When it comes to hi-tech methods of measuring blood pressure, newer may not be better.
Some 50 million Americans suffer from high blood pressure, or hypertension, a major risk factor for cardiovascular disease.
For more than a century, the mercury gravity (blood pressure measurement device) has been the gold standard for indirect measurement of blood pressure.
However, in recent years modern, hi-tech devices have begun to replace the mercury manometer. These include electronic instruments such as home pressure monitoring devices, or drugstore automated pressure-testing setups.
Non-mercury measuring devices are common in clinics and physician's offices -- they have round faces attached to a cuff, which is inflated while the doctor listens to the pulse with a stethoscope. These new devices are portable and simple to use, making them ideal in certain situations, especially for home monitoring.
However, a crucial issue with the newer instruments is their reliability.
In order to insure reliability, instruments must be calibrated -- in the same way that a scale is "zeroed" before you step on it to check your weight.
Unless the instrument is properly calibrated, the reading it gives cannot be accurate.
The American Heart Association's Council for High Blood Pressure Research, caution that the new electronic and non-mercury blood pressure devices are seldom calibrated regularly in hospital or office settings.
Most manufacturers of these instruments recommend calibration against a mercury manometer every six months. However, few hospitals and clinics have a regular program of evaluation and calibration. Indeed, most of these devices must be returned to the manufacturer for calibration.
Justification for replacement of the mercury manometers has focused primarily on concerns over the safety of the mercury used in the devices. Nevertheless, modern mercury blood pressure measurement devices are available in models that prevent accidental spillage of mercury, which essentially eliminates the concern for this rare occurrence.
The researchers warn that decisions by hospitals and clinics to replace the tried-and-true mercury-gravity based instruments with the newer non-mercury or electronic monitors have been made without proper consideration of the health risks involved in using less accurate devices to measure blood pressure in these settings.
At present the world primary standard for pressure measurement is a mercury manometer.
Hypertension: Journal of the American Heart Association, February 16, 2001
It is very important to have an accurate assessment of blood pressure as measurements even a few points off can make a big difference. This article emphasizes an important issue in measuring blood pressure. One needs to calibrate the electronic home devices periodically to the standard mercury meters.
This is usually easily done by bringing in your meter once or twice a year and making certain that both meters read the same. If you are buying a new blood pressure monitor it is important to keep the receipt and confirm that the meter measures your arm accurately. I have seen a great variability in many of these monitors and it is not necessarily related to the cost of the meter.
If you are a doctor and checking blood pressures it is important that you use a mercury meter as your standard.
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