Head Regional Differences in Thermal Comfort: Evaluating a Novel Surgical Helmet Cooling Method with Phase Change Material

Thermal comfort is a significant factor in maintaining a satisfactory perception of the body temperature and influences behavioral thermoregulation. This pilot study aimed to investigate regional differences in thermal comfort in the head and neck areas by applying a surgical helmet equipped with cooling pads containing octadecane (CAS 593-45-3) as a phase change material (PCM) in healthy volunteers. Forty-three surgeons and nurses were enrolled. Octadecane is an odorless alkane hydrocarbon with an appearance of white crystal and a melting point of 28 °C. The PCM pads, each with a diameter of 5 cm and containing 7 g of octadecane, were placed between the helmet and the wearer’s head directly in contact with the skin. To identify the areas of the head and neck investigated, the surface was sampled and numbered, with the identification of a total of 38 different locations. A climate chamber maintained at 23–26 °C was used for the experiment. Thermal comfort of the stimulated area was reported by the subjects in an evaluation questionnaire at the end of the local stimulation conducted for 1 h. The sensations were reported as 1 (maximum uncomfortable) to 7 (maximum cold comfort), with 4 indicating a neutral sensation. The duration of the thermal comfort effect was also recorded. The highest mean value reported was 6 in five areas. The frontal region, the frontotemporal region, and the neck region were the areas sensitive to thermal comfort. A neutral sensation was reported in 13 areas. No uncomfortable sensation was reported in any area. This pilot study provides preliminary evidence of the feasibility and potential benefits of integrating PCM cooling pads into surgical helmets to enhance thermal comfort.