Hypothermia is a well recognized consequence of severe injury, even in temperate climates, and the physiologic consequences of hypothermia are known to be detrimental. To analyze the frequency and risk factors for hypothermia and its effect on patient outcome, we prospectively studied 94 intubated injured patients at a regional trauma center during a 16-month period. Esophageal temperature probes were placed in the field or ER and core temperatures (T) were followed for 24 hours or until rewarming. Patients were designated as normothermic >36°C), mildly hypothermic (34°C-36°C) or severely hypothermic (<34°C) based on initial T. The risk factors for hypothermia evaluated included age, severity and location of injuries, blood alcohol level, blood transfusion requirements, and time spent in the field, ER, or OR.
The average initial T was 35°C, with no seasonal variation. Injury severity and survival correlated with severe hypothermia. Normothermic patients had an average ISS of 28 with a 78% survival. Severely hypothermic patients had an average ISS of 36 with a 41% survival (p <0.05). Patient age strongly correlated with outcome although there was no relationship between age and initial temperature. Sixty-two per cent of patients tested were positive for blood alcohol, and one half were legally intoxicated (BAC >100 mg%). However, no consistent correlation was found between alcohol intoxication and initial temperature or patient survival. Blood transfusion requirements paralleled injury severity and patients receiving greater than 10 unit transfusions had significantly lower core temperature (p <0.05). The average temperature change was positive in the ER, OR, and ICU with time to rewarming correlating with the aggressiveness of warming measures.
We conclude that: 1) The majority of severely injured patients are hypothermic. 2) Awareness of potential detrimental effects of hypothermia resulted in an average positive T change during initial care. 3) Rapid prehospital care and transport may offset the effects of age and alcohol intoxication on temperature regulation. 4) Severe hypothermia is common among severely injured patients.
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