Volume vs Pressure during Neonatal Ventilation

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1 Volume vs Pressure during Neonatal Ventilation David Tingay 1. Neonatal Research, Murdoch Children s Research Institute, Melbourne 2. Neonatology, Royal Children s Hospital 3. Dept of Paediatrics, University of Murdoch Children s Research Institute, 2018

2 Conflict of Interests Salary and research grant support from the National Medical and Health Research Council (Australian Govt) and the Royal Children s Hospital Foundation In the last 7 years received travel support from SLE Ltd (UK), Carefusion (USA), Curosurf (Italy) and Acutronic (Switzerland) Lab has received unrestricted equipment and software support from Carefusion, SLE Ltd, Curosurf and Swisstom (Switzerland) (This presentation is not very clinical) 2

3 Principles of Lung Protective Ventilation Lung protective Ventilation = Application of respiratory support that optimises oxygenation and ventilation whilst minimising potential injurious events All modes of respiratory support apply some form of positive pressure ventilation to an organ of motion that is designed to operate using negative pressure changes The Applied Pressure Volumetric interaction is integral to LPV Volumetric = behaviour of volume change over time and space 3

Volutrauma Barotrauma Lung protective ventilation Sailing a tight course between conflicting evils Patient Ventilator Asynchrony PEEP Atelectasis Sheer Force Injury 9 8 7 6 5 4 3 2 1 Extravascular

4 Volutrauma Barotrauma Lung protective ventilation Sailing a tight course between conflicting evils Patient Ventilator Asynchrony PEEP Atelectasis Sheer Force Injury Extravascular lung water (ml/kg) I 125 albumin (%) 0 HiP-HiV LoP-HiV HiP-LoV 0 HiP-HiV LoP-HiV HiP-LoV Biotrauma Oxidative Injury Low V T = Driving Pressure + PEEP Dreyfuss D, et al Am Rev Resp Dis,

5 The preterm lung is particularly susceptible to volutrauma Surfactant before 1 st inflation 1 st inflation before surfactant Tingay et al Under review 2018 Bjorklund Ped Res 1997; Tingay J Appl Physio

6 Avoiding Volutrauma Volume Targeted Ventilation Volume Targeted Ventilation modes are accurate Froese CCM 2005 Farrell et al ADC F&N

7 Volume Targeted Ventilation improves outcomes In the intubated infant the question should not be do I use VTV? but rather Why should I not use VTV in this infant? Klingenberg et al Cochrane Database 2017, Keszler Arch Dis Child Fetal Neo

What V T to target? 1. Somewhere between cyclic alveolar collapse and volutrauma 2.

Sufficient to support MINUTE VENTILATION CO 2 clearance = MV = Rate x Alveolar V T 3.

V T is influenced by lung development and disease V D /FRC and V D /V T change with

8 What V T to target? 1. Somewhere between cyclic alveolar collapse and volutrauma 2. Permissive hypercapnia 3. Sufficient to support MINUTE VENTILATION CO 2 clearance = MV = Rate x Alveolar V T 3. Alveolar V T = Delivered V T V D 4. The V T you set Alveolar V T 5. V T is influenced by lung development and disease V D /FRC and V D /V T change with maturation ml/kg at 24 w PMA 5 6 ml/kg at 34 w PMA 5 8 ml/kg in severe BPD Adapted from Jobe Neo 2008 Lista Ped Pulm 2006 If high V T needed is recruitment adequate? 8

9 Lung Recruitment PIP recruits the lung, PEEP maintains it, Surfactant prevents it PEEP 5 PEEP 10 Lung Volume = Applied Pressure Schiller et al AJRCCM

10 PEEP in the NICU Where do these numbers come from? PEEP levels have never be subjected to large systematic trial evaluation in NICU Van Kaam J Ped 2012, Bamat J Ped

11 But, what PEEP then? Low enough to avoid potential negative impact of PEEP Cardiovascular Airway/alveolar injury ( The COIN Trial Dilemma ) High enough to prevent atelectasis during expiration PEEP > Lower Inflection Point of the Lung Airleak and PEEP Excessive PEEP has the potential to cause airleak Inadequate PEEP has the potential to cause airleak Airleak is a result of shearing events Volume heterogeneity has the greatest potential to cause airleak Muscedere et al AJRCCM

12 Same baby, same PEEP, same injury potential? 12

13 PEEP End-Expiratory Volume Relationship Hysteresis and volume state of the lung For any given Pressure there is a range of volumes that can exist Deflation Limb Inflation Limb P cl < P op J Clin Invest 1959, Crotti AJRCCM 2001, Gattinoni AJRCCM

The concept of Dynamic PEEP The optimal PEEP for an infant can

behaviour of the lung to pressure change is known Pop > Pcl

recruited lung volume can be maintained with a low(er) PEEP

14 The concept of Dynamic PEEP The optimal PEEP for an infant can never be known, just postulated from the disease state But, the behaviour of the lung to pressure change is known Pop > Pcl Reversing atelectasis only requires a transient high PEEP Once recruited lung volume can be maintained with a low(er) PEEP Oxygen or compliance used to guide PEEP finding Dargaville et al ICM

Minimises volume heterogeneity Stabilises

injury markers Does not negatively impact

15 Dynamic PEEP and the preterm lung experimental evidence Dynamic PEEP: Minimises volume heterogeneity Stabilises both EELV and EILV Improves Oxygenation and C dyn Enhances the effect of surfactant Reduces regional lung early injury markers Does not negatively impact PBF No clinical trials of Dynamic/Individualised PEEP C dyn (ml/kg/cm H 2 O) 0.75 DynPEEP * SI No-RM Time (min) Tingay Ped Res 2014, Tingay AJRMCB 2016, Tingay AJP_Lung 2017, Smolich PAS Abstract

Barotrauma is still a thing but not a number Barotrauma is an interaction between

min of PPV Protein (mg/ml) 2.0 1.0 p=0.80 Protein (mg/ml) 2.0 1.0 p=0.046 0.0 2.

0 1.0 p=0.047 Protein (mg/ml) 2.0 1.0 p<0.001 0.

16 Barotrauma is still a thing but not a number Barotrauma is an interaction between the pressure that moves the lung and the lungs mechanical state 60 sec of PPV 60 min of PPV Protein (mg/ml) p=0.80 Protein (mg/ml) p= V T (ml/kg) V T (ml/kg) Protein (mg/ml) p=0.047 Protein (mg/ml) p< Driving Pressure (cmh 2 O) Driving Pressure (cmh 2 O) Tingay unpublished data 16

17 Lung protective ventilation vs Mechanotransduction preventive ventilation Minimal initial disease Rarely RDS Later deterioration +/- secondary events Mechanotransduction = conversion of mechanical stressors into biochemical responses BPD Recalcitrant respiratory needs +/- new events Injury Vs Inflammation Dargaville, Tingay JPCH 2012; Bancalari, Jobe J Peds 2012 Pereira-Fantini Under Review 17

The question is not volume vs pressure but the right balance of both Targeted tidal volume should be a default mode in intubated infants receiving

18 The question is not volume vs pressure but the right balance of both Targeted tidal volume should be a default mode in intubated infants receiving CMV 4 ml/kg should not be assumed to be the right V T High(er) PEEP should be used during atelectasis Low(er) PEEP should be used during gas trapping 18

19 Non-invasive Ventilation CPAP CDP influences Lung Volume 20 preterm infants <18 hr old treated with first intention CPAP Bhatia et al J Ped 2017

Physiological based management of hypoxaemic respiratory failure

Physiological based management of hypoxaemic respiratory failure David Tingay 1. Neonatal Research, Murdoch Children s Research Institute, Melbourne 2. Neonatology, Royal Children s Hospital 3. Dept of