Ultrasonography evaluation of the inferior vena cava collapsibility index and the superior vena cava distensibility index for predicting hypotension during general anesthesia in atrial fibrillation patients：a prospective observational study

Background: Atrial fibrillation (AF) is a prevalent arrhythmia, the ineffective contraction of the atria leads to a decrease in effective cardiac output. AF patients are prone to hypotension during anesthesia, especially in the early stages of general anesthesia. We explored whether the inferior vena cava collapsibility index (IVCCI) or the superior vena cava distensibility index (SVCDI) could predict the occurrence of post-induction hypotension (PIH) and early intraoperative hypotension (eIOH) in AF patients. Methods: A total of 77 AF patients undergoing left atrial appendage occlusion under general anesthesia were included in this study. The inferior vena cava was measured before induction and the superior vena cava after induction. The main outcome was the ultrasound measurements of IVCCI and SVCDI in AF patients and theirassociation with hypotension during general anesthesia. Hypotension was classified as the mean arterial pressure (MAP) below 60 mmHg or more than 20% below the baseline level. The correlation between IVC-CI, SVC-DI and the percentage decrease in MAP was assessed. Receiver operating characteristic (ROC) curves of IVC-CI, SVC-DI were separately generated to predict PIH and eIOH. Logistic regression was employed to validate the risk factors for PIH and eIOH in AF patients. Results: AF patients who developed PIH had a significantly higher IVCCI (P<0.001) and developed eIOH had a significantly higher SVCDI (P<0.001). ROC curve analysis showed that IVCCI had an accuracy of 85% to predict PIH at a cut-off point more than 34.1% (P<0.001). SVCDI had an accuracy of 86% to predict eIOH at a cut-off point more than 17.8% (P<0.001). After adjusting for confounding variables, IVCCI was an independent predictor of PIH ( P <0.001), while SVCDI was an independent predictor of eIOH ( P <0.001). Conclusion: Preoperative IVCCI>34.1% indicates a non-invasive predictor of PIH in AF patients; SVCDI>17.8% suggest a reliable predictor of eIOH in AF patients. Trial registration: This trial was registered on June 27, 2023 at the China Clinical Trial Center (http://www.chictr.org.cn; No. ChiCTR2300072846).