Validity of esophageal pressure measurements with positive end-expiratory pressure in preterm infants.

Previous research suggested that esophageal pressure changes (ΔPes) may not reflect pleural pressure changes (ΔPpl) in the presence of positive end-expiratory pressure (PEEP), making assessments of dynamic lung mechanics invalid in these circumstances. To test this hypothesis, we measured ΔPes using a water-filled catheter in 18 preterm infants with lung disease (9 intubated), and adjusted the catheter position to achieve a valid occlusion test. End-expiratory occlusions were then carried out at PEEP (cm H2O) of 0, 4, and 8, and plots of ΔPes against ΔPao during airway occlusion were examined to derive the ratio ΔPes/ΔPao and the r value (as a measure of linearity). There was no significant change in ΔPes/ΔPao, which remained close to 1.0 as PEEP was increased from 0 to 8 cm H2O, and r also remained close to unity, indicating no appreciable hysteresis or alinearity of the plots. Our results show that ΔPes, when measured with an appropriately placed water-filled catheter, continues to reflect ΔPpl accurately when lung volume is raised by applying PEEP up to 8 cm H2O. Pediatr Pulmonol. 2003; 36:216–222. © 2003 Wiley-Liss, Inc.