24-hour blood pressure monitor

Gold standard test for diagnosis of high blood pressure (hypertension)

Blood pressure

Blood pressure (BP) is a simple but powerful predictor of cardiovascular risk. However, blood pressure recorded in a clinic or GP surgery can widely fluctuate and often be elevated due to stress in an unfamiliar environment (‘white coat hypertension’ although nowadays most doctors don’t wear white coats!). A wrong diagnosis of hypertension may mean unnecessary life-long medication.

Measuring BP repeatedly over 24 hours in a patient's normal home and work environment overcomes this problem. It gives a much better idea of what is happening with the blood pressure during usual day-to-day activities than a recording taken during a visit to the doctor in the clinic. NICE (National Institute of Clinical Excellence) recommends 24-hour blood pressure (BP) monitoring as a gold standard in the diagnosis of hypertension. A 24-hour BP monitor records the blood pressure every 30 minutes during the day and every hour at night with a pressure cuff fitted to the arm. Upon completing the test, the data are downloaded to a computer, and individual readings are analyzed to give daytime, nighttime and 24-hour BP average.

The monitor is about the size of a mobile phone and attached to a belt or hung around the neck. The patient is asked to keep a diary of any symptoms to be correlated to the recorded blood pressure. The patient is encouraged to go about their normal daily routine with the monitor to get representative recordings.


  • To confirm or exclude hypertension in a patient with borderline clinic blood pressure readings.
  • To assess the degree of blood pressure control in patient with known and treated hypertension.
  • To assess the effectiveness of new or changed medication on blood pressure control.
  • To see if low blood pressure (hypotension) is responsible for symptoms such as tiredness, breathlessness, dizziness, and blackouts.

Risks and complications

A 24-hour blood pressure monitor is a noninvasive test with no known risks. Some people do not like the feeling of the cuff tightening on their arm, but this is nothing to worry about.

Before the procedure

Dr Ruzicka will discuss the indication for a 24-hour blood pressure monitor during your consultation. The monitor will be usually arranged in the week following the consultation. If desired, the monitor can also be requested on NHS with the usual waiting time.

When you come for the monitor to be fitted, one of the cardiac physiologists will again explain the process and answer your questions. You will be asked to remove all your clothing above the waist, excluding any underwear. A cuff will be placed around your arm and attached to the recorder. The recorder works automatically and will measure your blood pressure in the same way as the doctor does by tightening the cuff and slowly releasing it. It will do this every 30 minutes during the day and every hour at night. You can wear the monitor over the shoulder like a shoulder bag, or you can clip it to a belt or pocket.

You will be given a diary card. You should record any symptoms, the time you had them, and what you were doing at that time. This is helpful when analyzing the recording for the correlation of your symptoms to the changes in blood pressure. You will also be asked to record when you go to bed when you get up, what medication you are taking, and when. The whole process takes approximately 15 minutes.

During the procedure

Once the monitor has been hooked up and you received instructions, you can return to your usual activities, including work, household chores, and exercise. You should go about your normal routine to obtain a representative recording of your blood pressure. As explained above, you will be instructed to keep a diary of your activities and corresponding symptoms.

After the procedure

You must return the following day to the hospital to remove the recorder, taking only a few minutes. The Alexandra Hospital physiologists will analyze the recording and deliver it to Dr Ruzicka. Dr Ruzicka will then discuss the report with you during your follow-up appointment, or he will write to you and your GP with the results. Depending on the results, your antihypertensive medication may need to be adjusted.

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