Human Ventilatory Response to Immersion of the Face in Cool Water
The cardiovascular response to facial cooling in man can be dramatic (3), and this is shown by one exceptional subject studied by us (Figure 1). Here there was an increase in cardiac interval from one second during the control period to seven seconds as the cool water reached the eyes. This response is very pronounced in diving animals (1) and is therefore commonly known as the diving reflex. The bradycardia is accompanied by vasoconstriction which diverts blood flow away from the robust periphery towards the hypoxically sensitive heart and brain. The reflex is most prominent during breath-holding, indeed it may be completely overridden by the act of breathing. An abstract of this work has been published (4).
KeywordsCool Water Trigeminal Nerve Ventilatory Response Ventilatory Effect Cardiac Interval
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