Dorsal foot skin temperature is correlated with comfortable footbath temperature

Abstract

The study aimed to identify associations between the temperature of the dorsal foot skin and comfortable water temperature during footbaths using a crossover design.

Footbaths were filled to a height of 8 cm or 15 cm, and the experiment was commenced with filling water that was 2°C warmer than a participant’s dorsal foot skin temperature prior to immersion (“skin temperature”). The water was gradually heated until they confirmed it to be comfortable (“comfortable temperature”), following which a questionnaire on warmth and comfort perceptions was administered. Skin temperature, comfortable temperature, and survey responses were compared between the depth conditions.

There were 21 participants (M/F: 4/17, age: 21±3 y/o), and no significant differences between depth conditions were observed in any objective factors (skin temperature [8 cm v. 15 cm]: 35.5±0.6°C v. 35.4±0.7°C; comfortable temperature: 38.3±1.1°C v. 38.0±1.1°C; differential: 2.8±0.8°C v. 2.5±0.8°C) or the subjective responses endorsing comfort or water warmth. Comfortable temperature was positively associated with skin temperature in both depth conditions (8 cm: r=0.726, p=0.000, 15 cm: r=0.597, p=0.004).

Participants reported footbaths to be comfortable in the 37–39°C range (38±1°C), which was slightly lower than the conventionally-considered optimal range (38–40°C). The positive correlations observed between baseline skin and preferred footbath temperatures indicate that people with cooler feet generally find slightly cooler footbaths to be more comfortable. Before footbaths, nurses should measure patients’ dorsal foot skin temperature and heat the water by 2–3°C than the prior state.