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

Sinert R, Zehtabchi S, Bloem C, Lucchesi M. Acad Emerg Med. 2006 Dec;13(12):1269-74. Epub 2006 Nov 1. Department of Emergency Medicine, State University of New York, Downstate Medical Center-Kings County Hospital Center, New York

BACKGROUND: 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.

OBJECTIVES: To test the diagnostic utility of BD in distinguishing minor from major injury after administration of NS.

METHODS: 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 inhematocrit 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.

RESULTS: 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.

CONCLUSIONS: Base deficit was able to distinguish minor from major injury after four hours of resuscitation, irrespective of the volume of NS infused.