Authors: Stannard B et al.
Anesthesia & Analgesia 141(6):1203–1210, December 2025.
Summary
This single-center retrospective cohort study evaluated 25,234 adult surgical patients with at least one intraoperative arterial blood gas obtained between 2008 and 2019. The investigators examined whether intraoperative occult hypoxemia—defined as SaO2 <88% despite SpO2 >92%—was associated with postoperative mortality.
Among more than 62,000 paired SaO2–SpO2 measurements, 351 patients (1.4%) had at least one occult hypoxemic event. Overall mortality in the cohort was 3.3% at 30 days and 10.2% at 1 year. After adjusting through propensity score overlap-weighted Firth logistic regression and Cox proportional hazards models, patients with at least one occult event showed nearly triple the odds of 30-day mortality (OR 2.89; 95% CI 1.46–5.72) and significantly higher 1-year mortality (HR 1.90; 95% CI 1.48–2.43).
No significant interaction was found between occult hypoxemia and self-reported race/ethnicity, indicating the mortality association was consistent across demographic groups. These results highlight the need to better detect patients whose true desaturation is missed by pulse oximetry and to strengthen intraoperative monitoring strategies.
Key Points
• Occult hypoxemia, though rare, is strongly linked to higher postoperative mortality.
• Even one occult event nearly triples the risk of death within 30 days.
• The association holds across racial and ethnic groups.
• Pulse oximetry may miss clinically important desaturation events in some patients.
• Improved detection strategies and identification of high-risk populations are needed.
Thank you for allowing us to use this article from Anesthesia & Analgesia.