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(1) High Blood Pressure

Introduction

High blood pressure (BD) is the most common continuing medical condition seen by family doctors.

At just what measurement 'normal' blood pressure becomes 'high' blood pressure that justifies action being taken to reduce it is still a subject for professional argument among doctors (although most now agree on a pressure of somewhere around 160/90 mmHg).

Whatever the definition, the numbers of people needing some sort of treatment for high blood pressure include at least 10% of any large group of adults, up to 33% of poorer city adults, and about 50% of all people over 65 years of age - a lot of people.

If you are one of this 10%-50%, and you need medication for your high blood pressure, you will probably go on needing it for the rest of your life.

If you lean/read, understand, and remember the following themes, you will be well on the way to understanding the nature of your high blood pressure, what can and what can't be done about it, and both the benefits and risks of treatment.

If not, your alternative is to let doctors take decisions about your life, without your help or informed consent. Most doctors today understand how dangerous it is for the people they treat to be so uninformed and uncritical.

Safe doctoring depends on the cooperative work of two sets of experts: expert professionals who know a lot about how the human body works but little about the personal lives of the people they are treating; and the people being treated, who are experts on their own lives but know rather less about how their bodies work.

Just as doctors can't look after you properly if they are completely ignorant of your life, so you can't interpret their advice safely if you are completely ignorant of human biology.

Even if you remember parts of this course, you will know more about the practical management of high blood pressure than many health professionals, who usually have to cover a much wider range of medical conditions and cannot concentrate only on this one.

With or without this knowledge, you, not your doctors, will be responsible for actually using the treatments they recommend.

Many different drugs are used to treat high blood pressure, but they all have one thing in common: they don't work if you don't take them.

Yet many (if not most) people treated for high blood pressure don't take their tablets regularly.

They take them if they feel as though their blood pressure is high, but miss them if they feel well or plan to have a few drinks, or need to take other tablets for something else and are afraid of mixing them, or if they're afraid of side-effects and even more afraid of admitting this to their doctor.

Unless you are in hospital you have to take your own treatment decisions - there are no nurses' rounds to see that you follow orders.

To medicate yourself safely you need far more information than any doctor or nurse can impart in the few minutes usually available for a consultation, and one purpose of this course is to provide you with that information.

What high blood pressure is and what it is not.

Everybody's blood is under pressure; otherwise it wouldn't circulate around the body.

If blood pressure is too high it damages the walls of your arteries.

After many years, this damage increases your risks of coronary heart disease, heart failure, stroke, bleeding or detachment of the retina (the back of the eye), and kidney failure.

High blood pressure itself is not a disease, but a treatable cause of these serious diseases, which are thereby partly preventable.

All these risks are greatly increased if you also smoke or have diabetes.

Unless it has already caused damage, high BP seldom makes you feel unwell.

It can be very high without causing headaches, breathlessness, palpitations, faintness, giddiness, or any of the symptoms which were once thought to be typical of high BP. You may have any or all of these symptoms without having high BP, and you may have dangerously high BP with none of them.

The only way to know if you have high blood pressure (and how high it is) is to measure it with an instrument called a sphygmomanometer while you are sitting quietly.

Because BP varies so much from hour to hour and from day to day, this should be done at least three times (preferably on separate days) to work out a true average figure before you take big decisions like starting or stopping treatment.

 Mechanisms

Your level of BP depends on how hard your heart pumps blood into your arteries, on the volume of blood in your circulation, and on how tight your arteries are.

The smaller arteries are sheathed by a strand of muscle which spirals around them: if this muscle tightens and shortens, it narrows the artery.

In this way smaller arteries can be varied in diameter according to varying needs of different organs in different activities.

In people with high BP something goes wrong with this mechanism, so that all the arteries are too tight.

The heart then has to beat harder to push blood through them.

This tightening-up may be caused by signals sent by the brain through the nervous system, or by chemical signals (hormones) released by other organs in the body (such as the kidneys).

Causes

The causes of short-term rises in blood pressure which last only seconds or minutes are well understood, but these are not what we normally mean by high blood pressure.

High blood pressure is important only when it is maintained for months or years � it is a high average pressure which is significant, not occasional high peaks.

The causes of a long-term rise in average pressure are not fully known, but we do know that it runs in families.

This inherited tendency seems to account for about half the differences between people; the rest seems to depend on how they live and what they eat (not just in adult life, but what they ate in infancy and childhood and how well-nourished they were before they were born).

We don't know enough about this to be able to prevent most cases.

 Foreword

One cause we do know about is overweight (particularly in young people) and weight reduction is a sensible first step in treatment.

Weight loss depends mainly on using up more energy (measured in calories) by taking more exercise, and reducing energy input (the number of calories eaten in food).

In practice the most healthy way to do this is by reducing the amount of fats, oils, meat, sugar and alcohol in the diet, and instead eating more fruit, vegetables, cereal foods and fish (some of these foods have other good effects as well as helping weight loss).

Eating less fat and oil is by far the most important of these changes.

Another benefit from these changes in diet is that they help lower blood cholesterol levels and so reduce the risk of developing coronary heart disease.

Another known cause is excessive alcohol (which means more than 4 units of alcohol a day for a man or 3 units a day for a woman - a unit of alcohol is one glass of wine.

Again, the biggest effect is in young people. Limiting alcohol intake often brings high BP back to normal without any other treatment.

 Stress

If you are anxious, angry, have been hurrying, have a full bladder or if you are cold then your BP will rise for a few minutes or even a few hours (so BP measured at such times is not reliable) - but none of these things seem to be causes of permanently raised blood pressure.

High blood pressure seems to be just as common in peaceable, even-tempered people without worries as it is in excitable people with short fuses.

However, feeling pushed at work or at home may be an important cause in some people, if not for everyone.

The word 'hypertension' is used in medical jargon with exactly the same meaning as high blood pressure.

This does not mean that feeling tense necessarily raises blood pressure, nor does it mean that most people with high blood pressure feel tense.

Blood pressure falls considerably during normal sleep, both in people with normal blood pressure and in those whose blood pressure is high.

Training in relaxation certainly lowers blood pressure for a while, and may have a useful long-term effect on high blood pressure in people who learn how to switch off often during the day, but there is no evidence that treatment by relaxation alone is an effective or safe alternative to drug treatment for people with severe high blood pressure.

 Salt and Sodium

Table salt is sodium chloride: it is the sodium which is important for your blood pressure, not the chloride.

High blood pressure is unknown among those peoples of the world whose normal diet contains about 20 times less sodium than a normal Western diet, and even very high BP can be controlled by reducing sodium intake to this low level.

The diet required for this consists entirely of rice, fruit and vegetables and would be intolerable to most people in European Union countries and United States.

The usual Europeans and Americans diet contains much more salt than anyone needs. It certainly does no harm to reduce sodium intake by not adding salt to cooked meals, and by reducing or avoiding high sodium processed foods (crisps, sausages, sauces, tinned meats and beans, and 'convenience' foods generally), Chinese takeaways (which contain huge quantities of sodium glutamate) and strong cheeses.

Salt can be found in the most unexpected foods - for example, both milk and bread contain salt in amounts which would surprise most people.

There is no convincing evidence that the roughly one-third reduction in sodium intake you can achieve by these dietary changes is an effective alternative to drug treatment for severe high blood pressure.

Reducing fat in your diet by about a quarter reduces the potential complications of high blood pressure much more effectively than reducing your salt intake by about half.

Most people find it difficult to reduce fat and salt at the same time, and fat reduction deserves a higher priority (especially as cutting down on fats will help you lose weight). However, people whose blood pressure is high enough for them to need to take drugs for it may manage on lower doses of their tablets if they reduce their sodium intake, and very heavy salt-eaters should try to cut down.

 Smoking

Smoking is not a cause of high blood pressure, but it enormously increases the risks associated with it.

If you have high blood pressure already, then if you also smoke you are three times more likely to have a heart attack than non-smokers if you are less than 50 years old, and twice as likely to have one if you are over 50.

Heart attacks in people under 45, and in women at all ages, happen much more frequently in smokers.

Smoking is a powerful risk factor in its own right, not only for coronary heart disease and stroke, but also for cancer of the mouth, nose, throat, lung, bladder and pancreas, and for asthma and other lung diseases.

Unlike all other risk factors, it also affects your colleagues, family and friends (through passive smoking and the example you set to your children) and it costs a lot of money you could spend better in other ways.

When to have drug treatment

You will probably be advised to have drug treatment for your high blood pressure if there is already evidence of damage to your arteries, brain, heart, eyes or kidneys, or if you also have diabetes.

As a very rough guide, drug treatment is otherwise rarely justified unless your average blood pressure (averaged from at least three readings on separate days) is at least 160/100 mmHg.

While you don't need to know exactly what these figures mean, you should know what they are in your own case, just as you do your own height and weight.

This threshold figure (plus or minus 5 mmHg either way) is based on evidence from large controlled trials in UK, Australia, Scandinavia and the USA, which have shown worthwhile saving of life in many thousands of people.

The benefits of drug treatment are greatest in the people with the highest pressures, or those who already have evidence of organ damage.

Most of the benefit has been in reducing strokes, heart failure and kidney damage; the effects on coronary heart attacks have been much smaller (more important ways to prevent heart attacks are to stop smoking, maintain regular exercise, and stick to a diet low in saturated fats).

 Blood pressure-lowering drugs

When severe high blood pressure is reduced by drugs, people live longer than if they are left untreated.

Their treatment will not affect how they feel - it seldom makes people feel better, and they may sometimes even feel worse.

The aim of all present treatments for high blood pressure is not to cure it, but to prevent its consequences by keeping pressure down to a safer level (whatever the underlying causes of high blood pressure are, they seem almost always to be permanent and are not affected by any of the treatments now available).

Treatment must therefore nearly always continue for life - if you stop taking your tablets, your blood pressure will probably rise again, although this may take several months.

Unfortunately, all the drugs used for high blood pressure can cause unpleasant side effects in some people, although the newer blood pressure lowering drugs are generally easier to live with than the older ones.

If you think your drugs are upsetting you, then say so, as there are alternatives. With so many blood pressure-lowering drugs now available your doctor should be able to tailor an individual treatment for you that minimizes side effects or even eliminates them altogether.

Included among the side effects of blood pressure-lowering drugs are tiredness, depression and failure of erection: if any of these happen to you, then tell your doctor or nurse, as if they really are caused by your drugs, they will clear up soon after your medication is changed.

If you have any wheezing or asthma, then some blood pressure-lowering drugs can be very dangerous, so make sure your doctor knows about this.

Some drugs used for back and joint pains can interfere with the effect of drugs given for high blood pressure, and you should ask your doctor about these if you take them.

(Don't try to alter your medication yourself.)

 The contraceptive pill occasionally raises blood pressure very seriously, so women with high blood pressure should discuss other methods of birth control.

Foreword

Remembering to take tablets is difficult for many people.

Take them at set times, and ask your partner or a friend to help you learn the habit of regular medication.

Don't stop taking your tablets just because you're going out for a drink - all blood pressure-lowering drugs can be taken with moderate amounts of alcohol.

 Follow-up

Always bring all your tablets (not just those for your high BP) with you in their original containers when you see your doctor or nurse for follow-up, so that they know exactly what you are taking.

If your blood pressure doesn't fall despite apparently adequate medication, think about your weight or your alcohol intake.

Follow-up visits should be frequent at first, perhaps once a week until your blood pressure is controlled to under 160/90 mmHg.

After that most doctors will want to check your blood pressure every three months or so; never go longer than six months without a check.

 The end of the beginning

All this (and I mean all) is the least you need to know to take an intelligent share in responsibility for your future health, not just as a passive consumer of medical care, but as an active producer of better health (as everyone should be).

However, I hope by now you are interested enough to want to know more than this.

The rest of this course will tell you a lot more both of what we do know about high blood pressure and - just as important - what we don't know.

Most of you learning this will have been told that either you, or someone in your family, have raised blood pressure.

The questions in this course are those asked by people like you every day; the answers are intended to help you be as informed as possible about your own care so that your treatment will be more successful and you will feel more in control.

Remember that no one involved in this subject (including doctors and nurses) ever stops learning more about it. In fact, a few of you may learn not because of your own health problems, but because in your work you are concerned with the health problems of other people.

Because different people have different requirements for information about high blood pressure, this course has been designed in a way that means you do not have to learn-read all unless you wish to do so.

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