How to Measure Blood Pressure Correctly: Doctors Explain the '722 Rule'

Accurate blood pressure measurement is vital for diagnosing and managing hypertension, but many people are unaware of the correct methods. Endocrine and metabolism specialist Dr. Tsai Ming-chieh emphasizes that home blood pressure monitoring is often more reliable than readings taken in a clinical setting, primarily due to "white coat hypertension" – an anxiety-induced spike in blood pressure when seeing a doctor or entering a clinic.

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In the clinic, many people have 'white coat hypertension': as soon as they see a doctor or walk into a clinic, their sympathetic nerves involuntarily become excited, and their blood pressure immediately soars.

According to Taiwanese guidelines from the Society of Cardiology and the Ministry of Health and Welfare's National Health Administration, normal blood pressure is defined as systolic below 120 mmHg and diastolic below 80 mmHg. Blood pressure between 120-129 mmHg systolic and below 80 mmHg diastolic is considered elevated, often manageable through lifestyle changes. A diagnosis of hypertension is typically made when systolic pressure is 130 mmHg or higher, or diastolic pressure is 80 mmHg or higher.

Dr. Tsai strongly advises against relying solely on a single in-clinic reading for a hypertension diagnosis. He explains that "white coat hypertension" can lead to unnecessary medication and potentially dangerous low blood pressure if dosages are based on these artificially high readings. To ensure accurate assessment, the "722 rule" is recommended for home monitoring: measure blood pressure for seven consecutive days, twice a day (morning and evening), and take two readings each time, one minute apart, averaging the results.

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Home blood pressure measurement is far more important than in-clinic measurement!

Beyond the 722 rule, proper technique is paramount. Measurements should be taken within one hour of waking up, after emptying the bladder and before eating or taking medication. In the evening, readings should be taken within one hour of bedtime. Crucially, individuals should avoid smoking, eating, caffeine, alcohol, and strenuous exercise for 30 minutes prior to measurement. They should also rest quietly for five minutes before starting, sit with their back supported and feet flat on the floor, wear loose clothing, and ensure the arm cuff is at heart level. Consistent adherence to these guidelines ensures reliable data for accurate diagnosis and effective management of blood pressure.

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Continuous measurement for 7 days. Measure once every morning and evening (total 2 times). Measure twice each time, with an interval of 1 minute, and take the average of the two times.