No one ever answered your question about blood pressure. In the US, we also use mm Hg. However, Continental Europe mostly uses the kilopascal.

Converting “real” columns of mercury to pascals involves latitude and height above sea level (for local gravity) and temperature for thermal expansion of both the mercury and the brass scale. However, “conventional” mercury is based on 760 mm Hg = 101.325 kPa, regardless of gravity and temperature; aneroid instruments are usually calibrated on this basis. A VERY close approximation, easier for mental conversion is 750 mm = 100 kPa.
120/80 (mm Hg) becomes 16/10.7 (kPa). Hectopascals would provide better resolution (using integers) but the possibility of a units mistake if units are omitted as is the norm.

@Ralph,
If the nurses can’t work out metric dosing, grains or av. scruples per stone/pound must just be a delight. And after working that out, you still have to consider liquid medicine in grains/fluid drachm and find a suitable syringe. And, of course, you mustn’t confuse your apoth scruples and fluid scruples, drams, etc.

“Working on an elderly acute ward I am continually asked to work out stones and pounds, feet and inches for people who will never wish to go metric.”

What exactly needs to be worked out? Drug doses are worked out by the doctors and are based on metric amounts, including body mass in kilograms. The patients, no matter what their age, don’t need to know the details of how the dose is derived.

“Why should we be compelled to? My experience of drug errors is of mathematically incompetent nurses using metric measures.”

You should be compelled to because that is the agreed standard for the industry. If you don’t like it then resign from the medical industry.

If the nurses are incompetent using metric measures, why are they still employed? Aren’t they reviewed? Doesn’t someone check to make sure medical professional are fully capable of doing their job? If they can’t do the math in metric, there is no way they would be able to do the more complex math using imperial.

On the flip side of the coin, are they really incompetent in using metric or are they just unable or don’t wish to bother with metric to imperial conversions, pushing the burden on you? Which is it?

http://www.philly.com/philly/blogs/healthcare/132410488.html

Let’s hope we here in the USA finally take at least this step towards better measurement.

I presume the NHS, chemists, etc. all use metric for dosages including printed inserts and directions on packaging. Is the conversion to metric-only weighing scales being pursued as well?

You raise a number of issues but I will deal with just one of them as my response to it is a bit lengthy.

If the UK goverment had handled the changeover to metric, announced in 1965, properly and completed the project within 10 years according to their stated intention, then the people now in your care, who would have been younger and more adaptable at the time, would have understood the advantages of us using the metric system and the reasons for the change. By now they would have been happy to be weighed in kilograms just as they count their money in (new) pence instead of shillings and old pence.

Alas it didn’t happen that way. The government never bothered to promote the change or educate people accordingly. Worse still they betrayed the whole process and sent out the wrong message by not changing road signs, a major element directly under their control. They did instigate changes in health, education and other public service practices but only because there was no short term impact on the chancellor’s budget.

However, it is not too late to put this right. It is not realistic to expect the people in your care to change belatedly – true enough – and we can sympathise with the situation you now face, but at the same time we shouldn’t condemn future generations to the same fate.

As it is, being stuck half-way through the change, we all have to cope with both imperial and metric which, as you have experienced directly, is not easy or convenient and certainly not necessary.

The only realistic way out of this enpasse is to complete the changeover and phase out imperial measures decisively.

If ever a case was needed for not returning to the dark ages of mathematically-complicated and error-prone imperial units in medical dose calculations then this is it.

It would be quite reckless to increase the potential for errors in anything to do with medical use. Fortunately, medicine in the UK has been 100% metric for decades.

2. Is Ralph suggesting that all nurses choose the measurement system they want to work in? If this is the case he is encouraging some nurses to do conversions between systems.

3. Does Ralph also spend time doing money calculations using Pounds, Shillings, and Pence for people in his care?

The weird thing is that the air pressure is measured in terms of the pressure needed to maintain a column of water x cm high. So, in my case the machine is calibrated for “13 cm of H2O”).

Does the NHS measure CPAP pressure in this same bizarre fashion? I don’t even know how this got started (though I understand the first CPAP machine was invented in Australia back in the 70′s).

In any case the goal should clearly be for all personnel in the medical professions to use true SI exclusively. Let’s hope that can be accomplished soon.