Validation procedures of automated blood pressure measuring devices are carried out at rest only.
We aimed to determine whether venous blood redistribution affects the accuracy of the OMRON HEM-705CP (Osc). Lower body negative pressure stimulus (−40 mmHg) (LBNP) was used to simulate changes of body position.
Fifty-four young healthy volunteers had their blood pressure (BP) measured simultaneously by Osc and mercury sphygmomanometer (HgS) at rest (at 3 and 5 min) and during LBNP (at 7 and 9 min).
Differences (Δ) between HgS and Osc for systolic and diastolic BP (SBP and DBP) were calculated. The ΔSBP obtained in minute 9 (ΔSBP–9) was bigger than the one taken in minute 5 (ΔSBP–5) (–2.89 ± 4.3 versus −1.35 ± 5.2 mmHg, P < 0.02). The rest of the ΔSBP values and all the ΔDBP values were constant at rest and during venous blood redistribution caused by LBNP. We calculated the fall in SBP separately for HgS and Osc by subtracting SBP–9 from SBP–5 for each patient. The fall measured by Osc was bigger than by HgS (−5.87±4.0 versus −4.3±4.5 mmHg; P < 0.02). When graded according to British Hypertension Society protocol, Osc remained in the class of recommendation (A or B) for every minute of the procedure.
Even if an oscillometric device passes various validation tests, they do not give sufficient information about its accuracy during venous blood redistribution. This knowledge is of particular importance when BP regulation abnormalities occurring during changes in body position are diagnosed with the oscillometric method.
aDepartment of Internal Medicine and Endocrinology, Medical University of Warsaw
bThe Military Institute of Aerospace Medicine, Department of Physiology, Warsaw, Poland
Correspondence and requests for reprints to Marek Czarkowski, Chair and Department of Internal Medicine and Endocrinology, Medical University of Warsaw, ul. Banacha 1A, 02-097 Warszawa, Poland
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Received 5 September 2003 Revised 15 December 2003 Accepted 18 December 2003