Exploratory clinical trial on the acoustic variability index for predicting fluid responsiveness during hepatectomy

The acoustic variability index (AVI), derived from continuous phonocardiographic analysis of heart sounds via an esophageal stethoscope, is a novel minimally invasive method for intraoperative hemodynamic monitoring. We evaluated the ability of AVI to predict fluid responsiveness in patients undergoing hepatectomy and compared its performance with that of the conventional indices. Forty adult patients who underwent hepatectomy were enrolled in this prospective, single-center observational study. After major surgical resection and stabilization, a 500 mL crystalloid fluid challenge was administered. Hemodynamic parameters including AVI, central venous pressure (CVP), stroke volume variation (SVV), and pulse pressure variation (PPV) were recorded before and after volume expansion. Patients with ≥ 10% increase in cardiac output (CO) were defined as responders. Thirty-seven patients were included in the final analysis, of which 12 (32.4%) were classified as responders. After fluid loading, responders showed a significant decrease in AVI (11.4% ± 2.5% to 7.8% ± 2.9%, p = 0.004), while non-responders showed no significant change (7.1% ± 3.2% to 6.3% ± 3.0%, p = 0.356). AVI demonstrated predictive performance comparable to SVV and PPV, with an optimal cutoff of > 9.8% and an area under the receiver operating characteristic curve of 0.873 (95% CI: 0.743–0.967). Real-time intraoperative monitoring of the AVI shows potential as a predictor for fluid responsiveness in patients undergoing hepatectomy. AVI offers a promising, minimally invasive approach for guiding fluid therapy. Further research is warranted to validate its utility in broader surgical populations.