variability of blood pressure

ABSTRACT

Blood pressure in all individuals fluctuates from minute to minute, depending upon the physical and psychological state of the individual. The most reliable way of assessing these fluctuations is by continuous direct ambulatory monitoring, which can measure the beat-to-beat variation of arterial pressure in a reproducible manner, free of the effect of an observer. The variability of mean blood pressure increases with advancing age and with hypertension. Variability can be roughly predicted, in a particular individual from his response to pressor stimuli, whether psychological or physical. The sino-aortic baroreceptor reflexes, the sympathetic nervous system and the renin-angiotensin system appear to act in concert to regulate these variations in normal and hypertensive man. The extent to which the arterial baroreceptors act as long-term buffers of blood pressure is still controversial. Borderline blood pressure elevation does not appear to be associated with an increase in blood pressure lability; moreover, it would not seem to confer any immunity from subsequent cardiovasuclar events. We agree with Pickering's view that borderline hypertension represents an arbitrary distinction in a continuously distributed variable. We similarly believe that the term 'labile hypertension' should be dropped and replaced with a numerical description of the standard deviation of arterial pressure over a defined period and with specified conditions with regard to activity and state of wakefulness