Effect evaluation of a heated ambulance mattress-prototype on thermal comfort and patients' temperatures in prehospital emergency care--an intervention study

Abstract

Background: The ambulance milieu does not offer good thermal comfort to patients during the cold Swedish winters. Patients' exposure to cold temperatures combined with a cold ambulance mattress seems to be the major factor leading to an overall sensation of discomfort. There is little research on the effect of active heat delivered from underneath in ambulance care. Therefore, the aim of this study was to evaluate the effect of an electrically heated ambulance mattress-prototype on thermal comfort and patients' temperatures in the prehospital emergency care.

Methods: A quantitative intervention study on ambulance care was conducted in the north of Sweden. The ambulance used for the intervention group (n=30) was equipped with an electrically heated mattress on the regular ambulance stretcher whereas for the control group (n=30) no active heat was provided on the stretcher. Outcome variables were measured as thermal comfort on the Cold Discomfort Scale (CDS), subjective comments on cold experiences, and finger, ear and air temperatures.

Results: Thermal comfort, measured by CDS, improved during the ambulance transport to the emergency department in the intervention group (p=0.001) but decreased in the control group (p=0.014). A significant higher proportion (57%) of the control group rated the stretcher as cold to lie down compared to the intervention group (3%, p<0.001). At arrival, finger, ear and compartment air temperature showed no statistical significant difference between groups. Mean transport time was approximately 15 minutes.

Conclusions: The use of active heat from underneath increases the patients' thermal comfort and may prevent the negative consequences of cold stress.

Keywords: Cold Discomfort Scale; active heat; cold exposure; cold stress; finger temperature; heat transfer; thermal comfort; thermal discomfort.

Fig. 1

The heated mattress on the stretcher connected to 12 V electrical system.

Fig. 2

CDS measurement for intervention and control group at arrival to the patient, after 10 minutes transport and at arrival to the ED. Friedman test: Intervention (p<0.001), Control (p=0.014).