Do you have high blood pressure? There’s a 50% chance that you do. That’s because anything above 120/80 is now considered hypertension. But was your blood pressure measured correctly? There’s a strong possibility the answer is no. Perhaps you do not have hypertension after all.
Listening to Blood “Whooshing:”
There was a time when doctors did not diagnose hypertension until a patient’s systolic blood pressure was over 140. Diastolic blood pressure had to be above 90.
In the 1980s the doctor (and it usually was the doctor back then) measured your blood pressure with a sphygmomanometer and a stethoscope. He (and it often was a he) would listen to the sounds over the brachial artery in the crook of your elbow.
The first “whoosh” of blood equals systolic blood pressure and the last “whisper” represents diastolic blood pressure. These “Korotkoff” sounds correspond to the peak pressure at the moment the heart contracts (systole) and pumps blood through arteries and the lowest blood pressure when the heart relaxes (diastole).
Lowering the Bar:
If you had your blood pressure measured 30 years ago and it was 145/95, your chart would probably say you had “mild” or “borderline” hypertension. You might have been told to lose weight, cut back on salt or exercise more.
In 2017 the same reading would be interpreted quite differently. More specifically, you would be diagnosed with stage 2 hypertension. That year the American College of Cardiology and the American Heart Association (AHA) determined that hypertension was anything over 130/80 (Annals of Internal Medicine, March 6, 2018).
Previous guidelines urged doctors to treat patients whose blood pressure measured 140/90 or higher. The first and higher number is systolic blood pressure: the pressure within the vascular system when the heart is squeezing blood through it. The second number, diastolic blood pressure, is the pressure remaining while the heart relaxes between beats. Under the new criteria, blood pressure at or above 130/80 is defined as high blood pressure. Most people at that measurement will need to take steps to reduce it.
Why the Change In Defining High Blood Pressure?
The lower threshold appears to flow from a study called SPRINT that was published two years ago. It showed clearly that people who were able to lower their systolic blood pressure close to 120 were 25 percent less likely to have a heart attack or a stroke. In absolute terms, the difference did not look enormous: 1.65 percent of those getting systolic blood pressure down near 120 had a cardiovascular complication compared to 2.19 percent of those whose systolic blood pressure was lowered only to 140. Still, when you consider how many millions of us (approximately 103 million) have blood pressure at or above 130/80, a little difference can add up to an awful lot of people. Avoiding a heart attack or stroke will be a huge benefit for them.
Roughly half of all adults in America (over 100 million people) were instantly labeled hypertensive. Even though their American colleagues were lowering the bar, European cardiologists retained the 140/90 cutoff (Circulation Research, March 2019).
Do You Have High Blood Pressure?
If you live in the U.S., you now have high blood pressure if your readings are greater than 120/80. “Normal” blood pressure is defined as anything less than 120/80. That’s true whether you are 25 or 85. If you can’t get your blood pressure below that cutoff with weight loss, exercise or a low-salt diet, many doctors feel obligated to prescribe medications. It is possible to lower blood pressure without drugs, but it requires diligence and effort: exercise, meditation and a DASH diet with plenty of vegetables and fruits can work.
Measuring Blood Pressure is Challenging:
Since the outcome matters so much, you would think blood pressure measurement would be highly accurate. That turns out to be harder than you might imagine.
Clinics and hospitals are trying to be more efficient. Time is money. To save both time and money doctors and nurses rarely check your blood pressure themselves. That’s because there are automated electronic BP machines. This equipment seems so easy to use that hospitals and doctors’ offices may not spend a lot of time training the technicians who use it.
We have personally observed an astonishing number of mistakes when blood pressure is measured. And we cannot always blame a technician. Even doctors and nurses may make serious errors when taking automated blood pressure readings.
Measuring Blood Pressure Correctly:
We have not made up these recommendations. They come from the American Heart Association (AHA)(Hypertension, May, 2019)
You should always empty your bladder prior to blood pressure measurement. If you had to deal with traffic congestion, parking problems or any other stressors, you should be given time to go to the bathroom and then recover your equilibrium.
When it comes time to have your blood pressure taken, you should be given more time to sit quietly (for at least five minutes) in a comfortable chair prior to any measurement. Feet should be flat on the floor and the back must be supported. The temperature in the room should be at least 72 degrees F. Blood pressure should never be measured while the patient sits on an exam table with feet and arms dangling.
Most important, the blood pressure cuff should be the right size for your arm, neither too big nor too small. When was the last time someone actually measured your arm for cuff size? The arm must be supported at heart height.
Equally important, there should be no talking during blood pressure measurement. Even casual conversation can artificially raise blood pressure.
Multiple readings are appropriate with at least a minute between each reading. The AHA recommends three measurements. You should not be told you are hypertensive based on one reading!
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Readers Sound Off About Bad BP Measurements:
Readers frequently complain about faulty blood pressure technique. One woman reported that having her blood pressure measured is like being pinched really hard.
“If pain can elevate BP during other procedures, why not if someone is squeezing the daylights out of my arm?”
The answer is yes, pain can raise blood pressure (Journal of Clinical Hypertension, June 10, 2013). The cuff is likely the wrong size.
Another reader asks:
“I have seen techs, nurses, and doctors place the blood pressure cuff over heavy sweatshirts and take a blood pressure. When I asked about this, they all said it did not matter. Does it?”
Answer: yes. The article in the journal Hypertension that describes the AHA’s recommendations about proper blood pressure techniques states:
“Remove clothing covering the location of cuff placement.”
By the way, take a look at the photo at the top of this article. How many mistakes did you count? Here are some hints:
Is the patient sitting in a comfortable chair?
Is her back supported?
Does the patient have her feet resting on the floor?
Is the patient’s arm supported at heart height?
Is the blood pressure cuff the right size?
How Can You Tell If You Have High Blood Pressure?
Because so many mistakes can be made in a doctor’s office or hospital clinic, we encourage people to measure their own blood pressure at home. Our eGuide to Blood Pressure Treatment provides guidelines and strategies for both measurement and management of hypertension. It is available in the Health eGuide section.
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.” Read Joe's Full Bio.
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Carey, R. M., et al, “Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: Synopsis of the 2017 American College of Cardiology/American Heart Association Hypertension Guideline,” Annals of Internal Medicine, March 6, 2018, DOI: 10.7326/M17-3203
Muntner, P., et al, “Measurement of Blood Pressure in Humans: A Scientific Statement From the American Heart Association” Hypertension, May, 2019, https://doi.org/10.1161/HYP.0000000000000087
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