Miscellaneous Topics in Transfusion Michael Wong Department of Pathology PMH

Outline Transfusion threshold Haemolytic transfusion reaction Fever during transfusion Leukocyte depletion Transfusion in autoimmune haemolytic anaemia Platelet refractoriness Delay in availability of blood products Product recall and look back

Red cell transfusion threshold Quoted from HA transfusion guideline There is no single haemoglobin value that must be taken as the transfusion trigger. However, a trend towards cautious blood transfusion trigger has been observed but patients’ condition may affect clinical decision. The initiation of transfusion is a clinical decision by the attending clinician. In general, the following principles are considered: Haemoglobin concentration <7g/dL and assessment on the rate of ongoing red cell loss. For haemoglobin concentration between 7 and 10 g/dL, transfusion strategy is less clear but general view is that transfusion is often not justified purely based on haemoglobin concentration. A higher haemoglobin concentration may be required in patients who may tolerate anaemia poorly, e.g. patients over the age of 65 years and patients with cardiovascular or respiratory disease.

Transfusion threshold

Mortality

An audit of PMH One case from ICU_HDU has transfusion give while Hb is 10.1, the patient is suffering from acute coronary syndrome and the attending clinician considered it is desirable to have a higher Hb level for the patient.

Mortality

Myocardial Ischemia and Transfusion (MINT)

Myocardial Ischemia and Transfusion (MINT) Liberal Transfusion Strategy Restrictive transfusion strategy Patients randomly allocated to the liberal transfusion strategy will receive one unit of packed red cells following randomization and receive enough blood to raise the hemoglobin concentration above 10 g/dL any time the hemoglobin concentration is detected to be below 10g/dL during the hospitalization for up to 30 days. Any transfusion following the initial unit of packed red cells must be preceded by blood test documenting a hemoglobin concentration below 10 g/dL. Receive a transfusion if they develop symptoms related to anemia. Transfusion is also permitted, but not required, in the absence of symptoms only if the hemoglobin concentration falls below 8 g/dL. Blood is administered one unit at a time and the presence of symptoms is reassessed. Only enough blood is given to relieve symptoms. If the transfusion is given because the hemoglobin concentration falls below 8 g/dL, then only enough blood is given to increase the hemoglobin concentration above 8 g/dL. Symptoms of anemia that will be indications for transfusion are: 1) Definite angina requiring treatment with sublingual nitroglycerin or equivalent therapy. 2) Unexplained tachycardia or hypotension.

Platelet transfusion threshold Quoted from HA transfusion guideline Platelet <10 x109/L in stable patients (usually NOT indicated in ITP, SLE, TTP and HUS). Platelet <20 x109/L in patients with fever or sepsis. Platelet <50 x109/L with diffuse microvascular/mucosal bleeding, major bleeding or before invasive procedures. Platelet <100 x109/L with retinal or CNS bleeding/ surgery, or with active bleeding in postcardiopulmonary bypass. Platelet <50 x109/L in stable premature neonates or platelet <100 x109/L in sick premature neonates Suspected platelet dysfunction with active bleeding or before invasive procedures. Suspected platelet deficiency with severe active bleeding or following massive transfusion.

Prophylaxis vs. therapeutic

Threshold 10 vs. 20

Haemolytic transfusion reaction Acute / delayed Usually due to antibody in recipient binding to red cells of donor resulting in acute hemolysis ABO mismatch – anti-A, anti-B (type) Antibodies to minor blood group e.g. anti-Jka (screen) Occasionally due to antibody in donor binding to red cells of recipient Transfusion of excessive group O FFP or platelet concentrate to a group A or B individual

ABO mismatch transfusion Could result in immediate shock to totally asymptomatic Group A individual has less anti-B than group O individual Elderly have might have lower antibody level Particularly difficult to detect in unconscious or sedated patients Need a high index of suspicion for ICU physicians

Fever during transfusion Acute haemolytic transfusion reaction Septic reaction Platelets are more the common cause. However Platelets are all cultured Stored less than 5 days Red cells if contaminated will be very severe due to the prolonged storage time Febrile non-haemolytic transfusion reaction Most common The reason of stopping transfusion and reassess is due to the above 2 differential diagnosis

Leukocyte depletion WBC in packed cell could Cause FNHTR Transmit CMV cause transfusion graft versus host disease Now 50% of the red cells supply are leukocyte depleted There is no need to use bed side filter

Transfusion in AIHA

Transfusion in AIHA In patient with AIHA, the autoantibody is pan reacting (i.e. it will bind to all sorts of red cells with no specificity) So cross matching will always give incompatible result What we worry is whether the patient has alloantibody (antibody against a blood group that the patient does not have e.g. anti-Jka) So instead of matching ABO and RhD only, we match every clinically significant minor blood group C, c, E, e, K, k, Jka, Jkb, Fya, Fyb ………….

How safe A total of 7052 units was issued for 1685 patients; no haemolytic reactions were reported. Sokol RJ, Hewitt S, Booker DJ, Morris BM. Patients with red cell autoantibodies: selection of blood for transfusion. Clin Lab Haematol. 1988;10(3):257-64. But it is not wise to over transfuse AIHA patients as rate of haemolysis is directly related to red cell concentration

Platelet refractoriness Corrected count increment = (post – pre transfusion platelet count) / number of platelet transfused x body surface area CCI = (15000 – 10000)/(4 x 0.7) x 1.7 = 3035 CCI (60 minutes) < 5000 or CCI (24h) < 2500 are considered platelet refractory Usually due to HLA antibodies We could use HLA matched platelets Platelets only have HLA-A and HLA-B antigen, they do not have HLA-DR antigen

Delay in availability of blood products Require phenotype matched blood e.g. AIHA Require blood with rare phenotype e.g. anti-Jka + anti-Jkb (need Jka –ve and Jkb –ve blood) These rare red cells are stored in frozen state Rare blood group e.g. Bombay

Common product recall / look back Platelet culture positive All platelets are cultured and release on day 3 if culture negative, but culture will continue until day 5 Even if culture positive the dose is fairly low Platelets culture are pooled in 5 There is 80% chance that the platelet transfused by your patient is not culture positive Usually just need to observe and treat accordingly if fever

Common product recall / look back Donor develop illness (usually URTI) after donation Usually just observe Donor report high risk behavior after donation Check baseline and 6 month post exposure HBV, HCV, HIV, HTLV-1, VDRL Donor seroconverted during subsequent donation Check baseline and 6 month post exposure of the concerned infection

Questions?