Relationship between the updated oxygen reserve index and arterial partial pressure of oxygen: a prospective observational study
Abstract Introduction The oxygen reserve index (ORi™), a non-invasive variable that continuously reflects oxygenation, was first reported in 2016. With the 2018 update of ORi, the scaling between 0.00 and 1.00 was modified. This article provides a follow-up report on the relationship between the upd...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2025-06-01
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| Series: | JA Clinical Reports |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s40981-025-00796-7 |
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| Summary: | Abstract Introduction The oxygen reserve index (ORi™), a non-invasive variable that continuously reflects oxygenation, was first reported in 2016. With the 2018 update of ORi, the scaling between 0.00 and 1.00 was modified. This article provides a follow-up report on the relationship between the updated ORi and arterial partial pressure of oxygen (PaO2), based on our previous study using the original version of ORi. Methods The updated ORi version analyzed in the present study used a Revision M sensor. Twenty adult patients who were scheduled for surgery under general anesthesia with arterial catheterization were enrolled. After induction of general anesthesia, arterial blood gas analysis was performed with the fraction of inspiratory oxygen (FiO2) set at 0.33. The PaO2 and ORi at the time of blood collection were recorded. After that, FiO2 was changed to achieve an ORi of around 0.5, 0.2, or 0, followed by arterial blood gas analysis. The relationship between ORi and PaO2 was then investigated using the data obtained. Results Seventy-six datasets from the 20 patients were analyzed. When PaO2 was < 240 mmHg (n = 73), linear regression analysis showed a relatively positive correlation (r 2 = 0.4683). The cut-off ORi value obtained from the receiver operating characteristic curve to detect PaO2 ≥ 150 mmHg was 0.45 (sensitivity 0.833, specificity 0.810). Four-quadrant plot analysis demonstrated that ORi has good trending ability with respect to PaO2 (concordance rate was 100.0%). Conclusion Although the original and updated versions of ORi demonstrate similar properties regarding their ability to track PaO2 changes, the updated version has a wider absolute value range. Therefore, caution is warranted when interpreting ORi values, as absolute values may vary significantly between versions, even at the same PaO2 level. |
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| ISSN: | 2363-9024 |