Issuu on Google+

Ventilation strategies in neonatal RDS Dr David Tingay Neonatologist, Royal Children’s Hospital, Melbourne, Australia Senior Research Fellow, Murdoch Children’s Research Institute & University of Melbourne


What is Lung Protective Ventilation? •  Every Neonatologist applies ventilation with a LPS •  Everyone does it different Van Kaam & Rimensberger European Practice study

•  Lung Protective Ventilation: -  Optimises gas exchange and lung mechanics -  Does so without exposing the lung to increased risk of VILI -  Be driven by the infant


VILI

NAVIGATION  TOOLS  

Biotrauma   Oxida:ve  Injury  

Volutrauma   Barotrauma  

Atelectasis   Sheer  Force  Injury  

Between Scylla and Charybdis


Region of Optimal Ventilation Defla:on  Limb  

Infla:on  Limb  

Alveolar  stability   maintained  

Recruitment  is   ongoing   (inhomogeneity)  

&  Albaiceta  CCM   2004  

At  no  point  can  all   mechanical  causes   of  VILI  be   minimised  

Opening   pressure  >   collapsing  forces  

&   Hickling  et  al   AJRCCM  2001   &  Jonson  ICM  2005  

&  Rimensberger   ICM  2000  

  Mechanical  Ven:la:on  

&  Froese  AJRCCM  2002  

&  Froese  CCM  1997  


Lung  Recruitment     How?  

  35   30   25   20   15   10   5   0  

Incremental  

ΔTGV (expressed as %TLC)

 

40

Pre-recruitment Paw 17 cm H2O

SDI   RS   Standard  

During recruitment Paw 35 cm H2O

*p  =  0.04  ANOVA   Target Paw

1  

5  

 

Time (mins post-recruitment)

15  

&  Pellicano  et  al  ICM  2009  


Relationship between CDP and EELV Term  Infants  (n=15)  

&  Tingay  et  al  AJRCCM  2006  

Preterm  Infants  (n=15)  

&  Miedema  et  al  J  Peds  2011  

•  PV relationship can be mapped •  Identify hysteresis in the atelectatic neonatal lung


Relationship between CDP, EELV and SpO2

&  Miedema  et  al  J  Peds  2011  

•  S p O 2   r e l i a b l y   i d e n : fi e d   T L C   (overdistension)  and  CCP  (collapse)   •  SpO2   cannot   precisely   delineate   between  small  volume  state  changes   &  Tingay  et  al  AJRCCM  2006  


OLV during HFOV in newborn infants Rimensberger et al Pediatrics 1999 •  LVO (If FIO2 >0.4): 1-2 cm H2O Paw steps every 1-2 mins UNTIL FIO2≤0.4 (max Paw 25 cm H2O) •  THEN Paw decreased until FIO2 ≤0.4 and PaO2 ≥60 mmHg Less ventilator days, Lower oxygen dependency, Less CLD Transient high Paw is well tolerated, even in preterm infants DeJaegre et al AJRCCM 2006 Similar LVO strategy: –  Pmax FIO2 at CDPOPT ≤ 0.25 before surfactant FIO2 at CDPOPT ≤ 0.25 in 75% and ≤ 0.3 in 98% An aggressive recruitment strategy using oxygenation to guide the recruitment process is feasible and safe during HFV in preterm infants with RDS. Tingay et al AJRCCM 2006 OLV resulted in optimal SpO2, TcCO2, VT and Crs Optimal Paw identified after aggressive recruitment at CCP+2 – 4 cm H2O


A new definition of the optimal region of ventilation?

VTRIP MVHF VTao TcCO2

50

Optimal Paw range

VL (%)

Region of optimal volume

0

Pmax

SpO2

100

Pfinal

Safe Zone

Pinitial

0

25

50

Paw (%)

75

100


Achieving aeration at birth

•  Both PEEP and SI achieve aeration •  By 7 min no difference in FRC between SI + PEEP and PEEP alone How long do you need to apply a SI? How do you know? How do you know what PEEP to use after? •  These DR strategies lack feedback mechanisms •  Ventilation should be titrated to the patient

Te  Pas  et  al  Ped  Res  2009  


SI vs OLV at birth (126d lamb) Oxygenation FiO2

Oxygenation

SI  

300 200

SPR  

0.6 0.4 0.2

100 0

0.8

FIO2

AaDO2

400

1.0

Surfactant

500

0.0 8

15

25

40

55

70

Time (mins)

p<0.05  SI  vs  SPR  at  all  :me  points  

All  data  mean+SD  

0

10

20

30

40

Time (mins)

p<0.05  SPR  vs  SI  

50

60

70


SI vs OLV at birth Regional Lung Mechanics 1-­‐min  post-­‐SPR  

50

Anterior:Posterior CRS Ratio at 70-min

Global  

1.50

Non-­‐dependent  

1.25

30

20

10

Dependent  

0 0

10

20

30

40

50

Pressure (cm H2O)

Crs Ratio

ΔZ (cu)

40

1.00 0.75 0.50

50

SI

1-­‐min  post-­‐SI  

SPR

CRS

30

20

10

0 0

10

20

30

Pressure (cm H2O)

40

50

CRS (mL.kg-1/cm H2O)

ΔZ (cu)

40

1.2 1.0 0.8 0.6 0.4 0.2 0.0

0

5

10 15 25

40

Time (min) (mins) Time

55

70


Fetus  

SI  in  different  lung  states  

R  

20s  SI  

PEEP  6  

L  

SI  in  surfactant  replete  lung  

PPV  

R  

SI  in  lung  without  surfactant  

L  


CPAP Answers or questions? •  CPAP is the most common form of respiratory support -  90% IPPV + CPAP and 43% CPAP only & ANZNN 2011

•  CPAP is an alternative to IPPV, even without surfactant & COIN 2010

•  COIN found higher PTx rates, but why? •  How (if) to deliver surfactant without intubation? -  INSURE, OPTIMIST

•  How do we know what CDP to apply? •  How do we respond to changes in lung mechanics? •  How do we minimise technical limitations that may influence efficacy?


What is the correct CPAP CDP in early RDS? Recruiters  (n=11)  

Non-­‐Recruiters   N=20   (n=9)  

GA  29  (1)  wk   Bw  1181  (417)g   Age  15  (12,18)  hr   FiO2  0.24  (0.21,0.33)  

Risha  Bha:a  PhD  Thesis  2012  


Oxygen Saturation Targeting What is the ideal SpO2 range? Preterm infants •  In older preterm infants targeting SpO2 88-92% reduces O2 duration and hospitalisation without increased morbidity (BOOST 1) •  SUPPORT (NEJM 2010; n=1316) •  85 – 89% SpO2 range = less ROP but higher mortality

•  BOOST II (85-89% vs 91-95%; n=2315) •  •  •  • 

Stopped early in 2010 Identified calibration algorithm issue in monitors Mortality higher in 85-89% group (21.8% vs 13.3%; p<0.001) Pooled mortality also higher (17.3% vs 14.4%; p=0.015)

•  Term Infants?


Presentation 20 - Tingay