Oxygen reserve index versus conventional peripheral oxygen saturation for prevention of hypoxaemia

Abstract

BACKGROUND Hypoxaemia occurs frequently during paediatric laryngeal microsurgery. OBJECTIVE The oxygen reserve index is a noninvasive and continuous parameter to assess P aO2 levels in the range of 100 to 200 mmHg. It ranges from 0.0 to 1.0. We investigated whether monitoring the oxygen reserve index can reduce the incidence of SpO2 90% or less. DESIGN Randomised controlled trial. SETTING A tertiary care paediatric hospital. PARTICIPANTS Paediatric patients aged 18 years or less scheduled to undergo laryngeal microsurgery. INTERVENTION The patients were randomly allocated to the oxygen reserve index or control groups, and stratified based on the presence of a tracheostomy tube. Rescue intervention was performed when the oxygen reserve index was 0.2 or less and the SpO2 was 94% or less in the oxygen reserve index and control groups, respectively. MAIN OUTCOME MEASURE The primary outcome was the incidence of SpO2 90% or less during the surgery. RESULTS Data from 88 patients were analysed. The incidence of SpO2 ≤ 90% did not differ between the oxygen reserve index and control groups [P = 0.114; 11/44, 25 vs. 18/44, 40.9%; relative risk: 1.27; and 95% confidence interval (CI): 0.94 to 1.72]. Among the 128 rescue interventions, SpO2 ≤ 90% event developed in 18 out of 75 events (24%) and 42 out of 53 events (79.2%) in the oxygen reserve index and control groups, respectively (P < 0.001; difference: 55.2%; and 95% CI 38.5 to 67.2%). The number of SpO2 ≤ 90% events per patient in the oxygen reserve index group (median 0, maximum 3) was less than that in the control group (median 0, maximum 8, P = 0.031). CONCLUSION Additional monitoring of the oxygen reserve index, with a target value of greater than 0.2 during paediatric airway surgery, alongside peripheral oxygen saturation, did not reduce the incidence of SpO2 ≥ 90%.