Ambulatory Blood Pressure Monitoring (ABPM)

Did you know that ambulatory blood pressure monitoring is a stronger predictor of mortality than clinic-based blood pressure monitoring?

The United States Preventive Services Task Force (USPSTF) has recommended using ambulatory blood pressure monitoring for diagnosing hypertension. By the way, USPSTF is a team of national experts in disease prevention and evidence-based medicine in the US.

In recent studies, it has been found that ambulatory blood pressure monitoring is more accurate than office blood pressure monitoring in diagnosing cardiovascular diseases.

In this article, I will discuss ambulatory BP monitoring, its use, how it is performed, the pros, cons, and much more.

What is Ambulatory Blood Pressure Monitoring (ABPM Test)?

Ambulatory blood pressure monitoring is a modern way to test the blood pressure of an individual wherein the blood pressure is measured continuously for 24 hours in general.

It means your blood pressure is being measured while you are on the move, living your normal daily life, even while you are sleeping, amazing, isn’t it?

The blood pressure is monitored through a small blood pressure machine that is attached with a belt around your body and connected with the cuff on your upper arm. The BP machine takes many readings at regular intervals within the 24 hours period.

Use of Ambulatory Blood Pressure Monitoring

Do you know that blood pressure fluctuates a lot throughout the whole day? For some people, it may decrease by up to 20% during sleep and for others, it may not drop at all but rather rise during sleep.

These blood pressure fluctuations go unnoticed when you visit a doctor’s clinic, but can be easily detected with ambulatory blood pressure monitoring.

Patricia Castellano on ABPM
Source: Ert.com

Ambulatory blood pressure monitoring helps in determining the type of hypertension patient is suffering from which helps in ensuring better options for treatment. 

Ambulatory blood pressure monitoring (ABPM) can be used to detect several types of hypertension including:

White Coat Hypertension

Some people might experience an increase in their blood pressure levels when measured at the hospital, doctor’s office, or clinic and have normal blood pressure at home. This condition is known as White Coat Hypertension.

ABPM can help detect white coat hypertension. If a patient suffers from white coat hypertension, he/she doesn’t have to take any antihypertensive drugs, so ABPM can save a person from taking unnecessary drugs.

White coat hypertension (WCH) may be seen in up to 15%-30% of patients having high BP readings.

Masked Hypertension

Masked hypertension is exactly the opposite of white coat hypertension, Under this, people experience elevated ABPM readings at home and normal BP at the clinic.

It may be seen in up to 10%-20% of patients having high BP readings.

Masked hypertension is more common in diabetic patients. It should be identified and treated adequately to control blood pressure.

Nocturnal Hypertension

Generally, our blood pressure falls by more than 10% during night time which is also known as Nocturnal Dipping. But in some people, BP doesn’t fall much, rather it elevates on some occasions, known as Nocturnal Nondipping or in simple terms, Nocturnal Hypertension.

Nocturnal Nondipping is common in diabetic patients. ABPM helps in diagnosing nocturnal non-dipping effect.

Sustained Hypertension

Sustained hypertension is a condition wherein the blood pressure readings are elevated irrespective of the patient’s location, be it in the doctor’s office or at home. Sustained hypertension is linked to heart and kidney damage.

Other Uses of Ambulatory Blood Pressure Monitoring

Apart from the uses listed above, ambulatory BP monitoring is used in various ways such as:

  • Determine the efficacy of antihypertensive drugs in controlling high blood pressure
  • Determine the timing and dosage of antihypertensive drugs based on the ABPM readings
  • Predict the chances of cardiovascular and cerebrovascular diseases linked to hypertension
  • Used when BP is not coming under control with medications
  • Effective in combating fainting problems due to low blood pressure
  • Effective with borderline hypertension (also known as prehypertension)
  • Effective in pregnant women with hypertension

What happens During 24-hour ABPM?

When a person undergoes 24-hour ambulatory blood pressure monitoring, he/she has to wear an ambulatory blood pressure monitor which is small enough that you can easily wear it on a belt on your waist. The cuff remains on your upper arm for the whole 24 hours.

The ABP monitor records blood pressure at regular intervals throughout the day and night. The monitor inflates the cuff around your upper arm and then releases the pressure slowly after recording BP reading.

Ambulatory blood pressure machine
Source: Midwestheartclinic.com

During the night, you can keep the ambulatory blood pressure monitor under the pillow or on the bed while you sleep. You can do all your activities normally apart from swimming or taking a shower.

The ABP monitor will store all the BP readings recorded throughout the 24 hours period which will then be analyzed by your doctor.

What to do During 24 hour Blood Pressure Monitoring?

Just before measuring the blood pressure, the machine will give a beep sound. Whenever you hear the beep sound, you are advised to:

  • Sit down if possible
  • Keep your arm steady
  • Ensure that the cuff is at the same level as your heart (You can keep your arm on a table if it is nearby)

Generally, your doctor will also advise you to always keep a diary with you where you can note down some of the key details such as your sleeping time, waking time, at what time you took your medications, what were you doing before the reading was taken, etc.

If you feel uncomfortable, stressed, or distracted or any other issue when the machine takes your reading, you can inform and consult your doctor as it may affect your reading.

Precautionary Steps to Follow During ABPM to Get Accurate BP Data

  • To get accurate data from a 24-hour ABPM, make sure that you use a machine that is approved by international standards.
  • Ensure that you choose the correct cuff size to get accurate readings
  • ABPM should be done on a normal weekday and not on a weekend to get a typical BP profile
  • The readings should be taken every 15-30 minutes during the day and every 45-60 minutes at night
  • ABPM readings may not be accurate during exercise, driving, or in movement
  • Avoid swimming or taking a shower

Know everything about blood pressure monitoring at home here.

How Many Ambulatory BP Measurements Should You Take in a Day?

According to the guidelines issued by the European Society of Hypertension (ESH), it is recommended to take 14 measurements during the day and 7 measurements during the night.

So in total, there would be 21 measurements in the 24 hour period.

The measuring time should be:

This is because from 9 PM to 1 AM (known as retiring time) and 6 AM to 9 AM (known as rising time), blood pressure is subject to considerable variation. It helps in eliminating the variations to some extent.

ABPM Thresholds For Hypertension Diagnosis

On average, the blood pressure values in ambulatory blood pressure monitoring is lower than clinic blood pressure measurements.

Thresholds for Hypertension Diagnosis Based on ABPM

You should be worried if your:

  • 24 Hour Average BP is higher than 130/80 mmHg
  • Day Time Average BP is higher than 135/85 mmHg
  • Night Time Average BP is higher than 120/70 mmHg

If any condition mentioned above is valid in your case, you may be suffering from hypertension.

Ambulatory BP measurements VS Office-based BP Measurements

Nowadays doctors are moving towards ambulatory BP measurement over office-based BP measurement, as there are many advantages of ABPM over office-based BPM.

  • Ambulatory monitoring is more efficient as even a small sample size can detect a given BP change compared to 3-4 sets of daily BP readings required in office-based blood pressure measurement
  • ABPM requires fewer visits to your doctor’s clinic and can be easily done with the comfort of your home
  • The use of ABPM devices requires less training and are more acceptable among patients
  • ABPM gives you more precise results, especially in special cases such as white-coat hypertension, masked hypertension, nocturnal non dipping, etc.
  • It has been found in the studies that the likelihood of underestimating or overestimating BP control is high when you rely only on office blood pressure measurement
  • USPSTF confirmed that ABPM is the best confirmatory test for hypertension due to its large evidence base
  • In-office blood pressure monitoring give inaccurate readings in white coat affected people
  • In-office BP monitoring requires more several visits and repeated measurements in order to give reliable readings

Pros of Ambulatory Blood Pressure Monitoring

Some of the advantages of ABPM are:

  • Ambulatory monitors have the ability to take readings in every 15-30 minutes
  • It can save people from taking unnecessary prescriptions of hypertension drugs by ruling out the possibility of white coat hypertension
  • It can also detect masked hypertension and nocturnal nondipping which can save patients from heart diseases, stroke, organ damage, etc.
  • ABPM is very much useful in evaluating a patient’s response towards antihypertensive medications
  • ABPM eliminates observer error and biasing to give more accurate BP readings
  • It correlates better with end-organ damage
  • ABPM offers detailed information on blood pressure variability

Cons of Ambulatory Blood Pressure Monitoring

You may face some problems while undergoing ambulatory BP monitoring such as: 

  • You may experience some discomfort physically due to 24 hours of monitoring
  • Repeated cuff inflations may cause soreness in your upper arm
  • Blood pressure measurements during the night may disturb your sleep
  • Skin irritation and mild rashes on the arm

FAQs

Q1) What is Normal Ambulatory Blood Pressure?

Ans) Normal ambulatory blood pressure is less than 130/80 mm Hg. Along with that, normal day-time ambulatory blood pressure is less than 135/85 mm Hg, and normal night-time ambulatory blood pressure is less than 120/70 mm Hg.

Q2) Is ABPM costly?

Ans) Some people believe that ABPM is costly as compared to other BP measurement techniques. But in reality, ABPM is cost-effective, both in primary care and specialist services. ABPM can help you save 3%-14% of the total cost of hypertension care and 10%-23% in hypertension treatment if it is used in the diagnostic process.

Q3) I am a diabetic patient, should I go for ABPM?

Ans) Yes, you should try ABPM as it is particularly more important for the management of hypertension in diabetic patients. As diabetic patients are more likely to be nocturnal nondippers, office-based BP monitoring does not give the real picture of cardiovascular risks.
So as hypertension is more dangerous for diabetics, it becomes important to perform ABPM.

If you find this article valuable, please share it with your friends and family members. If you have any query related to ABPM, feel free to ask me in the comments below.

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