http://www.hmc.psu.edu/healthinfo/b/blooddonation.htm
How is this procedure performed? Before you donate blood, the healthcare professional will check your blood pressure, temperature, and pulse. You will lie down on a bed or cot, then he or she will tighten a wrapping, called a tourniquet, on your upper arm to increase the pressure on the veins in your arm so they will swell. This makes it easier to identify the larger veins and to insert the needle into the vein. The healthcare professional will clean the area where the needle will be inserted with an antiseptic wash, then insert a large needle into the vein. You will feel a slight sting as the needle goes in, but the rest of the procedure should be painless. The blood flows through a tube into a sterile plastic bag that holds around one pint (450 ml) of blood, also called one unit. People usually donate one unit at a time. The average man has 10 to 12 pints of blood in his body, while the average woman has 8 to 9 pints. A small sample of the blood you donate is put aside for testing for infectious diseases. No blood is used until all test results have shown that it is safe. All donated blood is also classified and labelled by type, either A, B, AB, or O, and as RH-positive or RH-negative. This is because donor blood must be matched to the recipient's blood type. The sterile bags, which contain preservatives and an agent that prevents clotting, are kept refrigerated. Whole blood is usable for 42 days. The above article defines the blood pint as 450 mL. This is equal to neither a UK nor a US pint. It sure makes FFU very confusing. Euric ----- Original Message ----- From: "Terry Simpson" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Friday, 2004-08-06 14:39 Subject: [USMA:30651] Re: Save the Pint > > Of David King > >I have seen this site before. They even have the cheek to have > >a link to donate a pint of blood, yet in the UK blood donations > >are not done in pints. Although the blood site itself uses the > >word pint, it also states the actual amount donated is around > >400 ml I think. > > The amount of blood in a blood pack varies quite widely. You can see the > official UK specifications at: > http://www.transfusionguidelines.org.uk/uk_guidelines/ukbts6_099.html > > I believe that the word 'pint' comes from the US pint. The amount is > certainly closer to a US pint than an imperial pint. > > I can't believe that the British 'Save the pint' campaign wants Britain to > adopt the US pint. Non-metric campaigners might have had more friends in the > import/export trade if they had agreed on a single international set of > terms and definitions. > >
