Determinants of the esophageal-pleural pressure relationship in humans

Abstract

Esophageal pressure has been suggested as adequate surrogate of the pleural pressure. We investigate after lung surgery the determinants of the esophageal and intrathoracic pressures and their differences. The esophageal pressure (through esophageal balloon) and the intrathoracic/pleural pressure (through the chest tube on the surgery side) were measured after surgery in 28 patients immediately after lobectomy or wedge resection. Measurements were made in the nondependent lateral position (without or with ventilation of the operated lung) and in the supine position. In the lateral position with the nondependent lung, collapsed or ventilated, the differences between esophageal and pleural pressure amounted to 4.4 ± 1.6 and 5.1 ± 1.7 cmH2O. In the supine position, the difference amounted to 7.3 ± 2.8 cmH2O. In the supine position, the estimated compressive forces on the mediastinum were 10.5 ± 3.1 cmH2O and on the iso-gravitational pleural plane 3.2 ± 1.8 cmH2O. A simple model describing the roles of chest, lung, and pneumothorax volume matching on the pleural pressure genesis was developed; modeled pleural pressure = 1.0057 × measured pleural pressure + 0.6592 ( r2 = 0.8). Whatever the position and the ventilator settings, the esophageal pressure changed in a 1:1 ratio with the changes in pleural pressure. Consequently, chest wall elastance (Ecw) measured by intrathoracic (Ecw = ΔPpl/tidal volume) or esophageal pressure (Ecw = ΔPes/tidal volume) was identical in all the positions we tested. We conclude that esophageal and pleural pressures may be largely different depending on body position (gravitational forces) and lung-chest wall volume matching. Their changes, however, are identical. NEW & NOTEWORTHY Esophageal and pleural pressure changes occur at a 1:1 ratio, fully justifying the use of esophageal pressure to compute the chest wall elastance and the changes in pleural pressure and in lung stress. The absolute value of esophageal and pleural pressures may be largely different, depending on the body position (gravitational forces) and the lung-chest wall volume matching. Therefore, the absolute value of esophageal pressure should not be used as a surrogate of pleural pressure.

Oesophageal pressure as a surrogate of pleural pressure in mechanically ventilated patients

“…In addition, Terzi et al (14) showed in a ventilated pig model that in supine position, mean difference between P es and P L, D was 2. Therefore, the principal strength of our study is to confirm and duplicate in a human in vivo setting, results from previous experimental and clinical studies (3,10,14) with the unique characteristic to investigate simultaneously dependent, non-dependent pleural pressures and esophageal pressure.…”

“…From previous clinical and experimental studies, we know that 1/ because of the weight of the heart and of the increase of the gravitational gradient of pleural pressure during ARDS, P es is higher in supine patient ventilated for ARDS than those of non-ventilated healthy subject in upright position(2,7,8) 2/ from experimental study in dogs (9), and recently in man (10), it was demonstrated that absolute pleural pressures are approximately 7 cmH 2 O lower than Pes in the non-dependent regions and 5 cmH 2 O higher in the dependent regions at low intrathoracic pressure. Therefore, some authors have proposed to apply a correction subtraction between 2.5 to 5 cmH 2 O to the actual measured esophageal pressure to calculate the transpulmonary pressure (8,9,11).…”

Assessment of different computing methods of inspiratory transpulmonary pressure in patients with multiple mechanical problems

“…This method requires deconnection of patient from the ventilator [ 13 , 14 ]. As previously shown by Pelosi et al and recently confirmed by experimental and clinical studies there is not a single P pl value among the thorax [ 24 – 28 ]. In these studies authors placed pleural catheters to the dependent and nondependent lung regions and compared P pl with the P es and showed that the static P pl increases from nondependent to dependent regions in supine position, creating a vertical pressure gradient.…”

Transpulmonary driving pressure during mechanical ventilation–validation of a non‐invasive measurement method

“…To assess lung and chest wall mechanics separately it would be ideal to be able to measure pleural pressure. In clinical work that is not possible so instead esophageal pressure is used as a surrogate for pleural pressure [48,126,127]. Esophageal pressure has been used in several studies aiming to optimize mechanical ventilation in patients with ARDS [49,[72][73][74] and in the weaning process [128].…”

“…All things considered, using the tidal change to calculate transpulmonary pressure is more accurate than using the absolute esophageal pressure [120,127] although it cannot precisely represent the pleural pressure. This is especially true in prone position as has been shown in both paper IV and in a recent article by Terzi et.al [81].…”