Filtered signal-averaged P-wave duration during pneumoperitoneum in patients undergoing laparoscopic cholecystectomy: A reflection of pathophysiological cardiac changes

Background: Induction of pneumoperitoneum (PP) may lead to adverse cardiac functions secondary to changes such as decreased venous return and hypercarbia. The assessment of cardiac electrical activity by signal averaging may reflect various hemodynamic derangements and serve as a prognostic marker for arrhythmias. The aim of the study is to examine characteristic electrocardiographic changes that may occur during PP, by using signal-averaged P-wave analysis. Methods: Twenty healthy (ASA I and II) patients were enrolled in a prospective paired control study, and underwent elective laparoscopic cholecystectomy. A standard ECG together with computerized filtered signal-averaged P-wave duration measurement (leads X, Y, Z) were carried out during awareness, under anesthesia before and during PP, and after CO ₂ evacuation. Depth of anesthesia was controlled by bi-spectral index (BIS). Results: An increased duration of P-wave was observed during PP in comparison to the anesthesia phase before PP (111 versus 115 ms, t-test and Wilcoxon signed rank test). A significant increase was also detected in the maximal value of P-wave duration between these phases of the operation. The difference in the number of patients in whom the duration increased by at least 5 ms was also found to be significant. Conclusions: Primarily, a decreased P-wave duration was expected, due to cardiac autonomic sympathetic predominance during PP. Its prolongation during PP may reflect some cardiac pathophysiological (structural and functional) changes, including influence on cardiac ion channels during depolarization. Usually, clinical consequences related to laparoscopic cholecystectomy are absent, but clinical awareness should be maintained for cardiac diseased patients undergoing prolonged laparoscopic procedures.