From the Guidelines
Arm blood pressure measurements are generally more accurate and preferred over wrist measurements for clinical decision-making. When taking blood pressure, the upper arm (brachial artery) should be your first choice, as it provides readings that better reflect your true blood pressure and align with established clinical guidelines 1. Wrist monitors can be acceptable alternatives for people with very large arms where proper cuff fit is difficult, but they require precise positioning at heart level to obtain reliable readings. To use a wrist monitor correctly, rest your elbow on a table with your wrist at heart level. Blood pressure readings from the wrist tend to be less accurate because the arteries are narrower and closer to the skin surface than those in the upper arm. Additionally, the distance from the heart affects the pressure reading, which is why proper positioning is crucial. If you must use a wrist monitor, validate its accuracy by comparing readings with those from an arm monitor at your healthcare provider's office. For ongoing monitoring and especially for diagnosing or managing hypertension, upper arm measurements remain the gold standard.
Some key points to consider when choosing between radial (wrist) and brachial (arm) blood pressure measurements include:
- The standard location for blood pressure measurement is the upper arm, with the stethoscope at the elbow crease over the brachial artery 1
- Monitors that measure pressure at the wrist and fingers have become popular, but it is essential to realize that the systolic and diastolic pressures vary substantially in different parts of the arterial tree
- Mean arterial pressure falls by only 1 to 2 mm Hg between the aorta and peripheral arteries, but the systolic pressure increases in more distal arteries, whereas the diastolic pressure decreases 1
In terms of clinical guidelines, the American Heart Association recommends using the upper arm for blood pressure measurements, as it is the most reliable and has been used in all epidemiological studies of high blood pressure and its consequences 1. Therefore, upper arm measurements should be the primary choice for clinical decision-making, and wrist measurements should only be used as an alternative in specific situations, such as when proper cuff fit is difficult.
From the Research
Comparison of Radial and Brachial Blood Pressure
- There is no direct comparison between radial (wrist) blood pressure and brachial (arm) blood pressure in the provided studies 2, 3, 4, 5, 6.
- However, the studies discuss the factors that influence the accuracy of blood pressure measurement, such as arm position, cuff size, and sleeve conditions.
Factors Influencing Blood Pressure Measurement
- Arm position: The study by 6 found that arm positions, such as resting on the lap or unsupported at the side, resulted in higher blood pressure readings compared to the standard position with the arm supported on a desk.
- Cuff size: The study by 5 found that using a large cuff resulted in lower blood pressure readings compared to using a small cuff, especially for systolic blood pressure.
- Sleeve conditions: The study by 2 found that there was no significant effect of sleeved arms on the accuracy of blood pressure measurement.
Inter-Arm Blood Pressure Differences
- The study by 3 found that there were significant inter-arm blood pressure differences, with the right arm measuring higher than the left arm in some cases.
- The study by 4 found that the discrepancy between oscillometric blood pressure measurement and invasive mean arterial blood pressure measurement was significant, especially when using smaller cuff sizes than recommended.
Radial Blood Pressure Measurement
- The study by 4 mentions the use of radial artery cannulation for invasive mean arterial blood pressure measurement, but does not compare it directly to brachial blood pressure measurement.