Effect of normal saline infusion on the diagnostic utility of base deficit in identifying major injury in trauma patients.

Abstract

Base deficit (BD) is a reliable marker of metabolic acidosis and is useful in gauging hemorrhage after trauma. Resuscitation with chloride-rich solutions such as normal saline (NS) can cause a dilutional acidosis, possibly confounding the interpretation of BD. To test the diagnostic utility of BD in distinguishing minor from major injury after administration of NS. This was a prospective observational study at a Level 1 trauma center. The authors enrolled patients with significant mechanism of injury and measured BD at triage (BD-0) and at four hours after triage (BD-4). Major injury was defined by any of the following: injury severity score of > or =15, drop in hematocrit of > or = 10 points, or the patient requiring a blood transfusion. Patients were divided into a low-volume (NS < 2L) and a high-volume (NS 2L) group. Data were reported as mean (+/-SD). Student's t- and Wilcoxon tests were used to compare data. Receiver operating characteristic (ROC) curves tested the utility of BD-4 in differentiating minor from major injury in the study groups. Four hundred eighty-nine trauma patients (mean age, 36 [+/-18] yr) were enrolled; 82% were male, and 34% had penetrating injury. Major-(20%) compared with minor-(80%) injury patients were significantly (p = 0.0001) more acidotic (BD-0 mean difference: -3.3 mmol/L; 95% confidence interval [CI] = -2.5 to -4.2). The high-volume group (n = 174) received 3,342 (+/-1,821) mL, and the low-volume group (n = 315) received 621 (+/-509) mL of NS. Areas under the ROC curves for the high-volume (0.63; 95% CI = 0.52 to 0.74) and low-volume (0.73; 95% CI = 0.60 to 0.86) groups were not significantly different from each other. Base deficit was able to distinguish minor from major injury after four hours of resuscitation, irrespective of the volume of NS infused.