Rr. Fogelholm et al., DIURNAL BLOOD-PRESSURE VARIATIONS AND ONSET OF SUBARACHNOID HEMORRHAGE - A POPULATION-BASED STUDY, Journal of hypertension, 13(5), 1995, pp. 495-498
Objectives: To analyse the association between time of onset of subara
chnoid haemorrhage and diurnal blood pressure variations of ambulant n
ormo- and hypertensive subjects. Design: Retrospective, population-bas
ed study. Setting: The population (246 000) of the Health Care Distric
t of Central Finland. Patients: During 1980-1987 a total of 332 subjec
ts in the study population had their first subarachnoid haemorrhage, T
he hour of onset could be obtained for 287 patients, and these form th
e basis of the present study. Results: The onset of subarachnoid haemo
rrhage occurred significantly more often during the waking hours than
during the night. The correlation between the hourly numbers of patien
ts suffering a haemorrhage and the corresponding mean systolic and dia
stolic blood pressure values of ambulant normo- and hypertensive subje
cts was highly significant (r = 0.88, P < 0.001). The results were sim
ilar when the 224 patients with proved aneurysmal bleed were analysed
separately (r = 0.79-0.85, P < 0.001). Conclusions: The diurnal blood
pressure variations of ambulant normo- and hypertensive subjects, espe
cially the transient blood pressure peaks reaching much higher levels
of pressure during the waking hours than during the night, may be cruc
ial in determining the time of rupture of a critically weakened aneury
sm wall.