Minimizing admission laboratory testing in trauma patients: use of a microanalyzer

Routine admission laboratory test protocols in injured patients are costly and involve excessive phlebotomy and turnaround time. The purpose of this prospective study was to evaluate the utility of (1) a microanalyzer, NOVA-SP5 (which provides rapid results on minimal blood volume), and (2) each component of our standard laboratory test battery.

Laboratory test results for 200 consecutive injured patients admitted to a level I trauma center were evaluated by paired sample analysis. Our standard battery [60 mL: ($348): type and screen, complete blood count, PT/PTT, electrolytes, BUN, creatinine, glucose, calcium, amylase, ethanol level, and arterial blood gas] run "stat" in the central laboratory was compared to the microanalyzer profile [< 1 mL: ($182): hemoglobin, hematocrit, electrolytes, glucose, Ca2+, and arterial blood gas] run by the trauma team in the resuscitation area. Patient data and laboratory turnaround time (from time of admission to time results obtained) were recorded. Data were analyzed by linear regression.

Components of the paired samples correlated well (r2 0.78 to 0.99). Turnaround times were 64 (+/- 3) and 6 (+/- 1) minutes for standard analysis and microanalysis, respectively. Only two of the 26 patients requiring emergent surgical procedures had standard results available preoperatively. These patients had twice as many laboratory abnormalities as the remainder. Minimal diagnosis or intervention resulted from those values exclusive to standard analysis (white blood count, amylase, ethanol level, BUN, creatinine, platelet count, PT, and PTT). Six of ten abnormal BUN or creatinine results normalized, including two values in patients who received contrast for portable intravenous pyelography, and in all patients without a history of hypertension or diabetes. Platelet count and PT/PTT were normal in 85% of non-head-injured patients, compared with 58% of those with GCS score < or = 8.

Microanalysis is accurate, expedient, conserves blood, and is sufficient for evaluation of most trauma patients. Those with hypertension, diabetes, or severe head trauma may require additional testing. Routine use of this technique could reduce cost substantially ($16,000/100 patients). The role of microanalysis in follow-up laboratory evaluation of injured patients remains to be elucidated.