Transfusion Technique:
- Maximum time over which blood products can be administered is 4 hrs for 1 unit because of danger of bacterial proliferation & RBC hemolysis;
- If slower infusion rate is required, half of the unit may be infused while other portion remains refrigerated in the blood bank;
- If flow rate is interrupted for >30 minutes, unit must be discarded;
- Blood should be administered through 170 um filters to prevent infusion of macro-aggregates of fibrin and debris as well as leukocytes;
- Patients should be observed for the first 5-10 min of a transfusion and then examined frequently for signs of fluid overload and other adverse reactions;
- Emergent transfusion:
- In most cases an Rh type and screen takes 10 minutes and is safer than using O negative blood;
- Characteristics of pRBC;
- approx 300 +/- 25 mL
- hematocrit: 70 +/- 5%;
- one unit of pRBCs should increase hemoglobin by approximately 1 gm/dl;
- citrate is used as an anticoagulant in blood products during plasmapheresis;
- citrate is converted to bicarb by liver & causes metabolic alkalosis
- induction of a metabolic alkalosis may produce an abrupt increase in the hemoglobinn oxygen affinity;
- w/ transfusion actual amount of potassium administered is approx between 5.2 to 6.6 mEq per unit of pRBC;
- since the mean age of blood administered to trauma pts is 13.5 days (and not 35 to 49 days - expiration date of blood), the actual amount of potassium administered per unit may be only 1 to 3 mEq;
- w/ massive transfusion hypokalemia is more frequently encountered than hyperkalemia;- this may be also due to alkalosis (from citrate)
- DPG:
- w/ blood that is stored in acid citrate dextrose (ACD) solution for upto to three weeks is based on the survival of at least 70% of cells in recipients circulation;
- during 3 week period, there is decline in 2-3 disphosphoglycerate (DPG) and a progressive increase in hemoglobin oxygen affinity (left shift of the oxygen dissociation curve);
- after transfusion DPG levels require 24 hours or longer to return nl;
- Citrate toxicity:
- can be prevented or its effects minimized by the administration of Ca;
- historically 1gm of CaCl has been given for every four units of blood administered until such time as the pt is normothermic, euvolemic, and is known to have reasonably normal hepatic function;
- if Ca gluconate is used, dose must be 4 times greater than w/ CaCl;
- improved approach is to measure the ionized calcium level.
Complications of Blood Transfusion:
- Blood Product Menu:
- pRBCs - Fresh Frozen Plasma - Platlets - Cryoprecipitate - Transfusion Therapy - Coag Pathway
- Acidemia and Hyperkalemia: from massive transfusions;
- massive transfusion: transfusion of pRBC >6-8 units, must also provide platlets;
- 8 units platlets for ea 10-12 units pRBC's transfused;
- 2 units of FFP
- Ca replacement if hypocalcemic (2nd to citrate)
- references:
- Electrolyte and acid-base disturbances caused by blood transfusions.
- Hyperkalemia after packed red blood cell transfusion in trauma patients.
- Post-Transfusion Alkalosis:
- the early net result of successful resuscitation is post-transfusion alkalosis in
the patient;
- the sodium citrate is converted to bicarbonate
- the alkalosis is associated with increased potassium excretion;
- Hypocalcemia:
- some recommend calcium supplementation for patients receiving greater
than 100 ml/min;
- give 0.2 gm of CaCl in a separate line for each 500 ml given;
- some believe that most patients will tolerate 1 unit pRBC q 5 min without
requiring calcium supplementation;
- Hemolysis:
- Non hemolytic reaction:
- typically, this reaction occurs after a significant portion of the blood has
already been transfused;
- note: hives + hypotension = anaphylaxis
- management:
- by itself, may continue the transfusion (benadryl 50mg PO/IV);
- prior to future transfusions, the patient should be pre-medicated
w/ benadryl 50mg PO/IV (not IM);
- if this fails to prevent urticarial rxn, washed RBC's should be
given;
- w/ mild febrile transfusion reactions fever w/o evidence of
hemolysis or more severe symptoms), antipyretics can be used;
- Acute hemolytic reaction:
- most severe and potentially dangerous transfusion reactions;
- acute intravascular hemolysis occurs during or shortly after transfusion of
incompatible blood and is usually due to preformed antibodies;
- typically this reaction occurs early w/ as little as 30 cc of
transfused blood;
- Manifestations:
- fever, chills, back or chest pain, N/V, and evidence of
hemodynamic instability;
- Required labs:
- spin a hematocrit to look for a pink plasma layer indicates
hemolysis;
- pink-red (spun) plasma indicates that greater than 20 mg/dl of
free hemoglobin is present;
- send off a DIC screen: PT/PTT, fibrinogen, fibrinogen
degradation products, serum bilirubin;
- culture of the patient and the donor blood is indicated if there is
suspicion of bacterial contamination;
- repeat cross match;
- Coomb's Test, Free Hb;
- CBC, RBC morphology;
- send Donor's Blood back to the blood back;
- repeat cross match;
- Management:
- try to preserve intravascular volume and protect against acute
renal failure;
- NS 500 ml IV "wide open"
- monitor the urine output closely and maintain a brisk diuresis
(greater than 100 ml/hr);
- consider alkalinization of the urine with bicarbonate (1 mEq/kg
IV until urine pH =7.5-9.0)
- will facilitate the excretion of free hemoglobin
- Reference:
- Extracorporeal hemolysis in orthopedic patients. Report of two
cases.
- Transmission of disease:
- Increased infection rate:
- septic reaction: considered when high fever and hypotension accompany a
transfusion reaction;
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