmann’s solution is also known as Ringer’s lactate solution and consists of: • sodium chloride 0.6 percent • sodium lactate 0.25 percent • potassium chloride 0.04 percent • calcium chloride 0.027 percent.
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the management of fluids
Suggested answer
Infusion of excess chloride ions as a result of large volumes of sodium chloride beingadministered can lead to hyperchloraemic acidosis.
Suggested answer
The mechanism is as follows:1. Sodium and chloride ions are present in equal proportions in sodium chloride
0.9 percent.2. The proportional increase in plasma chloride is greater than that of sodium (due to
lower pre-existing plasma concentration of chloride ions).3. The strong ion difference is therefore reduced as a result of the proportional change.
Compensatory mechanisms then act to restore the strong ion difference.4. Acidosis occurs.
Suggested answer
Compound sodium lactate solution contains:1. fewer chloride ions compared to sodium, and so there is a smaller proportional
increase in plasma chloride levels and a lesser effect on the strong ion difference compared to sodium chloride 0.9 percent
2. lactate, which is converted to bicarbonate by the liver and has an alkalinising effect (by ‘mopping-up’ hydrogen ions).
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CASE STUDY 5 – REBECCA
Rebecca Altman has been undergoing treatment for ovarian cancer for several months. Dueto the severe side-effects that she experienced with her previous cycles of chemotherapy,Rebecca has been admitted to an oncology ward for the final cycle of cisplatinchemotherapy.
Due to the potential nephrotoxicity of this drug, Rebecca is given the following fluid regime:
Following the above, post-hydration, Rebecca appears short of breath and has puffy ankles– symptoms of heart failure.
Have Rebecca’s body fluids caused these symptoms? How?
Infusion fluid and additives
Sodium chloride 0.9%
Sodium chloride 0.9%
Mannitol 20%
Cisplatin 106 mg
Mannitol 20%
Sodium chloride 0.9% + 2 g magnesium sulphate + 20 mmol potassium chloride
Ensure urine output > 100 mL/hour prior to giving cisplatin.
Volume
1000 mL
500 mL
100 mL
1000 mL
100 mL
1000 mL
Infusion time
1 hour
30 minutes
10 minutes
2 hours
10 minutes
2 hours
Suggested answer
Rebecca’s peripheral oedema is the result of fluid leaving the intravascular compartmentand sequestering into the interstitial compartment.
Her breathlessness is caused by the accumulation of fluid in the lungs (pulmonaryoedema), again lost from the intravascular space.
Learning portfolio
How should Rebecca’s symptoms be managed?
Rebecca remains in hospital for a further 24 hours for monitoring and to ensure symptomsresolve. She is then discharged home.
A couple of weeks later she attends the ward complaining of symptoms similar to thoseexperienced post-chemotherapy; her weight has increased by 10 kg and she is sufferingfrom shortness of breath, with reduced exercise tolerance and swollen ankles.
A blood sample is taken with a request for albumin levels to be measured. Why would thisbe done?
The patient has a normal albumin level (37 g/dL) and is admitted to cardiology with adiagnosis of heart failure.
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the management of fluids
Suggested answer
You should administer furosemide intravenously to ensure excess fluid is removed, asgastric oedema could affect absorption. A dose of 20 mg to 40 mg is usually suggested,but 50 mg can be used.
Some trusts use bumetanide instead (1 mg), as they feel that it is less nephrotoxic thanfurosemide. In addition, Rebecca would have her fluid intake restricted.
Suggested answer
Albumin maintains osmotic pressure in the intravascular space. Patients with low albuminlevels therefore suffer from oedema due to loss of fluid from their intravascularcompartment.
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What drug treatment should be commenced?
By what mechanism do these drugs improve the signs and symptoms of heart failure?
Suggested answer
A diuretic is essential to remove the excess fluid – for example, furosemide using astarting dose of 20 mg in the morning. You may need to titrate this up depending on theresponse.
You should also begin an ACE inhibitor – for example, ramipril, using a starting dose of1.25 mg daily and titrated up depending on the patient’s blood pressure. This may betitrated up to a maximum of 10 mg once daily.
Suggested answer
Diuretics remove the excess fluid that causes the breathlessness and oedema from thebody.
ACE inhibitors cause vasodilation and, as a result, reduce blood pressure and cardiacpreload, thus preventing fluid being forced out of blood vessels (which is the cause ofoedema).
Learning portfolio
References
1. Floss K, Borthwick M, Clark C. Intravenous fluid therapy – background and principles. Clinical Pharmacist 2008;15: 271-274. http://www.pjonline.com/backissues.
2. O’Hara D, Richardson P. Fluid and electrolyte balance, anaemia and blood transfusion. Surgery 2008;26(9): 383-391.
3. Staples A, Dade J, Acomb C. Intravenous fluid therapy – what pharmacists need to monitor. Clinical Pharmacist 2008;8: 277-282. http://www.pjonline.com/backissues.
4. National Patient Safety Agency. Patient Safety Alert 20: Promoting safer use of injectablemedicines. London: NPSA; 2007.http://www.nrls.npsa.nhs.uk/resources/type/alerts/?entryid45=59812&p=3.
5. Powell-Tuck J et al. British Consensus Guidelines on Intravenous Fluid Therapy for Adult Surgical Patients. GIFTASUP. The British Association for Parenteral and Enteral Nutrition, the Association for Clinical Biochemistry, the Association of Surgeons of Great Britain and Ireland, the Society of Academic and Research Surgery, the Renal Association and the Intensive Care Society; 2011. http://www.bapen.org.uk/pdfs/bapen_pubs/giftasup.pdf.
6. The SAFE Study investigators. A comparison of albumin and saline for fluid resuscitation in the intensive care unit. The New England Journal of Medicine 2004;350: 2247-2256.
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the management of fluids
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Notes
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