Acute effects of PEEP on center output during tidal volume and respiratory 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. Objectives: 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 H2O for 2-3 min each) and at two levels of inspired CO2. 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 CO2 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 H2O, and FiO(2): 0.31 +/- 0.06 were studied. At both levels of inspired CO2, 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 Conclusion: Higher PEEP levels can have acute negative effects on lung mechanics and ventilation in preterm infants without a sufficient compensatory increase in RCO.