Time of day to monitor ambulatory blood pressure affects the outcome.
OBJECTIVE
The reproducibility of blood pressure variables from ambulatory blood pressure monitoring (AMBP) initiated at the same time of day (SAME: 1700-1900 h) was compared with the reproducibility of blood pressure variables when monitoring was initiated at opposite times of day (OPP: randomized, morning=0700-0900 h and evening=1700-1900 h). It was hypothesized that the reproducibility for SAME (n=18) would be no different than the reproducibility for OPP (n=13).


METHODS
The order of AMBP sessions was randomized. The Accutracker II was used to determine average blood pressures, Crest (CrBP), Trough (TrBP), and TrBP : CrBP ratio; Averages were divided into 24-h, daytime (0600-2200 h), and night-time (2200-0600 h) for both systolic and diastolic blood pressures. A paired t-test with an intraclass correlation was used to determine the reproducibility of AMBP for both SAME and OPP. A chi-square was used to compare the distribution of reproducible AMBP variables between SAME and OPP. Significance was at P<0.05.


RESULTS
The reproducibility of AMBP variables for SAME and OPP was a significantly different for systolic blood pressure. All of the ambulatory systolic variables measured in the SAME group were reproducible except for the TrBP : CrBP, whereas only the systolic night-time averages of the OPP group were reproducible. Similarly all of the ambulatory diastolic variables measured in the SAME group were reproducible except for TrBP : CrBP, whereas 24-h, night-time averages, and TrBP were reproducible in the OPP group.


CONCLUSIONS
Ambulatory blood pressure variables were consistently higher when the monitoring session began in the morning hours.
Wallace
Janet P
JP
Clinical Exercise Physiology Laboratory, Department of Kinesiology, Indiana University, Bloomington, Indiana 47405, USA. wallacej@indiana.edu
Park
Saejong
S
Zakutansky
Donald W
DW
Lehmkuhl
Larissa A A
LA
Jastremski
Chester A
CA
D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods*; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013995:Time