Objective
To determine if pH measured at the time of hospital admission and corrected for PCO2 was an independent predictor of trauma survival.
Design
Phase 1 was a retrospective case-control analysis of 1708 patients, followed by multivariate multiple logistic regression analysis of a subset of 919 patients for whom the Revised Trauma Score (RTS), Injury Severity Score (ISS), and pH were available. Phase 2 was a prospective comparison of a mathematical model of survival derived in phase 1 (pH-TRISS) with the TRISS method in 508 of 1325 subsequently admitted trauma patients.
Setting
Urban level 1 trauma center.
Patients
All patients admitted with blunt or penetrating trauma during the study period.
Main Outcome Measures
Survival vs mortality.
Results
In phase 1, factors significantly associated with mortality by t test and 
2 analysis included the RTS, ISS, Glasgow Coma Scale, corrected pH (CpH), and sum of the head, chest, and abdominal components of the Abbreviated Injury Scale–85 (AIS85) (HCAISS) (for all, P<.0001). The TRISS statistic was also a significant predictor of survival (P<.004). Age, sex, and the extremity and soft tissue components of the AIS85 were not associated with mortality. In a multivariate analysis of the RTS, HCAISS, and CpH, all were significant predictors of mortality. Even when controlling for RTS and HCAISS, CpH remained a significant predictor of mortality (P<.008). In phase 2, when pH-TRISS was tested prospectively against TRISS in a new group of patients, the new statistic appeared to provide a more accurate prediction of survival.
Conclusions
The arterial pH measurement obtained on hospital arrival and corrected for PCO2 is a significant independent predictor of survival and adds to the predictive accuracy of the TRISS survival statistic. Age, sex, and the extremity and soft tissue components of the AIS85 did not contribute to the accuracy of the TRISS statistic in this patient population.
(Arch Surg. 1995;130:307-311)
