The Blood Pressure Oracle - How Accurate is the Result of an Electronic Blood Pressure Monitor?

Quite often I have received letters with statementslast reading if you want to compare them. At the
like "My doctor says that all digital machines aredoctor's office, you might also suffer from what is
inaccurate and that only a doctor or an experiencedcalled "white coat hypertension", where you are
nurse can take blood pressure accurately". It isnervous and this causes the blood pressure to rise
difficult to give an answer to such a statementtemporarily. It is now a given fact that measurement
without offending someone. There are still someof blood pressure at home, also called HBPM (Home
people who believe that the earth is flat and that theBlood Pressure Measurement) IS MORE
moon is made out of blue cheese. The fact is thatREPRESENTATIVE OF THE PATIENTS REAL BLOOD
the first digital blood pressure monitors (from 30PRESSURE than the casual one taken at the doctor's
years ago) were very difficult to use accurately andoffice. This is provided of course that the patient
because it was a new technology, it was not welluses the device correctly.
accepted by the medical sector. However, in the lastMany doctors and nurses prefer the stethoscope
30 years, tremendous progress has been made andmethod because they can listen to the signals and
most monitors that are sold today (from reputableget a deeper impression of the patient's condition. A
brands) are as accurate as a traditional mercury ordigital monitor only measures blood pressure and
aneroid device.pulse, whereas an experienced doctor using a
There are in fact international validation standardsstethoscope can listen to many other sounds to get
that compare digital monitors to "gold standard"a better overall view of the patient's health.
mercury devices and then grade the devicesThe technique of mercury or aneroid devices (also
according to the results. So when you need to buy acalled auscultatory) requires careful training and
device for home use, you should look for a validationapplication of specific methods. A slow deflation rate
standard that has been applied to the device thatof 2 to 3 mmHg per second is essential to obtain
you are planning on buying, such as the BHS (Britishaccurate results with the doctor's measurement.
Hypertension Society), the GüteZiegel (GermanHowever, more often than not, doctors or nurses
validation standard), or the AAMI (Americanuse a much higher deflation rate and obtain wrong
Association of Medical Instruments). If you find suchresults. This is because quite often, the doctor does
a logo on the packaging or the advertising, it isnot have the necessary time to really measure blood
probably a very accurate device.pressure. In fact, for a blood pressure measurement
Today, most digital monitors measure pressure byto be representative at the doctor's office, he should
applying the so called 'oscillometric method'. In anmeasure the blood pressure at least three times in a
oscillometric measurement, the blood pressure isrow. It is important to realize that your blood
accurately detected by analyzing the pressurepressure is fluctuating constantly and that the results
oscillations that happen during the deflation or inflationare never exactly the same. When you use an
of the cuff. This method has been well acceptedelectronic blood pressure monitor at home, you tend
worldwide for more than thirty years and incidentally,to do several measurements because it is so easy to
it is applied in hospitals every day, whenever thedo and you have more time than at the doctor's
patient's pressure needs intensive and highly accurateoffice. It is quite normal for the measurement results
control. Many doctors do not realize that home usenot to be identical to each other. If your doctor
digital monitors use exactly the same technology aswere to measure the pressure three or four times
the 20 000 dollar machines that they use in intensive(which he never does!) he would also get different
care. If they did, they would probably change theirvalues.
opinion of home devices.The most convincing fact is that the world's leading
One of the main factors for different readings at theexperts on blood pressure monitoring prefer frequent
doctor's office and at home using a home monitor ishome measurements by electronic devices against
that the conditions for measuring blood pressure atthe casual measurements taken in their office! So if
the doctor's office are not ideal. To accuratelyyour doctor continues telling you that all digital
measure your blood pressure, you should consciouslydevices are crap, it might be time for you to change
relax for at least 5 minutes before taking it. Youyour doctor.
should also take it at the same time of day as your