If the patient's arm is maintained at heart level during measurement, the reading is most likely:

• A. Higher than actual
• B. Lower than actual
• C. Accurate
• D. Not measurable

Answer: (C)

Keeping the arm at heart level ensures the cuff measures arterial pressure without a gravity-related offset. The blood pressure read in the arm is influenced by hydrostatic pressure; roughly, every 10 cm of height difference from the heart adds or subtracts about 7–8 mmHg. At heart level, there’s no height difference, so the reading reflects the true pressure generated by the heart. If the arm were higher, the reading would be lower than the actual pressure; if the arm were lower, it would be higher. So this position yields an accurate measurement. For best accuracy, ensure proper cuff size and that the patient is seated with back supported, feet uncrossed, and the arm supported at heart level, with the patient resting and not talking during the measurement.