Blood Pressure Is on the Rise

Edition: March 2003 - Vol 11 Number 03
Article#: 1484
Author: Chris Kelly

The controversy surrounding noninvasive clinical blood pressure measurement has been an issue for hospitals and clinicians since June 1998. That’s when the Environmental Protection Agency (EPA) and the American Hospital Association (AHA) developed an initiative to immediately limit – and ultimately eliminate – the use of mercury in hospitals, because mercury is classified as a toxin with a number of negative effects. The target date for elimination is 2005.

At the heart of the controversy is the proposed elimination of mercury blood pressure measuring devices, or sphygmomanometers, which have long been considered the gold standard for accuracy in blood pressure measurement. Many argue that eliminating properly functioning mercury columns will have adverse effects on accuracy and, as a result, diagnosis and treatment. Others argue new technology is readily available, and if properly maintained, it will be every bit as accurate as devices using mercury. Unfortunately, there are no clear-cut answers to resolve the controversy. Opinions, however, are numerous.

The issue has even gone mainstream with the New York Times and Good Morning America weighing in on the debate (on opposite sides, of course), bringing the controversy to the forefront for millions of Americans who are affected by high blood pressure or hypertension. Techniques and choices made by physicians and clinicians when it comes to blood pressure measurement have also been questioned. Many expect the FDA to assume a larger role in regulating, testing and validating these devices.

Disease Stats

Today, an estimated 50 million Americans have hypertension, with a third of them unaware they have it, according to the American Heart Association. High blood pressure is defined as either having systolic pressure (while the heart is beating) of 140 mm HG or higher, diastolic pressure (while the heart is at rest) of 90 mm HG or higher, or taking anti-hypertension medications. Uncontrolled blood pressure can lead to coronary heart disease, congestive heart failure, stroke, kidney disease and even death.

High blood pressure is the primary cause of death in an estimated 43,000 cases each year in the United States. It’s also a contributing cause of death in 227,000 cases.

When properly diagnosed, high blood pressure is usually controllable. Given the statistics above, accurate measurements of blood pressure are critically important. If inaccurate instruments produce falsely low readings, the error could deprive patients of the therapy needed to control their blood pressure, increasing the risk of serious medical complications. Likewise, if instruments produce falsely high readings, people may be misdiagnosed as having hypertension. As a result they may suffer the adverse effects of being improperly medicated, as well as the costs of treatment.

Measurement Options

For noninvasive clinical blood pressure measurement, three options (described below) are currently available – mercury, aneroid and digital. All devices work in a similar fashion. The measuring devices are connected to a cuff’s bladder. Technically, the physician monitors the pressure in the cuff, meaning the patient’s blood pressure is tested indirectly. The devices all work either manually or automatically. In a manual instrument the cuff is pressurized until the artery is occluded and the clinician uses a stethoscope to interpret the sounds. Automatic instruments also occlude the artery with a pressurized cuff, but instead of a stethoscope, the instrument uses an algorithm and microprocessor to derive a reading. Of course there are varying degrees of quality when it comes to any clinical instrument, which should be taken into consideration when selling your customers sphygmomanometers.

Aneroid. Aneroid blood pressure gauges – or those that operate without liquid – tend to be smaller than mercury gauges, and therefore easier to transport. They can be wall-mounted, portable (on a rolling stand) or pocket/hand gauges. A pressure bellows inside expands [??CK], and via gears and springs, transfers that movement to the needle in the gauge, allowing the clinician using a stethoscope to record the measurements. There is also a new aneroid technology that attaches directly to the cuff, which eliminates the gears using a direct-drive mechanism that results in a unit that is lighter in weight with fewer moving parts.

Digital. Digital units usually have two different measuring options available, oscillatory or auscultatory, though most clinical instruments utilize the oscillatory method (which utilizes an algorithm driven by a microprocessor analyzing waveforms in the cuff). Most electronic models currently on the market offer automatic cuff inflation, eliminating a need to preset inflation levels. One of the major benefits of digital units is that they take blood pressure the same way every time, helping eliminate user errors. Some units also have the ability to take multiple reading, throwing out the high and the low, to provide an average of all remaining readings. These instruments are also available in wall mounted and portable (on a rolling stand) versions.

Mercury. Properly functioning mercury-gravity sphygmomanometers are still considered the gold standard for blood pressure measurement. The mercury-gravity manometer consists of a calibrated glass tube with a reservoir containing mercury. When the cuff is inflated, the mercury rises in the glass tube. The clinician, using a stethoscope, records the readings. These units can be wall mounted, portable (on a rolling stand) or portable (in a case).

The Bottom Line

Regardless of what you choose to sell, remember that there are varying degrees of quality when it comes to any of these modalities. It pays to your homework. It’s also important to make sure your customers understand how to take an accurate blood pressure measurement. Ask your vendors for materials you can share with your customers. Be sure to explain the need for keeping varying sizes of cuffs on hand to accurately measure different sized patients. And finally, encourage your customers to check the calibration of their instrument at least once a year. (Many sales reps use this as a value-add with their key customers.)

Blood pressure is a vital sign of major importance that affects millions of Americans. The products you can offer your customers are numerous. It’s your job to stay up to speed on the issues surrounding noninvasive blood pressure measurement devices. That way, you can help your customers make informed decisions. Call the manufacturers you do business with and ask them for further training on their modalities. Ask them the hard questions. Then, make your own decision on what you believe is the best modality that will serve your customers well.

Manufacturers of Noninvasive

Blood Pressure Monitoring Devices:

American Diagnostics Corporation 800/232-2670

BV Medical 888/822-8293

GE Medical Systems Information Technologies 800/472-4141

Mabis 800/728-6811

Omron Healthcare 800/231-4030

Trimline 800/526-3538

VSM Medtech 877/876-8484

W.A. Baum 631/226-3940

Welch Allyn 800/535-6663