Early determinants of outcome in blunt injury

A critical set of 135 patients and a validation set of 202 patients who sustained blunt injury were examined for indices of outcome based on blood chemistry and the Glasgow coma scale. In both sets the nonsurvivors had significantly lower scores on the coma scale, higher levels of plasma glucose and increased leukocyte counts. Hypokalemia was also noted and a trend towards lower serum levels with increasing injury severity. Logistic discriminant analysis demonstrated that the most important variables were the coma scale score (as a continuous variable from 3 to 14) and the plasma glucose level (as a dichotomized variable with normal being defined as less than 10 mmol/L [i.e., the renal threshold] and abnormal as being above this level). A coma scale score cut-off at 10 with an abnormal plasma glucose level, and a cut-off at 8 with a normal plasma glucose level produced a maximum correct classification rate (into survivals and deaths) of 87%. Lower scores were associated with an increasing probability of death. Serum potassium levels and the leukocyte count did not contribute significantly to the discriminant function, although both were related to outcome. The reasons for the detected abnormalities are discussed. Metabolic markers, such as plasma glucose and serum potassium, in association with the coma scale score are simple and early determinants of outcome in blunt injury and may be useful indices of injury severity.