High blood pressure: is your doctor on the case?
Hypertension may cause no symptoms, but if it goes undiagnosed, you could be in for trouble. Barbara Rowlands reports
Tuesday 17 January 1995
"I'm slightly overweight, I smoke and have the odd drink but he never mentioned the effects of diet, smoking or alcohol," says Ms Hart, a 38-year-old publicity officer.
"He never explained what the consequences of high blood pressure could be. I went back two years ago and he just told me I should continue to be monitored. A year ago he put me on diuretics, [drugs that promote fluid loss by increasing urine production] but they didn't lower my blood pressure."
Caring for patients with hypertension is not always doctors' strongest suit. A study carried out at Charing Cross and Westminster Medical School three years ago revealed that a third of junior hospital doctors did not know how to take blood pressure properly.
"A lot of blood pressure measurement is very badly done, partly because medical students are only shown how to do it in their first year," maintains Professor Gareth Beevers, vice-president of the British Hypertension Society and a consultant general physician who runs an antenatal hypertension clinic at the City Hospital, Birmingham.
Mistakes are frequently made, he says. "Because it's a relatively simple procedure, familiarity breeds contempt. A significant minority of people are being treated for hypertension when their blood pressure is probably normal - and vice versa."
One in seven people in Britain has high blood pressure - and most of them feel perfectly well. There are usually no symptoms - the only way to find out if your blood pressure is creeping up is to have it checked regularly. High blood pressure puts a considerable strain on the heart and blood vessels and is dangerous: a 40-year-old with hypertension is 30 times more likely to have a stroke than someone with normal blood pressure.
"High blood pressure is very serious," says Dr Sylvia McLauchlan, director general of the Stroke Association. "The risk of a stroke increases if you're overweight, if you smoke and as you get older, and high blood pressure is an unnecessary additional risk. If you don't treat it, you will inevitably get trouble."
Some doctors prescribe drugs for hypertension on just one reading, which is often inaccurate because of "white coat hypertension", where blood pressure shoots up at the sight of a doctor wielding the arm cuff. It should be measured four times to get an accurate reading.
Blood pressure is the pressure exerted by the flow of blood through the main arteries and two levels of pressure are measured. The first, the systole, is when the heart contracts and the second, the diastole, is when it relaxes. Both are usually measuredwith a sphygmonamometer, a piece of equipment that has been largely unchanged for 90 years.
A cuff containing a rubber balloon is placed around the arm and inflated so tightly that it stops the blood from flowing. When the cuff is released the blood begins to pump, and at the height of the pressure wave it creates a thumping noise - the systolic pressure. As the pressure in the cuff falls the sound becomes muffled and disappears, and the blood flows steadily through the now open artery, giving the diastolic pressure. The device commonly used consists of a glass column filled with mercury or, in more modern instruments, a digital display.
Normal pressure in an adult is around 130/80 systolic over diastolic, expressed as millimetres of mercury (mm Hg). Blood pressure is considered to be high when the systolic is over 160 and the diastolic is consistently greater than 90. Deborah Hart's blood pressure was about 160/100.
For a diagnostic method that relies on the detection of sounds in the artery, and the observer's sharpness of hearing, taking blood pressure can be a hit and miss affair.
In a paper published in the Lancet last July, Professor Thomas Pickering, who runs the Hypertension Center at New York Hospital, wrote that even under ideal conditions blood pressure readings could be inaccurate by as much as 25mm of mercury.
In Britain, hospitals and general practices often have poorly maintained equipment, which is irregularly serviced. A service means checking that the tubing has not perished and that there is enough mercury in the machine. If the tubing is weak the mercury will drop too fast. "If the mercury drops too quickly many doctors just guess at the reading," says Michelle Beevers, president of the Nurses Hypertension Association, based at the City Hospital. "The diastolic sound should disappear completely, but some doctors take the reading from a muffled sound. Some use the wrong sized cuff - there are two adult sizes. The result is they can be up to 10mm out on a reading.
"It's worrying that people are on drugs for hypertension when there is nothing wrong with them. What is more worrying is that there are people who should be on drugs who aren't. They're the ones who are going to get strokes."
For those in need of treatment, there is a range of highly effective drugs on the market - beta blockers, calcium channel blockers (both lower blood pressure by reducing the contraction of heart muscle), diuretics, and ACE (angiotensin-converting-enzyme )
inhibitors, which reduce the constriction of blood vessels. In most people these drugs are well tolerated.
But some people who should be on anti-hypertensive drugs are refusing treatment. A recent survey by the Stroke Association revealed that some people who know they have hypertension fail to return to their GPs for treatment. Sylvia McLauchlan understands this ostrich-likeattitude.
"It's quite hard to keep on going back to the doctor, particularly when you've got something that doesn't make you feel ill. We do know that half the people with raised blood pressure go undetected, and only half of those who are detected have effective treatment."
Deborah Hart finally managed to control her blood pressure after holidaying in France where a doctor, worried by her condition, persuaded her to take up regular exercise. "During the summer in France I exercised every day and when I returned to Britain my blood pressure was normal.
I've just joined a gym and I eat healthily. So hopefully I've got it under control."
The Stroke Association, CHSA House, Whitecross Street, London, EC1Y 8JJ. Tel: 071 490 7999.
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