24-hour Ambulatory Blood Pressure (ABP) Monitoring — SozoCardiology - Dr Ooi Yau Wei Interventional Cardiologist

What is 24-Hour Ambulatory Blood Pressure Monitoring?

24-hour Ambulatory Blood Pressure Monitoring (ABPM) involves your blood pressure being measured at regular time intervals over 24 hours as you move around, going about your normal daily activities. It uses a small digital blood pressure machine that is attached to a belt around your body and connected to a cuff around your upper arm. It is small enough that you can go about your normal daily life and even sleep with.

What are the benefits of the 24-hour ABPM?

Blood pressure measurements by the doctor conventionally only take place when you are in the clinic. These readings may not reflect your usual blood pressure as the act of having one’s blood pressure taken may cause stress to you, resulting in a falsely-elevated reading (‘white-coat’ hypertension). The infrequency of such clinic measurements may not give sufficient information on your blood pressure profile, especially if it has been difficult to control with medication. Home blood pressure monitoring while often useful, is also limited by how frequently you monitor it, the accuracy of home BP machines and user error.

24-hour ABPM overcomes these difficulties. By measuring your blood pressure at regular intervals over 24 hours, our doctor will be able to get a clear picture of how your blood pressure changes throughout the day.

The unique data provided by 24-hour ABPM includes:

24-hour average blood pressure (BP)
Daytime (awake) average BP
Night-time (asleep) average BP
Blood pressure load – defined as the percentage of ambulatory systolic and diastolic BP exceeding 140 mmHg and 90 mmHg respectively during the daytime, and 120 mmHg and 80 mmHg respectively during sleep. This is a strong determinant of your cardiovascular risk
Noctural BP dipping – defined as a BP drop of at least 15% of the daytime values during sleep. Failure of BP to dip at night is a risk factor for the development of heart failure and other cardiovascular complications

Based on the above data, our doctor will be able to objectively and scientifically assess the following conditions and select the most appropriate treatment:

“White-coat” hypertension	When BP measurements are high in the doctor’s office but falls within the normal range when taken at home.
Undiagnosed hypertension	This occurs when BP measurements taken in the doctor’s office and at home exceeds 140mmHg systolic (top reading) and 90mmHg diastolic (bottom reading).
Resistant hypertension	When multiple anti-hypertensive medications fail to adequately control high blood pressure.
Masked hypertension	When clinic BP measurements fall within an acceptable range, but the mean blood pressure is actually above the acceptable range.
Nocturnal hypertension	When daytime BP measurements are in the ideal range but in the sub-optimal range at night.
Hypotensive symptoms	When the patients experiences symptoms such as giddiness due to over-lowering of BP with hypertensive medications

“White-coat” hypertension	When BP measurements are high in the doctor’s office but falls within the normal range when taken at home.
Undiagnosed hypertension	This occurs when BP measurements taken in the doctor’s office and at home exceeds 140mmHg systolic (top reading) and 90mmHg diastolic (bottom reading).
Resistant hypertension	When multiple anti-hypertensive medications fail to adequately control high blood pressure.
Masked hypertension	When clinic BP measurements fall within an acceptable range, but the mean blood pressure is actually above the acceptable range.
Nocturnal hypertension	When daytime BP measurements are in the ideal range but in the sub-optimal range at night.
Hypotensive symptoms	When the patients experiences symptoms such as giddiness due to over-lowering of BP with hypertensive medications

Who will benefit from this test?

Patients with white-coat hypertension

Avoids the unnecessary initiation of anti-hypertensive medications and its potential side effects

Patients with known hypertension

To see how well your medications are working to provide smooth & optimal 24-hour BP control
To see if your BP remains high at night when you are sleeping. If this is the case, your medications may need to be changed or adjusted

Patients with poorly controlled or resistant hypertension

Especially in patients who develop complications of hypertension (eg.heart failure, heart attack, kidney failure or stroke) despite being on anti-hypertensive medications.

How to prepare for the test

Take a bath before coming for the test as you will be asked to wear the small digital BP machine for 24 hours continuously
Wear a shirt that can be easily removed so as to facilitate placement of the BP machine and a pair of shorts/pants with belt loops. Bring a belt so that the machine can be worn on a belt on your waist
Continue taking your regular medications (if any) as instructed by our doctor

How is the test performed?

Taking only 5-10 minutes, our cardiac technician will fit a BP cuff suited to the diameter of your left or right arm and a small BP machine will be worn on a belt on your waist
The machine is programmed to take your BP at regular intervals of 30 minutes during the day and at 1-hour intervals at night. You will need to keep the monitor on through the night – you could put the machine under the pillow or on the bed while you sleep
At the end of the 24 hours, our cardiac technician will remove the machine and cuff and download the BP readings for analysis
Your entire BP recording will be reviewed by our doctor and a summarized report of your BP control will be provided and explained to you during your review

What do I need to do during the 24-hour BP monitoring?

Because the test is being carried out to find out what your normal daily blood pressure is, it is important to carry on with your normal routine and do all the things you would normally do
The only things you should avoid doing for the day are swimming and having a bath or shower
You will be advised not to remove the machine during the 24 hour period
To allow the machine to work properly, it is important to make sure that the tube to the machine is not twisted or bent. Also, just before the machine is about to take a reading, it will beep. When this happens you should:

sit down, if possible
keep the cuff at the same level as your heart
keep your arm steady

You will also be asked to keep a diary of what you were doing just before the reading was taken, what time you went bed and got up, and if and when you took medications

How does the doctor use this test to manage my BP?

1
Normal blood pressure profile

This confirms that you do not have true hypertension and will not need to be started on long-term anti-hypertensive medications

2
Newly-diagnosed hypertension

Depending on the severity of BP elevation, presence of other cardiovascular risk factors such as diabetes mellitus, high cholesterol, smoking and family history of stroke or heart disease; our doctor will guide you through the lifestyle modifications you can make to achieve a good and stable BP control. Medications may be needed and, contrary to popular belief, can be weaned off with good adherence to your doctor’s advice and follow-up

3
Resistant / Nocturnal hypertensive profile

This confirms that your BP is sub-optimally controlled despite being on medications and you are at risk of developing long-term complications of hypertension such as heart failure, heart attack, stroke, kidney failure or blindness. By identifying the period of BP spikes during the day or night, our doctor will adjust the type, dose or timings of your medications to achieve good and stable BP control

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