What's the first thing that'll probably happen to you if you're rushed into hospital? Apart from waiting for hours in some freezing corridor, someone will probably take your blood pressure.

It's standard procedure, and hospital staff takes a measurement almost on autopilot. Trouble is, it's hopelessly unreliable, as a recent study has discovered.

Researchers followed the progress of 171 patients in one emergency room whose blood pressure was taken either manually or using automated devices. The automated devices all failed to meet even the basic criteria as laid out by the British Hypertension Society or the Association for the Advancement of Medical Instrumentation. In other words, they were faulty.

Not surprisingly, the readings were all over the place, and blood pressure levels decreased enormously as more tests were done.

While on the subject of blood pressure screening, researchers have found it doesn't help predict a heart attack or stroke. The study says, and we quote, 'although high blood pressure can cause heart disease, it is not present in most people with heart disease.' (ED: Anyone out there who can explain this, please?)

Instead of screening, it's better to teach people how to lower their blood pressure, the researchers conclude.

(Sources: Hospital study: Academic Emergency Medicine, 2004; 11: 237-43; Heart disease study: Journal of Medical Screening, 2004; 11: 3-7).