Heart rate response during face immersion test to evaluate autonomic nervous function

We examined the heart rate response to face immersion in 17 normal subjects and 9 diabetics. The subjects immersed their face fully in a basin filled with ice water at 4-6°C in a forward leaning position for 20 sec. Two-lead electrocardiogram (ECG) was continuously recorded from 20 sec before the immersion to 5 min after. The R-R intervals were measured on the recorded ECG. In the control group, heart rate response to face immersion showed 4 phases: an initial increment after the immersion of the face (phase 1), decrease after the initial increment (phase 2), second increment after phase 2 (phase 3) and second decrease after the second increment (phase 4). Repeated face immersion test with a 10 min interval revealed reproducibility of the test. Parasympathetic blockade with atropine sulphate attenuated the phase 2 response, suggesting that cardiac parasympathetic nerve tone increases in response to the initial increment in the heart rate due to sympathetic response. In diabetic patients, phase 2 response was reduced in patients with a shorter history of diabetes, while in patients with a longer history, heart rate response was diminished in all phases. Therefore, heart rate response to face immersion was attenuated relative to the duration of the illness.The present study suggests that the analysis of the heart rate response to face immersion is useful as an autonomic nervous function test.