1.2B Care of the Device
For prolonged life of your blood pressure monitor, note the following instructions:
•
Do not
drop or bang the unit. Prevent sudden jerks, jars or shocks to the device to prevent damage.
•
Do not
insert any foreign objects in any device openings or vents.
•
Do not
disassemble the unit.
• If the unit has been stored at very low or freezing temperatures, allow the unit to reach room temperature
before using it.
•
Do not
store the unit in direct sunlight, high humidity or in places with a lot of dust.
• Clean the device with a soft dry cloth.
Do not
use gasoline, thinner or similar solvents.
Carefully remove spots on the cuff with a damp cloth and soap.
Do not
wash the cuff.
1.2C Comparing Readings to Other Blood Pressure Devices
Many questions arise when two blood pressure devices are compared in an effort to check accuracy. An accurate
comparison requires repeatable measurements under the same conditions, and significant time is required to
reduce naturally occurring blood pressure variability during the test. For proper comparisons, the subject should be
seated comfortably with feet flat on the floor, and have rested for 5 minutes before the first reading to allow blood
pressure levels to stabilize. The patients back, elbow and forearm should be supported, and the middle of the
cuff should be at the level of the right atrium. There should be no talking or moving during the measurement and
if comparing to an aneroid gauge or mercury column, observers should avoid parallax and be careful not to round
measurements.
The most accurate way to compare devices is to take two readings at the same time. However most people and
doctor’s offices do not have the equipment necessary to measure blood pressure from two devices simultaneously.
To take sequential measurements properly requires a pair of initial measurements to determine the subjects blood
pressure level: first with the reference equipment, followed by 60 seconds, then with the monitor-under-test.
The actual accuracy test requires three pairs of measurements with 60 seconds between measurements. These
measurements are averaged and a comparison can be made. Since most people tend to relax and their blood
pressure falls with subsequent measurements, following this protocol reduces these natural changes in blood
pressure levels. The standard technical error of both consumer and professional devices is normally ±3 mmHg, so a
discrepancy of 6 mmHg is acceptable even when the devices are working within their specifications.
Any comparisons without following the procedures described above will not yield reliable results. In addition, to
do an accuracy test properly the reference device must also be tested to a known reference to confirm its accuracy,
prior to being used as the reference for comparisons.
1.2D Calibration
Digital blood pressure monitors do not require recalibration. If the unit turns on and does not display an error
code, the product is working properly. In extremely rare cases, the cuff may have developed a pin-hole leak, or the
gasket where the cuff connector enters the monitor may not have a proper seal; both of these leaking air issues
will potentially cause errors in accuracy, but otherwise the product will work accurately without drifting out of
calibration.
