By Dr Joe

One of the things high blood pressure sufferers talk about and feel bewildered about is why we recommend home monitoring of blood pressure to be done after they have rested.

Well, the truth is; checking your blood pressure after resting is the best way to get your true blood pressure reading.

Why…because a lot of positive things can happen to your blood pressure in those precious 5 minutes. The 5-minute rest allows time for your circulatory system to come to a rest. Doing so stabilises your blood pressure.

I have written a piece on this previously. That article explains why we measure resting blood pressure as opposed to measuring it during active times.

Not doing the at-rest blood pressure measurements means you have to consider the alternative. The alternative is 24 hours blood pressure monitoring. This is a continuous home blood pressure monitoring over a 24-hour period.

The secondary terminology for this pratice is ambulatory blood pressure monitoring.

what is ambulatory blood pressure monitoring

What is ambulatory blood pressure monitoring and how is it done?

As the name implies, ambulatory blood pressure monitoring is a blood pressure monitoring system that measures the pressure inside your blood circulatory system outside of the clinical setting. Checking your blood pressure when you are ambulant.

Of course, the ambulatory blood pressure monitor will measure your blood pressure when you are active and inactive. For instance, when you are sitting on your sofa watching TV and when you are asleep too.


In short, ambulatory blood pressure monitoring checks your blood pressure regardless of whatever you are doing at fixed intervals. Fixed intervals BP checks could be every 30 minutes or much more frequently.

As long as you have the ambulatory BP monitoring attached to you, it will do its own thing whether you are active or inactive. Readings are certainly more accurate than wrist monitors.

See also pros and cons of wrist blood pressure monitors

Ambulatory blood pressure monitoring can be done over a longer time but usually ambulatory blood pressure takes readings over a 24-hour period.

The cuff of the ambulatory monitor is wrapped around your arm and the blood pressure reading device or meter is given to you along side it.

You go about your business during the day and night and at fixed intervals, the blood pressure cuff will inflate and deflate spontaneously to measure your blood pressure at that moment in time.

These readings are recorded digitally over the 24-hour period.

It helps if you can manually record your activities over the 24-hour period you have the ambulatory BP device on you. In particular, a timeline of your activities will help your doctor interprete the results a lot better.

There is evidence that ambulatory blood pressure monitoring provides lower blood pressure readings compared to clinic setting readings. That can make them desirable.

Who needs 24-hour ambulatory blood pressure monitoring?

Anyone with high blood pressure really, truth be told.

But it is not practical to use the ambulatory device on everyone. Don’t forget millions of people have problems with high blood pressure all over the world.

So, getting the device to everyone will be an expensive undertaking. Although the companies making the ambulatory blood pressure monitors will not complain.

That would be good business for them. But for now, with limited resources, it makes sense to strategically deploy the devices to those in whom the need is strongest.

Who are these people?

People for whom the need for 24-hour ambulatory moniring is strongest include:

  • Anyone with suspected wild blood pressure swings during the day
  • Individuals with suspected huge blood pressure rises at night
  • Someone with suspected sustained high blood pressure
  • If white coat hypertension is thought to be an issue
  • An individual who may actually have masked high blood pressure
  • Poor response to high blood pressure medications
  • Borderline high blood pressure individuals
  • A need for prediction of risk of blood pressure complications

Why is ambulatory blood pressure monitoring important?

In 2018, we woke up one morning in spring, with screaming headlines in 3 newspapers – The Times, The Daily Mail and The Telegraph, all UK Newspapers trashing the use of clinic blood pressure readings. The implication was that current methods were not just outdated but bordered on being unsafe.

Whilst the headlines may be true such as stated by Laura Donelly of the Telegraph:

“White coat syndrome is real, confirms a new study, showing blood pressure measurements taken by a doctor are 50 per cent less accurate than those taken at home. The research confirms theories that readings taken in a doctors’ surgery bear little relation to the true state of heart health”

It still doesn’t mean that we should throw away our regular blood pressure monitors used in hospitals and clinic settings because they are useless. These regular BP monitors still have a huge role to play in the diagnosis and management of high blood pressure.

For one, they are convenient to use and the digital versions are now widely available which means patients can actually monitor their blood pressure at home.

We should not underestimate the role of these new digital blood pressure monitors that are so easy to use. They only require very little training. Meaning patients can have an input into their high blood pressure management.

In any case, doctors hardly use one-time readings in clinical settings to make decisions anyway unless the reading is astronomically high. Even then the measurement needs to be repeated a couple of times before intervention is suggested.

By the way, these newspaper headlines were the result of a study that was published in the New England Journal of Medicine.

It’s a Spanish study that tracked the health of over 63,000 adults over 18 years of age. Over a 10-year period. They measured their blood pressure the usual standard way in the clinic and were given the 24-hour ambulatory blood pressure monitor to take home.

The monitors were set to record blood pressure at 20-minute intervals during the day and 30-minute intervals at night. The participant’s records were entered as valid and included in the study only if 70% of the readings included both systolic and diatolic.

What the researchers found:

They found out the ambulatory 24 hours blood pressure monitoring was a better predictor of cardiovascular death than one-time blood pressure readings in the clinic. This was particularly linked to 24-hour systolic blood pressure rises.

They also found that masked high blood pressure had the highest risk of death.

Hear them:

“In our study, unlike most previous studies, we observed consistently greater mortality associated with masked hypertension than with sustained hypertension, which might be due to the delayed detection of masked hypertension in patients, who consequently could have more organ damage and cardiovascular disease than patients with sustained hypertension”

Interesting!

Another thing is that we tend to be dismissive of white coat hypertension as nothing to worry about. Well, be careful of how quickly you reassure yourself or doctor reassures you.

Because white coat hypertension was associated with increased risk of death. Although not as high as masked hypertension.

By the way, masked hypertension are individuals who were thought to have normal blood pressure with the standard clinic blood pressure measurement techniques but in actual fact aren’t.

The net effect is silent damage to target organs. This exemplifies the ‘silent killer’ image of high blood pressure. You couldn’t make it up!

Suggested further reading:
What can the Nitric Oxide Dump exercise do for your blood pressure?