Q: Where can we find a dependable blood pressure monitor?
A: Almost anywhere – from your local pharmacy to a medical supply house. A monitor is known as a sphygmomanometer, a big word for what could be a very small unit. The device is composed of an inflatable cuff that restricts the flow of blood in the arm and a mercury or mechanical manometer that measures the pressure. Manual units are used in conjunction with a stethoscope The ordinary unit of measurement of blood pressure is in millimeters of mercury (mmHg)
There are several types of units available. The first is a manual unit that requires a stethoscope for auscultation. It is considered to be the gold standard of all units and is most commonly found in a physician’s office. It measures blood pressure by watching a gauge and observing the height of the column of mercury therein. Then there is an aneroid sphygmomanometer (a manual type with a dial) that will require calibration checks except for those aneroids mounted on walls or on stands that don’t become jarred as easily as free-standing units. Lastly and the easiest to use is a unit with a digital readout. They are easy to operate, don’t require any training, and measure systolic and diastolic readings using a piezoelectric pressure sensor with electronic components. Many of the units also have a bonus in that they have the capability of displaying a pulse rate. This is okay but be aware of, and stay away from those units that also claim to measure arterial stiffness. They should not be used by the average individual at home because of the rates of inaccuracy known to occur. Look for a home unit that has a cuff that goes around the upper arm. There are others with a cuff that goes around the wrist, or has a device in which to place a finger. In the order of accuracy for home devices, the most accurate readings will come from a cuff that fits around the upper arm, followed by one for the wrist and lastly, one for the finger.
On to calibration. If you intend to purchase a unit, you should bring it with you to your next medical appointment. Have your physician, his nurse, or assistant take a reading with his unit. Then you should take one with yours. You may be pleasantly surprised to find the two units are in sync, but what is more likely the case is that yours has been jarred either by you or when it was shipped to the facility where you purchased it, and needs to be re-calibrated. This is something that must be done by an organization that is certified. The process takes less than a week and there are actually some mobile calibration labs available. You might ask your local pharmacy if they can assist you in this regard.
The units that are available in most pharmacies, chain stores and even on the internet are relatively comparable in performance. Purchase a unit you think might work for you that is reasonably priced. Take a reading at about the same time each day (within reason) and record those numbers on a scratch pad so you can review them at leisure. Then you can share them with your doctor at your next appointment. Lastly, you can always check with Consumer Reports for opinions on what they feel is the best unit to purchase for home use.