Admission Temperature and Survival in Patients Admitted to Burn Centers

Abstract

It is commonly believed that hypothermia occurring during burn resuscitation is associated with poor outcome, but there is little direct supporting evidence. The authors conducted an analysis of a statewide trauma registry to determine whether hypothermia (T ≤36.5°C) was associated with mortality when controlling for clinical confounders. They included all patients treated at an accredited burn center from 2000 to 2011 where the trauma registrar recorded the primary injury type as a burn. They excluded records with missing data and nonphysiologic temperature (<26°C or >42°C). The primary exposure of interest was hypothermia. The authors constructed a hierarchical, multivariable logistic regression model to examine the effect of hypothermia on survival, controlling for potentially confounding variables. Predictors of mortality are presented as odds ratio (95% confidence interval). Primary burn injury was coded 17,098 times during the study period. Of these, 3809 were not treated at a burn center and 1192 were excluded for missing data. Admission hypothermia was independently associated with mortality (1.91 [1.58-2.29]) when adjusting for age, sex, total second- and third-degree burn surface area (TBSA), comorbid conditions, injury severity score, direct transport vs referral, method of temperature measurement, year, and the hospital providing care. Increasing age, female sex, TBSA >40%, presence of multiple comorbid conditions, and increasing injury severity score were associated with mortality. Other variables in the model were not independently associated with outcome. There was a weak correlation between TBSA and admission temperature (r = .18). Hypothermia at hospital admission is independently associated with mortality in burn patients when controlling for clinical confounders. Future studies should address potential causes underlying this observation.

Risk Factors for Hypothermia in EMS-treated Burn Patients

“…16 In this report we have restricted the analysis to burn patients treated by EMS and transported directly to a burn center in part because this subset is more severely injured and severely burned but also because these patients are likely receiving the best care when compared to those patients presenting to the hospital without accessing the EMS system. Singer et al also examined the association between hypothermia and mortality.…”

“…Hypothermia for injured patients is variously de-fined in the literature as ≤36.0 • C, 19,20 ≤35.0 • C, 14,21 and ≤34.0 • C. 22 A visual examination of the temperature data from the full cohort supported our definition of hypothermia. 16 Singer et al defined hypothermia as ≤35.0 • C measured by rectal or oral route. 18 They noted that 1.6% of burn patients met that criteria on ED arrival (15 of 929 patients).…”

“…This is concerning given the association between mortality and hypothermia among burned patients. 16 Patients at risk for hypothermia are readily identifiable by prehospital providers. Elderly patients, patients with burns of 20% TBSA or more, and patients exposed to the elements as a result of extrication or cooler environmental temperatures are at increased risk.…”

“…We defined a subject as hypothermic if the subject had a temperature on hospital admission ≤36.5 • C. This has been associated with increased mortality in prior work. 16 Total burn surface area (TBSA) was categorized into clinically meaningful categories of <20, 20-39, and ≥40%. The mass of the patient in kilograms was divided into quartiles.…”

“…[11][12][13][14][15] We have recently reported a similar association between hypothermia and mortality in a large cohort of burned patients. 16 However, little is known about factors associated with hypothermia during the prehospital phase of burn care.…”