Association Between Percutaneous Oxygen Saturation and Mortality of Patients with Mild Traumatic Brain Injury at ICU Admission: An Analysis of the MIMIC-III Database

Introduction Research related to the result of patients with mild traumatic brain injury and the role of percutaneous oxygen saturation (SpO2) level is rarely reported. Our study investigated the relationship between SpO2 and the 30- and 90-day mortality among patients with mild TBI. Methods A total of 1027 patients with mild TBI [Glasgow Coma Scale (GCS) > 12] were enrolled from the Medical Information Mart for Intensive Care (MIMIC-III) database. The patients were classified into low-SpO2 (< 95%), moderate-SpO2 (95–98%), and high-SpO2 groups (> 98%). With 30- and 90-day mortality rates as the main outcomes, Cox regression and confined cubic spline models were adopted. Results There was a U-shaped curve in confined cubic splines for the relationship between SpO2 and mortality. Compared with the moderate-SpO2 group, the high-SpO2 group exhibited a much higher risk of mortality after modification, with hazard proportions of 2.108 (95% CI 1.211–3.670, P < 0.05) for the 30-day mortality and 1.760 (95% CI 1.140–2.720, P < 0.05) for the 90-day mortality, and the low-SpO2 group exhibited a much higher risk of mortality after modification, with hazard proportions of 2.215 (95% CI 1.194–4.110, P < 0.05) for the 90-day mortality. Conclusion Among patients with mild TBI, the correlation between SpO2 level and 30- and 90-day mortality followed a U-shaped curve. Both low and high SpO2 level exerted potential harmful effects on the outcomes of patients with mild TBI. The SpO2 range of 95–98% could be the optimal SpO2 level for mild patients with TBI.