Just a few thoughts about blood pressure
At the beg
inning of the last century, the measurement of arterial pressure is not yet current. On this cliché taken at the Hôpital de la Charité in Paris in 1918, Emile Spengler measures the systolic blood pressure of Charles Laubry, the man who invented the first upper arm blood pressure monitor, used in this picture. Carried out by the manufacturer himself, the gesture is delicate and photogenic.
The moment is not yet banal.
The measurement of blood pressure has now become commonplace. Anyone can now buy or borrow a home blood pressure monitor that is more accurate than anything that was produced in the last 100 years. However, it is important to use the device in the correct manner to get accurate and reliable results.
A few basics about blood pressure
There are a few undeniable facts and rules about digital blood pressure monitors. These rules are very important but are often forgotten. They are worth repeating here.
Your digital blood pressure monitor does not magically transform you into a doctor.
Your blood pressure monitor is probably really easy to use. It probably inflates automatically, makes cool sounds and then incredibly gives you a clinically accurate result. Isn’t that great? It’s child’s play to measure your blood pressure… Well it certainly feels like it… However, your blood pressure monitor is not intended to replace regular medical examinations. It is there to be used together with your doctor as a tool to better manage your blood pressure. Only a physician is qualified to interpret changes in your blood pressure.
When in doubt, ask your doctor for advice.
The first commercially usable blood pressure monitor was manufactured at the turn of the century. In the 70ies digital devices made their appearance and by the 90ies they were commonly available to the untrained public. According to the statistics from our various service departments worldwide, an incredible 94% of all “faulty” devices sent back to manufacturers show absolutely no problem at all and are simply badly used. Faults can range from silly mistakes such as batteries being put in upside down to using the wrong size cuffs. We have even received devices where the batteries were still wrapped up in plastic. Your doctor has been working and studying blood pressure for most of his life and is an expert on the subject. Please ask him to show you how to correctly use your monitor.
Never make adjustments to your medication unless you are advised to do so by your physician.
As mentioned earlier, your blood pressure monitor does not replace a regular medical examination. Your doctor has prescribed medication for you after a careful examination and it can be very dangerous to make your blood pressure fluctuate by changing your medication or by reducing the dosage on your own. If you suspect that your blood pressure medication is wrong because you regularly get low or high blood pressure readings on your device at home, please keep a regular record of your blood pressure for at least three days in a row and then contact your doctor. He will appreciate the fact that you present all the evidence to him in a clear format. To do so, use a blood pressure passport. There is a multitude of blood pressure passports available out there. You can also download one that I have designed to fit in your wallet on my diabetes company website.
You should know that when the doctor at his office measures blood pressure, there is a multitude of reasons why the blood pressure measured by the doctor can be higher or lower than the one measured at home. One of the most common reasons is what is called “White Coat Hypertension” and occurs when the patient is subconsciously nervous at the medical examination and this makes his blood pressure go up. On average, the systolic pressure will vary by about 30 points during the day, so it is normal for you to have a different blood pressure at home than at the doctor.
This is one of the main advantages of home monitoring, in that it gives you a much better overall picture of your blood pressure over time than the single blood pressure reading that is taken at the doctor’s office.
Do not believe in urban legends or marketing hype when it comes to your health.
When making decisions about your health, question what is commonly believed. There are many “urban legends” about blood pressure, such as salt intake, anti-oxidants in grape seeds and drinking alcohol every day is good for the heart. Although there might be a grain a truth to these kinds of stories, they are not necessarily completely true and are certainly misunderstood. In some of my blogs, I try to demystify these stories.
Digital blood pressure monitors are for adults.
There are 2 main obvious reasons why children should not use digital blood pressure monitors. The most important one is that it is sometimes very difficult to find a cuff that is of the correct size for a child. The second reason is much more subjective, but as important as the first. When you measure a blood pressure the cuff has to be inflated to 30 or 40 points higher than the systolic pressure and this can prove to be quite uncomfortable for children, especially infants who cannot express themselves. Often, as a result of this, they move their arm or cry or get stressed, and this negates any diagnostic value of the reading. Children should not use a digital blood pressure monitor unless it is under the strict supervision of an adult.
Another reason why children should not use automatic blood pressure monitors is that the amplitude of the pulse waves generated by a child is very small (an infant has less than 1/2 liter of blood in his body so by definition his blood pressure is quite low) and more often than not an oscillometric (digital) blood pressure monitor will not “hear” the first “Korotkov” sound on which the blood pressure is calculated and will thus give an artificially low result for the blood pressure.
So what is blood pressure really ?
Blood pressure is the measure of the force that the blood exerts on the inside walls of your arteries. Blood pressure is expressed as a ratio (e.g. 120/80). The first number is called the systolic pressure, and is the pressure in the heart when it is beating. The second number is the diastolic pressure, and is the pressure in the heart when it is resting (between beats). Blood pressure is historically expressed in mmHg, or millimeters of mercury, even though there is no longer any mercury used in electronic devices. It is interesting to note that in most French speaking countries, blood pressure is expressed cm/Hg, or centimeters of mercury, which means that the doctor would express your blood pressure as 12/8 (twelve over eight) instead of 120/80.
It is also interesting to note that most doctors use rounded figures for blood pressure and will use the number 120/80 for any value considered as being in the normal range, so instead of telling you that your blood pressure is 134 over 76, he will quite often just tell you that you are 120 over 80. One could almost say that 120/80 is a generic number for normal blood pressure. We have noticed over the years that this is often a cause of complaints from patients who do not understand that the doctor is using this number (120/80) as a reference only. Over the past 15 years, we have received hundreds of letters from patients telling us that they think that their device is inaccurate. An example is Patient X who states that she would like a refund on her blood pressure monitor because “it is giving me a result of 133 over 84 and my doctor told me that I was 120 over 80”. In fact the result of 133/84 of Patient X is much more accurate than the doctor’s estimation, but it is of no medical consequence because both results are perfectly normal. In this case, the doctor of Patient X just gave her the “generic” figure for a normal blood pressure, which is 120/80.
When the blood pressure is measured, it should ideally fall within a specific range. Knowledge of this range and of your blood pressure should allow you to better manage your health. This is the blood pressure classification chart for adults set by the World Health Organization:
*Ranges may be lower for children and teenagers. Talk to your child’s doctor if you’re concerned your child has high blood pressure.
**Note: These recommendations address high blood pressure as a single health condition. If you also have heart disease, diabetes, chronic kidney disease or certain other conditions, you’ll need to treat your blood pressure more aggressively.
In general, it is better to have a lower blood pressure than a high one. With high blood pressure, the heart works harder, your arteries get damaged and your chances of a stroke, heart attack, or kidney problems are greater.
Your blood pressure fluctuates greatly in the course of a day. Many factors, such as exercise, conversation, alcohol, stress, movement, food or smoking can cause your blood pressure to rise and fall temporarily. This is why it is important to always measure and record your blood pressure at the same time and under the same conditions every day and to be completely relaxed when you measure your blood pressure.
Uwe DIEGEL
www.medactiv.com
