Neonatologist, Perth Children’s Hospital, Australia · Neonatologist, Perth Children’s Hospital, Australia MBBS, MD, DNB, DM, FRACP, MSc (Biostatistics) ... Basics of different

Neonatologist, Perth Children’s Hospital, Australia

MBBS, MD, DNB, DM, FRACP, MSc (Biostatistics)

Probiotics in surgical infants, biostatistics, systematic reviewsA/Prof Shripada Rao

Volume Guided Ventilation: Why is there gap between evidence

and practice?

A/Professor Shripada Rao, MBBS, MD, DNB, DM, FRACP

Neonatologist

Perth Children’s Hospital

University of Western Australia

Topics to cover

1. Basics of different types of ventilation

2. Evidence for Volume Targeted Ventilation in neonates

3. Barriers to implementation

4. How to facilitate implementation

5. Scope for further research

Pressure Controlled Ventilation

• In pressure controlled ventilation, clinician sets the pressure to achieve the desired tidal volume

• Standard modality in neonates

• SIMV, SIPPV, PSV

Pressure Controlled Ventilation

Stiff lung Low tidal volume

After surfactant High Tidal Volume

ETT secretions Decreases TV

Pneumothorax Decreases TV

Excessive crying Widely fluctuating TV

Muscle relaxation Decreases TV

Thorough suctioning Increases TV

For the same set PIP

Pressure controlled ventilation

• Consistent VT delivery is not possible with pressure control

modes

• Variable tidal volumes, lead to Volutrauma

Morley et al. Clin Perinatol. 2012

Experiments in rats

High PIP, High VT strategy

Low (Negative) PIP, High VT

High PIP, Low VT

(Strapped chest and abdomen)

Controls: very low PIP, very low VT

P<0.01

Volutrauma is more harmful than barotrauma

Adapted from Dreyfuss, Am Rev Respir Dis 1988

Horizontal linerepresents the upper 95% CI limit for control values

Pulmonary capillary permeability

Adapted from Dreyfuss, Am Rev Respir Dis 1988And Goldsmith: Assisted Ventilation in neonate

Experiments in rats

High PIP, High VT strategy

Low (Negative) PIP, High VT

High PIP, Low VT

(Strapped chest and abdomen)

Controls: very low PIP, very low VT

Horizontal linerepresents the upper 95% CI limit for control values

Other problems with fluctuating tidal volumes

• Variable tidal volumes can lead to hypercarbia and hypocarbia

Kaiser, Pediatrics, 2007

Hypercarbia and hypocarbia increase the risk of IVH and PVL

Fabres J, Pediatrics 2007Fujimoto, Arch Dis Child 1994;

• Volume Guided Ventilation may be the solution

• In PCV, the control variable is PIP

• Cycling is by time (or flow)

• Volume depends on compliance/resistance

• In traditional volume-controlled ventilation, VT delivery is directly controlled;

• Cycle ends when set VT is delivered• PIP rises passively

Martin Keszler and Colin Morley; In JP Goldsmith, Textbook of assistedventilation in neonates, 2017

Pressure Ventilation vs Traditional Volume Control

Traditional Volume Controlled Ventilation

• Used in Adults and Children

• May not be feasible in neonates

Martin Keszler and Colin Morley; In JP Goldsmith, Textbook of assisted ventilation in neonates, 2017

Traditional Volume Controlled Ventilation is difficult in neonates

• A relatively large portion of the

volume delivered into the circuit is

lost to:

1. The humidifier

2. elastic tubing

3. Leak because of uncuffed

ETTs

VT reaching the lungs is different

from the set VT

Alternative is Volume Targeted Ventilation

• VT -targeted ventilations are modifications of conventional pressure-

controlled ventilation

• They deliver a target VT by microprocessor-directed adjustments of

PIP

• There is automatic adjustment of PIP to deliver a user-set VT

Kezsler 2019, Archives in Childhood-Fetal and Neonatal Ed

Types of Volume Targeted Ventilation

• Volume limit ventilation; Targeted tidal volume (TTV)

• Pressure regulated volume control (PRVC)

• Volume assured pressure support (VAPS)

• Volume Guarantee: Most common type of volume targeted ventilation

Keszler, Early Human Development, 2006

1. The clinician sets the VT

2. The clinician sets the maximum

PIP

3. The flow sensor at the ETT end

measures the exhaled VT

4. And feeds info to the ventilator

5. The ventilator adjusts the PIP up

or down accordingly

Volume Guarantee Ventilation

Adapted from Samir Gupta et al. Pediatrics and Child Health, 2015

Upper limit PIP

• Volume Targeted ventilation can be used along with SIPPV, SIMV or PSV Mode

Hummler H et al. Pediatr Pulmonol 1996;22:305–13.

Triggered vs Untriggered breaths in VG mode

• Because of VG, tidal volume remains relatively constant

• For triggered breaths, the ventilator uses lower PIP

• For Untriggered breaths, it uses higher PIP

Klingenberg C. J Perinatol 2011

Potential advantages of Volume Guarantee Ventilation

• Stable VT delivery; Less Volutrauma

• Auto-weaning of PIP, Less barotrauma

• Stable VT>Stable Minute Volume>Stable PaCO2

• Results in stable cerebral blood perfusion and reduced brain injury

• Weaning occurs in real time, rather than in response to blood gases

• Faster weaning from mechanical ventilation

The ventilators we use for VG

Babylog 8000+ VN 500

Evidence for beneficial effects of Volume Targeted Ventilation in neonates

• Klingenberg C, Wheeler KI, McCallion N, Morley CJ, Davis PG.

Volume‐targeted versus pressure‐limited ventilation in neonates. Cochrane Review 2017

Cochrane Review

• 1065 neonates from 20 RCTs

• Majority: preterm infants <32 weeks or <1500g

• Individual study sample size: 15 to 212 infants

• 17 trials recruited infants in the early neonatal period (<3 days)

• Three trials enrolled preterm infants with mean postnatal age between 33 and 37 days

• RR: 0.73 [0.59, 0.89]

• Total Sample size: 584

Cochrane Review 2017

Death or BPD

• RR: 0.75 [0.53, 1.07]

• N: 771

Mortality before discharge

• RR: 0.68 [0.53, 0.87]• Sample size: 620


BPD

RR: 0.53 [0.37, 0.77]Sample size: 712

Severe IVH

RR: 0.45[0.21, 0.98]Sample size: 508

PVL

RR: 0.52 [0.31, 0.87]Sample size: 825


Pneumothorax

MD: -1.35 [-1.8, -0.86]N=736


Duration of Ventilation

RR: 0.71[0.42, 1.21]

N=246


Death (<1000g)

RR: 0.79 [0.62, 1.01]N=224


Death or BPD (<1000g)

MD: -0.82 [-4.43, 2.80]

N=198


Duration of positive pressure ventilation (<1000g)

RR: 0.63 [0.29, 1.37]

N=247


Pneumothorax (<1000g)

Severe IVH (<1000g)

RR 0.53 [0.27, 1.04]N=184


Severe IVH or PVL (<1000g)

RR 0.39, 0.99]N=145


Severe disability (<1000g)

RR 0.86 [0.47, 1.59]N=209


Conclusions by Cochrane Reviewers

• Compared to PLV ventilation, Infants ventilated using VTV modes had reduced rates of

• Death or BPD

• Pneumothoraces

• Hypocarbia

• Severe cranial ultrasound pathologies

• Further studies are needed to identify whether VTV modes improve neurodevelopmental outcomes and to compare and refine VTV strategies


Barriers to Implementation

Keszler M, 2013

North American survey-2019

• USA and Canada

• VTV use: 39% in the USA

81% in Canada

Gupta A, Keszler M. Am J Perinatol. 2019

Admin Issues 11%

Equipment not available

26%

Lack of training 13%

Lack of understanding

49%

Miscellaneous 6%

Gupta A, Keszler M. Am J Perinatol. 2019

Reasons for not implementing

Lack of support from senior colleagues!!

Australian and Nordic Survey-2011

• 50 Neonatal Units

• VTV was routinely used in 50% of units

Klingenberg C, Arch Dis Child Fetal Neonatal Ed 2011

Italian Survey

• Volume Targeted ventilation was used in 28% of the NICUs (31/113)

Petrillo F, Italian J Pediatrics, 2019

Too many terminologies and modalities

• Volume Controlled Ventilation; Volume Targeted Ventilation

• Volume Guided Ventilation; Volume limit ventilation

• Volume Guarantee Ventilation; Volume Cycled Ventilation

• Targeted Tidal Volume Ventilation; Pressure regulated Volume control

• Volume assured pressure support ventilation; AND much more!!

How to Introduce VG in the Unit?

• Implement it after much training

• Have a clearly written protocol

• Follow evidence based guidelines for VG

• Don’t try on very sick babies

• Try on stable babies initially

• Have a local champion or ‘super-user

Recommended initial tidal volume and peak inflation pressure settings

Condition Initial VT Initial PIP limit

Preterm RDS 1250–2500 g

4–4.5mL/kg 26 cm H2 O

Preterm RDS 700–1249 g

4.5–5mL/kg 24 cm H2O

Preterm RDS<700g

5.5–6mL/kg 24 cm H2O

Preterm evolving BPD, 3 weeks old

5.5–6.5mL/kg 26 cm H2 O

Severe BPD 7–12 30 cm H2 O

Keszler 2019, Archives in Childhood-Fetal and Neonatal Ed

Recommended initial tidal volume and peak inflation pressure settings

Condition Initial VT Initial PIP limit

Term MAS with classic CXR* 5.5–6 28 cm H2O

Term MAS with white-out CXR

4.5–5 30 cm H2 O

Term CDH 4–4.5 24 cm H2 O

Term or late preterm; Normal lungs

4-4.5 18 cm H2O

Keszler 2019, Archives in Childhood-Fetal and Neonatal Ed

The larger VT/kg requirement in the smallest infants is due to the larger impact of dead space of the flow sensor (0.7 to 1.1mL)

Nassabeh-Montazami. Pediatr Pulmonol 2009

Keszler 2006, Early Human Development

Future RCTs?

• Limitations of evidence: Individual studies had small sample size (20 to 212)

• Largest study (n=212) found no evidence of benefit

• No confirmed evidence of benefit in infants<28w

• Multicentre Mega trial/s, especially <28w

• Long term respiratory and neurodevelopmental outcomes needed

• RCT: Less likely in countries where VTV has been standard of care

• Multicentre RCT in India: Why Not?

Conclusions

• We need to Implement VTV or conduct a mega trial

• Status Quo may not be a great approach

Useful Resources

• Keszler M. Arch Dis Child Fetal Neonatal Ed. 2019 Jan;

• Klingenberg C. A practical guide to neonatal VG ventilation. J Perinatol2011

• Gupta, Samir; Janakiraman, Sundaram. Volume ventilation in neonates. Paediatrics and Child Health, January 2018

• Morley. Volume-limited & volume-targeted ventilation. Clin Perinatol2012

• Textbook of Assisted Ventilation in Neonates: JP Goldsmith

Thank you

Documents

Neonatologist, Perth Children’s Hospital, Australia · Neonatologist, Perth Children’s Hospital, Australia MBBS, MD, DNB, DM, FRACP, MSc (Biostatistics) ... Basics of different