High blood pressure

Everything you need to know about  Blood Pressure

(Well nearly everything!)

What is Blood Pressure?

Just as the water supply to your home must be at a certain pressure to fill your tanks, give you a good shower or water the garden, so the blood needs a certain force to drive it around the arteries, through the capillaries, thence through the veins and back to your heart.  The “pump” to drive it around the circulation is the heart, and the elasticity in the arteries helps to ‘level out’ this force while the heart is not in contraction. Hence we get a “peak” pressure while the heart is contracting (the “systolic” or top reading) and  a “trough” pressure (the “diastolic” pressure or bottom reading), while the heart is at rest between contractions.

 

How is it measured?

Traditionally a cuff filled with air, connected to a column of mercury (chosen because it is a very heavy, liquid metal), is inflated around the upper arm until the blood supply shuts off. The pressure in the cuff is then very gradually reduced while listening over the brachial artery for the first squirt of blood. At this point, the height of the column of mercury is noted (in millimetres of Mercury) and recorded as the “systolic pressure”; the “diastolic pressure” is also noted and occurs when the

sound of the blood going down the artery stops altering its note.

 

What is “High Blood Pressure” (also known as “hypertension”)

In a normal person the blood pressure varies from moment to moment, lowest when we are asleep and highest when we are under extreme physical and/or emotional stress.  However, some people maintain a higher level of blood pressure than others and at a certain level this is designated as “hypertension”.

 

Why does “Hypertension” matter?

We know that a person with high blood pressure is far more likely to suffer a heart attack, a stroke or kidney failure; therefore we should think of hypertension, not as a “disease” but as a “risk factor” i.e. a state which puts you at increased risk of arterial disease by narrowing and hardening your arteries, forming a clot on them or even rupturing. Hypertension is the “leading risk factor for disease world wide”!

 

Why do some people get hypertension and others don’t?

Very rarely the hypertension may be due to some other problem in the body – e.g. certain hormonal or kidney diseases – but far, far more commonly it occurs for no reason whatsoever – none! However, it is very, very common with 50% of people over 60 and 75% of the over 75s having it!

 

What symptoms do people with hypertension get?

 None – absolutely None!  In particular, hypertension  does not cause headache and does not cause dizziness. In my 42 years of general practice I have seen only one patient who had symptoms from a high blood pressure; this patient had a blood pressure reading of 310/210 and went on to have a kidney transplant. The only way to know if you have this “risk factor” of hypertension is to get your BP measured!

 

How should I have my blood pressure measured?

Certainly not when you see your G.P.!  Ideally you should be relaxed and calm for a meaningful BP reading  and this is very unlikely in the setting of General Practice! The best way to diagnose hypertension is with “ABM” – Ambulatory Blood Pressure Monitoring –  in which a device is fitted to your arm for a few days and this takes readings during the day and records them; however, these devices are not always available when you want them and almost as good (better in the opinion of this doctor) is to get your own automatic machine and get loads of readings at different times during the day, write them down and show them to the doctors when you consult with them.

Here are some tips for reliable  readings:

Sit down comfortably with the cuff placed accurately.

  1. Your arm should be roughly at the same level as your heart.
  2. Take several readings at one “sitting”; you will find that the first ones are higher. Ignore these, but note the reading when the Blood Pressure ‘levels out’. The first reading is higher due to the “alerting response”.
  3. Take readings daily until you become familiar with the machine; take readings at different times during the day
  4. Take readings especially if you feel dizzy or faint or if you become conscious of your heart beating (the sphygmomanometers also record your pulse)
  5. Bring the readings to your doctor or nurse at your next appointment
  6. Check and compare the BP in the other arm about once per year; if there is a big difference (15 mm or more) then let your doctor know.

Choosing your Sphygmomanometer

  1. Use the upper arm machines – not the wrist devices which are not reliable.
  2. Make sure the cuff is wide enough for your arm and it is placed accurately.
  3. Many sphygmomanometers have been evaluated by ‘the experts’ – e.g. the British Hypertension Society (for complete list, visit the BHS web-site)
  4. My own preference – based on years of experience and laziness to explore elsewhere – is the Omron range. (Omron Healthcare UK Ltd at 0870 7502771)
  5. To make life easier, I would just decide on the device you want, then shop on the internet for the best price, but NB: when ordering ask for both a normal and a wide cuff – especially if you have a fat arm!
  6. If you have any doubts about your machine, take it along to your G.P.s surgery and ask for a check against their machines.

 

Will I have hypertension for the rest of my life? Is there anything I can do to help myself?

Yes, almost certainly you will have it for the rest of your life and indeed will need to take medications indefinitely.

However, there are certain things you can do which will certainly help and occasionally make medications unnecessary:

  1. Exercise! (groans – you’ve heard it all before). But even 20 to 25 minutes of moderate exercise is all you need to make a significant difference to your BP!
  2. Weight Reduction (more groans). A weight loss of 10 lbs will reduce your BP 4-5 mm.   If you are  struggling to lose weight, try my Homer Simpson Weight Loss Plan – 5 simple rules for people too busy to get into complicated regimes.
  3. Stop Cigarettes. They really do send your BP up; you can prove it by taking readings within 20 minutes of a cigarette.
  4. Try stopping alcohol. Some people are very sensitive to the blood pressure effects of alcohol. Try stopping for just one week, keeping a track of your home readings; you should see the difference within 4 days if you are an alcohol-susceptible sort.
  5. Try stopping caffeine. In most people, caffeine (in tea, coffee, cola etc) makes no difference as we “adapt” to caffeine . However, some people don’t adapt, so exclude caffeine for a week while monitoring your BP and see if this is relevant to you.
  6. Reduce salt intake, but bear in mind that most salt in our diet comes in the packet of pre-prepared foods – especially bread and cheese! A high potassium diet (ie loads of fruit, vegetables, nuts, prunes and dates) is a big help.
  7. Learn better ways of coping with stress. Remember the two rules of stress busting:
  8. Don’t worry about the small stuff.
  9. It’s all small stuff (and it is in the greater scheme of things)

 

How do the pills work?

Basically in four ways:

  1. They reduce the pumping action of the heart
  2. They open up the various blood vessels.
  3. They reduce the levels or block the effects of the various bodily hormones that send blood pressure up.
  4. They reduce the volume of bodily fluids.

Some pills work synergistically together – i.e. they magnify the effect of each others’ BP lowering. Note also that most medications can be given just once per day, so even though you may need two or three types of medicine, you will only need to take a few pills per day.

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Do they cause side-effects?

Usually none; however, if they do we can easily change to a medication which suits you better. We minimise side-effects by using several drugs in very low dosages. Do bear in mind also that some BP lowering drugs have beneficial side-effects such as jhkidney protection, reduction of anxiety, improvement of diabetes control, reduction of frequency of migraine attacks etc.

 

What about alternative medicines such as homoeopathy, herbal medicine etc?

Definitely unproven and probably totally useless; they tend to be safe (but even this has not been evaluated properly with many herbs) so you could try them while monitoring your own blood pressure. If anything does work, please tell me!

 

How should I measure my own BP?

First buy a really good automatic machine with a cuff that goes around the upper arm. Bear in mind that patients with a fatter arm need a bigger cuff, so make sure your cuff is wide enough. Then ensure it is always handy, so that when you are sitting around the house, you can always run off a few readings. Always ignore the first reading, but make a note of the others; in the studies which proved that value of lowering BP, they would take the “trough sitting” as the true value. i.e. Keep  measuring your BP every couple of minutes or so until it topped falling and levelled out. It doesn’t matter which arm you use as they are usually the same; if they vary by 15 mm or more, let your doctor know. You should compare the BP in both arms once per year.

What BP should I aim for?

Below 140/90 would be ideal for most normal people. However, if you are at particular risk of arterial disease, as for instance with diabetes, the target will be lower; the target in pregnancy is also far lower than “normal”.

 

Should I worry more about the systolic (top reading) or the diastolic bottom reading)?

Almost always it will be the top reading which guides treatment – especially in patients older than 50 years old

 

If you think that looking after your blood pressure is expensive in time and effort, be aware that not looking after it will be extortionate!  You are “only as old as your arteries”; looking after your BP helps you stay young!

 

 

Good Luck!

 

Bernard Shevlin     b.shevlin02@gmail.com

(I’m happy to receive e-mail comments about this guide!)