1. Mechanical ventilation versus CPAP -what are the pros and cons
Mechanical ventilation versus CPAP -what are the pros and cons? Anne Greenough Professor of Neonatology & Clinical Respiratory Physiology Division of Asthma, Allergy and Lung Biology King’s College, London, School of Medicine

3. Bronchopulmonary dysplasia
PREDISPOSED INFANT
Immaturity
Family History
RDS
SEVERE LUNG DISEASE
PDA/Fluid overload
PIE
CONTRIBUTARY FACTORS
Infection
Surfactant abnormalities
Disturbance of elastase/protease
HIGH LEVEL OF RESPIRATORY SUPPORT
Baro/volutrauma
Oxygen Support
Bronchopulmonary dysplasia

4. Which ventilation strategy?
Strategies to reduce the likelihood of baro/volutrauma:
(i) Avoidance of intubation and mechanical ventilation
- nasal continuous positive airways pressure (nCPAP)
(ii) Respiratory support working synergistically with the
infant’s respiratory efforts
- patient triggered ventilation
(iii) Minimisation of excessive “tidal” volumes
- volume targeted ventilation
- high frequency oscillation

5. Early nCPAP Reduced incidence of intubation and mechanical ventilation
Jacobsen 1993, Poets 1996, Gitterman 1997
Eight centre comparison, the centre with the lowest occurrence of BPD used CPAP in preference to IPPV
- avoided hyperventilation and muscle relaxants
- used permissive hypercapnia
- one individual supervised ventilatory care
Avery 1987

6. Nasal CPAP or intubation at birth (COIN trial)
610 infants 25 to 28 weeks gestation
IPPV CPAP
O2 dep 28 days % % <0.001
Days of IPPV <0.001
O2 dep at 36 weeks % % ns
Pneumothorax % % =0.003
Morley et al NEJM 2008

7. Early surfactant and extubation to CPAP versus selective surfactant and IPPV
Meta-analysis of six trials demonstrated CPAP:
Reduced BPD ( )
Reduced need for IPPV ( )
Reduced airleaks (0.28,0.96)
Surfactant (1.41,1.86)
Stevens et al Cochrane 2007
But early versus selective surfactant reduces airleaks and BPD/death and improves survival

9. Nasal trauma 20% infants on dual prongs affected
Robertson et al ADC 1996
40 infants randomised nasaopharyngeal tube or binasal prong
- similar trauma incidence
Buettiker et al Intens Care Med 2004
89 infants randomised to binasal prong or mask
-no significant difference in nasal trauma incidence
- nasal injury (32%) related to CPAP duration
Yong et al ADC 2005

10. PTV (ACV/SIMV) versus CMV
Oxygen dependency:
at 28 days ( )
at 36 weeks 0.91 ( )
Severe IVH: ( )
Reduction in ventilation duration:
hours ( )
- only when PTV was started in the recovery phase
Greenough et al Cochrane review 2007

11. Pressure support (PS)
Infant triggers an inflation which is pressure supported at a preset level
The beginning and end of inflation are triggered by the start and end of inspiration
Inflation is terminated when the inspiratory flow is reduced to a certain level
- 15% maximum flow (Draeger Babylog PSV)
- 5-25% maximum flow (Bird VIP - termination sensitivity)

12. Randomised trial of SIMV versus SIMV and pressure support (PS)
107 infants birthweight gms >one week
PS group SIMV rate reduced by 10bpm and PS added at 30-50% of the PIP-PEEP
PIP decreased to PaCO2 and Vt: 3 and 5 ml/kg
SIMV reduced to keep between 40-65mmHg
Reyes et al Pediatr 2006

13. Randomised trial SIMV versus SIMV + PS
all infants
SIMV PS p SIMV PS p
Age at final
extubation (days)
IPPV (days)
IPPV 28 days (%)
O2 at 36wks (%)
O2 (days)

14. Work of breathing during SIMV with and without pressure support
20 infants mean gestational age 31 weeks, being weaned from mechanical ventilation
SIMV SIMV + PS p
PTP (93) (85) <0.001
PaO (2.6) (1.8)
PaCO (1.3) (1.6)
Resp rate (13) (11)
Patel et al ADC 2009

15. Volume targeted ventilation
No significant reduction in death or death and BPD
Reduced duration of ventilation 2.39 days
Reduced pneumothoraces RR 0.23
Reduced 3-4 ICH RR 0.32
4 trials identified – 178 infants
McCallion et al Cochrane database 2005

16. Volume targeted ventilation
Volume support – desired volume is selected, the duration of inflation depends on the time taken for the volume to be delivered
Bird VIP
Volume limited – pressure support for any inflation is aborted if the measured volume exceeds the preset upper limit
SLE 5000, Bearcub 750
Volume guarantee – preset expiratory tidal volume is delivered, but the preset Ti determines the duration of inflation
Draeger Babylog
Volume controlled – constant flow during inspiration – the required volume is delivered over the Ti
Stephanie

17. Delivery depends on ventilator type
Draeger positive pressure plateau
Stephanie pressure increasing till Ti termination
SLE and VIP Bird inflation terminating when the volume was delivered
At the same settings – different MAP delivery
Sharma et al Acta Ped 2006

18. Impact of VG on CO2 tensions
Randomised trial of 40 infants 27 weeks gestation
SIMV +/-VG 4mls/kg
In infants > 25weeks VG halved the incidence of hypocarbia
Ineffective in infants <26 weeks GA
Cheema et al EHD 2006

19. Volume controlled vs pressure limited
Randomised trial infants BW 600 to 1500gms, GA 24 –32 wks
Bird VIP, volume controlled (VC) or pressure limited
Success criteria oxygenation/MAP reached at 23 hrs VC versus 33 hrs (p=0.15) (BW<1000gms p=0.03)
No significant differences in other outcomes
Singh et al J Pediatr 2006
VT 4-6mls/kg

20. VG level and work of breathing
20 infants mean GA 28 weeks (10 ACV; 10 SIMV)
PTP levels at VG levels of 4, 5 and 6 mls/kg
VG level ACV SIMV
(47) (88)
(82) (100)
(59) (78)
(47) (51)
Patel et al Pediatr 2009

21. Prophylactic HFO 13 published prophylactic trials ( < 12 hours)
BPD at 36 weeks PMA or discharge in survivors
RR 0.88 (0.79 – 0.99)
Death by 36 weeks PCA RR 0.98 (0.83 – 1.16)
Death or BPD at 36 weeks PMA or discharge
RR 0.92 ( )
Pulmonary airleak RR 1.14 ( )
3-4 IVH RR 1.11 ( )
PVL RR 1.10 ( )

22. UKOS Trial
Infants between 23 weeks and weeks gestational age, CMV or HFOV within 60 minutes of birth
CMV HFO n
Died % 25%
Survived O2
dependant at 36 weeks 41% 41%
Airleak % 16%
Cerebral abnormality 25% 17%
Johnson et al NEJM 2002

23. Pulmonary function at one year
Means and 95% CI of the differences in the means:
CMV HFOV (95%CI diff)
Respiratory rate (bpm) (-6.1,0.7)
TGV (mls/kg) (-2.5,3.4)
FRC (mls/kg) (-2.1,3.2)
FRC:TGV (-0.06,0.06)
Resistance (cmH2O/l/s) (-8,6)
Thomas et al ARJCCM 2003

24. V’maxFRC z-score Crown-heel length (cm)
Effect of preterm delivery on airway function in first year of life
V’maxFRC z-score
Crown-heel length (cm) 24

25. Worsening V’maxFRC in infants with BPD
36 infants mean birthweight 837 (152) gms and gestational age 26.8 (1.7) gms
BW < 1250gms, IPPV>7 days, BPD
Initial ventilation: IPPV or HFOV in the youngest and smallest infants
Evaluated at 6 and 12 months
Maximum flow at functional residual capacity
(V’maxFRC)
Hofhuis et al AJRCCM 2002

27. Mechanical ventilation versus CPAP
Current evidence:
High volume HFO reduces BPD, but whether it improves long term lung function requires follow-up of infants entered into RCTs
Weaning is best by modes supporting every breath
–whether ACV or PSV is better merits testing
Severe respiratory distress – a trial of rescue HFOV with long term outcomes is needed
CPAP as the preferred mode?