An update on: cardiovascular and respiratory changes during sleep in normal and hypertensive subjects
Authors: F Lombardi
Journal: Cardiovascular Research (2000)

Introductionsleep in normal and hypertensive subjects; the significant reduction of total peripheral resistance as a major deter- In 1969, Bristow, Honour, Pickering and Sleight [1] minant of nocturnal arterial pressure reduction in the provided us with one of the very first descriptions of the absence of significant changes in cardiac output; the cardiovascular and respiratory changes occurring during identification of changes in baroreflex sensitivity as well as sleep in normal and hypertensive subjects.The study was a resetting of the arterial baroreflex during sleep in carried out in 19 subjects, eight with normal and ten with hypertensives.high blood pressure, while one subject was suffering fromThe final conclusion was that ''there does not appear to postural hypotension.The design of the study was rather be any qualitative difference between subjects with normal complex: all subjects had to sleep for three consecutive and high blood pressures in their hemodynamic adjustment nights in the laboratory.On night one, systemic arterial during sleep except that the latter have an almost five-fold pressure was non-invasively determined by an automatical-reduction in baroreflex sensitivity both awake and asleep'' ly inflated sphygmomanometer.On night two, a continuous [1].electroencephalogram recording was performed, whereas,In the present article, we will briefly discuss some on night three, continuous recording of brachial intra-particular features of this pioneering work.We will then arterial-pressure was obtained through a small poly-report on the further developments that have followed ethylene cannula that was also used to collect arterial these initial observations up to our times.blood without disturbing the patient.An i.v.line was also available for injection of various compounds.By following the steps of such a protocol they were able 2. Hemodynamic changes during sleep (a) to identify the different stages of sleep, (b) to monitor noninvasively arterial blood pressure before, during and That sleep is characterised by signs of parasympathetic after nocturnal sleep, (c) to determine baroreflex sensitivity predominance had been shown by the same group of by quantifying the reflex RR interval lengthening which investigators only a few months before, when Smyth et al. follows a pharmacologically-induced increase in systolic[2] reported the occurrence of a nocturnal reduction of blood pressure (obtained through i.v.injection of angiotenheart rate and arterial pressure either in the absence of sin 11 or phenylephrine), (d) to perform repeated measuresignificant changes or in the presence of an increase in ments of cardiac output by the dye dilution method and (e) baroreflex sensitivity.In the present study [1] the same to analyse blood gases during sleep and wakefulness.authors found that the degree of fall of pressure was A number of important results were derived out of these roughly proportional to the waking pressure and that the measurements: a description of the changes in intra-arterial lowest pressure values were observed during REM sleep.blood pressure, cardiac output, arterial blood gases and During sleep, normal subjects did not exhibit any baroreflex sensitivity that occur between wakefulness and significant change in cardiac output, whereas a small and not significant reduction was observed in hypertensive subjects.The nocturnal reduction in arterial pressure was