Dear Paul, I have interspersed some remarks in red this time.
On 2007 02 15 3:52 AM, "Paul Trusten, R.Ph." <[EMAIL PROTECTED]> wrote: > Pat, in the healthcare world, a blood pressure of 117/75 is instantly > understood, despite the lack of metrological integrity. This is understood in the healthcare world because it has become a jargon. To the unfortunate person who has been delivered to the doctor because he suddenly collapsed it is pure jargon with little or no meaning. > Here in the U.S., you would also cringe to hear the symbol for square meter to > be uttered as "meters squared," but I hear people do it all the time. They see > a letter "m" with the exponent, and won't announce it as "square meters." I understand your point that naïve people will read what they see without understanding the underlying concept. However, in this case, a little explanation puts it right and square metres will be recognised in future. The jargon of blood pressure testing is more difficult in that there are several orders of magnitude that need to be overcome. Let me repeat the questions I need to know as I lie on the operating table gasping for breath as the doctor explains my immediate options: If I am told that 'your blood pressure is 117 over 75', I then have to know: >> >> * that the unit used to measure blood pressure is a millimetre of mercury >> * that two blood pressures have been measured: systolic blood pressure and >> diastolic blood pressure >> * that these are gauge pressures and not an absolute or real pressures >> * that these two pressures are commonly written separated by a slash >> * that the slash used does not imply division, it is simply used a separator >> of the two different pressures > This is the land of the inchified centimeter (grin). I like the thought, but I know that in the USA any inchified centimetre would soon become 'hidden metric' as is seems to be so shameful to admit that you have used a metric unit there. Cheers, Pat Naughtin PO Box 305 Belmont 3216 Geelong, Australia 61 3 5241 2008 Pat Naughtin is manager of http://www.metricationmatters.com an internet website that focuses on the many issues, methods and processes that individuals, groups, companies, and nations use when upgrading to the metric system. Contact Pat Naughtin at [EMAIL PROTECTED] > >> >> ----- Original Message ----- >> >> From: Pat Naughtin <mailto:[EMAIL PROTECTED]> >> >> To: U.S. Metric Association <mailto:[email protected]> >> >> Sent: 07 Feb 13,Tuesday 23:49 >> >> Subject: [USMA:37960] RE: Australia's blood pressures measured in >> kilopascals >> >> >> Dear Bill, >> >> I have interspersed some remarks in blue. >> >> >> On 2007 02 14 6:15 AM, "Bill Hooper" <[EMAIL PROTECTED]> wrote: >> >> >>> >>> On 2007 Feb 13 , at 11:45 AM, Pierre Abbat wrote: >>> >>> >>>> >>>>> >>>>> What is 120/80, or whatever else anyone >>>>> >>>>> >>>>> has? Is it a gauge pressure ... ? >>>>> >>> >>> Yes, it is "gauge pressure", that is, pressure above the surrounding >>> pressure (atmospheric pressure). It is in mmHg and the two values usually >>> quoted are systolic and diastolic. Systolic is the pressure of the impulse >>> when the heart contracts, forcing blood through the blood vessels. >>> Diastolic is the pressure between beats, when the heart relaxes. >> >> And care needs to be taken that the blood pressure is taken at the same >> height as your heart. This is why you have the cuff placed around your upper >> arm at heart level. I believe that blood pressure can also be taken on any >> part of your arm or even your leg if you are lying down when that blood >> pressure cuff is still placed level with your heart. >> >> >>> The gauge pressure is the only meaningful pressure, here. If the heart does >>> not beat at all (if you're dead), the pressure is 760 mmHg because the body >>> is subjected to atmospheric pressure (equal to 101.3 kPa). >> >> So an actual (rounded) pressure in your blood might be 760 mmHg plus 10 kPa >> = 111 kPa >> >> >>> One cmHg equals 1.333 kPa, so 1 mmHg = 0.1333 kPa. >>> >>> (Millimetres of mercury (Hg) may be preferred but >>> cmHg has an easier to remember conversion factor to kPa, >>> namely one and a third, or 4/3.) >> >> I try to avoid making conversions easy. I think that the only future >> following a conversion is continual conversions back and forth between the >> various values. I am watching the world's political leaders try to come to >> terms with global warming at the same time as the various energy factions >> (coal, nuclear, oil, solar, wind, etc) all clamor for lobbying attention as >> they scream their own peculiar energy units (tons or short tons of coal, >> atomic energy units of nucular energy, barrels of oil, and kilowatt-hours of >> solar or wind energy). >> >> >>> My blood pressure, taken just now, is 117/75 (in mmHg) as given by my >>> blood pressure gauge. >>> (It is commonly written with the systolic and diastolic pressures separated >>> by a slash. >>> The slash does not imply division.) >>> Those figures above convert to: >> >> What a muddle! If I am told that 'your blood pressure is 117 over 75', I >> then have to know: >> >> * that the unit used to measure blood pressure is a millimetre of mercury >> * that two blood pressures have been measured: systolic blood pressure and >> diastolic blood pressure >> * that these are gauge pressures and not an absolute or real pressures >> * that these two pressures are commonly written separated by a slash >> * that the slash used does not imply division, it is simply used a separator >> of the two different pressures >> >> >>> 15.6 kPa / 10.0 kPa. >>> >>> My doctor says my blood pressure is fine. >>> >>> Bill Hooper >>> 1810 mm tall >>> BP 15.6/10.0 kPa >>> Fernandina Beach, Florida, USA >>> >> I would rewrite this to read: >> >> My doctor says my blood pressure is fine. He says my systolic pressure is 16 >> kilopascals and my diastolic pressure is 10 kilopascals. >> (Note the use of direct metrication without any reference to conversion, >> without fractions or decimals, and without any of the confusion brought >> about by deliberate obfuscation.) >> >> Cheers, >> >> Pat Naughtin >> PO Box 305 Belmont 3216 >> Geelong, Australia >> 61 3 5241 2008 >> >> Pat Naughtin is manager of http://www.metricationmatters.com an internet >> website that focuses on the many issues, methods and processes that >> individuals, groups, companies, and nations use when upgrading to the metric >> system. Contact Pat Naughtin at [EMAIL PROTECTED] >> >> >
