Knowledge on medical instruments

　　Identification of unacceptable blood collection tubes
　　The tube should be unacceptable when any of the following five test results is out of requirements in accordance to Medical Industry Standard P.R.C YY 0314-1999 idt ISO 6170:1995.
　　1. Draw Volume Test: it should be unacceptable when error of draw volume is not within ±10%.The principal problem today is inaccurate blood quantity, which may not only result in inaccurate test results, but also block or damage test instruments.
　　2. Container Leakage Test: Put the tube containing fluorescein sodium compound bottom up in deionized water for sixty minutes. The tube should be acceptable when no fluorescence is observed with normal eyesight in darkroom under the irradiation of long wave UV light.Leakage is the first cause of inaccurate blood quantity today.
　　3. Container Strength Test: The tube should be acceptable when it remain unbroken after it has been put on running centrifuge at a centrifugal acceleration of 3000g for ten minutes.According to some stricter foreign standards, the tube should remain unbroken when falling down at a height of two meters, which prevents the tube from damage and protects the sample from being lost.
　　4. Least Free Space Test: Least space for ensuring mixing blood sufficiently.Least space > +25% of blood quantity when it is between 0.5-5ml, and > 15% of blood quantity when it is greater than 5ml.
　　5. Solute to Solvent Proportion and Solution Add-on Volume Test: The error should be within ±10% of specified value.This is a common problem that be often neglected which could result in inaccurate test data or blockage damage of test machine.

　　Analysis on courses of instrument blockage damage:
　　1. The factor of instrument itself;
　　2. The factor of extracted blood tube;
　　　2.1 Because of incomplete anticoagulation, there happens coagulation of blood articles for anti-coagulant tube;
　　　2.2 Because of incomplete blood coagulation, there exit fibrinogens in minute quantity in centrifugally separated blood serum, which causes re-coagulation and forms fiber flocs that are hard to see by naked eyes and result in instrument blockage.