Trans pulmonary Pressure Variations during Two and One Lung Ventilation and Change of Patient`s Position

Background: Esophageal balloon catheters are used to measure esophageal pressure (Pes) which correlates with pleural pressure, thus enables to calculate trans pulmonary pressure (TPP). Monitoring Pes facilitates optimizing the ventilator settings to suit patients with acute respiratory distress syndrome individually.

Objective: This study aims to introduce Pes monitoring to Video Assisted Thoracoscopic Surgery (VATS), which includes change in patient’s position and ventilation of one and two lungs alternately. Our hypothesis is that TPP may enable one to individualize ventilator settings during VATS and help find the balance between oxygenation and lung protection.

Method: Following IRB approval, 19 patients undergoing VATS lobectomy consented to participate in this study. Following induction of general anesthesia, an esophageal balloon device was placed, and pressure was measured as long as the chest was closed. We compared the pressures during ventilation of the two lungs, and then during OLV in the supine position and in the lateral position.

Results: TPP increased significantly throughout the respiratory cycle. Peak inspiration TPP increased from 10.4± 7.1 cmH20 to 17.2± 5.8 cmH20 (P=0.002), TPP during inspiratory plateau increased from 4.4± 5.6 cmH20 to 11.8 ± 5.0 cmH20 (P<0.001) when changing from conventional ventilation in the supine position to one-lung ventilation in the lateral position.

Conclusion: Variation of Pes can be measured during one and two lung ventilation, to facilitate TPP calculation at different stages of the inspiratory cycle of two or one lung ventilation. The clinical application of that information is yet to be discovered.