Taking Blood Pressure at Home Reliably Using the Traditional Mercury Way

Dr Lim Ju Boo On Medicine or Physiology

(The blogger wishes to acknowledge with thanks the express consent granted by the author for publication of this highly educating article.)

Summary:

1. Ready a mercurial or aneroid blood pressure set, a small pillow, and a stethoscope on table at the same level as your heart.
2. Sit comfortable and place left arm on the pillow.
3. Get someone help initially to wrap arm cuff around the left arm sufficiently loose to allow two fingers to go in between cuff and arm. You need this help only once, but do not unwrap the cuff after each measurement has been taken. Just slip the loop of cuff in and out of the same arm like wearing a shirt for future measurements.
4. Next, wear a stethoscope over the ears, and get ready.
5. Next, connect the rubber tube between the pump-bulb with the BP set.
6. Next, place the hand pump-bulb on the right hand and pump to about 180 mm mercury, and tighten screw of air valve to prevent air from escaping and to maintain pressure.
7. Next, transfer the hand pump to the left hand, and with the right hand place the stethoscope over the brachial artery at mid-line of the inner elbow just below the cuff.
8. Next, operate the screw of the air-valve, and release the air pressure slowly with your left thumb and index finger as you listen for the sounds of Korotkoff with the stethoscope.
9. Next, the moment the sounds of Korotkoff appear, read the mercury level. This is your systolic (maximum) pressure.
10. Next, continue to release the air very slowly until the sound completely disappears. Note the mercury reading mentally. That is supposed to be your diastolic pressure.
11. Next, continue to release the air very slowly until you really hear no more tapping sounds reappearing. If the sound reappears, ignore it, and continue to lower the air pressure slowly until there is real no more Korotkoff sound is heard. The last disappearance of the sound was your diastolic pressure.
12. Next, write down both highest (systolic) pressure and lowest (diastolic) pressure.
13. Next, log them down with date and time in an exercise book with a small note on your physiological, mental state under which that pressure reading was taken.
14. Next, repeat the same procedure each time 3 times a day over a few months with notes written at rest, peak of physical activity or just before bedtime, with or without medication.

Full Text:

Thank you once again for your further question on blood pressure measurement.

A lot of non-medical home users do not know how to use a conventional mercurial sphygmomanometer for self measurement. They think it is very hard and cumbersome to use this instrument and only a doctor, nurse, paramedic or health care provider know how use it. They only think it is very difficult to use. This is not true at all.

Learning to use a traditional mercurial sphygmomanometer (BP set) to measure your own blood pressure is not rocket science.

This very simple and convenient method of measuring blood pressure in humans was discovered in 1905 by Nikolai Korotkoff, a Russian Physiologist and Physician who submitted it as his thesis for his doctoral degree. His method is so famous now and yet so simple that clinicians, physicians, surgeons, physiologists, nurses and paramedics all over the world till today use his method.

You don’t need a PhD in Cardiovascular Physiology, or be a Consultant Cardiologist to know how to measure blood pressure. You don’t even require being a medical doctor, a nurse, or even a hospital attendant to know how to use a mercurial set. Even a moron after some persuasion and training will be able to measure blood pressure as good as a professor of cardiovascular science or cardiology. So what’s so difficult about using mercurial BP set instead of a digital one?

The Sounds of Korotkoff:
The method discovered by Dr Korotkov is so simple. Let me explain how this is done in your home without all those unreliable digital set that consistently give lower and frustrating undulating readings. Those digital BP sets are the most unreliable blood pressure instruments I have experienced. But not all are unreliable. Some models are good and dependable, and I can recommend them.

The Silent Gap:

However, be careful of the ‘auscultatory gap’ where the sounds may appear again before disappearing completely in some cases. This is normally encountered in either a mercurial or aneroid sphygmomanometers to where you need to auscultate (to listen) with stethoscope. Digital sets cannot detect auscultatory gap. Only a human ear can hear this. The gold standard thus for blood pressure measurement is still the mercurial sphygmomanometer. Many studies have shown digital BP sets are not reliable except just one model.

A lot of doctors are unaware of auscultatory gap. Hence sometimes doctors do make mistakes even with blood pressure measurements. They release the pressure too quickly and recorded the diastolic pressure immediately when the second sounds disappear. This is not correct, because there is a possibility of the sound appearing again when the mercury is further lowered.

Furthermore, for individuals whose heart beat is slow (bradycardia) or with irregular heart beat (arrhythmias), we never can know when the next beat will appear again after it seemingly have disappeared. So you tend to record the last disappearance of the sound in haste giving no time for the next beat to appear again. I know of many doctors make this mistake; giving the impression the patient has high diastolic pressure when it is not. Repeated measurements done elsewhere independently showed the patients were actually normotensive.

Release Pressure Slowly:

Always release the cuff pressure steadily but slowly, and pump it up and lowering it down again a few times for the diastolic reading. Never rush to measure blood pressure. Measure it a few times, and at least three times a day in the convenience of your home – early morning before getting up from the bed, at mid activity of the day, say around noon, and once more before retiring to bed.

Log all the readings for at least a month and look at your trend of blood pressures over a long duration under various physiological conditions. That is your true ‘real time’ blood pressure, which are vastly different from that single reading at your doctor’s office. Throw away his single ‘white coat’ ‘hypertensive’ reading and his medication away if he takes just one reading and ask you to take his blood pressure pills.

Never rely on just one reading. Always monitor your own blood pressure in the comfort of your home under realistic living conditions. These would be your true living blood pressure, and not those ‘white coat hypertension’ single reading by your doctor.

For clinical reliability I always use the traditional mercurial set whether at home to measure my own blood pressure or the pressures of other people or patients. Most of the home-use digital models were all shown to be unreliable and fluctuating for various reasons. See papers published on this in references. This is the same as I found in my own experimentation and clinical experience.

How to use a mercurial sphygmomanometer:

Let me explain to you how to use a mercurial BP set in a scientific, yet easy way at home. The difficulty most home users encounters is that they do not know how to listen through a stethoscope, and they need someone to wrap the cuff around their arms each time they make a measurement. That is the most inconvenient part of it. The mistake they do is to un-wrap the arm cuff after each measurement, after which they seek the help of someone wrap it around their arm again each time they want to use the sphygmomanometer.

You need not have to wrap and unwrapped the arm cuff each time you take your blood pressure. They only do this in the hospitals, clinics and the doctor’s office because there they have to deal with so many types of patients with different arm circumferences. But for your own use you need not do this all the time because your arm circumference does not change unless you are drastically becoming too thin or obese until you need to wrap and unwrap the arm cuff each time your arm circumferences changes.

But if your body weight or arm circumference remains stable, all you need is to get someone help you wrap it round once loosely in such a way your two fingers can easily slip between the arm wrap and your arm. Then after each measurement all you need is to slip the cuff in and out from your arm like the sleeve of your shirt. It is as easy as that. This first problem is solved.

Use Only One Arm:

The next difficulty is how to use the other arm to press the diaphragm of the stethoscope over the brachial artery at the inner bend of the elbow and at the same time pump up the mercury, control the air valve of the mercurial sphygmomanometer to adjust the levels of the mercury, and at the same time listening through the stethoscope since you actually have one arm to operate the sphygmomanometer while the other with the cuff on has to be rested on a pillow, and should not be moved when reading is taken. That is the only difficulty I believe most self-user encounter.
Initial help:

Let me tell you how I do my own blood pressure measurement with a mercurial BP set without help from anyone.

My only initial request for help is to ask someone to wrap the cuff over my left arm lightly in such a way that I can slip my two fingers between the cuff and the arm , and later able to take it off and slip it on again without unwrapping the arm cuff. It is like wearing a shirt.

First, sit comfortably and let left arm rest on a small pillow on a table where all your instruments would be.

Next, wear the stethoscope over the ears and get ready.

Next, get someone help us wrap the cuff over the arm that is seldom used, usually it is the left arm, if we are right-handed.

Slipping two fingers between the cuff and the arm after wrapping not only ensure the wrap is loose enough for the arm cuff to easily slip in and out of the arm without unwrapping and wrapping, but it also ensures that the cuff is neither too loose or too tight that may affect pressure readings. Here the same two-finger space allowance is also standardized.

This method is far more scientific than the wrapping and unwrapping method because the same space allowance and pressure is needed each time the mercury is being pumped up.

Pump Pressure with Right Hand:
Assuming you are right handed, next, pump up the pressure to about 180 mm Hg. If you suspect your systolic (upper) pressure is high, else about 160 mm Hg will suffice.

Do not use your left hand to operate the pump as the left arm should be resting comfortably on the pillow, and should not be exercised as the pressure is going to be taken on this arm.

Working up the muscles of the left arm and fingers by moving and contracting the muscles by pumping up the mercury is definitely going to affect the blood pressure of this arm. Do not do that. Just let it rest there comfortably as the pressure is being measured. We want a resting pressure over this (left) arm, not artificially worked-up pressure through exercise and contraction of the muscles.

Transfer pump and air valve to the left hand:
Once the pressure is high enough, tighten the air valve and quickly transfer the pump bulb to the left hand where the blood pressure is going to be taken.

Next, use your right hand to place the stethoscope diaphragm over the brachial artery (mid point at pit of the inner elbow) of the left arm and begin to listen.

Using the left hand index fingers and thumb to control the air pressure, lower the pressure slowly. Do not move your entire left arm as the pressure is being lowered and read.

Appearance of Systolic Sound:
Continue to bring down the air pressure until the first Korotkoff sound is heard. This is your systolic pressure, the maximum pressure exerted by the blood in the arteries. The tapping sound is caused by the resistance of a higher pressure the cuff over the brachial artery just being overcome by shots of blood that just managed to shoot through into brachial artery.

In other words, the blood is just able to force itself through giving that knocking sounds. That is the highest pressure within the arteries.

Disappearance of Korotkoff Sound (Diastolic):
Next step, continue to lower the mercury slowly and uniformly according to your heart rate. It is easier if you have a fast heart & pulse rate (tachycardia) because you would easily know when the sound of Korotkoff suddenly disappears.

If your heart and pulse rate is slow (bradycardia), lower the mercury slowly as you may miss the sound from a delayed beat.

Next, continue to lower the pressure until the sounds abruptly stopped. This is your diastolic pressure as the blood is now able to flow smoothly and quietly through the brachial artery without anymore knocking sounds unlike the knocking sounds of forced entry of a higher systolic pressure.

If you have irregular heartbeats (arrhythmia) or slow heart rates < 60 b /m (bradycardia) it would be much harder to decide when the next delayed beat is coming. It is harder because you can never know when the sounds may appear again because of a slow or irregular beat. You may think it has disappeared. Unfortunately you may miss it by lowering the mercury too quickly.

Should the last sound you thought has disappeared, pump up the mercury again by another 20 mm Hg and then slowly, slowly lower it again, and listen carefully.

Good Clinical Practice:

In good clinical practice always lower the pressure slowly, stopping intermittently as you auscultate (to listen) through the stethoscope.

Make sure it does not appear again. Repeat the diastolic pressure many times to make sure the Korotkoff sound cannot be heard anymore.

Sometimes the sound may appear to have disappeared, do not be in a haste to take that as your diastolic pressure. Continue to lower the mercury pressure until you are sure the sound does not appear again.

If it does then you have entered into the ‘auscultatory gap’. A lot of doctors do not even know this.

If the sounds of Korotkoff appear again, do not take this reading. Continue to lower the pressure until the re-emerging sound completely and permanently disappeared. Now take this reading. This is your true diastolic pressure, the minimum pressure within the arteries.

Added Sounds:

Actually there are many more other sounds (murmurs and bruits) in between the appearance and disappearance of the sounds of Korotkoff, but they are not of any clinical significance in retinue blood pressure measurements or retinue medical examination, unless you are a cardiovascular physiologist conducting clinical or physiological research for the advancement of medicine. Bruits and murmurs in this case have no clinical importance.

So Simple:

Taking blood pressure is as simple as learning ABC. It is not something so fantastic like rocket science that you need a brain of a rocket scientist to figure this out.

You don’t even need a doctor, a physiologist, a nurse, a paramedic or a health-care provider to do this for you. You can easily do this by yourself in the comfort of your own home using a mercurial BP set. This is just an elementary measurement in haemodynamics.

Deaf patients:

I would strongly recommend using a mercurial or an aneroid sphygmomanometer for self measurement at home. Digital sets are meant for deaf or completely helpless people who cannot hear anything, not even the sound of Korotkoff.

Even if you are deaf, you can still see. So you can still see the mercury bouncing up and down slightly in the column of mercury about the same time as the Korotkoff sound is first heard due to the waves of blood shoot through the brachial artery.

Digital sets may be useful in noisy places, because sometimes the Korotkoff sound is very faint especially if you place the cuff or stethoscope incorrectly.

Just a Law of Physics:

Just follow my very simple instructions here. Mercurial BP set is based on the principles of physics on a balancing column of mercury or on a manometer which Russian physician Korotkoff first discovered. This method is consistent, accurate, reliable and highly scientific. The laws of physics can never go wrong. It just has to be obeyed.

Monitoring Instruments in hospitals:

I am aware of those highly expensive and very sophisticated digital monitoring machines for monitoring blood pressures they use in the hospitals, ICU, and even in ordinary clinics.

They use them only for continuous monitoring purposes only which is not possible using the manual auscultation method which is still the gold standard.

The second reason they use digital measurements is because environmentalists are against the use of mercury being thrown into the drains, rivers and the sea when the mercurial set is old or broken.

Environmental Concern:

Mercury is highly toxic, so they are trying to phrase this out and use environmentally friendly measurements. These are the only two main reasons. But the traditional measurement with levels of mercury exerted by blood pressure is still the gold standard, provided these instruments are regularly serviced and the mercury tube cleansed of oxidized mercury which is less dense.

Disadvantage:

The less dense oxides of mercury will give a higher column reading to balance a corresponding blood pressure registered on the arm cuff. This gives false higher readings.

Almost all doctors I spoke to, were all unaware of this, let alone patients. Let this be an eye opener for clinicians and patients alike. It is not just ‘white coat hypertension’ but also mercury scrums, narrower tubes due to dirt and oxidized mercury scum, never been serviced before, and un-recalibrated instruments, hurried readings, old instruments used on hundreds of patients previously that gave a lot of problems.

Rocket Science for Clinicians:

This information may come like rocket science for most clinicians and home users. Additionally do not rely on a single hurried reading taken by your GP unless it is extremely high like 180 / 150 mm Hg. In that case immediate hospitalization may be needed even with a single measurement. It is best to do hundreds of your own measurements at home.

Statistical Analysis:

If you are mathematically and statistically savvy, apply statistical procedures to analyze all those hundreds of data under different conditions and do a distribution curve, calculate the mean, the standard deviation, and analyze for ‘statistical significance’ at ‘95 % (0.05) confidence level’ using t-test (student test) and p-value.

Those would be your powerful clinical data to show to your doctor, and not his single ‘white coat hypertension’.

But I doubt if an ordinary doctor who has never been involved in medical research before, would understand your powerful statistical analysis and their interpretation of your blood pressure readings over time. All he knows is take one pressure reading in his office, and makes unacceptable scientific conclusions.

This conclusion is made worse by rushing into his clinic through the notorious traffic jam in the heat of a hectic hour. Just throw away all those readings whoever, whether doctor or nurse takes them. Take hundreds of your own measurements at least 3 times a day over 1-2 months, and look at the trend of readings, and never just a single data.

Don’t rush to medicate:

One more thing, never take any of those antihypertensive medication over just one borderline elevation of blood pressure hurried taken at your doctor’s office.

Conduct your own studies under real living conditions at home and at work. Take hundreds of readings under various physiological conditions and evaluate them yourself.

These would be your real blood pressures in real life.

Electronic medical devices:

As to your comment about all those electronic devices being used by doctors and in hospitals these days, these are actually not the brain-child and inventions of medical doctors. These are inventions of medical engineers with training in electronics, and basic medicine.

They then sell them to hospitals at exorbitant prices, and the bill is passed down to the unfortunate patients. That is how medicine is practiced in this mechanical-electronic age. We are all aware of all issues.

Business venture hand-in-gloves:

There is no need to say any further because everybody, from the businessmen, the engineers, the doctors are all making money with all these devices. The machines take over from the doctors. The practice of medicine as we know it now has no personal touch anymore. They depend very heavily on lab tests, imaging, and other diagnostic investigations based on technology rather than conservative medical history, good sense, good clinical acumen and judgment. No one in the health care profession can deny this anymore.

Practical objective:

But as far as those blood pressure monitoring devices are concerned, they are used in hospitals for a practical purpose, namely to prevent their ears from being pinched by a stethoscope all day long just to measure blood pressure of each patients all day long. In a busy outpatient department of a hospital there may be around 200-300 patients a day for each doctor to see.

Imagine trying to take the blood pressure manually of every of these patients all day long, and repeat the whole episode the next day? Wouldn’t be easier if all these can be done electronically without needing to use a stethoscope to listen?

Manual sets also cannot be used at the bed-side all day long on a patient laying there half conscious say in an ICU all day for weeks or months. The doctors and nurses will have nothing else to do but to stand there taking blood pressures continuously for every comatose patient. This is highly impractical in a modern hospital.

Multiple readings:

Secondly, with just one electronic monitoring machine, they not only can measure blood pressures continuously, but also haemoglobin-oxygen levels using pulse oximetry, respiratory rates, ECG, and all those vital signs simultaneously. That’s one.
Thirdly, and a very important one, is that they are now trying to phase out the mercurial set because of environmental concern about mercury being discharge into the waterways, soul and environment, and finally enter into the food change.

Mercury Toxicity:

Mercury is highly toxic which can damage the brain, kidney, and lungs. Several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease have all been shown been linked to mercury poisoning.

The symptoms of mercury poisoning presented included peripheral neuropathy such as paraesthesia, itching, burning sensation, changes in skin coloration such as pink cheeks, and discoloration of fingertips and toes, swelling, and desquamation of the skin.

Aneroid Sphygmomanometer:

Alternative to a mercurial BP set is an aneroid sphygmomanometer which does not use mercury. This is also a good substitute for personal use or for just a few patients.

But for those who really do not know how to listen, or are lazy, paralyzed or lonely patients they may still use a home digital set, but they must compare as many readings as are practical with readings from a mercurial or aneroid sphygmomanometer set.

Using the data, apply statistical analysis to see whether the differences between a traditional sphygmomanometer and a digital set are ‘statistically significant’ (too long and complex to explain here).

Use it if Not Statistically Significant:

If the data are not statistically significant or is very small, then accept the digital readings, and thereafter always use the same digital instrument for all measurements with a correction if necessary. All you need is to see your blood pressure trend over many months. But always take at least 3 readings per day - before waking up in the morning, at peak of activity around noon or in the afternoon, and again just before going to bed at night.

If you are on medication for hypertension, repeat this same procedure, just before medication, and about an hour after medication. Do this many times to see the trend of blood pressure over the entire day.

If Results Consistently High:

But if you are consistently getting high readings even at home under real time situations, only then see your cardiologist or GP. But take this advice seriously. You should never depend on one reading taken in your GP’s office and in haste put yourself under unnecessary medication especially in borderline cases which can easily be controlled by lifestyle changes such as reducing stress, managing overweight, reducing sodium (salt) intake, cessation of smoking if you are a smoker, meditation, moderate and regular exercise, physical activities, etc, etc.

Take your own reading over many months. Take the mean reading; calculate out the distribution curve and standard deviation from hundreds of readings over a period of time. These would be your true blood pressures under various physiological states. Throw away that single reading taken by your GP especially when the pressure is just at the borderline of say 140 / 90 mm Hg. Institute the measures I have briefly mentioned instead of taking unnecessary medication.

Antihypertensive drugs:

There are many classes and genera of drugs that can lower blood pressure if your blood pressure is excessive high. These include commonly used classes like thiazide diuretics, beta blockers, the ACE inhibitors, the calcium channel blockers, and more recent generations are the angiotensin II receptor antagonists. The strategy on their usage is the prevention of heart attack, stroke and heart failure, and other end-organ failures. But if you are just mildly hypertensive, it is best to avoid and become dependent on medication for life. All that is needed is a change in the way you eat and live your life.

Since this article about blood pressure measurements, and not about the pharmacology of antihypertensive drugs or on the management of high blood pressure using pharmacological approach, it suffices just to briefly mention the classes of drugs being used rather than specific generic agents (drugs) of choice. The choice depends on the medical history, severity of each case, drug tolerance and clinical complications.

Alternative to Pharmacological Intervention:

Even if the pressures are constituently above normal even at resting stage, there are still many other alternative ways to normalize blood pressures. Some of them are dietary approaches, stress management, meditation, acupressure, qigong, mental and psychological relaxation, spacing out work schedules.

Taking antihypertensive drugs by the tons for life is no cure for high blood pressure. Only lifestyle changes are the permanent solution especially in borderline cases.

What if Left-handed:

As to your other question if a patient is left-handed, how do we take readings? The answer is so simple. Just switch to the other hand. The instructions are still the same.

But the golden rule of the thumb is: if you are just measuring blood pressure routinely, then always measure them on the same arm, whether right, or left-handed no matter what your vascular status is on the other arm.

Do not switch left and right all the time because you are not conducting some physiological or medical research to compare physiological or pathological difference. Leave this to a research scientist. That is not your job. Neither is this even for a clinician whose job is just to treat your illness.

I hope it answers your question.

jb lim ----------------------------------------- The blogger's note: There is another article written by Dr JB Lim on “Blood Pressure Difference between Right and Left Arms” and this can be found in the content of “The Thoughts of Dr JB Lim”.

The Summary of that article is as follows:

1. There is a slight and insignificant difference between blood pressure on the right and left arm.

2. This difference is between 5-10 mm Hg, but should not exceed 10 mm of mercury.

3. This difference is physiologically due to compression of the artery by the stronger and more developed arm muscles in the more frequently used arm, majority of the people of the right arm.

4. Should differences exceed 10 mm Hg then there is a possibility of a blocked artery in the arm that registers a lower pressure. In that event, it is advisable that an angiogram be done to locate of any narrowing or blockage along the brachial artery.

5. Because of a physiological difference between the right and left arm, it is better to always measure the blood pressure on the less dominant arm, mainly the left arm than on the more muscular side.

6. Whichever the arm chosen, always standardize the measurement over that same arm for all future and subsequent measurement so that trends in blood pressures can be homogenized in a scientific way for comparison. Never be disorderly and indecisive here or there.