Arm position is important for blood pressure measurement
Netea RT, Lenders JW, Smits P, Thien T.
Clinical trial
https://pubmed.ncbi.nlm.nih.gov/10100058/
Aim: To test the effect of positioning the arm on the arm-rest of a common chair, below the officially recommended right atrial level, on the blood pressure (BP) readings in a group of out-patients.
Patients and methods: A group of 69 patients (58 hypertensives; 39 males; mean +/- s.d. age 54.1 +/- 16.0 years) participated in the present study. BP and heart rate values obtained in each of the following two positions were compared: (1) sitting with the arms supported on the arm-rests of the chair and (2) sitting with the arms supported at the level of the mid-sternum (the approximation of the right atrial level). BP was measured simultaneously at both arms, with a mercury sphygmomanometer at the right arm and with an automatic oscillometric device at the left arm.
Results: Both the systolic and diastolic BPs were significantly higher (P < 0.0001) when the arm was placed on the arm-rest of the chair than at the right atrial level. The same differences +/- s.d. in BP between the two positions were obtained with both measurement techniques: 9.7 +/- 9.4 mm Hg (systolic) and 10.8 +/- 5.8 mm Hg (diastolic) with the mercury sphygmomanometer and respectively 7.3 +/- 8.9 mm Hg and 8.3 +/- 6.0 mm Hg with the oscillometric device. No difference in the heart rate was found between the two positions.
Conclusions: Placing the patient's arms on the arm-rest of the chair instead of at the reference right atrial level, BP measurement will result in spuriously elevated BP values. This may be of great importance for the diagnosis and the subsequent treatment decisions for patients with hypertension.
Body position and blood pressure measurement in patients with diabetes mellitus
Netea RT, Elving LD, Lutterman JA, Thien T.
Clincial trial
https://pubmed.ncbi.nlm.nih.gov/11982738/
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.