Centrifuge for determination of hematocrit volume

1. principle

In a 100-gauge glass tube filled with anticoagulant to the mark, after centrifugation for a certain period of time, the red blood cells sink and press tightly in the glass tube, and the percentage of the red blood cell column is read, that is, the hematocrit volume (PCV Said pressure capacity, specific volume). 

2. Equipment

(1) Wen's tube: tube length 11cm, internal diameter of about 2.5mm, 100 wall scale. One side from top to bottom marked 0 ~ 10, for the determination of ESR, the other side marked with 10 ~ 0, for the determination of specific capacity. If there is no such special pipe, use a small 100 glass tube instead.

(2) Long needles and rubberized nipples: Use a needle with a length of 12 to 15 cm to flatten the tip of the needle, and then connect the rubber needle to the shank of the needle. Elongated capillary suction tubes can also be used instead. 

(3) Horizontal electric centrifuge: The speed can reach 4000rpm. 

3. Method

(1) Using a long needle to absorb anticoagulant blood, insert the bottom of the Wen's tube, and gently pinch the rubber nipple. Push the blood from the bottom up to the scale 10. 

(2) Centrifuge, centrifuge at a speed of 3000 rpm for 30 to 45 minutes (horse's blood is centrifuged for 30 min, and the blood of cattle and sheep is centrifuged for 45 min), take out the observation, record the height of the erythrocyte layer, and then centrifuge for 45 min, such as with the first centrifugation The heights are consistent, and the number of scales occupied by the red blood cell column at this time is the PCV value expressed in %.

4. Note 

(1) The Wenstube and liquid-filled utensils must be dry to avoid hemolysis. 

(2) At this time, the rotation speed of the centrifuge must be 3000 rpm or more and the prescribed time is to be observed. 

(3) After centrifugation with a general centrifuge, the erythrocyte layer is beveled, and the number of scales corresponding to 1/2 slope should be taken when reading. The gray layer between the plasma and erythrocyte layers consists of white blood cells and platelets and should not be counted. 

5. Clinical significance (1) Increased hematocrit: seen in various causes of blood concentration, increased red blood cell relatives, such as acute gastroenteritis, intestinal constipation, intestinal metaplasia, valve gastric obstruction, exudative pleurisy, and peritonitis, And some infectious diseases and febrile diseases. Since the increased value of the hematocrit is proportional to the degree of dehydration, it is possible to extrapolate the dehydration of the body according to the change of this index in clinical practice, and to calculate the amount of rehydration and the actual effect of judging the amount of rehydration. In addition. Also seen in a variety of reasons caused by the absolute increase of red blood cells, such as polycythemia vera, pulmonary artery stenosis, methemoglobinemia and so on.

(2) Reduced hematocrit: seen in various anemias, but the degree of reduction is not necessarily consistent with the number of red blood cells, because anemia has small cell anemia, macrocytic anemia, and positive cellular anemia.