ORI for Detection Of Hyperoxemia and Titration of Oxygen Therapy in Intensive Care: A Prospective Observational Cohort Study

INTRODUCTION: Hyperoxemia(PaO2>100mmHg) in intensive care unit(ICU) is associated with adverse events with high morbidity and mortality.(1) Pulse oximetry(SpO2) can detect only hypoxemia or normoxemia, but not hyperoxemia. Its detection primarily depends upon arterial blood gas(ABG), invasive technique. The Oxygen Reserve Index (ORI) is new, realtime, noninvasive parameter based upon a multi-wave pulse cooximetry that detects hyperoxemia.(2) OBJECTIVES: The primary objective was to evaluate the utility of ORI for the duration required to detect hyperoxemia in ICU patients. Secondary outcomes were to measure the incidence of hyperoxemia in ICU patients, time required for titration of oxygen therapy in hyperoxemic patients, number of ABGs required, complications associated with ABGs. MATERIALS AND METHODS: This was a prospective, single centre, observational study conducted in ICUs of All India Institute of Medical Sciences (AIIMS), New Delhi, India, from October 2023 to April 2024. RESULTS: The incidence of patients with hyperoxemia at presentation was 46 out of 90 cases recruited (51.1%). Mean duration required to detect hyperoxemia by using ABG and ORI device was 12.14 ± 3.97 and 2.34 ± 0.63 minutes respectively (p<0.001). Time required to titrate oxygen therapy below the hyperoxemic range was found to be 15.11 ± 15.64 hours. The mean number of ABGs required to titrate oxygen therapy was found to be 3.06 ± 1.06. 6 patients (6.6%) developed ABG needle puncture related complications. CONCLUSION: Use of ORI was associated with significant early detection of hyperoxemia in ICU patients. Also use of ABG was associated with significant delay in titrating oxygen therapy exposing patients to hyperoxemia for longer duration, in addition to the local complications associated with ABG procedure.