The effect of body position on blood pressure measurement: a clinical observational study

Abstract

Background: Accurate blood pressure (BP) measurement is vital in diagnosing and managing hypertension. However, the patient's body position during measurement can influence BP readings, potentially affecting clinical decisions. Despite established guidelines, variations in measurement practices are common in clinical settings.

Objective: To evaluate how different body positions (sitting, supine, and standing) affect blood pressure readings in adults and to determine the most consistent and clinically reliable position for measurement.

Methods: This observational study included 180 adults aged 25-65 years. Each participant's BP was measured in three body positions: sitting, lying supine, and standing, with a standardized protocol. Mean systolic and diastolic BP readings were compared using paired t-tests and ANOVA. Secondary outcomes included evaluating the presence of orthostatic hypotension and inter-arm BP variation.

Results: Significant differences in BP were found among the three positions. The highest systolic and diastolic readings were recorded in the standing position (SBP: 129.2±12.4 mmHg; DBP: 83.6±9.7 mmHg), followed by sitting (SBP: 126.5±11.6 mmHg; DBP: 81.3±8.9 mmHg), and the lowest in the supine position (SBP: 123.4±10.9 mmHg; DBP: 78.5±8.5 mmHg) (p<0.001). Orthostatic hypotension was observed in 14% of participants.

Conclusion: Blood pressure varies significantly with body position. For consistent monitoring, the sitting position remains the most reliable and clinically practical. Awareness of postural variations is essential to avoid misclassification of hypertensive status and ensure accurate treatment decisions.