I. Dosage
Platelet transfusion depends on the patient’s platelet count and the expected platelet count to be achieved before platelet transfusion and whether the patient has bleeding or isoimmunization. There are two types of platelets currently in use: platelet concentrate and platelet monohydrate.
1. Platelet Concentrate: It is the component blood made by separating platelets and suspending them in plasma in a fully closed condition at 20 —-24 degrees within 6 hours after collection of whole blood kept in a multi-linked bag at room temperature. Domestic platelets prepared by separating 200ml of whole blood are 1U concentrated platelets, and the national standard requires the content of platelets to be ≥2.0×1010.
In general, transfusion of 10U manual platelets can raise the platelets of patients by 36×109/L, but the actual situation is related to the patient’s condition and transfusion history, etc. The first transfusion of platelet concentrate can be done at 2U/10kg body weight, and later adjusted according to the patient’s condition.
2. Platelet mono-collection: It is a single-collection component blood made by using a blood component mono-collection machine to automatically separate platelets from whole blood and suspend them in a certain amount of plasma under fully enclosed conditions. The national standard is that one unit of single-collected platelets (i.e., one therapeutic amount) contains ≥ 2.5×1011.
Adults should receive one bag (≥2.5×1011) per transfusion, and those with severe bleeding or who have developed alloimmunity should receive an increased dose, such as two therapeutic volumes in one transfusion.
In pediatric patients, one therapeutic volume of platelets is infused in 2-4 infusions depending on age and condition.
In neonates, 1/5 —-1/10 of the adult dose can be transfused at one time, and the volume is controlled at 20 —-30ml.
▲ The survival period of the transfused platelets is 5 days, so it should be transfused once in 2 —-3 days.
II. Method
1. Shake the blood bag gently before transfusion so that the platelets and plasma are well mixed.
2. The transfusion should be done with a Y-shaped standard transfusion set and at the fastest rate tolerated by the patient (usually within 4 hours), because of the risk of bacterial contamination.
Platelets retrieved from the blood bank should be transfused as soon as possible, and if not transfused in time should be stored temporarily at room temperature.
4. During the transfusion process, changes in the condition should be closely monitored. Patients such as infants, elderly and cardiac insufficiency should slow down the transfusion rate as appropriate.
Attention should be paid to the following during the transfusion.
①If platelet concentrates are prepared from whole blood, multiple units should be transfused as soon as possible (usually within 4 hours) because of the risk of bacterial contamination;
② Platelets should not be stored in a 4°C blood storage refrigerator before transfusion because the function of platelets can be reduced;
③The transfusion should be finished within 30 minutes;
④ Platelets from Rh(D)-positive donors should not be transfused to Rh(D)-negative women who may be pregnant;
⑤ ABO isotype platelets should be transfused because there is ABO blood group antigen on the platelet surface, and the interaction of anti-A/anti-B in the recipient’s body with the red blood cell A/B antigen on the surface of the input platelets can lead to platelet destruction; if suspended in high titers of anti-A and anti-B plasma, it can cause hemolysis of the recipient’s red blood cells.