Body position and blood pressure measurement in patients with diabetes mellitus.

Aims: World Health Organization (WHO) guidelines recommend that the blood pressure (BP) should be routinely measured in sitting or supine followed by standing position, providing that the arm of the patient is placed at the level of the right atrium in each position. The aim of our study was to test the influence of body and arm position on BP measurement in diabetic patients.

Methods: In 142 patients with diabetes mellitus the BP was measured using a semiautomatic oscillometric device (Bosomat-R): (i) after 5 min of rest sitting on a chair with one arm supported at the right atrial level and with the other arm placed on the arm support of the chair, (ii) after 5 min of rest lying on a bed with both arms placed on a bed, and (iii) after 30 s and after 2 min of standing with one arm (the same as in sitting position) supported at the right atrial level and with the other arm vertical, parallel to the body.

Results: Both systolic (SBP) and diastolic (DBP) blood pressures were significantly lower in sitting position with the arm at the right atrial level than in supine position (by 7.4 and 6.6 mmHg, respectively, P < 0.01). In sitting and standing positions, SBP and DBP were higher when the arm was placed either on the arm support of the chair or vertical, parallel to the body, than when the arm was supported at the level of the right atrium (by 6-10 mmHg, P < 0.001). Duration of standing did not influence the estimation of orthostatic hypotension.

Conclusions: The data of this study indicate that the WHO recommendation with regard to the equivalence of sitting and supine BP readings is incorrect at least in diabetic patients, as the sitting BP is lower than the supine BP when the arm was positioned at the right atrial level. In addition, incorrect positioning of the arm in standing position results in an underestimation of prevalence of orthostatic hypotension. We conclude that during BP measurement the arm should be placed at the right atrial level regardless of the body position.