Comparison of Skin Temperature and Bed Climate of Bedridden Elderly Patients in Summer and Winter

Purpose:  Peripheral skin temperature fluctuations are susceptible to the external environment. When exposed to a low-temperature environment, usually the peripheral blood vessels quickly contract to prevent heat dissipation and a lowering of the body temperature. However, because elderly people have lower thermoregulatory functions than younger people, such reactions are sluggish, heat is deprived, and the skin temperature decreases. Therefore, covering behaviors, which is one behavioral thermoregulation, are critical. However, since it is difficult for bedridden elderly patients to cover themselves with blankets, nurses must adjust the bed climates (temperature and humidity). Failure to properly control the peripheral skin temperature also increases the risk of pressure ulceration due to insomnia or peripheral circulation failure caused by getting chilled. In our previous study, we confirmed the change in skin temperature caused by placing blankets on healthy elderly people, but the actual situation remains unknown for elderly who are bedridden. In addition, due to the obvious climate difference between summer and winter, we must adjust the bed’s climate based on a hot and humid environment in the summer and winter’s low-temperature environment. Unfortunately, few studies have clarified this point. Therefore, to examine the adjustment method of the covering environment for feet, we compared the skin surface temperature and the humidity of the feet of bedridden elderly patients covered by a blanket in summer and winter.

Methods:

1) Participants: 20 hospitalized, bedridden patients who required assistance in excretion, eating, and changing their clothes.

2) Experimental period: August-October 2016 (summer) and December 2015-February 2016 (winter).

3) Procedure: After resting for more than 15 minutes without a blanket covering their lower feet and legs, they rested for 30 minutes with a blanket covering their whole body, and then rested for 15 minutes with their legs uncovered below the knee again. We measured the temperature and the humidity of the feet’s soles and bed climate by a temperature/humidity data logger called Maxim ibutton Hygrochron (DS1923). We attached a temperature/humidity data logger to the three locations on the subject’s feet and at the foot of the bed and measured the values every minute. The material of the used blankets is feathers in the summer, and down and feathers in the winter. We calculated the average of the temperature and humidity data of following period: for 30 minutes that the feet were covered by blanket and for 15 minutes after removing the blanket. The values are expressed as mean (SD).

Results:  Our analysis included 20 participants (6 males, 14 females), 84.6 (5.7) years old in the summer experiment and 18 participants (5 males, 13 females), mean age 83.3 (8.7) years old in the winter experiment. The mean temperature at the bed’s measurement location was 26.2°C (0.03) in summer and 24.2°C (0.2) in winter, and the mean humidity was 53.6% (0.1) in summer and 35.1% (0.4) in winter. Regarding the temperature and humidity under the blanket, the mean temperature 30 minutes after being covered was 26.4°C (0.1) in the summer and 24.5°C (0.3) in the winter, and the mean humidity was 54.8% (0.3) in the summer and 38.4% (0.7) in the winter. The mean temperature for 15 minutes after removing the blanket was 26.4°C (0.08) in the summer and 24.4°C (0.4) in the winter, and the mean humidity was 52.3% (0.6) in the summer and 34.8% (1.0) in the winter. The mean temperature of the feet’s soles for 30 minutes covered by a blanket was 31.6°C (0.3) in the summer and 30.3°C (0.6) in the winter, and the mean temperature 15 minutes after the blanket was removed was 31.1°C (0.3) in the summer and 30.0°C (0.6) in the winter. Regarding the humidity, the mean of the feet’s soles covered by a blanket for 30 minutes was 67.1% (0.9) in the summer and 53.2% (2.3) in the winter, and the mean humidity in the 15 minutes after the blanket was removed was 64.1% (1.0) in the summer and 51.0% (2.1) in the winter. The changes in the skin temperature of the feet’s soles reached an equilibrium state 30 minutes after being covered in the summer 17 minutes after being covered, whereas in the winter, the skin temperature continued to rise continuously for 30 minutes after being covered. Even after being uncovered, equilibrium was reached in eight minutes in the summer, but it continued to decrease for 15 minutes in the winter. The feet’s soles temperature rose by 1.0°C for 30 minutes after being covered in the summer and decreased by 1.1°C in　15 minutes after the blankets were removed. It increased by 2.0°C in 30 minutes after being covered and decreased by 1.6°C in 15 minutes after the blankets were removed in the winter.

Conclusion:  The changes in the skin temperature of the feet’s sole due to the presence or absence of a blanket were small in the summer after it was removed, and fluctuation in the winter was large. The time required for the temperature change also quickly reached an equilibrium state in the summer, but it continued to change during the measurement time in the winter. In other words, warming up was more difficult in the winter than in the summer, and cooling off was also easier in the winter. In our previous studies on healthy elderly people, the skin temperatures of their feet were about 2°C higher in the summer and 3°C higher in the winter than in this paper’s subjects. Effective warming is necessary to adjust the bed climate of bedridden elderly patients, especially in the winter. In the future we will continue to discuss concrete methods for adjusting the covering environments of the feet.