Have you ever had a nurse or doctor measure blood pressure? Of course you have. It’s almost impossible to avoid having your BP tested these days. The trouble is that more often than not it is measured incorrectly. It is not unusual for allied health personnel (not physicians or nurses) to check your blood pressure. We have seen first hand that 1) they may not support the arm at heart level 2) the arm cuff could be the wrong size 3) they may not wait for you to calm down 4) a chair with proper back support and leg height is not always available and 5) they may ask you questions during the reading. Such mistakes can lead to inaccurate BP measurements.
The Good Old Days?
In the early 20th century, doctors and nurses made quite a ritual out of measuring blood pressure. There was a glass tube containing mercury, a blood pressure cuff and tubing to connect them. In addition, the health care professional had to wear a stethoscope to listen to the blood passing through the brachial artery in the elbow.
The process was complicated and required good hearing to detect the on-off “Korotkoff” sounds. Most health professionals did not think this procedure could ever be mastered by patients at home.
Digital Blood Pressure Machines:
When digital blood pressure monitors became available, many physicians were skeptical about the benefits of such instruments. A review of the machines found in drugstores concluded (Blood Pressure Monitoring, Dec. 2013):
“On average, drug store monitors recorded lower systolic blood pressures and higher diastolic blood pressures than a validated monitor, but the difference was neither statistically nor clinically significant. Single reading comparisons showed a much broader range. In three participants, drug store monitors did reflect the average home blood pressure.”
That’s not to say all the electronic devices are accurate. And the skill of the user will impact the readings. That said, Consumer Reports has been evaluating BP home equipment for many years. Their current recommendations include:
- Omron 10 Series BP786N
- Rite Aid Deluxe Automatic BP3AR1-4DRITE
- Omron Evolv BP7000 (a wireless device with no hoses or wires)
- A&D Medical UA767F
Can Patients Learn to Measure Blood Pressure?
Many health professionals doubted the value of having patients measure their own blood pressure. There was a sense that this procedure was too complicated for people to master.
A new study in The Lancet puts those concerns to rest (March 10, 2018). British researchers recruited physicians from 142 general practices in the UK. Patients with poorly controlled hypertension (blood pressure readings over 140/90) were randomized to one of three groups.
What They Did:
Nearly 400 participants monitored their blood pressure at home using an Omron M10-IT electronic device (the self-monitoring group). They were asked to measure their blood pressure two times in the morning and twice each evening for the first week of every month. They were asked to record the readings and send them to their general practitioners for oversight.
A comparable number of volunteers recorded their blood pressure at home in a similar manner but sent the information to their doctors via text message and a web-based data entry system (telemonitoring group).
The “usual care” group had their blood pressure readings measured exclusively in the doctor’s office. The study lasted a full year. All participants were also monitored by research nurses who measured the volunteers’ blood pressure at each follow-up appointment. Blood pressure medications were adjusted based on the measurements from all three groups.
The Envelope Please!
The investigators found that self-monitoring, with or without telemonitoring, produced significantly better blood pressure control than clinic-monitored readings. The authors recommend self-monitoring for all patients who wish to use it.
An editorial in the same issue of The Lancet noted that if self-monitoring were sustained:
“such reductions in blood pressure could be expected to reduce stroke risk by 20 percent and coronary heart disease risk by 10 percent.” The physicians who wrote this editorial titled their article:
“Hypertension: time for doctors to switch the driver’s seat?”
They ask even more controversial questions:
“Should not the driver’s seat be co-chaired by health literate patients and dedicated professionals from allied fields? Could it be a valuable option to empower patients whenever possible, introducing them to self-titration and self-initiation of antihypertensive drug therapy?”
Blood Pressure Varies Enormously!
We have always been fascinated to read articles about the accuracy of home blood pressure monitoring. Many health professionals get excited if the electronic machines are not absolutely perfectly validated. Relying upon one or two readings in a doctor’s office does not reflect day-to-day blood pressure any more than reading a page from the middle of a book will reveal the full story.
Blood pressure varies enormously hour to hour, day to day or even month to month. A huge study published in the American Journal of Hypertension (online, Dec. 23, 2017) included data on over 56,000 individuals from 185 countries. Nearly 17 million BP measurements were analyzed.
Here is what they discovered:
“Novel findings from our study of serial, self-monitored BPs is that BPV [blood pressure variability] is higher during weekdays and winter season, supporting that environmental factors such as job stress and the outside environment influence BPV.”
They found that Monday readings were highest whereas Saturday and Sunday were lowest. Morning BP readings (7:00-10:00 am) were higher than afternoons. The authors conclude:
“Home BP measurements rather than office BP are recommended for the optimal assessment of BP changes. Home BP measurement, which is reliable, reproducible, and free from white-coat effect and observer dilution bias, is associated with target organ damage and offers better prognostic value than office BP measurement. Recently, home BPV measured over 7 consecutive days showed an association with future cardiovascular events.”
People’s Pharmacy Perspective:
We have come a long way from the old-fashioned approach to measuring and treating hypertension. Technology may also enable patients to be more active participants in the treatment of diabetes, irregular heart rhythms and blood thinning regimens. The expanding self-care movement should lead to shared decision making between patients and health professionals.
To learn more about the proper way to measure blood pressure, along with the Dos and Don’ts of managing blood pressure, we offer our Guide to Blood Pressure Treatment.