Modern medicine: Why the sphygmomanometer is a liar


Before we delve into this, please understand that the sphygmomanometer is merely an instrument that measures Blood Pressure (BP), but the difficulty in using a “sphyg” is that it measures something which is not stable. The other problem is that people (including doctors) take the reading as absolute, which it most definitely is not.

Many factors can influence the reading. For starters, the size and position of the blood pressure cuff can affect the accuracy of blood pressure readings. If the cuff is too small, the measurements will be falsely elevated.

As a general guideline, if your arm measures more than 33.02 cm around as its widest point, you will need a cuff in which the inflatable bag portion is at least 33 cm long. These large adult cuffs are available at most hospital and medical supply stores.

Secondly, your blood pressure may vary considerably from day to day and from moment to moment. Blood pressure also tends to be higher in the morning and lower at night. Stress, smoking, eating, exercise, cold, pain, noise, medications, and even talking can affect it, so you can see it is not a stable number you are measuring.

A single elevated reading does not mean you have high blood pressure (hypertension). Conversely, a single normal reading does not necessarily mean you do not have high blood pressure.

The average of several repeated measurements throughout the day is more accurate than a single reading.

First off, buy a blood pressure measuring device from the pharmacy. Not expensive and read the instruction manual. Now read it again. The simplest to use has a circular cuff you put one arm through. The ones in shopping centers are like that.

Record your blood pressure while you are seated in a comfortable, relaxed position. Try not to move or talk while you are measuring your blood pressure. Be aware that the blood pressure readings may be 10 to 20 mm Hg different between your right arm and your left arm. For this reason, use the same arm for every reading. Blood pressure readings also vary throughout the day. This is normal.

For electronic models, press the on/off button on the electronic monitor and wait until the ready-to-measure symbol appears next to zero in the display window. Then press the start button. The cuff will automatically inflate to approximately 180 mm Hg (unless the monitor determines that you require a higher value). It then begins to deflate automatically, and the numbers on the screen will begin to drop. When the measurement is complete, the symbol stops flashing and your blood pressure and pulse readings are displayed.

Now repeat the same procedure two more times, for a total of three readings. Wait 5 to 10 minutes between recordings. Record your systolic and diastolic pressures, the date and time. Inspect your blood pressure cuff frequently to see that the rubber tubing, bulb, valves, and cuff are in good condition. Even a small hole or crack in the tubing can lead to inaccurate results.

Generally, as long as you don’t have symptoms such as lightheadedness or faintness, the lower your blood pressure the better. If your blood pressure is usually below 90/60 mm Hg and you feel well, don’t worry. However, if your blood pressure “normally” runs high consult our health professionals.

Do not adjust your blood pressure medications based on your own home blood pressure readings without first discussing any change with your doctor.

Early detection and treatment with a combination of medication and lifestyle changes (weight loss, diet, exercise, cessation of smoking and stress reduction) may reduce the health risks associated with high blood pressure. If you are under treatment for high blood pressure, monitoring your blood pressure once a week is sufficient, though more frequent monitoring may be useful if your blood pressure is not well controlled or if your medications are being changed. Talk to your treating physician about how often you should monitor.

A large difference (greater than 20 mm Hg) between the blood pressure measurements of the right and left arms can indicate a problem. Once again, take this information to your doctor.