Individual facial areas in the human circulatory response to immersion.

Heart rate (HR) and forearm blood flow (FBF) during 30 sec. breath holding (BH) were recorded in 10 healthy men. (1) during whole face immersion (FI) in water between 5 and 30°C; (2) during FI with waterproof film covering the face (five subjects); (3) with certain facial areas covered with insulating masks; (4) during immersion of selected uncovered facial areas. HR and FBF decreased during BH in air; bradycardia increased on FI, becoming greater as water temperature was reduced. FI bradycardia was greater at each temperature, except 30°C, compared to FI without wetting. Insulation of nose, nose and eyes or nose, eyes and mouth on immersion at 15°C. led to reduced bradycardia compared to whole FI. Selective immersion (15°C.) of uncovered nose, mouth or cheek had little effect on HR compared to whole FI. FBF changes on 'dry' immersion and with selective insulation or immersion were variable and did not parallel HR changes.