Research Story Tip: Study Says Blood Pressure Readings Accurate with Less Than a Three-Minute Rest
Physicians, nurses and other health care providers traditionally been taught to let patients rest three to five minutes between blood pressure measurements. Now, researchers at Johns Hopkins Medicine have shown that this established time span may not be as medically necessary as previously believed and that shorter rest periods are just as accurate if the patient’s blood pressure reading is not elevated (greater than or equal to a systolic over diastolic reading of 140/90).
The findings were presented virtually on Sept. 10, 2020, during the American Heart Association’s Hypertension 2020 Scientific Sessions, and appear in the October 2020 issue of the journal Hypertension.
“Reducing the rest period prior to taking readings to less than three minutes could enable more patients to be screened in a shorter timeframe, which could be beneficial to medical facilities in high demand or that are understaffed because of economic reasons,” says study lead researcher Tammy Brady, M.D., Ph.D., medical director of the pediatric hypertension program at Johns Hopkins’s Children’s Center and an associate professor of pediatrics at the Johns Hopkins University School of Medicine.
In a simulated clinical setting, the Johns Hopkins Medicine team studied 113 adults ages 18 to 80 — with both normal and high blood pressure — who each received four sets of three blood pressure measurements after different rest times: zero, two and five minutes. To estimate the repeatability of these readings, the blood pressure of each participant was recorded once more at five minutes after the last measurement.
The researchers then compared the difference in average blood pressure measured after the first and second five-minute rest periods with the difference in the readings following the first five-minute rest period and the two-minute one. They also compared the difference between the measurements after the first five-minute rest period and the zero rest time.
“We were expecting to see significant differences in these average blood pressure and overall readings,” says Brady. “Instead, we discovered only marginal changes — overall, no more than a plus or minus two-point difference between the systolic blood pressures obtained after five-minute resting periods and the readings taken with rest periods of less than a minute and two minutes.”Based on their findings, the researchers believe that a reasonable approach is measuring blood pressure after minimal to no rest, and then repeating the measurement after a five-minute rest only if the patient has an initial systolic reading of greater than or equal to 140.