Acidosis and mortality in severe sepsis and septic shock evaluated by base excess variation

Introduction

Hypoperfusion in sepsis may be identified by lactate levels, but there are many other unmeasured acids that may be better represented by negative base excess (BE). Successful resuscitation should be followed by increased BE.

Objective

To evaluate the utility of BE variation in mortality in severe sepsis (S) and septic shock (SS).

Methods

A prospectively collected database was retrieved for BE at days 1 and 3 (D1 and D3), APACHE II, lactate, creatinine, albumin, and mortality at 28 days. Patients with S or SS were included, except if renal failure was diagnosed at D1 (creatinine > 3.5 mg/dl; diuresis < 500 ml). Patients were classified as increased (less acidosis) BE vs decreased BE, based on the difference between D1 and D3.

Results

Forty patients had a mean (± standard deviation) age of 48.4 (± 19.8) years, and an APACHE II score of 19.6 (± 9.1). At D1 and day 14, 20% and 65% of patients were in SS, respectively. Table 1 summarizes the main findings. Binary logistic regression analysis showed that only the APACHE II score (odds ratio 1.114) and a decreasing BE from D1 to D3 (odds ratio 5.687) were independent predictors of mortality. Kaplan–Meier survival curves are shown in Figure 1.

Figure 1

Twenty-eight day survival.

Table 1

Conclusions

In patients with S and SS, increased BE from D1 to D3 seems to be a good predictor of morbidity and mortality, and may be considered a possible goal.