Evaluation of Inferior Vena Cava Collapsibility Index as a Predictor of Hypotension Following General Anaesthesia with Thiopentone Induction: An Observational Study

Introduction: Hypotension during surgery can significantly increase morbidity and mortality. Volume depletion poses a major risk for intraoperative hypotension. The role of the Inferior Vena Cava Collapsibility Index (IVCCI) in assessing volume status is crucial, but its utility in predicting hypotension after the induction of general anaesthesia has been less evaluated.Aim: To evaluate the usefulness of IVCCI in predicting post induction hypotension after general anaesthesia, with the primary objective being to assess the correlation between IVCCI and hypotension.Materials and Methods: An observational study was conducted in the Department of Anaesthesiology and Critical Care, Pt. B.D. Sharma, PGIMS, Rohtak, Haryana,India. Total 100 patients scheduled for elective surgery under general anaesthesia with thiopentone induction. IVCCI was measured preoperatively in spontaneously breathing patients. The patients were grouped into CI+ (Collapsible) and CI-(Non collapsible) groups based on IVCCI values of >= 50% and <= 50%, respectively. Haemodynamic parameters were recorded for up to one hour after anaesthesia induction. Hypotension was defined as a fall of more than 20% in Systolic Blood Pressure (SBP) or SBP <90 mmHg or a mean blood pressure of <60 mm Hg. Receiver Operating Characteristic (ROC) curve was used to evaluate the performance of IVCCI, and multivariate logistic regression was employed to identify predictors of hypotension. Independent t-test was used for quantitative associations, while Chi-square and Fisher's-exact test were used for qualitative associations, with a p-value <0.05 considered significant.Results: The mean age of the patients in the study was 42.11 +/- 12.6 years. Out of 100, total 44 patients experienced post-induction hypotension, which was significantly higher in females compared to males (p-value=0.02). The mean Basal Metabolic Index (BMI) of the study population was 21.2 +/- 3.06 kg/m2, but hypotension was more common in underweight patients with a BMI <18.5 kg/ m2 (p-value=0.0007). The results showed a significant correlation between IVCCI and hypotension (p-value<0.05). The mean value of IVCCI (%) was 47.34 +/- 6.96 in hypotensive patients, which was significantly higher than non hypotensive patients with a mean of 28.45 +/- 7.05 (%) (p-value<0.0001). The ROC curve demonstrated an excellent representation of IVCCI (%) (Area Under the ROC Curve (AUC) 0.944; 95% CI: 0.879 to 0.980) in predicting hypotension, with a sensitivity of 95.5% and specificity of 94.6% for hypotension. IVCCI (%) was a significant independent risk predictor of hypotension with a cut-off point of >38, as determined by performing multivariate logistic regression.Conclusion: Preoperative assessment of IVCCI is highly sensitive and specific for prediction hypotension induced by general anaesthesia. It is recommended as a screening tool for high-risk patients.