E. Casiglia et al., 24H RHYTHM OF BLOOD-PRESSURE AND FOREARM PERIPHERAL RESISTANCE IN NORMOTENSIVE AND HYPERTENSIVE SUBJECTS CONFINED TO BED, Journal of hypertension, 14(1), 1996, pp. 47-52
Objectives To define whether a diurnal rhythm of peripheral resistance
exists in normotensive and hypertensive subjects, has any relationshi
p with that of blood pressure and differs in dipper and non-dipper hyp
ertensives. Design and methods Forty-three subjects (13 normotensives
and 30 mild-to-moderate essential hypertensives) confined for 24 h to
bed were included. Blood pressure was recorded for 22 h at 15 min inte
rvals, plethysmographic forearm flow was simultaneously measured and f
orearm resistance calculated, The analysis was performed for the whole
22 h period and for three 4 h truncated periods, two of certain wakef
ulness and one of certain sleep. Results A circadian rhythm of forearm
resistance was shown in the normotensives, paralleling that: of blood
pressure. All the normotensives were dippers, with a nocturnal blood
pressure dip (systolic/diastolic) of -4.5/-6.0%, In the hypertensives,
the day/night blood pressure trends were not homogeneous: 21 showed h
igher blood pressure values during waking time, with a trend quite sim
ilar to that of the normotensives, whereas the other nine were non-dip
pers, Resistance was lower during sleep than during waking both in the
normotensives and in the dipper hypertensives, whereas in the non-dip
pers it was higher during sleep. Conclusions A sleep/waking rhythm of
peripheral resistance with the highest values during daytime and the l
owest during night-time does exist in normotensive as well as in the m
ajority of hypertensive subjects resting continuously in bed, and ther
efore is largely independent of physical activity. Only in a minority
of hypertensive patients are higher values of peripheral resistance pr
esent during sleep.