How to prevent backflow of blood taken by vacuum blood collection tubes?

The vacuum blood collection tube was invented in 1937, and began to circulate in Europe and the United States in 1943. After that, it was continuously improved in practical use. The vacuum blood collection tube appeared in Japan in 1964, and was officially used in Japan in 1971. Vacuum blood collection test tubes are becoming more and more popular, gradually replacing the method of syringe blood collection, standardizing blood collection technology, and improving the quality and speed of testing specimens. In 2004, Takahashi Katsuyuki reported that due to the fluctuation of the pressure difference between the internal pressure of the vacuum blood collection tube and the intravascular pressure, the blood that has been collected may flow back into the blood vessel and there is a possibility of infection risk. Japan has been using vacuum blood collection tubes for 35 years since 1971, and there has been no case of infection caused by vacuum blood collection. In 2004, Yoshiro Katsuta et al. reported the detection of Serratia marcescens from some vacuum blood collection tubes. If there is a risk of infection due to reverse blood flow, safer blood collection techniques have attracted attention from all walks of life.

Why it can cause blood backflow: The “vacuum” of the vacuum blood collection tube refers to a state of completely no air, which is lower than the atmospheric pressure state. The pressure (negative pressure) of the vacuum blood collection tube is increased or decreased according to the blood collection volume.

When the cuff is tightened, the intravascular pressure rises – after the blood collection needle is inserted into the cubital vein, the blood flows into the vacuum blood collection tube under negative pressure. The blood collection ends when the pre-measured negative pressure is exhausted. At this time, the intravascular pressure = the internal pressure of the vacuum blood collection tube! At the end of blood collection, the rapid reduction of intravascular pressure after removing the blood drive belt is more important than returning to normal pressure. At this time, the intravascular pressure < the intravascular pressure of the vacuum blood collection tube, there is a risk that the blood that has been pumped will return to the blood vessel.

Blood collection methods to prevent blood reflux:
(1) Remove the blood strip when collecting blood. Avoid touching the spit part of the lancet with the blood taken.

(2) Do not remove the expelling belt when collecting blood, and the collected blood should avoid contact with the part spit out by the lancet (the tube seat should be downward during blood collection to avoid contact with the part spit out by the lancet and the blood that has been collected), so as to avoid blood backflow .

How to use the butterfly-wing two-way blood collection needle The plastic tube of the butterfly-wing two-way blood collection needle has a larger blind area, which has the advantage of effectively preventing the risk of backflow of blood already collected in the blood collection tube into the blood vessel, but its disadvantage is that the blood collection in the blind area is not enough. precise. The butterfly wing blood collection needle is connected to the plastic tube to minimize the error of blood collection. Butterfly-wing lancet is especially suitable for infants and those who have difficulty collecting blood.