Efficacy of Ultrasonographic Inferior Venacaval Collapsibility Index and Caval-Aorta Index for Averting Spinal Anaesthesia Induced Hypotension: A Randomised Controlled Trial

Background: USG hydration status assessment by Inferior venacava collapsibility index (IVCCI) & caval aorta index detects the early phase of hypovolemia caused by spinal anaesthesia. Objectives: To evaluate IVCCI & Caval Aorta index guided preoperative volume optimization in reducing the incidence of spinal induced hypotension (SIH), requirement of vasopressors, total fluid requirement & to correlate the utility of these indices in predicting SIH. Design: Randomized controlled trial. Setting: Operating room Single centric study during the period December 2020 to May 2022. Patients: Overall, 120 patients of 18-65 years, ASA I or II, scheduled for infraumbilical surgeries were randomly divided into Group A, Group B with IVCCI guided and caval aorta index guided volume correction respectively. Patients’ refusal for consent, need for IBP, Mean arterial pressure (MAP<70mmHg), contraindications for SAB and BMI>30kgm-2 were excluded. Interventions: USG guided hydration status optimization in preoperative period incorporating IVCCI & caval aorta index measurements before the commencement of Spinal anesthesia. Main outcome measures: The primary aim of this study was to compare the incidence of SIH between the groups. Results: Statistical Analysis was done in 158 patients with SPSS version19. After fluid correction Group A showed higher SIH 55.17% (32/58) than Group B 37.93% (22/58) P<0.0001 thus suggesting a significant reduction of hypotension in Group B (62%) than Group A (44.82%) P<0.0001. Dose of Vasopressors given intraoperatively were higher in Group A 34.48% (20/58) than Group B 17.24% (10/58) P<0.001. The total fluids given were approximately similar in both the groups (P>0.005) ROC analysis showed that Caval-Aorta index was a better predictor of SIH with 94.4% sensitivity,96.9% specificity & 74% accuracy with area under the curve (AUC) 0.956 when compared to IVCCI which showed 94.4% sensitivity, 65.6% specificity and 60% accuracy in predicting SIH with AUC of 0.793. Conclusion: Prespinal USG guided Caval aorta index directed fluid optimization reduces the incidence of SIH and vasopressor requirements and is found to be a superior predictor of SIH than IVC collapsibility index.