Monitoring Blood Pressure at Home: Smart, Simple

Blood pressure (BP) monitoring seems like such a simple thing. A patient arrives in the clinic, places him or herself in the hot seat, and presents the arm—usually the left one—for the grip of the sphygmomanometer. Today, almost all BP monitoring devices are electronic, and after a brief mechanical whir and a whish as the cuff deflates, the screen displays the patient’s numbers. If BP exceeds that golden number of 130/80, it’s time to talk about interventions. Hypertension and its measurement are not quite that simple, however. It’s time to heighten awareness of how BP fluctuates and the best way to monitor it.

For several years now, home blood pressure monitoring devices (HBPMD) have been inexpensive and reliable. That’s why a number of organizations have recommended that patients who have, or are at risk for hypertension monitor their BP regularly. Patients who are most likely to purchase and use HBPMD are those who have already been diagnosed with hypertension, or who have concerns about cardiovascular disease or stroke in the future. Today, approximately half of hypertensive individuals use HBPMD, and most report the results of monitoring to their primary care providers.

Up, Down, and All Around

BP follows a circadian pattern in most patients. It falls to its lowest levels during sleep (10% to 30% below daytime levels), rises as the patient awakens in the morning, and tends to be higher and more variable during the daytime. It’s the morning surge in BP that is often associated with adverse events (eg, myocardial infarction, stroke, sudden cardiac death).

Retail health care providers might consider recommending HBPMDs for patients who are prehypertensive or who have overt hypertension. One advantage of home BP monitoring is that it gives clinicians a more comprehensive picture of the patient’s circadian rhythms. It also eliminates “whitecoat hypertension” (isolated BP elevations in the primary care provider’s office). Between 10% and 20% of people experience whitecoat hypertension, yet they have BP that falls within normal limits at home.

Conversely, home BP monitoring can identify the presence of “masked hypertension.” Masked hypertension is the presence of a normal BP reading while the patient is in the office, but elevated readings when the patient is at home—the opposite of whitecoat hypertension, sometimes called “reverse whitecoat hypertension” or “whitecoat normal tension.” Certain people are at elevated risk for masked hypertension: patients who have stressful jobs, chronic kidney disease, sleep apnea, diabetes, or left ventricular hypertrophy. People who smoke, are obese, or have family histories of masked hypertension are also at elevated risk. Recent studies indicate its prevalence is approximately 20%, which is higher than previously assumed. This group of patients is of concern because study results have shown that they incur extensive target organ damage. They often experience left ventricular hypertrophy and escalated plaque deposition.

Recommending HBPMD

More than one-third of American adults older than age 20 are hypertensive, and 40% of these patients are untreated. Even among patients who do receive treatment, almost two-thirds don’t reach their target BP. Heightened awareness is critical, and retail health providers can catch some of these undiagnosed or undertreated patients and intervene. The following are some guidelines for interventions:

• Recommend home blood pressure monitoring for all patients who:are taking antihypertensives but remain uncontrolled, especially if BP is extremely elevated.appear to have whitecoat hypertension.report elevated BP in settings other than your office; these patients may use public BP monitoring devices during the day and see high readings.have prehypertension or are suspected to be hypertensive.have been diagnosed with chronic kidney disease.
• Ensure that patients have a reliable HBPMD and have the mechanical and cognitive skills to take BP accurately.For patients who are uncoordinated or cognitively impaired, ask if the caregiver can monitor BP at home.
• Once you work with the patient to select a device, review the directions carefully and use the teach back system to make sure he or she understands how to use the machine.

Since 2008, the American Heart Association, the American Society of Hypertension, and the Preventive Cardiovascular Nurses Association have recommended using HPBMD, as have many international guidelines. Their rationale is that home readings correlate closely with target organ damage. The well-respected, independent, nonprofit publicationConsumer Reportsprovides evidence-based product ratings for HBPMD. It’s a good source for retail health providers and patients when faced with the numerous devices in the OTC aisle. Individuals can usually access it via their public libraries.

Purchasing a Machine is Just the First Step

In addition to reviewing the HBPMD’s directions carefully with patients, retail health care providers must provide direction about how often to measure BP.

Counseling Patients about Home BP Monitoring

• Ask patients to bring their HBPMDs to the clinic so that you can validate the reading.Have the patient take BP using his or her own device.Then take a third BP reading using the clinic sphygmomanometer.Have the patient take a fourth reading using his or her own device.Then take a fifth reading using the clinic sphygmomanometer.Compare the readings to make sure they are all in the same ballpark.
• Initially, advise patients to take 2 or 3 readings while in a resting, seated position in the morning and at night for 1 week.
• Ask them to return to the clinic once they have 12 or more readings; initiate or adjust antihypertensives based on these readings.
• Concurrently counsel patients about lifestyle changes that may alleviate hypertension (smoking cessation, weight loss, dietary changes).
• Advise those who have diagnosed hypertension that they should measure their own BP routinely; for most patients, this may mean twice-daily readings every 2 weeks, whereas more frequent readings may be necessary for others.
• Ask patients to bring their HBPMD to the office annually to validate their readings.

Location, Location, Location!

Experts recommend either arm or wrist monitors. Arm monitors tend to be most reliable. For some patients, wrist monitors offer convenience and may be preferred in obese patients who have difficulty applying the cuff above the elbow. Retail health providers must remember that wrist monitors are only accurate when the arm is held above the level of the heart; many new wrist monitors ensure appropriate use because they only operate if the patient holds his or her wrist over the heart. In general, experts prefer the arm monitor.

Experts also warn that finger monitors are notoriously inaccurate.

Some patients may not have the financial resources to purchase an HBPMD. For these patients, advise checking with their insurers to see if an HBPMD is covered because plans now do cover them.

If the patient’s plan doesn’t, then recommend that the use the widely available retail automated devices; the likelihood is that your clinic probably has one of these devices right outside your door, and most grocery stores and malls now have conveniently located BP monitoring devices. Note that studies indicate that store monitors tend to record lower systolic BP and higher diastolic BP, but the difference between store monitors and other BP monitoring devices tends to be statistically or clinically insignificant. Many chain drugstores will now email the patient’s results to a cloud storage medical record or a smart phone, which makes tracking easy.

Recommended Reading

Margolis KL, Asche SE, Bergdall AR, et al. Effect of home blood pressure telemonitoring and pharmacist management on blood pressure control: a cluster randomized clinical trial.JAMA.2013;310(1):46-56. doi: 10.1001/jama.2013.6549.

Pickering TG, Miller NH, Ogedegbe G, et al; American Heart Association.; American Society of Hypertension.; Preventive Cardiovascular Nurses Association. Call to action on use and reimbursement for home blood pressure monitoring: a joint scientific statement from the American Heart Association, American Society of Hypertension, and Preventive Cardiovascular Nurses Association.J Cardiovasc Nurs.2008;23(4):299-323. doi: 10.1161/HYPERTENSIONAHA.107.189011.

Ross KL, Bhasin S, Wilson MP, Stewart SA, Wilson TW. Accuracy of drug store blood pressure monitors: an observational study.Blood Press Monit.2013;18(6):339-41. doi: 10.1097/MBP.0000000000000003.

Schwartz JE, Burg MM, Shimbo D, et al. Clinic blood pressure underestimatesambulatory blood pressure in an untreated employer-based US population: results from the Masked Hypertension Study.Circulation.2016;134(23):1794-1807.