Comparison of respiratory rate and peripheral oxygen saturation to assess severity in trauma patients

Objective: Physiological variables are important in the assessment of trauma patients. The role of respiratory rate (RR) and peripheral oxygen saturation (SpO(2)) remains a matter of debate. We therefore assessed the role of RR and SpO2 in predicting death in trauma patients. Design: Prospective analysis of a multicentric cohort of trauma patients in 2002. Patients: A cohort of 1,481 trauma patients cared for by a prehospital mobile intensive care unit (mean age 38 +/- 17 years, 91% blunt and 9% penetrating trauma). Intervention: None. Results: Systolic arterial blood pressure, heart rate, Glasgow coma scale, RR and SpO(2) were recorded and the Injury Severity Score (ISS) and Trauma Related Injury Severity Score (TRISS) calculated. TRISSn was obtained by neutralizing RR. Systolic arterial blood pressure (99.9%), heart rate ( 99.9%), and Glasgow coma scale (99.3%) were recorded in most patients, but not RR (63%) and SpO(2) (67%). In patients with both RR and SpO(2) recording (n = 675), the discrimination and calibration of TRISS was not significantly modified when RR was neutralized. Whatever the manner of expressing RR and SpO(2) (continuous, five classes, dichotomous), none was significant in predicting mortality with TRISSn. Initial SpO(2) was abnormal (< 90%) and recorded again at the hospital in 97 patients, and the proportion of patients with a non-measurable SpO(2) significantly decreased (8 vs. 42%, p < 0.001) and measurable SpO(2) markedly increased (median 99 vs. 85%, p < 0.001). Conclusion: Respiratory rate and SpO(2) do not add significant value to other variables when predicting mortality in severe trauma patients.