[Effects of nighttime and daytime interval definition on blood pressure and dipping in patients referred for ambulatory blood pressure measurement].
Ambulatory blood pressure monitoring (ABPM) has become indispensable for the diagnosis and control of hypertension. However, no consensus exists on how daytime and nighttime periods should be defined.


OBJECTIVE
To compare daytime and nighttime blood pressure (BP) defined by an actigraph and by body position with BP resulting from arbitrary daytime and nighttime periods.


METHODS
ABPM, sleeping periods and body position were recorded simultaneously using an actigraph (SenseWear Armband(®)) in patients referred for ABPM. BP results obtained with the actigraph (sleep and position) were compared to the results obtained with fixed daytime (7a.m.-10p.m.) and nighttime (10p.m.-7a.m.) periods.


RESULTS
Data from 103 participants were available. More than half of them were taking antihypertensive drugs. Nocturnal BP was lower (systolic BP: 2.08±4.50mmHg; diastolic BP: 1.84±2.99mmHg, P<0.05) and dipping was more marked (systolic BP: 1.54±3.76%; diastolic BP: 2.27±3.48%, P<0.05) when nighttime was defined with the actigraph. Standing BP was higher (systolic BP 1.07±2.81mmHg; diastolic BP: 1.34±2.50mmHg) than daytime BP defined by a fixed period.


CONCLUSIONS
Diurnal BP, nocturnal BP and dipping are influenced by the definition of daytime and nighttime periods. Studies evaluating the prognostic value of each method are needed to clarify which definition should be used.
Service de néphrologie et d'hypertension, CHU Vaudois, rue du Bugnon 17, 1011 Lausanne, Suisse.
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Muller
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Bochud
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Pruijm
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Iglesias
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Burnier
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Wuerzner
D056044:Actigraphy / Q000379:methods; D000328:Adult; D000368:Aged; D000465:Algorithms; D000553:Ambulatory Care; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects*; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D012307:Risk Factors; D013557:Switzerland / Q000453:epidemiology
D000959:Antihypertensive Agents