The mercury column sphygmomanometer is easy to use, simple to maintain and very accurate. Compare this with the modern digital sphyg; how many times have you seen an error message, unrecordable BPs with arrhythmias, or silly reading of 120mmHg diastolic when a few moments later it records 80mmHg?
The European Commission is currently discussing proposals to phase out healthcare mercury devices but in the UK drug regulator is objecting to the ban on mercury sphygs. I’m glad. Without them, how would we calibrate the digital oscillometric and aneroid deices?
The concerns over mercury sphygs are mainly environmental. US data suggest that it is an expansive exercise to clean up and decontaminate after mercury spillage. The environmentalists are worried that mercury is toxic and remains in the local environment for many years.
Here is a solution- the A&D UM-101 mercury-free sphyg. It uses a liquid crystal display instead of the mercury column. So, instead of pumping mercury, it pumps a pressure transducer that increases the length of a pressure bar of the LCD display. It is a simple idea that works rather well.
If you can use a mercury sphyg, then the UM-101 will seem familiar. Do you remember how the top of the mercury column bounced around with each squeeze of the rubber bulb? This does the same.
You can still round off the systolic and diastolic values to the nearest 5mmHg (observer bias digit preference), like you used to with the UM-101. but at the bottom of the scale, the BP is also displayed in figures, so with careful release of air, you should obtain an accurate result.
A nice touch is the facility to place a horizontal LCD mark on the vertical BP scale. This means you can simply mark the systolic and diastolic BP, and then write down the corresponding values after the air has been released, thus no digit preference.
At the end of the measurement, the pulse rate is displayed, and the unit even switches itself off. It keeps a running total of all the hours it has been in use for maintenance purposes. It is recommended that the unit be checked every two years.
The unit comes in a chunky plastic box in pale lilac and grey. You use it just as you would a mercury sphyg, except you must switch it on first. Unlike the mercury equivalent, the column does not have to be vertical, and can be set to any convenient viewing angle.
The measurement accuracy is +/-3 mmHg, which is average for most digital BP machines.
However, it has not yet been validated. I own several A&D devices and can therefore vouch for their quality of build and reliability. The UM-101 sphyg will last for ages, is easy to use and combines the advantages of the mercury sphyg with bonus digital technology.
• An independent review by Dr Lewis, a GP with an interest in cardiology in Guildford, Surrey
• Equipment supplied by Williams Medical Supplies.