Independent predictors of hyperoxemia following prehospital oxygen therapy: A prospective cohort study

Hyperoxemia is a potential consequence of prehospital oxygen therapy. However, data on independent predictors of hyperoxemia in patients managed by prehospital emergency medical services (PEMS) remain limited. This study aimed to identify factors associated with hyperoxemia in patients receiving prehospital oxygen therapy.

This prospective single-center cohort study was conducted in the emergency department of a tertiary-care hospital between May 2025 and February 2026. Adult patients transported by PEMS while receiving supplemental oxygen were enrolled. Demographic, hemodynamic, transport, oxygen delivery, and arterial blood gas data were recorded. Hyperoxemia was defined as PaO₂ >120 mmHg. Independent predictors were identified using multivariate logistic regression.

Of 245 patients, 60 (24.5%) had hyperoxemia on ED arrival. Hyperoxemic patients had higher intubation rates, longer transport durations, higher oxygen delivery rates, and higher ED SpO₂ levels (all p < 0.05). Multivariate analysis identified two independent predictors of hyperoxemia: intubation (OR 38.89, 95% CI 14.21-106.45) and transport duration ≥24 min (OR 13.74, 95% CI 4.43-42.66). ROC curve analysis revealed that an ED SpO₂ threshold of 96.5% predicted arterial hyperoxemia with an AUC of 0.70 (95% CI 0.62-0.77), sensitivity 0.57 (95% CI 0.43-0.69), and specificity 0.76 (95% CI 0.69-0.82).

Hyperoxemia was common among patients receiving prehospital oxygen therapy. These findings emphasize the importance of individualized oxygen titration and regular reassessment during transport, particularly in intubated patients and in those with longer transport durations, to reduce avoidable hyperoxemia.