Print � Bookmark
Choosing a Blood Pressure Monitor That is Best for You
Victor E. Battles, M.D. - June 24, 2009
In choosing a blood pressure monitor the accuracy of the device should be the most important consideration.
Secondly, the reliability of the readings should be considered. Thirdly, the ease of use of the device should be
taken into account.
Accuracy refers to the degree to which the blood pressure readings obtained actually reflects the true pressure
within the arteries at the time that readings are performed. Reliability on the other hand, refers to the degree to
which blood pressure readings reflect the average arterial pressure within a 24-hour period of time.
The technique of the individual performing the measurements, the attributes of the measuring device, and arm
selection are the main variables that determine accuracy. The frequency of readings, the recording of the readings
and understanding the many factors that can affect blood pressure are the main variables that determine the
reliability of the readings.
One of most common reasons for an inaccurate reading is malpositioning of the arm in relationship to the heart when
a reading is being taken. If the reading is taken with the arm hanging down well below the level of the heart the
reading is likely to be spuriously higher than the true pressure, and if the arm is positioned higher than the
level the heart the reading is likely to be spuriously low. Parenthetically, if the arm is not supported by a
stationary structure such as a stand or another person if someone else is performing the reading, but is held in
position against gravity by the individual on whom reading is being performed, a certain degree of isometric
exercise is being performed which can have an effect on the reading. If achieving proper arm positioning is a
problem, a wrist monitor with the Omron patented advanced positioning sensor technology is a likely solution. The
device will alert you with a characteristic beep signal and will not begin to read at all if the arm is not in
proper position. It allows you to take readings sitting and lying, knowing that at the accuracy of your readings is
not being compromised by improper arm position. Since sitting readings are performed with the arm flexed at the
elbow and supported by the hand of the contralateral arm isometric exercise is not performed during the
Another very common cause of an invalid blood pressure reading is an improper cuff size in relationship to the
circumference of the upper arm. Generally, if the cuff size is too small relative to the upper arm circumference
the reading will be higher than the true arterial pressure. Conversely, if the cuff size is too large for the
circumference of the arm the reading will be lower than the true pressure. The cuffs used for upper arm
measurements come in several adult sizes. There is no standardization of the sizes between manufacturers, but for
the sake of practicality the primary sizes are adult, adult large and thigh. Some manufacturers also produce an
extra large adult size which is the size in between adult large and thigh. To ensure use of the appropriate cuff
size the American Heart Association recommends that you measure your upper arm circumference and select a cuff with
a specified arm circumference range that includes your measurement. If your arm circumference exceeds that of the
largest cuff available you should consider one of the wrist monitors which generally accommodate wrist
circumferences between 13.5 cm to 21 cm or 5.25 inches to 8.5 inches.
If the cuff is not inflated high enough before deflation is begun the systolic reading might be lower than the true
arterial pressure. If the inflation and deflation process is interrupted and repetitive the overall reading is
likely to be inaccurate. To eliminate the inaccuracies associated with these technical flaws, an automated unit,
particularly one with the IntelliSense technology is a likely solution. IntelliSense is an exclusive technology
developed by Omron which allows monitors to automatically inflate and deflate at a level optimal for each
individual user, thus assuring accuracy and comfort. It requires no adjustments.
There are generally a few and sometimes several point differences in blood pressure readings between arms. The
dominant arm i.e. the right arm in a right-handed person and the left arm in a left-handed person usually has the
higher reading, which is considered to be the reading most reflective of the pressure within the arteries of the
body in general. Thus, that arm should be arm in which readings are taken. Some of the blood pressure devices,
particularly the wrist monitors are designed to take readings from left arm or wrist respectively, which means that
your readings might be invalid if your are right-handed. A likely solution to this problem, even if you are
left-handed but have higher readings in the right arm would be one of the units that can be adjusted to take
readings from the desired arm or wrist.
If you are visually impaired and have difficulty reading the screen of a blood pressure measuring device there are
some quality talking units that will give you an audio reading in addition to an LCD display.
The American Heart Association recognizes certain blood pressure monitors as approved, tested and validated by The
Association for the Advancement of Medical Instrumentation, the British medical Society and The International
Protocol for the Validation of Automated Blood Pressure Measuring Devices. A list of validated monitors is
available at the Dabl Educational Trust Web site* and the British Hypertension Society Web site*.
The fact that a particular brand or model monitor is not on the list means that it either did past the tests or has
never been subjected to the approval and validation testing protocol, which is the case with many of the newer
devices which have been launched since the last lists were generated in 2008. Based on my experience with blood
pressure monitors, the low-end priced units, i.e. $24.99- $39.99 range tend to be somewhat erratic in their
readings whereas units that began at the intermediate $50 price range tend to be much more accurate and consistent.
The higher-priced units are not necessarily any more accurate than the medium priced units but do provide some of
the aforementioned benefits as well as the benefit described in the following paragraph.
The sine qua non for reliable blood pressure readings is performing multiple readings in a 24-hour period which is
the basis for experts’ in the field of hypertension current recommendation to perform three readings in rapid
succession in the morning and three readings in rapid succession at night. There are monitoring machines that will
do this, average the readings, and allow downloading of the information into an accompanying software program
installed on your PC. The information can then be presented to your doctor for analysis and proper integration into
your treatment course.
In summary, you should take into account various factors relating to technique, anatomy, and attributes of the
monitoring device which affect the accuracy of readings, as well as the ease of use, particularly with respect to
obtaining reliable readings in choosing a blood pressure
Dr. Battles has been a principal investigator in several hypertension studies including ALLHAT
and has several years of experience treating high blood pressure.
To buy a blood pressure