A simple predictive formula for the blood requirement in patients with high-energy blunt injuries transferred within one hour post-trauma

Abstract

Aims: To recognize patients who require massive transfusion at the early stage of blunt trauma, we retrospectively investigated patients with high-energy blunt injuries transferred within 1 h post-trauma.

Methods: Between August 2007 and July 2011, 233 trauma patients were: (i) injured by a high-energy blunt mechanism with Injury Severity Score ≥9; (ii) not dead on arrival; (iii) older than 9 years; and (iv) at our center within 1 h after injury. The findings for 113 of those patients were analyzed, including those produced by ultrasonography, computed tomography, and arterial blood gas analyses.

Results: Of 113 patients, 33 underwent massive transfusion (≥6 units) within 8 h of arrival. A logistic regression analysis revealed that an arterial lactate level ≥28 mg/dL (P < 0.001; odds ratio, 105.11; 95% confidence interval, 12.58-2,718.84) and a flat ratio of the inferior vena cava on computed tomography ≥3 (P < 0.001; odds ratio, 32.50; 95% confidence interval, 4.44-714.44) were significant independent predictors for a massive transfusion within 8 h. In a receiver operating curve analysis, the area under the curve of the need for massive transfusion was 0.956, with a sensitivity of 0.94 and a specificity of 0.90. A linear predictive formula for the probability (P) of receiving a massive transfusion was generated as P = 2 × lactate (mg/dL) + 15 × the flat ratio of inferior vena cava - 103. Using another 52 trauma patients, the formula was validated.

Conclusions: An elevated level of arterial lactate and the flat ratio of inferior vena cava were significant predictors for identifying the patients who would require a massive transfusion in the early stage after high-energy blunt trauma.

Keywords: Arterial blood gases; flat ratio; inferior vena cava; lactate; massive transfusion; trauma.

Figure 1

Receiver operator curves were generated to evaluate the predictive strength of the most important factors for a massive transfusion: the lactate level, focused assessment with sonography for trauma (FAST) positive findings, and the flat ratio of the inferior vena cava (IVC). When a combination of the lactate level and the flat ratio of the IVC was used, the area under the curve (AUC) was increased up to 0.956, with a sensitivity of 0.940, a specificity of 0.90, a false positive ratio of 0.07, and a false negative ratio of 0.02. A linear predictive formula for the probability of needing a massive transfusion using the lactate level and the flat ratio of the IVC was generated, as follows: P = 2 × lactate (mg/dL) + 15 × the flat ratio of the IVC − 103.

Figure A1

Receiver operator curve was generated to evaluate the predictive strength of the predictive formula for a massive transfusion. The area under the curve was 0.891, with a sensitivity of 0.84, a specificity of 0.94, a false positive ratio of 0.11, and a false negative ratio of 0.09.