Redistribution of pulmonary ventilation after lung surgery detected with electrical impedance tomography

Abstract

Background: Regional ventilation of the lung can be visualized by pulmonary electrical impedance tomography (EIT). The aim of this study was to examine the post-operative redistribution of regional ventilation after lung surgery dependent on the side of surgery and its association with forced vital capacity. Methods: In this prospective, observational cohort study 13 patients undergoing right and 13 patients undergoing left-sided open or video-thoracoscopic procedures have been investigated. Pre-operative measurements with EIT and spirometry were compared with data obtained 3 days post-operation. The center of ventilation (COV) within a 32 × 32 pixel matrix was calculated from EIT data. The transverse axis coordinate of COV, COVx (left/right), was modified to COVx′ (ipsilateral/contralateral). Thus, COVx′ shows a negative change if ventilation shifts contralateral independent of the side of surgery. This enabled testing with two-way ANOVA for repeated measurements (side, time). Results: The perioperative shift of COVx′ was dependent on the side of surgery (P =.007). Ventilation shifted away from the side of surgery after the right-sided surgery (COVx′-1.97 pixel matrix points, P