Evaluation of oxygen reserve index vs. Peripheral oxygen saturation for the prediction of hypoxemia in morbidly obese patients: a prospective observational study.

Abstract

BACKGROUND: Intraoperative anesthetic monitoring techniques have also been developed in parallel with the development of surgical instruments over the years. Blood pressure, heart rate, and blood oxygen saturation level are routinely monitored during intraoperative anesthesia.

AIM AND OBJECTIVE: To study the oxygen reserve index vs. peripheral oxygen saturation for the prediction of hypoxemia in morbidly obese patients.

MATERIAL AND METHODS: This was a prospective observational study conducted in the Department of Anaesthesia at a tertiary care hospital. Total 100 patients were included in this study, in which 50 were morbidly obese (BMI>40 Kg/m² ) and 50 were non obese (19<BMI<25 kg/m² ) undergoing an elective surgery requiring tracheal intubation. Oxygen reserve index sensor were placed and baseline values were recorded. The patients received preoxygenation until 90% of their end tidal expiratory oxygen concentration was attained.The breathing circuit was not attached to the tracheal tube until the SpO2 dropped to 95% during the induction of anaesthesia and tracheal intubation.Chi-square, t-test, and Mann Whitney U test were used for the study.

RESULTS: The total number of patients included in this study was one hundred, out of which fifty were non obese (19<BMI<25 Kg/m²) and fifty were morbidly obese (BMI > 40Kg/m² ). Out of which 38 were males and 62 were females and their age ages ranged from 19 to 72 years. The oxygen reserve index alert period was longer than the SpO2 alert period in both groups because the alert began before the SpO2 level reached 97%. The oxygen reserve index alert period was found to be 31 seconds for patients who were morbidly obese and 92 seconds for people with a normal body mass index. In contrast, the SpO2 alert period was found to be 13 seconds and 32 seconds for these patients.

CONCLUSION: Consequently, in morbidly obese patients, oxygen reserve index can act as an early warning system for detecting sudden hypoxia before saturation starts to decline.