Advice from the BP Measurement Experts
The American Heart Association just released a scientific statement on blood pressure (BP) measurement that outlines new guidelines for accurately measuring blood pressure. This is the first time the AHA has made significant updates to their recommendations since 2005. In the statement they describe and compare different methods of measuring BP and make many recommendations. What are the key points that a physician should learn from this new paper?
In my last blog, I introduced some of the claims and confusion around the NIH Sprint study but today I’d like to clear up the main point of confusion and discuss the actual blood pressure (BP) reading technique used to obtain the SPRINT study’s “research readings”.
We will be examining the SPRINT claims of benefit to medicating to a Systolic BP of 120 mmHg, but that will be for another day. Today the focus is on BP averaging, how it was implemented in the SPRINT study, and why it makes sense even if you aren’t sold on the SPRINT findings.
Designing a better User Interface (UI) and User Experience (UX) for medical devices presents unique challenges not typically present in other products or applications. If you press the wrong button when ordering your mocha latte, you may not get whipped cream. If you press the wrong button when administering medicine through an infusion pump, your patient may overdose. One study showed that infusion pumps account for up to 35% of medicinal errors that result in significant harm. A large percentage of those errors were attributed to poorly designed user interface. For instance: a clinician might have entered “lbs” instead of “kg” for the weight of the patient, or perhaps they did not see a decimal point on the display, or they selected the incorrect dose mode while administering medicine. That is one of the many reasons medical devices must pass through numerous regulatory tests to make sure user errors are minimized.
Should you take medication in order to acheive a Blood Pressure of 120/80? The SPRINT trial (Systolic Blood Pressure Intervention Trial) originally published in 2015 is the NIH’s landmark blood pressure (BP) lowering trial. According to the NIH press release (bold emphasis mine),
"When SPRINT was designed, the well-established clinical guidelines recommended a systolic blood pressure of less than 140 mm Hg for healthy adults and 130 mm Hg for adults with kidney disease or diabetes. Investigators designed SPRINT to determine the potential benefits of achieving systolic blood pressure of less than 120 mm Hg for hypertensive adults 50 years and older who are at risk for developing heart disease or kidney disease." (1)
SunTech announced just last week that a new veterinary blood pressure algorithm is under development. This new algorithm will be fine-tuned for equine physiology and will offer a non-invasive way to measure blood pressure on horses. To make the announcement, SunTech exhibited at the 64th Annual Convention of the American Association of Equine Practitioners in San Francisco. I had the opportunity to attend the convention with the primary goal of better understanding how veterinarians use and measure blood pressure today in their equine patients.
With the launch of SunTech’s innovative PLUS Cuff sizes, here are some of the reasons you should consider changing your blood pressure cuffs. The PLUS Cuffs were designed to specifically target the need to fit a greater range of patients – including bariatric patients, improve measurement reliability, and cut hospital costs and inventory.
On top of reducing the risk of cardiovascular disease, aggressive treatment of high blood pressure has shown effectiveness in mitigating risk of mild cognitive impairment. Mild cognitive impairment is viewed as a potential precursor to Alzheimer’s and dementia. A study showed that when treating patients to reduce systolic blood pressure below 120, as opposed to below 140, the past standard target, the risk of mild cognitive impairment was reduced by 19% comparatively.
Gone are the days where your cardiovascular health could be summed up in two numbers. Systolic and diastolic blood pressure, measured at the brachial artery, were the key tools for staving off heart attack, stroke and other cardiovascular disease (CVD). Have a BP of under 140/90? Great! You are going to live a long and healthy life. Over 140/90? Time to watch your salt and medicate away. While lowering BP in hypertensive patients has been proven to be an effective intervention, it may not be so simple any more. Research, such as the SPRINT study, are finding benefits for managing BP in pre-hypertensive patients. With that, a new series of indices and measurements are offering more tools for doctors to measure and treat hypertension.
On recognizing the fact that fifty percent of the world hypertensive population did not realize they had the condition, the World Hypertension League (WHL) dedicated May 17th to the promotion of hypertension awareness. Since that day in 2005, World Hypertension Day has been celebrated by offering free blood pressure readings through the volunteered efforts of numerous affiliated organizations across the globe.
Ambulatory blood pressure monitoring (ABPM) - a procedure in which a patient wears an automatic blood pressure device for 24 hours as readings are taken every 30-60 minutes - is a widely used hypertension diagnostic tool in many countries, but not the US.
Traditionally, blood pressure (BP) measurement is largely confined to the doctor's office, using manual measurements to provide a snapshot of a patient's blood pressure and cardiovascular risk.
Anyone who has had a stress test knows that stress tests are not easy and can even be painful! The commonly-used Bruce protocol for treadmill exercise tests includes 7 stages of 3 minutes each. The first stage starts at a 10% grade at a speed of 1.7 miles per hour. Each stage increases by 2% and between 5-9 miles per hour. Even though a stress test can last for over 20 minutes, most people don't last longer than seven minutes on the treadmill. However, it is important to keep going as long as possible to collect lots of data and be sure to reach the target heart rate. Each additional minute of a stress test could yield important information about the heart's condition.
Whether you take blood pressure readings on a regular basis or you’re taking a BP measurement for the first time, it's always good to review the latest standards on how to measure blood pressure. You may think that you're using the correct method however, incorrect results caused by improper technique are more common than you might think. Follow the steps in the infographic below to ensure you get an accurate blood pressure reading every time. Use it as a quick review to sharpen your skills or check out our video for a step-by-step “how to” with more in-depth instruction.
As beloved pets age, it can be difficult to know how their health care needs to change so we will be discussing 3 ways to better care for senior animals. After all, your cat or dog can’t tell you what he or she is feeling. To stay on top their health into old age, it is important to adjust their veterinary care as needed, including going to the vet more often. Here are a few tips for ensuring that your furry friend receives top notch senior health care.
Blood Pressure experts offer new advice based on a recent study conducted by the ACP/AAFP, which shows that the threshold for hypertension in healthy patients may not be as low as what the SPRINT study of 2015 concluded.
A recent study published in the American Journal of Hypertension shows the majority of blood pressure devices sold and used in people’s homes are potentially inaccurate as much as 70% of the time. Since lots of people measure their blood pressure at home to track their cardiovascular health, this study is understandably noteworthy. But what else can we learn from it?
First, let’s talk a little bit about oscillometry. Oscillometry is the general method that most automatic blood pressure devices use to measure blood pressure. This is true for devices in the home, in doctor’s offices, and even in hospitals. As the study pointed out, while the oscillometric method is commonplace, there are differences between devices from different manufacturers because of the mathematical formulas and algorithms used to calculate systolic and diastolic blood pressure values. The math is proprietary, and most private companies that have their own oscillometric technology—including SunTech—guard those calculations very closely.
Why? Well, the simple answer is that the math behind better-performing technologies is based on actual clinical research conducted over long periods of time—in SunTech’s case, decades. This research, and the analysis of the resulting data, is a significant and expensive undertaking that can provide an important commercial advantage when it comes to a device’s clinical accuracy. So if companies had to share their data with the rest of the world, what would be the incentive to conduct all of that research in the first place? So, proprietary data can result in devices with better clinical performance, which is better for physicians and patients. I say ‘can’ because it’s no guarantee, as this study clearly illustrates.
One other fact about this study merits some additional digital copy. The authors discuss several potential reasons for the reported inaccuracy of almost 70% of the home blood pressure devices analyzed. But there is one that the authors mention briefly that could actually explain a lot. And that’s the blood pressure cuff itself. Now, it’s pretty common for folks to call the entire device—digital box, hose, and fabric that wraps around the arm and inflates--a ‘BP cuff’. But what I’m talking about is just the part that goes on the arm. That’s the actual blood pressure cuff.
Blood pressure cuff sizes are incredibly important for any oscillometric blood pressure device. The math behind these devices assumes that the correctly sized cuff will be used on the patient. See, because of the physics around how non-invasive blood pressure is measured, there’s no such thing as a ‘one size fits all’ blood pressure cuff. To be accurate, the cuff must be sized correctly according the circumference of the patient’s upper arm, for a variety of reasons. The researchers in this study reported that the mean arm circumference of study participants was a bit less than 33cm, and that increasing arm circumference was a statistically significant predictor of an inaccurate measurement.
Now, 33cm is on the high side for most standard, adult-sized blood pressure cuffs. Since home blood pressure devices typically include only a single cuff, manufacturers generally pick a very middle-of-the-road size for the cuff, hoping that it will cover the majority of arm sizes. But in the case of this study, the mean arm circumference is already pushing the upper limit of a middle-of-the-road adult cuff. So it should come as no surprise that as arm circumference increases, accuracy suffers. The researchers didn’t publish any data on the sizes of the BP cuffs that were used with the home BP devices, and I think that would have been helpful.
But the point here is that that size matters when it comes to BP cuffs and oscillometric devices. It matters a lot. It might even matter more than the math inside the device—although that matters too. So if you find yourself in need of a home blood pressure device, the first thing that you need to do is make sure that the cuff that comes with it is the right fit for your arm. Your doctor can help you figure this out if you bring it with you to the doctor’s office. If the cuff isn’t the right size, contact the manufacturer and see if they have a cuff that is.
In fact, even when you are having your blood pressure measured in a doctor’s office, it’s not a bad idea to ask the clinician taking your BP to double-check the sizing of the cuff to your arm, as other studies have shown that using the incorrectly sized cuff in clinical settings is commonplace as well.
While data that points to inaccuracies with home blood pressure devices is important, for professionals in the medical world, it’s not exactly news. And while asking how to make home BP devices better is fine, we should also be asking if there are more accurate alternatives to home BP. And the answer is yes. 24-hour Ambulatory Blood Pressure Monitoring (ABPM) is widely considered to be the gold standard for assessing a patient’s blood pressure.
Unfortunately, the reimbursement for ABPM in the United States is currently quite low, and only valid for diagnosing white coat hypertension. In other countries, like the U.K., ABPM is becoming recognized as an important tool for treating general hypertension, and is therefore being treated as such by government and private payers.
At SunTech, our goal is to continue to evolve our Oscar 2 ABPM devices to make them more patient friendly, and allow them to deliver more valuable clinical data, so that clinicians can make better diagnoses and treatments. It doesn’t happen overnight, but we’ll get there.