Sonya Collins
Depending on your practice setting and patient population, you may take a dozen BP readings a day. Do you still do it exactly as you learned in training—with the midcuff at heart level and the patient’s arm supported on a desk or table?
Clinical skills such as these decay over time, sometimes in as little as 6 months after certification, research suggests. Clinicians may lapse into measuring BP while the patient’s arm hangs at their side or rests on their lap. These might seem like small differences, but they can result in significantly higher readings. That was the finding of the ARMS trial, a crossover randomized controlled clinical trial, published online in JAMA Internal Medicine, on October 7, 2024.
“All of those preparatory steps to measurement that you learn really impact accuracy,” said Tammy Brady, MD, PhD, coauthor of the study. “You do need to take the time to do these things. Otherwise, you’re not going to have an accurate measurement.” Brady is the medical director of the Pediatric Hypertension Program and a professor of pediatrics at Johns Hopkins Children’s Center in Baltimore.
Arm position matters
In the study, clinicians measured the BP of 133 adults, three times, using three different arm positions in random order: midcuff at heart level while the patient’s arm was supported on a desk; hand resting on the lap; and arm at the side. To account for normal variability in BP, clinicians took a fourth reading with the arm supported on a desk.
Both the lap and side positions resulted in statistically significant higher readings than the desk position. When the patient’s hand rested on their lap, the systolic pressure was 3.9 mm Hg higher and the diastolic pressure was 4 mm Hg higher. With the arm at the patient’s side, systolic readings were inflated by 6.5 mm Hg and diastolic by 4.4 mm Hg.
“That’s enough to push someone over the edge from prehypertensive to hypertensive diagnosis,” Brady said. “It absolutely can lead to changes in treatment that might not be needed.”
Lessons for pharmacists
Inconsistencies in arm position can lead to inconsistent readings, too. Over the course of a year, a patient being managed for hypertension might have their BP measured by multiple providers and may also measure it themselves at home. If each measurement involves a different arm position, patients and their providers cannot expect an accurate log of BP changes over time.
The findings of this study should serve not only as a reminder for pharmacists to position patients’ arms appropriately when taking a measurement themselves, but also to emphasize proper technique when educating patients on how to take their own BP at home.
This study and others underscore the need for pharmacists as patient educators. Other research has shown the importance of BP cuff size to accurate readings. Pharmacists can take the opportunity to both help patients identify an appropriate BP device and to drill correct arm positioning.
“We don’t have enough time in clinic to teach a patient the proper way to measure their blood pressure at home,” Brady said. “If there are other people like pharmacists, who are amazing partners in this, who could take the time to show them how to use the device and how to measure their blood pressure properly, I think we could do a great job at improving cardiovascular health in the U.S.” ■