Don't Rely On Drugstore Blood Pressure Readings
05/31/2000
If you've tried those automatic blood pressure machines found in many pharmacies, you should be aware that the readings aren't always reliable.
Researchers from the University of South Florida say they checked machines at 25 locations and found many readings to be off the mark, particularly for people with larger or smaller arm sizes than the average.
A normal blood pressure reading is about 120/80, but both the systolic and diastolic measurements can be off by as much as 10 millimeters of mercury in the self-monitoring devices, according to a report in The Journal of Family Practice.
Even a one or two millimeter change in mercury level is often enough to put you on drugs for life, so getting a correct reading is really important if you have blood pressure worries.
The researchers took three volunteers with arm circumferences in the low, medium and high ends of the range of adult cuff sizes and found that both systolic and diastolic readings were higher for the person with the small arm. The person with the larger arm had a significantly lower diastolic reading that could falsely indicate low blood pressure.
Even the volunteer with the medium arm size found variability in the self-monitoring machines, so the message here is to get your blood pressure taken by a professional. If you're going to self-monitor the pressure later, make sure you're aware of the differences that can occur.
Source: The Journal of Family Practice, May 2000