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Introduction: Hypotension is likely to occur following induction of general anesthesia which can be aggravated by various factors like the drugs used for induction, pre-existing cardiac dysfunction due to various causes, preoperative mean arterial pressure, physical status, pulmonary function and intravascular volume status of the patient before induction .Preoperatively assessing the intravascular volume status to detect any latent hypovolemia and if found, its timely correction can prevent hypotension to a great extent. This study aims to assess the role of inferior vena cava ( IVC) diameter measurements in relation to respiration assessed just before surgery in predicting hypotension following induction of general anesthesia. i. To assess the preoperative ultrasonographic measurement of IVC diameter during expi Objective: ration ii. To assess the IVC diameter variation during respiratory cycle to derive the collapsibility index (CI) measured using ultrasound and to assess predictability of hypotension after induction using CI. This was a prospective study including 65 patients of either Methods: sex belonging to ASA Physical status I and II ,undergoing elective surgery under general anaesthesia in the Department of Anaesthesiology, Regional Cancer Centre Trivandrum. IVC measurement was recorded preoperatively in the preoperative holding area and the diameter measured at end expiration was taken as the maximum IVC diameter (IVC dmax). IVC collapsibility index (IVC CI) is the difference between maximum and minimum diameter divided by maximum diameter expressed as percentage. Heart rate (HR), non invasive blood pressure (NIBP) , mean arterial blood pressure (MABP) was recorded every 2 minutes for rst 10 minutes following induction of anaesthesia. Signicant hypotension was dened as >20% decrease in MABP from baseline. The performance of the IVC CI as a diagnostic tool for predicting hypotension dened as mean arterial pressure ≥ 20% drop from the baseline was evaluated by ROC curve analysis. The relation between signicant hypotension and IVC-CI was evaluat Results: ed using ROC curve analysis. We found the area under curve to be 0.892 and a cutoff of 0.40 (40% collapsibility) with 65 % sensitivity and 92 % specicity, positive predictive value of 92 % and accuracy of 76.92%. Using 45 % as cut off value for collapsibility index to predict hypotension, showed 100 % specicity and sensitivity of 50% with a positive predictive value of 100 % and accuracy of 70.7 % . Patients with Conclusion: an IVC collapsibility index of more than 45%, as assessed by ultrasonography, are more likely to develop signicant hypotension after induction of general anaesthesia.
Dayal et al. (Fri,) studied this question.