From the Guidelines
Blood pressure readings can differ between arms due to several factors, and a difference of more than 10 mmHg may indicate underlying health issues, so it is recommended to measure blood pressure in both arms at the initial visit and use the arm with the higher reading for subsequent measurements. The most common causes of these differences include atherosclerosis, anatomical variations in blood vessels, peripheral artery disease, aortic dissection, subclavian steal syndrome, or thoracic outlet syndrome, which can create resistance to blood flow in one arm, resulting in lower pressure readings 1. When measuring blood pressure, it's essential to use a validated and calibrated device, enforce the correct measurement technique, and apply a consistent approach to blood pressure measurement for each patient 1.
Key Factors to Consider
- Atherosclerosis (narrowing of arteries) can restrict blood flow to one arm, resulting in lower pressure readings.
- Anatomical variations in blood vessels, peripheral artery disease, aortic dissection, subclavian steal syndrome, or thoracic outlet syndrome can also create resistance to blood flow in one arm.
- Measuring blood pressure in both arms at the initial visit can help detect these conditions and identify the arm with the higher reading for subsequent measurements 1.
- Using the arm with the higher reading for subsequent measurements is crucial, as it can provide a more accurate representation of the patient's blood pressure and help guide treatment decisions 1.
Recommendations for Blood Pressure Measurement
- Measure blood pressure in both arms at the initial visit.
- Use the arm with the higher reading for subsequent measurements.
- Use a validated and calibrated device to measure blood pressure.
- Enforce the correct measurement technique and apply a consistent approach to blood pressure measurement for each patient 1.
- Consider using out-of-office blood pressure measurement for diagnostic purposes and ongoing management to quantify the effects of treatment and guide blood pressure-lowering medication titration 1.
From the Research
Difference in Blood Pressure Between Arms
- A significant difference in blood pressure between the right and left arm could indicate an increased risk of heart and circulatory disease, and death 2
- National vascular disease guidelines recommend taking blood pressure measurements in both arms, but this is often not done in practice 2
Causes of Difference in Blood Pressure
- There is no direct evidence in the provided studies to explain why blood pressure might differ between arms
- However, studies suggest that hypertension is a major risk factor for cardiovascular disease, and controlling blood pressure is crucial to reducing this risk 3, 4, 5, 6
Importance of Measuring Blood Pressure in Both Arms
- Measuring blood pressure in both arms can help identify individuals at risk of cardiovascular disease and death 2
- It is recommended to take blood pressure measurements in both arms, especially in individuals over 40 years old 2