Hematocrit has Limited Prognostic Value in Penetrating Trauma

Abstract & Commentary

Source: Paradis NA, et al. Hematocrit as a predictor of significant injury after penetrating trauma. Am J Emerg Med 1997;15:224-228.

This study attempts to clarify the role of hematocrit (HCT) in the initial evaluation of patients with penetrating thoracoabdominal trauma. Sixty adults with penetrating injuries to the trunk had serial determinations of HCT at the time of presentation and at 15 and 30 min afterward. The subjects were classified as having sustained serious injury when they required operative intervention for hemostasis or had autopsy findings of hemorrhagic death; patients not requiring surgery and recovering uneventfully were classified as having non-serious injury.

Paradis and colleagues found that seriously injured patients had a lower HCT at the time of arrival than did non-seriously injured patients (mean HCT; 35% vs 41%). However, no threshold HCT value was found to be a clinically useful marker of serious injury. A normal HCT at 15 and 30 min after presentation was a good predictor of absence of serious injury, but a low HCT was a poor predictor of the presence of serious injury. The mean change in HCT in the first half-hour did not differ between seriously and non-seriously injured patients, although a change in HCT of at least 6.5% from baseline did predict serious injury.

COMMENT BY DAVID J. KARRAS, MD

This study needs to be interpreted cautiously. Although seriously injured patients were more likely than non-seriously injured patients to have a large drop in HCT in the first 15 min, this group also received far more intravenous fluids over the same period of time (914 cc vs 348 cc). The drop in HCT in seriously injured patients may thus be an artifact of the study. Furthermore, Paradis et al were unable to define an initial HCT value that serves as a sensitive, specific, or predictive marker of serious injury.

The conclusion I draw from these results is that physicians should not rely on the HCT in determining which penetrating injury victims require early surgical intervention. Indeed, penetrating injury to the abdomen is generally a clear indication for surgery, and the HCT would not be expected to be clinically useful in such cases.