Relationship between subclavian vein diameter and its collapsibility index with hypotension induced by general anesthesia in elderly patients undergoing gastrointestinal surgery: an observational study

Abstract Background Many studies have shown that the inferior Vena Cava (IVC) diameter and its collapsibility index are credible indicators for predicting fluid reactivity. For critically ill patients, the collapsibility index of subclavian vein (SCV) can replace the collapsibility index of IVC(IVC-CI) to evaluate patients' intravascular volume status. Methods A total of 188 elderly patients, aged 65 to 85 years, were recruited for gastrointestinal operation under general anesthesia. Ultrasonic measurements of SCV and IVC were performed before induction of general anesthesia. According to whether hypotension occurred after induction, patients were divided into the hypotension group and the non -hypotension group. The ROC curve was used to analyze the predictive value of ultrasonic measurements of SCV and IVC for hypotension after anesthesia induction. Pearson linear correlation analysis was conducted to evaluate the correlation between ultrasonic measurements and mini mental state examination (MMSE) scores. Results The maximum diameter of SCV(dSCVmax) and maximum diameter of IVC (dIVCmax) were unrelated to the percentage decrease in mean arterial blood pressure (MAP); the collapsibility index of SCV(SCV-CI) and IVC-CI were positively correlated with the percentage decrease in MAP with the correlation coefficients of 0.475 ( p < 0.001) and 0.577 ( p < 0.001), respectively. The areas under the curves (AUC) were 0.824 (0.759–0.889) for SCV-CI, and 0.874 (0.820–0.928) for IVC-CI. The optimal cutoff value of SCV-CI was 31.25% with a sensitivity of 71.7% and a specificity of 90.1%, while IVC-CI was 36.60% with a sensitivity of 85.9% and specificity of 79.0%. After adjusting for confounding variables, SCV-CI had a significant predictor on the occurrence of hypotension and percentage decrease in MAP after induction of anesthesia, similar to IVC-CI. The results of pearson correlation coefficient showed that SCV-CI(r=-0.472, p < 0.001) and IVC-CI (r=-0.422, p < 0.001) were negatively correlated with the postoperative MMSE scores. Conclusion dSCVmax was not correlated with hypotension after anesthesia induction, while SCV-CI, like IVC-CI, could make reliable prediction about the occurrence of hypotension and percentage decrease in MAP after anaesthesia induction in elderly patients undergoing gastrointestinal surgery; hypotension after induction of general anesthesia may be related to postoperative cognitive dysfunction. Trial registration: This study was registered in the Clinical Trial Registry of China on 05/06/2022 under the registration number ChiCTR2200060596