Tag Archives: wrist blood pressure

Wally’s High Blood Pressure Tales: Of Dentists, Wrist Cuffs and an Experiment

Today’s post comes from the Wally, the life coach of the skeptical cardiologist,  who (ultimately) relates what happened when he agreed to do a blood pressure experiment in exchange for medical advice.


Blood Pressure Story 1

I used to work for a company that, for a short time, rewarded healthy employees with lower insurance premiums. They based your score on body-mass-index (BMI), cholesterol, and blood pressure (BP). At the time, I was riding a bike a lot so my BMI was acceptable. My cholesterol was also within range since I take a low dose of a statin. But, my blood pressure? I’ve been doing battle with my blood pressure since the 1980s. So, on the morning of the screening, I took precautions: no alcohol the night before and no coffee before the test. Let’s talk about coffee for a moment: I’m an engineer and we use coffee for fuel. Never hire an engineer who doesn’t drink coffee. In fact, here’s how I interview a new engineering candidate:

Me: “Do you like coffee?”
Candidate: “Yes”
Me: “How do you like it?”
Candidate: “Black.”
Me: “Congratulations, you have the job!”

Back to the morning of the screening: I had no coffee and I may have had low blood sugar. I got in my car and started backing out. It’s 6:30AM and dark outside – backing, backing, backing, CRUNCH. In spite of having a backup camera I still somehow managed to hit my daughter’s car. I’m sure that sent my BP up. Fortunately, I had calmed down enough to pass all of my tests by the time I got to the screening center 30 minutes later. 

Blood Pressure Story 2

On another morning I had to go to the dentist – I always go early so that I don’t miss any work. So, with three cups of coffee in me I hit the road. Of course, I didn’t take traffic into consideration and  I was 10 minutes late. The staff at the dentist’s office didn’t mind but I was a little anxious because 1) I hate to be late and 2) I was at the dentist’s office. 

They have me sit in the adjustable padded chair and ask me the usual questions about changes in the meds I’m taking. While that’s going on, I’m trying to remember if this is the visit where they take X-rays or the visit where they use a needle to evaluate the pliability and travel of my gumline. Trust me, the gumline eval is not fun and as I start to think it’s going to happen, the hygienist puts a small integrated blood pressure cuff on my wrist. Really? You’re about to poke sharp things into my mouth and you’re measuring my BP? Of course, it’s terrible. They measure again: not so terrible. And on the 3rd measurement? Back to terrible.

Ever hear anybody say, “The dentist sure was fun today!” No, you haven’t. That sentence has never been spoken – unless the valve on the nitrous tank was leaking. This guy though, he liked to visit his dentist:

Blood Pressure Story 3

The Beginning

I had a semiannual physical coming up and I realized I better follow my doctor’s advice from my last visit and measure my BP first thing in the morning – before the coffee. Now, I have an old blood pressure cuff that I bought at a garage sale about 20 years ago and it still worked. But I started wondering how accurate it was given its age. So I went shopping on Amazon and decided to buy the same wrist cuff that they use at the demented dentist office. The morning after it came, I measured my BP and… well it wasn’t very good. So, I called my good friend The Skeptical Cardiologist and asked for his advice. And he graciously agreed to help – for a price. We made a deal: he would guide me on my journey to a lower BP. In exchange I would collect some data and provide an opinion on the different cuffs.

In other words: I volunteered to be the SC’s Lab Rat. At first I was proud that he was considering me to provide invaluable data. But, as time went on, I started thinking this might have been his revenge for a laboratory mishap that I caused when we were undergrads. Anyway, on to the experiment!

The Equipment

LifeSource UA-767

Your basic brachial BP cuff purchased at a garage sale.

OMRON 3 Series Wrist Blood Pressure Monitor

New. Can save data to your phone via bluetooth. Small.

The Protocol

First thing in the morning:

  1. Take three measurements on the left wrist with the Omron
  2. Take three measurements on the left arm with the LifeSource
  3. Take three measurements on the right wrist with the Omron
  4. Take three measurements on the right arm with the LifeSource

The Data

I’m a lousy scientist. I started off with good intentions but pretty soon, I started forgetting the evening measurements. And then, when I saw that there wasn’t too much deviation between the measurements on my left and right arms, I only made left arm measurements.

Here are the first two days of data:

January 1st:

The BP measured on my right side was lower in the morning and higher with the wrist cuff in the evening.

January 2nd:

On the 2nd day, left and right were more consistent but the wrist cuff was higher in the evening. About this time, I was already getting annoyed with the wrist cuff and decided to return it. My reasons for this are detailed below. 

I continued to measure my BP in the mornings using just the LifeSource cuff:

Other than the data from 1/5/20, there appears to be reasonably good correlation between the left and right arms.

Note the 12 day gap between the last two data sets. That’s because:

Tragedy Strikes

On the morning of January 8th, the LifeSource UA-767 blood pressure cuff crashed and burned on my kitchen table. The root cause of the failure was a small molded rubber doohickey that acted as an attachment point for the air system in the meter. I now had no means of measuring my BP. The experiment was over.

Review and Wrap Up

First of all this was not a very scientific experiment. By changing my meds I was able to get my BP down but I failed to collect all the data that the SC asked for. The reasons for this were 1) I returned the Omron wrist cuff early, 2) I kept forgetting to take my BP in the evening (it was a little crazy at my house over the holidays), and 3) the LifeSource died.  But I had used both instruments long enough to form an opinion:

Omron

I had high hopes for the Omron wrist cuff – it was new, and it was small with none of the awkwardness of the more traditional brachial style cuff. But I quickly started finding flaws:

  1. A wrist cuff has to be carefully positioned to get accurate measurements. While Omron says that the edge of the strap should be 1/2” away from the bottom of your palm, I had better luck just centering the strap over the vein where your radial pulse is measured. And besides, exactly where is the bottom of my palm? I could see where that would confuse some people.
  2. I found that manipulating the strap on the wrist cuff with one hand to be a little more difficult than the brachial cuff. Now maybe if I had kept it longer I would have become more adept but right away I felt that this could also lead to some positioning errors.
  3. To make accurate measurements with the Omron requires that you elevate your wrist to the same height as your heart. You can do this one of two ways: 1) physically hold up your wrist for the duration of the measurement or 2) prop it up with a pillow. This step is not required with an arm cuff because once applied it’s already positioned at roughly the same height as your heart. 
  4. Home blood pressure monitors have small air pumps in them to pressurize the cuff – that’s the buzzing sound you hear when you press the Start button. Since the enclosure for the Omron monitor is smaller than the LifeSource device, it has to use a smaller air pump. And a smaller air pump needs more time to pressurize the cuff. So you have to sit there and hold up your wrist while waiting for the cuff to pressurize – I found this a little tiring.

On the plus side the Omron did come with a small plastic case and didn’t take up too much space. And it had Bluetooth which allowed me to save my measurements on my phone using their app.  

LifeSource

The LifeSource was a boring old fashioned BP Meter that got the job done – until it died. My only complaint about these devices is that they’re awkward to store. There’s the cuff, the base, and the rubber tube connecting the two. Combined these things always get tangled up with other stuff.

Conclusions 

The old fashioned arm cuff is the way to go based on my experience. Yes, they’re awkward but they are solid and less prone to error. Because of this, I replaced the LifeSource with an Omron arm cuff monitor. And for storage I also bought a small enclosure for it.  And as for my BP, I was able to get it down in time for my doctor’s appointment.


When Wally is not creating laboratory mishaps or providing life coach consulting he dabbles in electrical engineering, tells mysteriously hilarious jokes,  and runs a website called Pi-Plates.com.

We met our freshman year at Oklahoma University and Jerry claims my first words to him were “Are you ready for the country?”

Skeptically Yours,

-ACP

The Full Omron HeartGuide Review: Is This Wearable Wristwatch Blood Pressure Monitor Right For You?

The Omron HeartGuide (OHG) is a digital wristwatch that takes oscillometric measurements of blood pressure. Named to TIME Magazine’s Best Inventions of 2019 list, the promise of this device was succinctly summarized by an Omron executive: “Integrating a blood-­pressure monitor into a sleek watch that also measures sleep and activity makes staying on top of cardiovascular health easy and provides a fuller picture of overall wellness.”

Previously on the skeptical cardiologist, I described my excitement at the HeartGuide’s ability to “serve as an accurate and unobtrusive daytime ambulatory blood pressure monitor.” After wearing the HeartGuide for a week and using it in a variety of situations to measure my blood pressure I had begun rethinking my usual recommendation against wrist blood pressure cuffs.

For me, the great attraction of the OHG was and still is the ability to measure your BP “anytime, anywhere.”

Despite my unabashed enthusiasm for the Heart Guide’s ability to provide facile daytime BP monitoring, certain limitations need to be recognized.

Herein is my more detailed, objective and pragmatic review of the device.

What Is In The Cube?

The OHG  is available on the Omron website for $499 but upon checkout currently, Omron is providing a 10% discount along with free economy shipping.

The device is available in medium and large wrist sizes. I sized my wrist as a medium using the measuring tool on their website.

Proper wrist sizing is crucial for accurate BP measurement.

The OHG ships in a black cube.

Inside the cube you will discover:

  • 1 Monitor
  • 1 Paper Sizing Guide
  • 1 Instruction Manual
  • 1 Quick Start Guide
  • 1 Charging Clip
  • 1 AC Adapter
  • 1 Charging Cable
  • 2 Replacement Cuff Sleeves

The OHG is large but stylish in appearance. It weighs 115 grams and the watch dial has a diameter  of 1.9 inches.

I found it took about 2 hours to fully charge the battery and that the device remained charged for about 48 hours.

Preparing For Blood Pressure Measurement

For accurate BP measurement, it is important to follow very closely the directions Omron provides.  The band should be positioned about 1 inch (2 fingers) below “the base of the hand.” The fit should be “snug.” Your index finger should not easily slide between the band the wrist.
The instructions ask you to sit in a chair for measurement and “position at heart level.” However, as I discussed in my previous post I found that I could make BP measurements under a variety of circumstances beyond chair sitting.
The OHG is fairly finicky about stability and positioning.  The directions for positioning state “position HeartGuide at heart level with 2 inches space between wrist and chest.” To ensure accuracy “do not bend your wrist or look at the display during measurement.”
Here’s what Omron says about its “Heart Zone Indicator”:

Your monitor has a built-in heart zone indicator that is used as an aid in determining if your monitor is at the correct height and position. It has been designed to work with most people so that when your wrist is at the correct position relative to your heart, your monitor will vibrate once. If it does not vibrate, your monitor may not be at the correct height and position relative to your heart.

Due to differences in individual size and physique, this feature may not be helpful in all cases and you may wish to turn off this feature. If you feel the position of the wrist, according to the heart zone indicator’s guidance, does NOT match your heart level, please turn off this feature and follow your judgment.

It’s not clear to me how the OHG knows that it is at heart level. I experimented with various positions including lying on my back and standing with my wrist definitely at heart level. Sometimes the OHG agreed, others not.

It is clear, however, that it does not like significant movement. It would not make a measurement if I was walking at any speed or while exercising on an elliptical or stationary bicycle.

Measuring A Blood Pressure

Once positioned properly simply push the top button on the watch and put your wrist in the appropriate position. You will notice a vibration followed by an initial mild inflation of the cuff that lasts about 15 seconds followed by a pause of a few seconds then a full , tight inflation of the cuff.

The entire process takes over a minute and is significantly slower than the upper arm BP cuffs I have been using.

When completed, the cuff deflates and the systolic and diastolic blood pressure along with pulse rate are displayed.

Not infrequently after triggering the device  I received an error message. Most commonly I encountered  Errors 4 or 5 which indicates excessive movement or talking

 

 

Accuracy

Before I could recommend the OHG in particular or wrist BP cuff devices, in general, I needed to know how they compared to the gold standard brachial artery, upper arm BP cuff.

I asked Omron for data supporting the accuracy of the OHG and they provided me with a copy of a 2019 paper entitled “Validation of two watch‐type wearable blood pressure monitors according to the ANSI/AAMI/ISO81060‐2:2013 guidelines: Omron HEM‐6410T‐ZM and HEM‐6410T‐ZL”

The lead author of this study is an MD, PhD working at the Jichi School of Medicine in Japan and his 3 co-authors all work for Omron Healthcare, Kyoto, Japan, which provided funding for the research so this skeptical cardiologist takes this information with a grain of salt.

The introduction to this paper points out that ambulatory blood pressure monitoring is important to help identify individuals who have higher blood pressure outside the clinic. Such individuals have masked hypertension, the opposite of white-coat hypertension.

The researchers concluded that both the large and medium wrist HeartGuide devices were accurate and fulfilled criteria set by the American National Standards Institute, Inc/Association for the Advancement of Medical Instrumentation/International Organization for Standardization.

Here are the Bland-Altman plots from that study

Note that although the average difference between the reference BP and the HeartGuide systolic BP is close to zero there is a significant variation from zero for individual measurements with some 20 mm Hg higher and some 20 mm Hg lower.

My experience confirms this significant individual variation. I took a number of simultaneous measurements using the HeartGuide on one wrist and a brachial BP cuff on the contralateral arm. I did this over multiple days under differing circumstances and with the devices on different arms.

I found that the HeartGuide systolic blood pressure was on average 10 mm Hg lower than the brachial BP when my blood pressure was high (>140 mm Hg).  When my systolic BP was between 120 and 130 mm Hg the HeartGuide was 5 mm Hg lower than the brachial and when my blood pressure was less than 120 mm Hg the Heart Guide and brachial BPs were identical.

I made similar measurements on other volunteers and found some had consistently identical wrist and brachial SBP whereas others had consistently higher blood pressures by wrist compared to brachial techniques.

Because of this individual variation I highly recommend users calibrate the OHG (or any wrist-based BP cuff) versus a standard BP cuff over a series of days with multiple measurements to see how the two measurements compare. If you find a consistent over or underestimate then the device can be used with this known adjustment.

Comfort, Form, Fit

The OHG is big. and it is bulky. The fastening strap is made of thick rubber and underneath that is the inflatable microcuff which works like the larger cuffs designed for brachial/upper arm measurement.

I was always aware of something on my wrist when I was wearing it. The OHG cannot be accessed if you are wearing a coat or any garment with thickish sleeves. Getting most upper garments on and off while wearing the OHG is a chore.

In the picture below you get a feel for how the OHG interacts with long sleeve garments. My shirt sleeve would not slip over it. When I was wearing a coat or sweatshirt I could not access or view the OHG as its large size prevented pulling back the sleeve.

IMG_5214.jpeg

Some Other Things the OHG Does

The OHG measures steps and it tells time. Omron also indicates it can be used to measure sleep quality. Frankly, I  did not test this feature because I felt I would not be able to sleep comfortably with the device on my wrist.

The OHG pairs via Bluetooth with the Omron smartphone app “Heart Advisor.” The app displays imported BP, pulse, activity and sleep data in various graphic formats.

IMG_5458

Data can be exported from the Heart Advisor app by email in either an Excel or PDF file. This feature would allow the user to conveniently send recorded BPs to their physician.

The OHG sends an alert when you receive a text message or phone call but you can’t see the text message or answer the call.

Overall Pros and Cons

I am still a fan of the OHG despite the limitations I have indicated above.

I don’t see most people using the OHG as their every day smartwatch The inconvenience and discomfort factors for most will outweigh the benefits.

However, I do see a very beneficial role in wearing the OHG periodically for targeted purposes. For example, it could be worn to work once per week to determine how one’s blood pressure is reacting to stressful situations or to the gym to assess one’s blood pressure before and after a workout. At least one study suggests that BP obtained at work is superior to 24 hour or sleep BP in predicting end-organ damage (manifested by echocardiographic left ventricular hypertrophy) from hypertension

If Omron can develop a method for the device to automatically trigger during sleep and provide accurate nocturnal BP measurements this would be a huge advance in the management of hypertension.

Skeptically Yours,

-ACP

N.B.Technical Specifications for the OHG

Model: BP8000-M
Display: Transflective memory-in-pixel LCD
Memory: Blood pressure measurement up to 100 times, Activity measurement up to 7 days, Sleep measurement up to 7 times, Event up to 100 items
Transmission method: Bluetooth® low energy technology
Power source: 1 Lithium ion polymer rechargeable battery, AC adapter
Battery lifespan: Will last for approximately 500 cycles, 8 times/day measurements in normal temperatures of 77 °F (25 °C) when new battery fully charged
Battery life: A typical user can expect to charge HeartGuide approximately 2-3 times per week, depending upon the frequency of use of HeartGuide’s features
Weight: Approximately 4.1 oz (115 g)
Dimensions: Diameter approximately 1.89” (48 mm), Case thickness approximately 0.55” (14 mm), Band width approximately 1.18” (30 mm)
Measurable wrist circumference: Medium – 6.3” to 7.5” (160 to 190 mm), Large – 7.1” to 8.5” (180 to 215 mm)

 

Omron’s HeartGuide Wristwatch Blood Pressure Monitor Allows BP Monitoring During Daily Activities Unobtrusively: Can It Replace Ambulatory BP Monitors?

I’ve been evaluating a wearable wrist watch blood pressure monitor for the last week.

After a Twitter interaction with Omron stimulated by Dr. Wen Dombrowski, the Omron people loaned me one of their HeartGuide devices.

Omron’s website describes the device as follows:

Engineered to keep you informed, HeartGuide is a wearable blood pressure monitor in the innovative form of a wristwatch. In tandem with its companion app HeartAdvisor, HeartGuide delivers powerful new technology making tracking and managing your blood pressure easier than ever before. Proactively monitor your heart health by turning real-time heart data into heart knowledge and knowledge into action. With HeartGuide wherever you go, you’re in the know.

I and the AHA have  not recommended wrist BP devices.  My decision was based on my personal research in the 1990s on arterial waveforms and the influence of wave reflection.  Studies have clearly shown a change in the arterial wave form as it proceeds from the ascending aorta to the periphery.

Therefore, the skeptical cardiologist was skeptical of the value of the HeartGuide

After wearing the HeartGuide for a week and using it in a variety of situations to measure my blood pressure I am rethinking my recommendation against wrist blood pressure cuffs.

I’ll give my full analysis of the device after more evaluation but what I’ve discovered is that it can serve as an accurate and unobtrusive daytime ambulatory blood pressure monitor.

Ambulatory blood pressure monitoring (ABPM) utilizes a portable BP monitor which includes a brachial BP cuff and a device that inflates the cuff every 20-30 minutes, makes a measurement and stores all the recordings for off-line review. Studies have shown ABPM is a better predictor of CV mortality than either clinic BP or home BP monitoring.

It has not been widely utilized in the US because it is poorly reimbursed.

The HeartGuide sits on my wrist and whenever I feel like it, wherever I am, I can quickly and simply make a recording of my BP.

 

 

With the HeartGuide I have made  BP recordings in a variety of situations which I would never previously have considered.

For example, earlier this week I wore the HeartGuide to work. I measured my BP at home and it was 125/76. After dropping my gear off at my office I walked to the 6th floor of the hospital to see inpatients. This involved going down several flights of stairs, crossing to the hospital via a pedway and climbing several flights of stairs.

When I emerged on the 6th floor I stopped (because the Heart Guide does not like it if you are moving), triggered the Heart Guide and put my right hand over my heart (the Heart Guide likes you to put your hand on your heart). Within 90 seconds I knew my BP (it had increased to 143/81).

In order to do this unobtrusively I wandered into the patient waiting area and pretended to be watching NFL highlights on the TV.  Nobody seemed to notice I was taking my BP!

Subsequently, I was paged to do a transesophageal echo/electrical cardioversion and went downstairs to our “heart station” where a room full of RNs, a sonographer, an anesthetist and a patient awaited me. While talking to the patient about the procedure I triggered the Heart Guide and made another BP recording. Nobody noticed!IMG_5220

The Heart Guide BPs are displayed on the watch face for a few seconds and can be sent via BlueTooth to the OmronAdvisor smartphone app.

The graph above shows my BP was high at 807 AM while I was talking to the patient and still up after the procedure.

One day I wore the HeartGuide to the gym and made BP measurements under a variety of conditions.

HG leg press

The HeartGuide will not activate while walking on the treadmill no matter how hard I try to keep my arm still. It does not like motion of any kind.

But the first reading on the left was immediately after running on the treadmill. I then performed an isometric leg press hold on a weight machine and was able to obtain a recording during this maneuver of 140/88.  Shortly after the leg press I repeated the recording and it had dropped down to 104/69.

I have to say this is an abundance of BP information that is quite interesting and heretofore I had never been aware of. It opens up intriguing clinical possibilities.

I will have to spend more time analyzing the Heart Guide before writing my overall impression and recommendations but thus far I see it expanding our toolkit for understanding hypertension and personalizing cardiovacular medicine.

Try to imagine yourself standing like me outside a restaurant unobtrusively taking your blood pressure and ponder the possibilities!

Soon you may find that wherever you go, you’re in the know. But be aware of the possibility of being arrested for loitering while checking your BP.

ap-HG.jpeg

Omnimanometrically Yours,

-ACP

If you’d like to read a detailed description of the HeartGuide check out this review while eagerly awaiting my more serious and more complete analysis.