Ambulatory Blood Pressure monitoring is the non-invasive, 24-hour monitoring of a patient’s systolic and diastolic blood pressure.
If the measurement is 120 systolic and 80 diastolic, the monitor should display “120/80 mmHg”.
As its name suggests, patients are required to wear a belt or strap with a blood pressure monitor. This is attached to a cuff placed on the patient’s non-dominant arm.
The device takes blood pressure measurements for a 24-hour period while the patient goes about their daily activities. These measurements are then collected, processed and evaluated by the doctor.
ABP monitoring can detect:
ABP allows your cardiologist to get a more accurate picture of your blood pressure patterns at different times of the day.
For example, it shows your cardiologist how your blood pressure dips at night. Additionally, a one-off blood pressure measurement would not be enough to determine the type of hypertension you may have or to help discern whether certain treatments or medications are working.
Measuring your blood pressure is a good indicator of whether you suffer from hypertension or hypotension.
Most underlying conditions related to blood pressure often go undiscovered until it is too late. An example would be hypertension, the “silent killer”. Hypertension refers to high blood pressure.
“SILENT”
“KILLER”
Only through blood pressure monitoring can hypertension be reliably diagnosed.
Conversely, hypotension refers to low blood pressure, or hypotension.
Hypotension is most reliably diagnosed by measuring blood pressure as well.
Hence, patients need to undergo blood pressure testing to correctly identify any underlying conditions such as hypertension and hypotension. This will help patients receive the proper treatment they need to get better and live life to the fullest.
The table below shows a quick comparison between Ambulatory, Home and Office Blood Pressure monitoring.
| Types of monitoring | Methodology | Advantages | Weaknesses |
|---|---|---|---|
| Ambulatory Blood Pressure (ABP) Monitoring | Blood pressure is measured at regular intervals over 24 hours | ABP can detect Variability in blood pressure at night, which indicates risk for cardiovascular disease. ABP is also able to detect: Whitecoat hypertension Masked hypertension, Blood pressure variability Hypotension Organ damage | ABP is More inconvenient for the patient compared to HBP and OBP monitoring as the device needs to be worn for 24 hours. The most costly |
| Home Blood Pressure (HBP) Monitoring | The blood pressure is recorded by the patient themselves, once in the morning and the evening for 4-7 days. Each recording should contain two consecutive blood pressure measurements, at least 1 minute apart, with the patient seated. | HBPM can detect Whitecoat hypertension Masked hypertension, Blood pressure variability Organ damage Hypotension HBP monitoring is less costly than ABP monitoring. | HBPM is unable to detect changes in blood pressure at night. less accuracy on average, as the patient has to take the measurements themselves. |
| Office Blood Pressure (OBP) Monitoring | Patients visit the doctor to get their blood pressure taken by an automated or non-automated oscillometric sphygmomanometer. | OBP monitoring can detect: Hypotension Hypertension Organ damage OBP monitoring is less costly than both HBP and ABP monitoring as well as more convenient for the patient | OBP monitoring is Unable to detect Whitecoat hypertension, masked hypertension. A less accurate predictor of cardiovascular events and other target organ damage. This will affect the effectiveness of treatments given as well as the accuracy of diagnosis. |
As seen from the table, ABP and HBP monitoring provide more prognostic value than OBP as they are better able to predict how likely conditions, such as cardiovascular disease, will occur. Both HBP and ABP monitoring are also more accurate in detecting target organ damage as compared to OBP monitoring.
There is no “better” means of measuring blood pressure. However, one may be more suited to diagnose your condition than the other.
HBP monitoring measures blood pressure variability twice a day, while ABP monitoring measures blood pressure variability of the patient for 24 hours, including at night. Studies have shown that nighttime measuring of blood pressure variability provides a more accurate prediction of cardiovascular events occurring compared to daytime measuring. Thus, using ABP monitoring leads to a more accurate diagnosis and medication being provided in more effective dosages than HBP monitoring.
Hence, while all three can detect similar issues, ABP and HBP monitoring are more comprehensive than OBP monitoring, with Ambulatory Blood Pressure monitoring being the most accurate predictor of future heart issues.
Two notable subtypes of hypertension include:
When a patient is in the clinic, their blood pressure readings may be higher as compared to when they are in other settings, leading to inaccurate diagnosis of hypertension.
Conversely, when the patient is in the clinic, they may not have high blood pressure reading. However, when they are out of the clinic, their blood pressure is high as a result of stress at work or sleep apnea. This may lead to a misdiagnosis of no hypertension, when there in fact, is.
These two subtypes are best detected using Ambulatory Blood Pressure Monitoring as compared to Home Blood Pressure and Office Blood Pressure monitoring.
During the test, some might be puzzled over the numbers appearing on the blood pressure monitor and how to interpret them.
For adults (aged 18 years and older), hypertension occurs when the systolic blood pressure is >140 mmHg or when diastolic blood pressure is >90 mmHg.
Hypotension, on the other hand, occurs when the systolic blood pressure is less than 100/60 mmHg.
The larger number or the number at a higher position usually is the systolic pressure, while the number below is usually the diastolic blood pressure.
For the ranges of blood pressure (BP) relating to specific stages of hypertension, please refer to the chart below:
Categories for Blood Pressure Levels in Adults (Aged 18 and older)
| Blood Pressure (BP) Level (mmHg) | |||
| Category | Systolic | Diastolic | |
| Normal BP | <120 | and | <80 |
| High-Normal BP | 130 | or | 80-89 |
| High BP | >140 | or | >90 |
| Stage 1 Hypertension | 140-159 | or | 90-99 |
| Stage 2 Hypertension | 160 | or | 100 |
| Isolated Systolic Hypertension* | >140 | and | <90 |
After interpreting the BP readings, this is what you can expect from your doctor:
No treatment necessary. However, it is still important you maintain your blood pressure, especially as you age
This indicates you may be at risk of developing hypertension. Medication might not be necessary but the doctor might advise you on lifestyle changes to help lower your blood pressure
Any reading above Stage 1 Hypertension means you are hypertensive. Your doctor may recommend medication and lifestyle changes to help lower blood pressure
Your cardiologist will generally recommend Ambulatory Blood Pressure monitoring if you have:
You may want to shower before ABP monitoring as it is best to avoid water during this time, and there is no need to fast. In fact, you should eat as you normally would. Other steps you can take are to:
To get a more accurate reading:
Some slight discomfort may be experienced when the blood pressure cuff inflates. You may also experience slight itchiness under the cuff. If this discomfort becomes intolerable, do inform your cardiologist instead of tampering with or removing the device.
Hopefully, we’ve helped you better understand ambulatory blood pressure monitoring. Decisions regarding your medical treatment should not be done alone, so if you have any needs or concerns, please contact your cardiologist for further discussion.
Dr Devinder Singh is the Medical Director of Cadence Heart Centre. He is an experienced Senior Consultant Cardiologist & Cardiac Electrophysiologist with over 20 years of clinical experience.
His expertise lies in clinical cardiology, cardiac rhythm disorders (arrhythmia), cardiac pacing (including cardiac resynchronisation therapy) and cardiac magnetic resonance imaging. He performs electrophysiology studies and radiofrequency ablation of cardiac arrhythmias, and is well versed in pacemaker and defibrillator insertions.
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