Initial Pulse Pressure and Shock Index Predict Mortality in Burn Patients

Abstract

Background: Burn injuries result in profound hemodynamic and cardiovascular dysfunction. Pulse pressure (PP) and shock index (SI) can be used to guide medical management in acute trauma settings however its application in acute burn settings is unknown. The purpose of this study was to determine whether pulse pressure and shock index on admission were early predictors of in-hospital mortality in burn patients. METHODS: This retrospective study analyzed burn patients admitted to John H. Stroger Hospital of Cook County in Chicago, Illinois, USA from 2013-2019. Inclusion criteria were patients aged >1 year with TBSA values ≥ 15%, 2nd and 3rd degree thermal injuries. Exclusion criteria included non-thermal burns, missing values and those dead on arrival.Variables studied were age, gender, TBSA, inhalation injury, Baux score, R-Baux score and vital signs (systolic blood pressure, diastolic blood pressure and heart rate) on arrival. SI and PP values were calculated from the vital signs. Baux and R-Baux score were calculated from data in the electronic medical records. Independent t-test compared mortality outcomes in survivors versus non-survivors. Pearson’s Chi square test compared mortality outcomes associated with gender and inhalation injury status. Adjusted odds ratio with corresponding 95% confidence intervals were calculated for R-Baux and SI. RESULTS: 108 burn patients were included in this study. Mean age was 40 years and 68 patients (64%) were male. Mean TBSA was 30% and inhalation injury was present in 30% (32/106) of the patients. Among eighteen non-survivors, fourteen (78%) had inhalation injury. For all patients, the mean Baux and R-Baux score were 70 and 75, respectively. Overall mortality rate was 17%.On bivariate analysis, mean SI in survivors and non-survivors was 0.7 and 1.0. Mean PP in survivors and non-survivors were 61 mmHg and 47 mmHg. Adjusted odds ratio (95% CI) for R-Baux and SI were 1.06 (1.03-1.09) and 26.48 (4.34-161.46), respectively. CONCLUSION: A lower PP and a higher SI on admission are predictors of mortality in patients with significant burns. SI is associated with 26-times higher likelihood of mortality. These initial parameters can help identify patients that may require close monitoring and aggressive resuscitation to improve survival rates in burn victims.