A recent American Heart Association scientific statement on BP measurement, published in the journal Hypertension, is the first comprehensive update on BP measurement in humans since 2005. It provides an overview of what is known about BP measurement and supports recommendations from the 2017 hypertension guideline, which came from a joint task force formed by the American College of Cardiology (ACC) and the AHA.
“Our patients deserve better. And I say that having seen the large variability in the measurement and the quality of measurements of blood pressures, even at academic medical centers,” Jackson T. Wright Jr., MD, PhD, said during a Target: BP webinar.
Dr. Wright directs the Clinical Hypertension Program at the University Hospitals Cleveland Medical Center and is emeritus professor of medicine at Case Western Reserve University. During the webinar, Dr. Wright outlined how applying the recommendations of the AHA’s scientific statement can improve accuracy of BP measurement in your patients.
The AMA has developed evidence-based tools and resources to support physicians and care teams in diagnosing and managing their patients’ high blood pressure. These resources are available to all physicians, care teams and health care organizations as part of Target: BP™, a national initiative co-led by the AMA and AHA.
Studies suggest underestimating systolic BP by 10 millimeters of mercury can result in a 10% to 40% increase in fatal heart attacks and strokes, while overestimation of five millimeters can unnecessarily result in recommendation for treatment intensity in about 30 million patients, explained Dr. Wright.
Many errors raise BP readings and result in inappropriately higher readings. For example, talking to the patient or asking questions can raise their blood pressure by as much as 10 mm Hg. A distended bladder, smoking within 30 minutes of the appointment, and an unsupported arm and back can also raise patients’ BP.
BP measurement in a chair versus on the exam table can also impact the reading. Studies have shown that taking a patient’s BP on the exam table rather than a straight-back chair can elevate the reading 6 mm Hg or more, said Dr. Wright, adding that “these errors need to be avoided in measuring blood pressures in the office and at home.”
There is a difference in BP measurement quality that can influence both outcomes and treatment intensity when using a manual monitor. The readings used to determine the need for treatment or change in treatment intensity can become less usable.
“That was the reason that there is now new guidance on the measurement of blood pressure in the clinic and in the use of out-of-clinic ratings,” said Dr. Wright.
The statement recommends that automated office blood pressure (AOBP) devices should be considered for use in measuring office BP and that AOBP may be preferred for use in clinical practice. Multiple blood-pressure readings can be taken automatically after the rest period, either with or without a team member in the room.
“Automatic blood pressure readings have been demonstrated to lessen white-coat effect and the data suggests that AOBP readings are more accurate than manual office readings,” Dr. Wright said.
Self-measured blood pressure (SMBP) readings “have been shown to be a better risk predictor,” said Dr. Wright, adding that when accompanied by adequate patient education, out-of-office BP measurements correlate better with cardiac and clinical outcomes than readings obtained in the office.
“Out-of-office measurement will help us identify white coat hypertension and masked hypertension,” he said. “Multiple readings throughout the day with the use of out-of-office readings may also reveal patterns in blood pressure or periods when blood-pressure control is inadequate.”
Out-of-office BP measurements also can be used to confirm a hypertension diagnosis and to assess the effectiveness of treatment intensification in patients with elevated or high BP.
“Only those monitors that have been validated should be used to measure home blood pressures,” Dr. Wright said. “We encourage writing a prescription giving the manufacturer and model name of the validated home blood-pressure monitor including the appropriately sized arm cuff and the presence of memory.”