Esophageal and pleural pressures in man, upright and supine

To assess the reliability of esophageal sampling of pleural pressure, both pressures were recorded simultaneously in seven subjects in the upright posture and, in five of these, in the supine posture. Esophageal pressure was obtained with air-containing latex balloons and pleural pressure was recorded from catheters introduced into the intrapleural space. Pneumothorax volumes were estimated to be between 5 and 350 ml. The closest correspondence between the pressures was observed in the upright posture. Expressing the difference in the amplitude of the respiratory excursions as the percentage of deviation of esophageal from pleural pressures, in the upright posture individual values ranged from +20 to -18, while the average value for the group did not differ significantly from 0. On the other hand, in the supine position individual variation was greater (range +60 to -25) and, on the average, esophageal pressure amplitudes were larger (average +27 during quiet breathing) than pleural pressure amplitudes. Submitted on August 22, 1958