Acute effects of PEEP on tidal volume and respiratory center output during synchronized ventilation in preterm infants.
BACKGROUND
Positive end expiratory pressure (PEEP) is routinely used in mechanically ventilated preterm infants to maintain lung volume. An acute increase in PEEP can affect lung mechanics and tidal volume, but it is unknown if these effects elicit compensatory changes in respiratory center output.


OBJECTIVE
To investigate the acute effects of changes in PEEP on tidal volume (V(T)), lung compliance (C(L)), and respiratory center output (RCO) during synchronized intermittent mandatory ventilation (SIMV) in preterm infants at different levels of basal respiratory drive.


METHODS
Preterm infants were studied during SIMV at three levels of PEEP (2, 4, and 6 cm H(2)O for 2-3 min each) and at two levels of inspired CO(2). Peak inspiratory pressure (PIP) was adjusted to maintain the same delta pressure at the airway. RCO was assessed by measuring total diaphragmatic electrical activity. The level of inspired CO(2) was adjusted by modifying the instrumental dead space.


RESULTS
Sixteen preterm infants GA: 25 +/- 2 weeks, BW: 786 +/- 242 g, age: 18 +/- 15 days, SIMV: rate 14 +/- 3 b/min, Ti: 0.35 +/- 0.01 s, PIP: 16 +/- 1 cm H(2)O, and FiO(2): 0.31 +/- 0.06 were studied. At both levels of inspired CO(2), C(L), V(T), and V'(E) from spontaneous and mechanical breaths decreased significantly with higher PEEP. RCO did not change, but at lower respiratory drive, there was a trend towards an increase in RCO with higher PEEP.


CONCLUSIONS
Higher PEEP levels can have acute negative effects on lung mechanics and ventilation in preterm infants without a sufficient compensatory increase in RCO.
Alegría
Ximena
X
Department of Pediatrics, Division of Newborn Medicine, University of Miami Miller School of Medicine, Miami, Florida 33101, USA.
Claure
Nelson
N
Wada
Yoshirou
Y
Esquer
Cristian
C
D'Ugard
Carmen
C
Bancalari
Eduardo
E
D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008170:Lung Compliance; D011175:Positive-Pressure Respiration / Q000379:methods; D012119:Respiration; D012126:Respiratory Dead Space; D015656:Respiratory Mechanics; D013990:Tidal Volume