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Updated: Jun 18, 2025
A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Oxygen reserve index versus conventional peripheral oxygen saturation for prevention of hypoxaemia: A randomised
Eun-Hee Kim1, Jung-Bin Park, Pyoyoon Kang
1From the Department of Anaesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Republic of Korea (E-HK, J-BP, PK, S-HJ, Y-EJ, J-HL, H-SK, J-TK).
Insights
Monitoring the oxygen reserve index (ORI) did not reduce the incidence of low oxygen saturation (SpO2 ≤ 90%) during pediatric laryngeal microsurgery. However, ORI monitoring was associated with fewer severe low oxygen events per patient.
Area of Science:
- Anesthesiology and Perioperative Medicine
- Pediatric Surgery
- Respiratory Physiology
Background:
- Hypoxemia is a frequent complication during pediatric laryngeal microsurgery.
- The oxygen reserve index (ORI) is a noninvasive parameter for assessing oxygenation, particularly useful in the 100-200 mmHg PaO2 range.
Purpose of the Study:
- To investigate whether monitoring the oxygen reserve index (ORI) can decrease the occurrence of SpO2 ≤ 90% during pediatric laryngeal microsurgery.
- To evaluate the effectiveness of ORI monitoring as an adjunct to standard pulse oximetry in preventing hypoxemia.
Main Methods:
- Randomized controlled trial conducted in a tertiary care pediatric hospital.
- Paediatric patients (≤ 18 years) undergoing laryngeal microsurgery were randomly assigned to either the ORI monitoring group or the control group.
- Rescue intervention was triggered by ORI ≤ 0.2 or SpO2 ≤ 94% (control group).
Main Results:
- The incidence of SpO2 ≤ 90% did not significantly differ between the ORI and control groups (25% vs. 40.9%, P=0.114).
- However, the number of SpO2 ≤ 90% events per patient was significantly lower in the ORI group (median 0) compared to the control group (median 0, P=0.031).
- While the overall incidence of severe hypoxemia was not reduced, the ORI group experienced fewer severe low oxygen events per patient.
Conclusions:
- Additional monitoring of the oxygen reserve index (ORI) with a target value > 0.2 did not reduce the primary outcome of SpO2 ≤ 90% during pediatric airway surgery.
- Despite not meeting the primary endpoint, ORI monitoring was associated with a reduction in the frequency of severe hypoxemic events per patient.
Background:
Hypoxaemia occurs frequently during paediatric laryngeal microsurgery.
Objective:
The oxygen reserve index is a noninvasive and continuous parameter to assess PaO2 levels in the range of 100 to 200 mmHg. It ranges from 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%.
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