Are wrist blood pressure monitors accurate? This is a question that I set about answering some years ago. Not out of medical research curiousity but as a patient myself.
Apart from knowing the answer to the accuracy of wrist monitors, I also explain why my answer is what it is and finally I’ll tell you if I recommend wrist BP monitors as a home blood pressure monitoring kit or not. That’s what you are going to get on this page.
Being a doctor and someone who suffers from high blood pressure, I accidentally found the answer to the question: are wrist monitors accurate for blood pressure; more out of luck rather than by design.
My curious search for an alternative to upper arm blood pressure monitor led me to discover the truth about wrist blood pressure monitors. The long and short of my short adventure was that the wrist blood pressure monitors are not accurate.
So, if you want to know the real answer to the question: are wrist blood pressure monitors measurements accurate? The answer is; No, wrist monitors are not accurate for blood pressure measurement.
My claim is based on my personal experience of 4 different brand of wrist monitors. These wrist monitors kept giving wild blood pressure readings. Usually BP readings that would suggest I am about to have a stroke or heart attack.
With doubts in my mind as to such ridiculously high readings, I had to do a validation of the readings. Fortunately I had an upper arm monitor at home.
When I checked my blood pressure with my upper arm monitor at the same time as the wrist monitor, I had normal blood pressure.
So, whereas the wrist monitor was producing BP readings that would suggest I needed to go to ER (A&E) immediately for medical attention, my upper arm monitor was giving readings that were perfectly normal.
The contrast between the wrist monitor and the upper arm monitor was as clear as the Biblical ‘Red Sea parting for Moses and his troops to go through’.
When you have recurrent episodes of false readings with different brands, it is not unreasonable to reach that conclusion that wrist monitors are not accurate for blood pressure measurements.
Mind you on each occasion, I validated with the upper arm monitor. Occasionally, there was a close match of the readings from the wrist monitor and the upper arm one.
But these episodes of the close match were very few and far between. Scenarios like that meant I had to reach that conclusion, that the wrist monitors were inaccurate and therefore unreliable.
Why are wrist blood pressure monitors not accurate for Blood pressure reading?
Okay I won’t just make a statement like that and not give you reasons for why wrist blood pressure monitors are not as effective as upper arm monitors.
One reason for this inaccuracy of blood pressure readings from the wrist monitors is the blood vessel from which the wrist monitor is getting its reading from.
Our body’s arterial tree is a high pressure system. But the walls of our arteries have been cleverly designed by nature to maintain a pressure gradient that drives blood onwards and forwards downstream.
This means smaller vessels are more muscular than larger vessels. Larger vessels closer to the heart are lot more elastic than smaller vessels downstream. The larger vessels have to be elastic to withstand the high pumping pressure of the heart ventricles.
Larger vessels – elastic
Smaller vessels – muscular
The brachial artery is larger than the radial artery. Meaning the brachial artery is more elastic than the radial artery. The smaller arteries will have a higher resistance i.e pressure, within them than the larger blood vessels because they are more muscular.
This differential pressure is necessary for the continuous flow of blood within the arterial tree. That’s the concept of the physics of flow through vessels of different sizes.
But of course nature is very clever, you have a sudden drop in pressure when blood arrives at the very small arteries called the arterioles. This is designed to protect us from harm and keep the delivery of nutrients and oxygen efficient.
I am digressing here for good reason but the video below explains it a little bit more about the physiology.
The point I am making is that; you will more than likely get higher blood pressure readings in the smaller radial artery (that the wrist monitors measures) than the larger brachial artery (that the upper arm monitor measures).
The second reason wrist monitors give inexact readings is that they are very sensitive to positioning. Any slight adjustment of your wrist position will lead to swings in blood pressure readings.
Which brings me nicely to the third reason for wrist blood pressure monitors inaccuracy. We advise high blood pressure patients to measure their blood pressure by placing the cuffed area to the level of the heart.
Now imagine trying to place the cuffed wrist at the level of the heart. It’s not a natural position for the wrist. That causes all sorts of positional problems.
Compared to the upper arm, which is almost at the level of the heart requiring just a little elevation, the wrist monitor will need a higher elevation. That’s a recipe for errors in blood pressure readings.
Would I recommend Wrist blood pressure monitors?
The short answer to that question is: No, I won’t.
They both recommend the upper arm monitors and I support the recommendation as well.
Why is this?
For the same reasons that I have outlined earlier on this article. It is clear. The wrist blood pressure monitor readings are not accurate. If you want to monitor your blood pressure at home, you’d want to use a device that is reliable.
You would use a blood pressure measurement device that produces clear, unambiguous blood pressure readings every time. Not some of the time but every time.
The wrist monitors cannot be trusted to do that. The wrist blood pressure monitors are not effective home BP monitoring kit.
The last thing you want is showing results of blood pressure readings to your doctor that are ambiguous and inaccurate. Situations like that will lead to your doctor making wrong management decisions.
You don’t want that. In fact, it could be downright dangerous. Avoid!
I shall be providing answers to these questions right here.
What are the pros and cons of wrist blood pressure monitors?
Sadly, I want to start with the cons of wrist blood pressure monitors. I apologize for this because it is never a good idea to begin a journey on a negative note.
Always start with the positives; my mother always told me when I was younger. But I am constrained to do disobey my mother in this instance, because I want to tell my story of my first romance with these wrist blood pressure monitors.
Wrist blood pressure monitor cons
And my story unfortunately does not lead to pros of wrist BP monitors but rather to the cons of wrist blood pressure monitors.
I am a sucker for innovation and innovative products. I needed to say this upfront as that’s how my relationship with these wrist blood pressure monitors started.
A couple of years ago, I saw a full-page newspaper ad on a brand of wrist blood pressure monitor. I was enthralled by the ad. Mainly because the focus of the ad was the simplicity of using this blood pressure machine. I was sold. In an instant.
I must admit at the time I had not heard of these wrist blood pressure monitors, so my curiousity was piqued. Really piqued. I went past curiousity and made a purchase straightaway.
I felt such an innovative product was something I needed in my life. I should say that I am a medical doctor and also someone who suffers from high blood pressure too. Therefore my need for the product was a match made in heaven.
In any case what’s the point of having your curiousity aroused by an innovative product and not do the follow through business – make the purchase, that is. Call it impulsive buying and you’ll be right.
I should also say that up until that point, I had not heard of wrist blood pressure monitors. They were not available in the hospital environment that I work at the time and still aren’t. I shall come to this point again later on…
Anyway, the product arrived a couple of days later and I was so keen to use it, I unboxed it straightaway.
Off I went, slammed it on my left wrist, pushed the button to inflate the cuff and measure my blood pressure. Oops…I got a ridiculously high reading. I sat back, rested a while, breathed deeply, tried another reading. Same high reading.
Tried wrist number 2 – same high reading.
Called the retailer who requested I send it back for exhange as that may be a faulty item. New wrist blood pressure monitor arrived days later. Same outcome.
Now, how do I know the wrist blood pressure monitor was the issue and not my blood pressure hitting the roof at 240/135 mmHg for instance? Well, that’s because I have an older upper arm monitor that I had been using reliably in the house.
I double-checked with that upper arm monitor and my blood pressure was perefctly normal at the same time the wrist blood pressure monitor was giving me ridiculously high blood pressure readings.
As stated in the video below, I tried some other brands of the wrist blood pressure monitors and I wasn’t impressed.
As you can tell from the above story, reliability and accuracy are big cons of the wrist blood pressure monitors.
The problem with accuracy and reliability are one big disadvantage of wrist blood pressure monitors that I find difficult to overlook.
One of the reasons wrist blood pressure monitors give higher readings that are not reflective ofyour true blood pressure is the artery who’s pressure is being measured.
Wrist blood pressure monitors take the blood pressure readings from the Radial artery unlike the upper arm monitors that measure the pressure in the Brachial artery.
The radial artery is narrower and more superficial compared to the brachial artery that is deeper and larger. If you remember your physics from secondary school, you will understand why the pressure in a smaller vessel will be higher than a bigger vessel.
Another problem with wrist blood pressure monitors is the placement of the blood pressure cuff. Ideally when measuring your blood pressure at home, we advise you to place the cuffed area at the level of the heart when the blood pressure measurement is taking place. This is actually the same advice offered by the American College of Cardiology too.
With the wrist monitors, the wrist where the cuff will be wrapped is not naturally at the level of the heart. Achieving that objective of having the cuffed wrist at the level of the heart makes for some awkward positioning.
This is very much unlike the upper arm monitors where the upper arm is almost at the level of the heart. Your arm only requires a little elevation.
Summary of the cons of wrist blood pressure monitors:
Difficulty positioning the cuffed wrist at the level of the heart
Readings very sensitive to positioning
Smaller blood vessel pressure being measured
Gives inaccurate readings most of the time
Reliable readings are few and far between
Therefore cannot be trusted as a home blood pressure monitoring kit
Pros of wrist blood pressure monitors
That said, it’s not all bad news with the wrist blood pressure monitors. They do have some advantages. May be it wasn’t a bad idea after all, that I started with the cons whilst tackling this subject of the wrist blood pressure pros and cons.
Saving the good news for last…
Anyway in the interest of a good balance of facts and without bias, here are the advantages of the wrist blood pressure monitors:
Wrist blood pressure monitors are small, therefore very easy to carry around. You can easily shove them in your handbag, briefcase and off you go. So, quite suitable for On-The-Go ambulatory blood pressure measurement.
Meaning they are very portable because they are small and lightweight.
They require very little dexterity to use them. You hardly need any handiwork to use the wrist blood pressure monitors. If you can wear a wrist watch, you can use the wrist blood pressure monitors.
Cuff size is usually not a problem with wrist blood pressure monitors. Because wrist sizes do not vary much, so you shouldn’t have an issue with cuff being too small or too big. Therefore suitable for those with big arms, although you can shop for bigger cuff for upper arm monitors too.
Practically all wrist blood pressure monitors are automatic as opposed to having to choose between manual and automatic. Meaning there’s very little learning curve involved.
This also translates to being very easy to use.
Summary of pros of wrist blood pressure monitors:
Small in size
Easy to use
Provides dual readings of systolic and distolic Blood pressure
Cuff size not usually a problem
Quite comfortable to wear and use
Little or no dexterity involved to get a blood pressure reading
Usually automated so little learning required
Wrist blood pressure monitors Vs Upper Arm Monitors: Which should I buy?
Those are the wrist blood pressure monitor pros and cons. Now, if you ask me which of these monitors to buy for your home use, my professional advice will be to go for the upper arm blood pressure monitors. Sounds crazy, right? After everything I’ve said…
See video below
As far as I am concerned, even though the wrist blood ressure monitors do have some really good advantages over the upper arm monitors, the one disadvantage I cannot get over is unreliability.
If you are going to monitor your blood pressure at home, you want something reliable. You want a blood pressure kit that gives you accurate readings that you can take to your doctor. Readings your doctor can trust.
Doctors don’t want to make decisions on blood pressure readings that are sketchy and probably accurate 25% of the time. Not even 75% of the time. We want to make decisions on readings that are accurate 99.99% of the time.
Why is this?
Doctors don’t want to make the wrong management decisions. Wrong readings lead to wrong decisions. That’s not the basis for a sound high blood pressure (hypertension) management.
Like I said in the video, given the fact that these wrist BP monitors have been around for a long time now, and are very easy to use, how come we don’t use them in hospital settings?
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