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Effect evaluation of a heated ambulance mattress-prototype on thermal comfort and patients’ temperatures in prehospital emergency care -an intervention study
Umeå University, Faculty of Medicine, Department of Nursing.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

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 a major factor leading to an overall sensation of discomfort. As far as we have seen, there is still 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.


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


Thermal comfort, measured by CDS, was improved during the ambulance transport to the Emergency Department (ED) 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 on compared to three percent in the intervention group (p<0.001). Concerning finger, ear, and compartment air temperature no significant difference between groups was found. Mean transport time was approximately 15 minutes.


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

Keyword [en]
thermal comfort, thermal discomfort, finger temperature, cold exposure, Cold Discomfort Scale (CDS), cold stress, active heat, heat transfer
National Category
URN: urn:nbn:se:umu:diva-102597OAI: diva2:808452
Available from: 2015-04-28 Created: 2015-04-28 Last updated: 2015-08-05Bibliographically approved
In thesis
1. Cold exposure and thermal comfort among patients in prehospital emergency care: innovation research in nursing
Open this publication in new window or tab >>Cold exposure and thermal comfort among patients in prehospital emergency care: innovation research in nursing
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]


Patients’ cold exposure is a neglected problem in prehospital emergency care. Cold stress increases pain and anxiety and contributes to fear and an overall sense of dissatisfaction. When left untreated, cold stress disturbs vital body functions until ultimately reaches hypothermia.


The overall aim was to investigate patients’ experiences of thermal comfort and reactions to cold exposure in prehospital emergency care and to evaluate the effects of an intervention using active warming from underneath.


Study I:

Persons (n=20) injured in a cold environment in the north of Sweden were interviewed. Active heat was given to 13 of them.

Study II:

In wintertime, 62 patients were observed during prehospital emergency care. The field study was based on observations, questions about thermal discomfort, vital signs, and temperature measurements.

Study III:

Healthy young persons (n=23) participated in two trials each. Data were collected inside and outside a cold chamber. In one trial, the participants were lying on a regular ambulance stretcher and in a second trial on a stretcher supplied with a heated mattress. Outcomes were the Cold Discomfort Scale (CDS), back, finger, and core body temperature, four statements from the State-TraitAnxiety-Inventory (STAI), vital signs, and short notes about their experiences of the two stretchers.

Study IV:

A quantitative intervention study was conducted in prehospital emergency care in the north of Sweden. The patients (n=30) in the intervention group were transported in an ambulance supplemented with a heated mattress on the stretcher, whereas only a regular stretcher was used in the ambulance for the patients (n=30) in the control group. Outcomes were the CDS, finger, core body, and air temperature, and questions about cold experiences.


Study I:

Patients suffered more because of the cold than from the pain of their injuries. The patients were in a desperate need of heat.

Study II:

Patients are exposed to cold stress due to cold environments. There was a significant decrease from the first measurement in finger temperature of patients who were indoors when the ambulance arrived, compared to the measurement taken in the ambulance. In the patient compartment of the ambulance, 85% of the patients had a finger temperature below the comfort zone and almost half of them experienced the patient compartment in the ambulance to be cold. The regular mattress surface temperature at the ambulance ranged from -22.3 to 8.4 ºC.

Study III:

A statistical increase of the participants’ back temperature was found between those lying on the heated mattress compared to those lying on the regular mattress. The heated mattress was experienced as warm, comfortable, providing security, and easy to relax on.

Study IV:

Thermal comfort increased for the patients in the intervention group and decreased in the control group. A significant higher proportion of the participants rated the stretcher as cold to lie on in the control group compared to the intervention group.


The ambulance milieu is too cold to provide thermal comfort. Heat supply from underneath increased comfort and might prevent cold stress and hypothermia

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2015. 50 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1718
thermal comfort, thermal discomfort, cold exposure, cold stress, hypothermia, patients’ experiences, active warming, prehospital emergency care, finger temperature, back temperature
National Category
Research subject
Caring Sciences
urn:nbn:se:umu:diva-102599 (URN)978-91-7601-234-5 (ISBN)
Public defence
2015-05-22, Vårdvetarhuset, Aulan, Institutionen för omvårdnad, Umeå, 09:00 (English)
Swedish National Board of Health and Welfare
Available from: 2015-04-30 Created: 2015-04-28 Last updated: 2016-06-30Bibliographically approved

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