Positive airway pressure and vertical transpulmonary pressure gradient in man.
Static transpulmonary pressure (Pao-Pes) and the vertical gradient of transpulmonary pressure were determined in five sitting conscious normal subjects at mean airway pressures of 0 (ambient), 11, and 21 cmH2O. All subjects exhibited a nonuniform transpulmonary pressure gradient down the esophagus. The vertical pressure gradient was consistently larger in the lower (8-20cm below esophageal artifact) than in the middle region (0-8cm) of the esophagus. The gradient was not significantly altered by continuous positive airway pressure (11 and 21 cmH2O) or by changes in lung volume (60, 70, and 80% of total lung capacity (TLC)). Continuous positive airway pressure also did not result in a consistent change of the overall static pressure-volume curve of the lung. There was a small but statistically significant increase in TLC with each increase in airway pressure.
D001696:Biomechanical Phenomena; D004947:Esophagus / Q000502:physiology; D006801:Humans; D007320:Inspiratory Capacity; D008176:Lung Volume Measurements; D008297:Male; D011312:Pressure; D012119:Respiration