Base deficit as an early marker of coagulopathy in trauma
Background. The acute coagulopathy of trauma is associated with hypoperfusion, metabolic acidosis and an increased mortality rate. Biochemical markers of hypoperfusion, namely base deficit (BD) and lactate, are commonly used to assess the degree of hypoperfusion. Early identification of hypoperfusion and acidosis using BD and lactate may help predict the development of coagulopathy in trauma patients and direct therapy.
Objectives. To identify whether a correlation exists between BD, lactate, injury severity, early-onset coagulopathy and mortality.
Methods. A retrospective chart analysis was undertaken of patients transferred directly from scene to the level I trauma unit at Inkosi Albert Luthuli Central Hospital, Durban, South Africa, from 2007 to 2008. Patients with evidence of hypoperfusion were selected. Hypoperfusion was defined as a base deficit >-2 and coagulopathy as an International Normalized Ratio (INR) of >1.2. BD, lactate, chloride, temperature, Injury Severity Score (ISS), INR and mortality were recorded in this cohort. Student’s t-test and Fisher’s exact test were used for continuous and categorical variables, respectively. Correlation curves were used to determine the degree of association between the variables BD, lactate and ISS with respect to the INR. A p-value of <0.05 was considered statistically significant.
Results. Of the 28 patients, males (n=18) accounted for 64.3% of admissions. The mean age was 31 years (range 1 - 75 years, median 30 years). The mechanism of injury was penetrating trauma in 5 cases (17.9%) and blunt trauma in 23 (82.1%). The median ISS was 24 (range 4 - 59). In 16 patients (57.1%) the INR was within normal limits, but in 12 (42.9%) it was over 1.2. There was a significant correlation between BD, ISS and INR (r=0.393; p=0.019 and r=0.565, respectively; p<0.001). Lactate showed a weak and non-significant association with the INR (r=0.232; p=0.18). There were a total of 12 deaths (42.8%) in this cohort of patients with biochemical evidence of hypoperfusion. There was a significant increase in mortality in patients with evidence of hypoperfusion and an elevated INR (75.0% v. 18.7%; p=0.006).
Conclusion. BD but not lactate correlates with the development of the coagulopathy of trauma. The ISS showed a significant correlation with coagulation disturbances, and the combination of hypoperfusion and coagulopathy was associated with a significant increase in mortality.