Monitoring of lactate and base deficit: what is their role in the predictive outcome of severe trauma?

Background

The evaluation of cellular metabolism in the critically ill patient, through measurement of the arterial lactate and arterial base deficit parameters, has proved to be a good means to guide the therapy and provide the outcome. We wanted to verify the prognostic ability of the blood lactate level and of the base deficit in patients with severe trauma surveyed during their recovery.

Methods

The values of the blood lactate level and of the base deficit were considered in 33 patients with severe trauma (ISS > 15) and observed from their arrival in the ICU (T0) for 24 hours (T24). The data of dead and live patients were analysed with the Student t statistical method.

Results

Ten of the 33 recovering (ISS 30) patients died. In the dead patients, medium values of lactate were more elevated than in discharged patients: T0 – dead patients 3.98 ± 4.03 mmol/l (min 0.5, max 11.8) vs live 2.13 ± 1.33 mmol/l (min 0.5, max 6.8); T24 -dead patients 2.57 ± 2.65 mmol/l (min 0.4, max 7.1) vs live 1.22 ± 0.86 mmol/l (min 0.4, max 4) (P = 0.037). The analysis of the trend of the base deficit cannot prove a statistically important difference: at T24 dead patients -2.57 ± 3.44 (min -9, max 2.1), and survivors 1.05 ± 7.18 (min -14, max 9.6) (P = 0.141).

Conclusion

The measurement of lactates seems to be a good index of prognosis. In particular, the values revealed during 24 hours are more predictable, perhaps because they are probable proof of the capacity of recovering the hypoperfusion of tissues and the anaerobic metabolism that is the cause of the development of organ failure and future complications. On the contrary, the analysis of the base deficit has less prognostic capacity because it is conditioned by other factors such as employed solutions, renal compensations, the rate of vascular filling and possible breathing deficit. In conclusion, the monitoring of blood lactate levels can be a good aid in guiding therapy in its initial phases and predicting the outcome of patients.