The influence of tobacco smoking on the relationship between pressure and flow in the middle cerebral artery in humans.

Background: Cigarette smoking is associated with an increased risk of stroke but the mechanism is unclear. The study examined whether acute and chronic cigarette smoking alters the dynamic relationship between blood pressure and cerebral blood flow. We hypothesised that acute and chronic smoking would result in a cerebral circulation that was less capable of buffering against dynamic fluctuations in blood pressure.

Cardiac baroreflex gain is frequency dependent: insights from repeated sit-to-stand maneuvers and the modified Oxford method.

Cardiac baroreflex gain is usually quantified as the reflex alteration in heart rate during changes in blood pressure without considering the effect of the rate of change in blood pressure on the estimated gain. This study sought to (i) characterize baroreflex gain as a function of blood pressure oscillation frequencies using a repeat sit-to-stand method and (ii) compare baroreflex gain values obtained using the sit-to-stand method against the modified Oxford method. Fifteen healthy individuals underwent the repeated sit-to-stand method in which blood pressure oscillations were driven at 0.