Trauma-associated hypothermia evolves from a combination of injury severity and potentially modifiable environmental and treatment-related factors, French investigators reported.
Higher Revised Trauma Score (RTS) increased the odds of hypothermia by almost 70%. Intubation, lower temperature inside the transport vehicle, and lower infusion fluid temperature also increased the risk.
The risk declined significantly if patients were clothed and did not have a head injury, as reported online in Critical Care.
"Optimal patient management could contribute to limit heat loss or even to increase patient temperature when required," Frederic Lapostolle, MD, of Hopital Avicenne in Bobigny, France, and co-authors wrote. "Undressing patients should be avoided. Mobile unit temperature and fluid infusion temperature were independently associated with hypothermia. They should be routinely measured."
In addition, the group pointed out that mobile intensive care units should be equipped with "a warming system "to allow 'body temperature' fluid infusion, especially in severely injured patients."
Trauma patients often have hypothermia on arrival to a hospital, and even moderate hypothermia can adversely affect prognosis. Causes of hypothermia remain unclear, and available data have come largely from hospital registries and retrospective studies.
To identify potential causes of hypothermia in trauma patients, Lapostolle and colleagues performed a prospective, multicenter, observational study involving a regional emergency medical service (EMS) and eight French hospitals.
EMS units in France are equipped for intensive care requirements, including anesthetics, catecholamines, laboratory facilities, and ultrasound, the authors noted. An EMS team consists of an emergency physician, critical care nurse, and a driver who has training in basic life support.
The study included all trauma patients older than 18 who received prehospital care from an EMS team and who were transported to a hospital by an EMS mobile unit.
Investigators recorded the following:
- Patients' demographic and morphologic information
- Nature and circumstances of the trauma incident
- Patient's condition upon arrival of the EMS team
- Environmental conditions (wind, rain, ground temperature)
- Clinical characteristics (wound features, vital signs, RTS, oxygen saturation, tympanic temperature)
Investigators also recorded pertinent aspects of each patient's care until arrival at the hospital.
The primary endpoint was hypothermia upon arrival at the hospital and the authors defined hypothermia as a body temperature of less than 35°C (95°F).
Data analysis comprised 448 patients, of whom 64 (14%) had a body temperature less than 35°C when they arrived at the hospital. Patients with and without hypothermia did not differ significantly with respect to demographic or morphologic traits.
In a univariate analysis, numerous clinical, environmental, and treatment-related factors were associated with the odds of hypothermia. Multivariate analysis revealed six factors that independently predicted lack of hypothermia on arrival at the hospital:
- No intubation: odds ratio 4.23, 95% CI 1.61 to 11.02 (P=0.003)
- Revised Trauma Score: OR 1.68, 95% CI 1.29 to 2.20 (P=0.0001)
- EMS unit temperature on arrival at site of trauma: OR 1.20, 95% CI 1.04 to 1.38 (P=0.01)
- Infusion fluid temperature (>21°C or 69.8°F): OR 1.17, 95% 1.05 to 1.30 (P=0.003)
- Patient remaining clothed: OR 0.40, 95% CI 0.18 to 0.90 (P=0.03)
- Absence of head injury: OR 0.36, 95% CI 0.16 to 0.83, (P=0.01)
"Routine temperature measurements should help improve the care of trauma victims," the authors concluded. "When providing early care, EMS should always look for hypothermia. The severity of injury, mobile unit temperature, and medical interventions were risk factors associated with hypothermia on the victim's arrival at hospital. Mobile unit and infusion fluid temperature should be measured and increased if necessary. Unclothing of patients [often done to examine the patient] should be avoided."
The authors noted several limitations, including the fact that the results cannot be generalized to all trauma victims because the most severe cases (failure of onsite resuscitation) and least severe cases were not transported in the medically equipped mobile unit.
Also, they did not include outcomes in this study but pointed out that "the relationship between hypothermia and death is now well established."
They called for a prospective study to assess the effect of warming on patient morbidity and mortality.
Primary source: Med Page-Critical Care