Mechanical ventilation versus CPAP -what are the pros and cons? Anne Greenough Professor of Neonatology

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Mechanical ventilation versus CPAP-what are the
pros and cons? Anne GreenoughProfessor of
Neonatology Clinical Respiratory
PhysiologyDivision of Asthma, Allergy and Lung
BiologyKings College, London, School of
Medicine
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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
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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
• infants respiratory efforts
• - patient triggered
  ventilation
• (iii) Minimisation of excessive tidal volumes
  
• - volume targeted ventilation
• - high frequency oscillation

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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

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Nasal CPAP or intubation at birth(COIN trial)

• 610 infants 25 to 28 weeks gestation
  
• IPPV
  CPAP
• O2 dep 28 days 63 51
  lt0.001
• Days of IPPV 4
  3 lt0.001
• O2 dep at 36 weeks 29 35
  ns
• Pneumothorax 3 9
  0.003
• 
  Morley et al NEJM 2008

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Early surfactant and extubation to CPAPversus
selective surfactant and IPPV

• Meta-analysis of six trials demonstrated CPAP
• Reduced BPD
  0.51(0.26-0.99)
• Reduced need for IPPV 0.67
  (0.57-0.79)
• Reduced airleaks 0.52
  (0.28,0.96)
• Surfactant
  1.62 (1.41,1.86)
• 
  Stevens et al Cochrane 2007
• But early versus selective surfactant reduces
  airleaks and BPD/death and improves survival

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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

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PTV (ACV/SIMV) versus CMV

• Oxygen dependency
• at 28 days 0.93 (0.77 - 1.14)
• at 36 weeks 0.91 (0.77 - 1.09)
• Severe IVH 1.03 (0.75 - 1.43)
• Reduction in ventilation duration
• - 45.2 hours (12.1 - 78.3)
• - only when PTV was started in the
  recovery phase
• 
  Greenough et al Cochrane review 2007

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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 2000 - PSV)
• - 5-25 maximum flow (Bird VIP - termination
  sensitivity)

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Randomised trial of SIMV versus SIMV and
pressure support (PS)

• 107 infants birthweight 500-1000gms gtone 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

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Randomised trial SIMV versus SIMV PS

• all
  infants 700-1000
• SIMV PS
  p SIMV PS p
• Age at final
• extubation (days) 44 35 .91
  29 24 .366
• IPPV (days) 34 22 .18
  25 15 .118
• IPPV 28 days () 69 47 .04
  53 30 .116
• O2 at 36wks () 48 33 .21
  58 38 .142
• O2 (days) 72 49
  .11 86 58 .034

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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 141 (93) 112 (85)
  lt0.001
• PaO2 8.6 (2.6) 8.5
  (1.8) 0.78
• PaCO2 5.9 (1.3) 6.0
  (1.6) 0.55
• Resp rate 64 (13) 55
  (11) 0.001
• 
  Patel et al ADC 2009

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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

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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

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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

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Impact of VG on CO2 tensions

• Randomised trial of 40 infants 27 weeks gestation
• SIMV /-VG 4mls/kg
• In infants gt 25weeks VG halved the incidence of
  hypocarbia
• Ineffective in infants lt26 weeks GA
• Cheema
  et al EHD 2006

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Volume controlled vs pressure limited

• Randomised trial - 90 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 (p0.15) (BWlt1000gms p0.03)
• No significant differences in other outcomes
• 
  Singh et al J Pediatr 2006
• VT 4-6mls/kg

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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
• 0 144 (47)
  173 (88)
• 4 203 (82)
  237 (100)
• 5 168 (59)
  180 (78)
• 6 135 (47)
  147 (51)
• 
  Patel et al Pediatr 2009

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Prophylactic HFO

• 13 published prophylactic trials ( lt 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 (0.85-1.00)
• Pulmonary airleak RR
  1.14 (1.00-1.29)
• 3-4 IVH
  RR 1.11 (0.95-1.1.3)
• PVL
  RR 1.10 (0.84-1.44)

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UKOS Trial

• Infants between 23 weeks and 28 6 weeks
  gestational age, CMV or HFOV within 60 minutes of
  birth
• CMV HFO
• n 397 400
• Died 26 25
• Survived O2
• dependant at 36 weeks 41 41
• Airleak 18 16
• Cerebral abnormality 25 17
• 
  Johnson et al NEJM 2002

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Pulmonary function at one year

• Means and 95 CI of the differences in the means
• CMV
  HFOV (95CI diff)
• Respiratory rate (bpm) 31.2 33.9
  (-6.1,0.7)
• TGV (mls/kg) 26.9
  26.5 (-2.5,3.4)
• FRC (mls/kg) 24.1
  23.5 (-2.1,3.2)
• FRCTGV 0.90
  0.90 (-0.06,0.06)
• Resistance (cmH2O/l/s) 33 34
  (-8,6)
• 
  Thomas et al ARJCCM 2003

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Effect of preterm delivery on airway function in
first year of life


VmaxFRC z-score
Crown-heel length (cm)
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Worsening VmaxFRC in infants with BPD

• 36 infants mean birthweight 837 (152) gms and
  gestational age 26.8 (1.7) gms
• BW lt 1250gms, IPPVgt7 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
• (VmaxFRC)
• 
  Hofhuis et al AJRCCM 2002

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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?