Gastric reactance as a marker for major perioperative complications in high-risk cardiac surgery patients undergoing cardiopulmonary bypass

Background: Gastric reactance (XL) is a bioelectrical property of the stomach lining that responds to changes in gut perfusion. It is measured through bioimpedance spectroscopy, a technology that assesses the tissue's electrical resistance and capacity to store electrical charge, providing insight into the physiological state of the gastric mucosa. Objective: This prospective observational study explored the relationship between XL and hemodynamic variables in high-risk adult patients undergoing elective cardiac surgery with cardiopulmonary bypass (CPB) at the National Institute of Cardiology, Mexico City. Methods: A binary composite endpoint was constructed to aggregate major perioperative complications into a single outcome measure. The sample size was calculated based on anticipated event rates. Associations among variables were examined using nonparametric statistical tests. Predictive performance, including confidence intervals, was estimated using bootstrapped receiver operating characteristic (ROC) curves. Results: Thirty-seven patients were enrolled and categorized according to the development of major perioperative complications (MPOC; n = 23) or absence thereof (Non-MPOC; n = 14). Baseline demographic and intraoperative variables did not differ significantly between groups. However, the MPOC group exhibited higher postoperative severity scores (APACHE II: 21.5 vs. 18.5, p = 0.231; SOFA: 12.5 vs. 12.0, p = 0.249) and greater postoperative bleeding (1.0 L vs. 0.4 L, p < 0.001). XL minimum values (XL_Min) were consistently elevated in the MPOC group throughout all perioperative events, with a significant shift of 6.14 -jΩ (95% CI [1.06, 11.34], p = 0.022) in Post-CPB. Conclusion: These findings suggest that gastric impedance spectroscopy is a safe and feasible technique for intraoperative and postoperative monitoring, and that elevated XL_Min values may aid in the early identification of patients at risk for MPOC by detecting gastric mucosal hypoperfusion during high-risk cardiac surgery.