Are you sure you’re accurately measuring BP? Here’s how to know.

Timothy M. Smith , Contributing News Writer

Twenty-seven. That’s how many potential sources of error can falsely raise or lower a patient’s blood pressure reading.

Eight of these potential errors involve patient-related factors such as caffeine use or bladder distension. But the 19 others can be managed by the care team—including use of the properly sized cuff, sufficient rest prior to measurement, proper positioning, and using a validated, calibrated device. That’s a lot for anyone to account for without proper or recent training.

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And there’s the rub: Care team members are not often supported with the tools and training to measure BP accurately. Many health professionals were trained only once, like during medical or nursing school, but never again.

“Many of us start to get the feeling that blood-pressure measurement is bread and butter—we can do it in our sleep—but it’s actually a very complex skill. And because it’s a complex skill, training is really important,” Kate Kirley, MD, a family physician and director of chronic disease prevention at the AMA, said during an AMA webinar.

“All health care professionals need to be trained in how to take an accurate blood pressure measurement, and we should all be receiving retraining every six months to one year, according to the clinical guidelines,” Dr. Kirley said. “This is because our skills in blood pressure measurement decay over time.”

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Fortunately, no one has to go back to school to get up to date on BP measurement. Target: BP™, a national initiative co-led by the AMA and the American Heart Association, features easy-to-use  resources for training clinical staff in how to accurately measure BP. It has an equally easy-to-use set of tools for training patients in self-measured blood pressure (SMBP).

Target: BP has released a template for BP-measurement policies and procedures “to guide health care organizations in a comprehensive approach to accurate BP measurement, including BP device procurement and maintenance, team training and testing, and clinical procedures and workflows,” added Alison P. Smith, MPH, BSN, RN, a nurse and Target: BP program director for the AHA and AMA. 

At the top of the list: using the right sized cuff.

“The No. 1 measurement error is incorrect cuff size,” said Jane Drage, improvement specialist at the AMA. “You always want to use the appropriately sized cuff for the arm being used to measure blood pressure. You always want to place the cuff on the bare upper arm. And if you're unsure of the correct cuff size to use for a patient … the range and index line usually found on that cuff bladder can provide that guidance. You can also measure the arm circumference to find the correct size cuff for the patient.”

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Linda Murakami, RN, MSHA, a nurse and senior program manager at the AMA, noted these other keys to ensure accurate measurement.

Use a device that has been validated for accuracy. The US Blood Pressure Validated Device Listing (VDL™) identifies the BP measurement devices that have been independently validated for clinical accuracy.

Use automated, oscillometric devices when possible.  They have the distinct advantages of obtaining and averaging serial, unattended BPs, eliminating many operator errors inherent in manual measurement, and need less frequent calibration.

Calibrate devices as needed. Handheld aneroid (manual) devices, for example, need to be calibrated every two to four weeks.

Position the patient and the cuff properly. The patient’s back should be supported, and legs uncrossed, with their feet flat on the floor and their arm supported, with a properly sized cuff placed on bare skin and situated at heart level.

Provide a chance to empty the bladder and for adequate rest period prior to measurement. Three to five minutes of rest is guideline-recommended.

Take into account the “alerting response.” This is when patients’ blood pressure spikes simply because a health professional is measuring it. This phenomenon is much more pronounced when a physician is doing the measurement, so try to have another member of the care team do it.

Beware of initial measurement. The best practice is to measure BP in both arms and then use the arm with the higher numbers in the future. Also, repeated, averaged measurements tend to be more representative of a patient’s average daily mean BP. This holds true for SMBP too.

The AMA is working to improve health outcomes associated with cardiovascular disease through efforts such as the AMA MAP™ Hypertension program, which helps physicians, care teams and health systems boost BP-measurement accuracy, increase the use of evidence-based treatment, and work with patients in self-management of their blood pressure.