INTRODUCTION: Balanced general anesthesia technique is a popular choice for induction because it can minimize potential side effects from individual drugs when otherwise used alone. However, hypotension is still a common occurrence during induction. Perfusion Index (PI) has been used as a measure of systemic vascular resistance and has shown to predict hypotension after regional anesthesia and propofol induction. This study aimed to determine whether baseline PI can predict hypotension following balanced general anesthesia induction and determine a cut-off value where hypotension is expected to occur. METHODS: Thirty-five ASA I/II adults for elective surgery under general anesthesia were enrolled. Heart rate, blood pressure and PI were measured every minute from baseline to 5 minutes following induction and 10 minutes after endotracheal intubation. Hypotension was defined as fall in systolic BP (SBP) by >30% of baseline and/or mean arterial pressure (MAP) to <60 mmHg. Severe hypotension (MAP of <55 mm Hg) was treated. RESULTS: No hypotension was observed in the first 5 minutes. Within 10 minutes, hypotension occurred in 8.6% by SBP criterion and 2.6% by MAP criterion. Within 15 minutes, hypotension was seen in 5.7% by SBP and MAP criterion, respectively. PI showed very low (r < 0.2) to low (r = 0.2 to 0.39), negative to positive and insignificant correlation (p > 0.05) with hypotension whether using SBP or MAP criterion and whether observed at 10 or 15 minutes of anesthesia induction. The Area under the ROC curve is 0.397, 95% CI [0 .126, 0.667], p = 0.431. CONCLUSION This study lends inconclusive evidence on the usefulness of Innovo Deluxe Fingertip Pulse Oximeter with Plethysmograph and Perfusion Index to predict intraoperative hypotension following balanced general anesthesia induction for this sample of patients. However, there was a positive, moderate (r=0.538, 0.501 and 0.469) and significant (p<0.05) correlation between perfusion index and SBP, Diastolic BP and MAP, respectively.
oximetry ; hypotension ; Anesthesia, General ; arterial pressure ; blood pressure ; Perfusion index