Base Deficit and Alveolar–Arterial Gradient During Resuscitation Contribute Independently But Modestly to the Prediction of Mortality After Burn Injury

Abstract

The main determinants of mortality after burn injury that can be measured on admission include age, total burn size (% burn), and inhalation injury (INHAL). Other variables, measured during resuscitation, may provide additional information about injury severity. We assessed the utility of early arterial blood gas (ABG) data in predicting mortality after burn injury. Data were limited to samples obtained during the first 2 days after burn injury and to those obtained during high-frequency percussive ventilation. Mean values for each patient's ABG data were calculated; subsequent analysis used these derived variables. Logistic regression analysis (LRA) was used to generate a mortality predictor using burn, age (as a cubic age score, AGE), and INHAL. LRA was then repeated with the ABG variables. A total of 162 patients were included. By univariate analysis, death was associated with increased alveolar-arterial gradient (AaDO2), AGE, % burn, full-thickness burn size, INHAL, and with decreased pH and base excess. LRA of % burn, AGE, INHAL, and full-thickness burn size retained the first three variables. The addition of ABG data demonstrated that mean burn excess and mean AaDO2 also contributed independently to mortality. However, there was no difference in accuracy (86%) between the two equations. By Kaplan Meier analysis, AaDO2 but not BE predicted earlier death in those who died. Measured during resuscitation, metabolic acidosis (ie, a base deficit) and oxygenation failure (ie, increased AaDO2) contributed independently, but modestly, to ultimate mortality after burn injury. The inclusion of these variables did not improve predictive accuracy. Whether therapies targeted at these endpoints would improve outcome is unknown.

Prospective comparison of packed red blood cell–to–fresh frozen plasma transfusion ratio of 4

“…Previous studies of burn resuscitation have demonstrated that base excess is a predictor of mortality in addition to age, TBSA, and inhalation injury. 34 Amelioration of acidosis in the 1:1 group, by correcting acidosis, may alter the trajectory of outcomes after burn injury. Further prospective studies will be necessary to confirm this hypothesis.…”

The Relationship of Serum Lactate and Base Deficit in Burn Patients to Mortality

“…6 Abnormalities of base deficit and lactate have been found to co-occur with appropriate urine output and blood pressure in burn patients during resuscitation. [7][8][9]11,13,14 Although these abnormalities suggest inadequate resuscitation, their precise role in the titration of therapy for burn shock remains ambiguous. Perhaps most important, were more aggressive fluid resuscitation to be pursued on the basis of measures of serum lactate or base deficit, the potential exists for increased secondary complications of resuscitation, including compartment syndromes and pulmonary failure.…”

Base excess

“…19 A more recent study of 162 patients with burn showed a correlation between BE and mortality. 20 A burn research group showed both retrospectively 21 and prospectively 22 that traditional end points such as MAP and urine output may be normal in the presence of a significantly abnormal BE. Similar to the patients with trauma, normalization of the BE in 24 hours is associated with decreased mortality.…”