Repetitive ramped neck suction: a quantitative test of human baroreceptor function

Bolus intravenous injection of an alpha-agonist is a widely accepted method used for studying baroreceptor function. However, the method is invasive, multiple baroreceptor regions are stimulated, and there are diverse direct effects of these pharmacologic agents, e.g., direct effects on the carotid sinus region. A recently described noninvasive neck suction technique may be highly specific for assessing the carotid sinus to sinoatrial node baroreflex. We compared neck suction-derived baroslopes with those obtained from the standard, invasive phenylephrine infusion method. These techniques were applied to 15 adult volunteers while awake and during 1.34 and 2% isoflurane anesthesia. The correlation coefficients between the two methods were 0.74 (P = 0.002) in awake subjects and 0.75 (P = 0.001) overall. The neck suction method of repetitive, ramped carotid stimuli yielded results that were qualitatively and quantitatively similar to those of the standard phenylephrine method. The neck suction method is simple, noninvasive, and can be repeated at frequent intervals. This method may be highly specific for determining carotid baroreceptor-cardiac reflex physiology in humans.