Arterial tonometry in the measurement of the effects of innocuous mechanical stimulation of the neck on heart rate and blood pressure.

Arterial tonometry was used to continuously monitor the effects on heart rate and blood pressure of a series of innocuous mechanical stimuli applied to the neck in conscious humans. The stimuli used were derived from procedures commonly employed in clinical examination and physical therapy of the neck. In alert subjects, the stimuli used generally caused small and sometimes statistically significant decreases in heart rate, systolic pressure and diastolic pressure. In alert subjects, statistically significant decreases in systolic and diastolic pressure were particularly associated with stimuli which involved full rotation of the neck. In the course of the prolonged series of stimuli, some subjects slept or reported being on the verge of sleep. In these subjects, the same stimuli produced mixed effects on heart rate and increases in systolic and diastolic pressure which were significantly different from the effects obtained in fully alert subjects.