Ultrasonographic Evaluation of Inferior Vena Cava: Aorta Index with a Cut-off Value of 1.0 as a Predictor for Hypotension after Induction of General Anesthesia; An observational study

Abstract

Background Hypotension after induction of general anesthesia (GA) is common due to pre-existing hypovolemia and has adverse effects on organ function. Out of several methods to predict post-induction hypotension, nowadays Inferior Vena Cava: Aorta (IVC: Ao) index has been studied with different cut-off values. However, limited studies have been performed in our part of the world.

Objective To evaluate the efficacy of pre-induction Inferior Vena Cava: Aorta index with a cutoff value of 1.0 for predicting the occurrence of post-induction hypotension after general anesthesia in the Nepalese population.

Method A total of 100 patients of ASA I and II, aged more than 18 years posted for elective surgeries under general anesthesia were enrolled in this cross-sectional, observational study. Ultrasonographic guided Inferior Vena Cava: Aorta index was calculated and based on a cut-off value of 1.0, two groups were formed. Seventy patients in group A with Inferior Vena Cava: Aorta index less than 1.0 and 30 patients in group B with Inferior Vena Cava: Aorta index more than 1.0 were enrolled. Vitals parameters were recorded every minute for five minutes after induction of general anesthesia. Incidence of hypotension was the primary outcome. Statistical analysis was done using student t-test, ANOVA test and Chi-square test.

Result Inferior Vena Cava: Aorta index with cut-off value of 1.0 predicted post-induction hypotension with excellent efficacy. Total 65 patients developed post-induction hypotension, out of which 63 patients had Inferior Vena Cava: Aorta index less than 1.0.

Conclusion We concluded that pre-induction Inferior Vena Cava: Aorta index with cut-off value of 1.0 have high diagnostic accuracy with high degree of sensitivity and specificity to predict hypotension after induction of general anesthesia.