Venous blood redistribution alters the accuracy of Omron HEM-705CP

Abstract

Background 

Validation procedures of automated blood pressure measuring devices are carried out at rest only.

Design 

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.

Methods 

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).

Results 

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.

Conclusions 

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.