1Cap La Mina, St. Adrià de Besòs (Barcelona), Spain
2Sap Litoral, Barcelona, Spain
Objective: It is recommended to wait at least 1 minute between blood pressure (BP) readings. However there is insufficient evidence on the usefulness of this recommendation using a validated automatic device. The aim was to assess differences in BP according to the waiting time between BP readings.
Methods: Cross-sectional descriptive study in an ambulatory setting with convenience sampling of 150 hypertensive patients. We excluded subjects with atrial fibrillation, or with body mass index higher than 40 kg/m2 or lower than 18 kg/m2.
Patients were seated for 5 minutes before 6 basal BP readings were taken with a validated device (Tensoval Duo Control, Hartmann): 3 BP measurements with no waiting time (noWT) between them and 3 BP measurements with 1 minute of waiting time (1mWT) between each reading, in random order. The first BP reading of each tercet was eliminated from the analysis. The intraclass correlation coefficient (ICC) was calculated between noWT and 1mWT mean BP measurements, with 95% confidence intervals.
Results: 49.3% women, mean age 65.6 ± 12.8 years, mean BP 137 ± 1.4 / 80 ± 0.9 mmHg, 37.3% with diabetes mellitus and 21.3% with associated cardiovascular disease.
Mean systolic BP (SBP) for noWT and for 1mWT was 135.9 ± 18.3 mmHg and 137.3 ± 18.9 mmHg (p = 0.045), respectively. Mean diastolic BP (DBP) was 79.2 ± 12.6 and 79.8 ± 13.0 mmHg (p = 0.409), respectively. There was 2.2 ± 10.3 mmHg and 1.2 ± 8.7 mmHg between the second and third SBP readings for 1mWT (p = 0.009) and noWT (p = 0.09), respectively. ICC between noWT and 1mWT were 0.946 (95% CI: 0.925–0.961) and 0.877 (95% CI: 0.831–0.911) for SBP and DBP, respectively.
Conclusions: BP measurement with 1 minute of waiting time between readings obtains SBP values significantly higher than the BP measurement without time interval between readings. These differences are not clinically relevant. The agreement between noWT and 1mWT is very good.