Transfusion Therapy Flashcards
What is the normal P50 for oxygen and hemoglobin?
26.3 mm Hg
What causes right-shift on an oxygen-hemoglobin dissociation curve?
Temperature, acidity (-pH), 2,3-DPG
What is the most optimal blood hemoglobin level for oxygen delivery?
16-20 g/dL. Above this, viscosity impairs delivery.
How is oxygen delivery (DO2) calculated?
Cardiac output x (Hb*1.39mL/g + 0.03 mL/mmHg)
At what anemia level do organ systems suffer?
Below 5g/dL
How does normal oxygen delivery (DO2) typically compare to oxygen consumption (VO2)?
Usually DO2 exceeds by a factor of 4. But in exercise and some diseased states, the ratio can approach 1.5. A ratio of 2 may trigger anaerobic respiration.
How much blood do the coronaries receive, and how is this regulated?
Up to 5% of cardiac output. Due to high basal oxygen extraction, coronaries can dilate to increase their flow up to 10-fold.
What is the benefit of an MSBOS?
Standardized transfusion practices in a workgroup, found to generally decrease the crossmatch:transfuse ratios.
What are some NON-indications for transfusion in HbSS disease?
Uncomplicated VOC
Priapism
AKI
Ulcers
What are some contraindications to platelet transfusion?
ITP, TTP, HIT
Bleeding due to coagulopathy only (not plt)
Bleeding due to anatomic/surgical defect
Platelet transfusion thresholds for:
Lumbar puncture
Line placement
Lumbar puncture: 50k per AABB (despite no benefit per Cochrane review)
Line placement: 20k
What happens to about half of platelets that are transfused?
They are sequestered in spleen and other reticuloendothelial organs. Some are also lost to the normal maintenance of vascular integrity.
Why does maintaining a hematocrit above 30% improve bleeding?
Higher crit facilitates more platelet-endothelial interactions through Bernoulli principles.
What is the goal of plasma therapy in coagulopathic patients?
Never to fully replete, but to give enough to maintain hemostasis.
What is a typical therapeutic dose of plasma for treatment of coagulopathy?
Aim to restore 30% of factor activity»_space; 30% of TBV transfused (usually ~4 units).
What coagulation factors have the worst recovery in transfusion?
Factor IX, II.
What are the best choices in treating congenital factor deficiencies?
Recombinant concentrates > PCCs > plasma products.
What what congenital factor deficiencies is plasma the only real option for repletion?
Thrombin Factor V Factor XI Protein S Plasminogen
What thrombophilias can be treated with replacement therapy?
Antithrombin deficiency (concentrate available) Protein C (concentrate) Protein S (plasma only) Plasminogen (plasma only)
What is the primary use for cryo-poor plasma?
Formerly for TTP, now due to evidence of worsened outcomes, mostly slated for fractionation.
How are PCCs dosed?
Based on patient weight and degree of INR abnormality.
Idaricizumab
Reversal agent for Dabigatran
Adnexanet alfa
Reversal agent for Xa inhibitors
What are the four causes of postpartum hemorrhage?
Tone (Uterine atony)
Trauma
Tissue (retained POC)
Thrombin (coagulopathy)
How does hemostasis change during pregnancy?
Gestational thrombocytopenia
INCREASE in circulating von willebrand factor
INCREASE in fibrinogen (400-600mg/dL normal)
How is blood loss during peripartum hemorrhage calculated?
Colorimetric methods Gravimetric methods (weigh sponges)
How is pregnancy in HbSS patients managed?
Transfuse up to 10g/dL per NIH recs. Keep HbS <30%. Beware increased risk of fat embolization?
Review the general management algorithm for HDFN.
Check titers (and paternal testing)»_space; MCA (1.5x)»_space; IUT.
What special requirements are applied to units chosen for IUT?
O-neg, volume-reduced, fresh, CMV-seroneg, irradiated, HbS-neg, washed (if maternal)
How is IUT performed?
Cannulate umbilical artery or intraperitoneal space. Transfuse slowly. Multiple volume calculations to determine dose…
