Background Research 06-21-2020:

- blood warmers are rarely needed during routine transfusions, they are used when rapid transfusion of components is required
- blood storage temperature, 2 to 6degC (whole blood/red cell component)
- blood tranfusion temperature, 30 to 37degC
- suggested rate of transfusion (adult)
    + whole blood 150-200mL/hr
    + PRBC (packed red blood cells) 100-150mL/hr
    + platelets/plasma 150-300mL/hr
- suggested rate of transfusion (pediatric)
    + whole blood/PRBC, 2-5mL/kg/hr (17 mL/min allows transfusion in less than 30 minutes)
    + platelets/plasma, 1-2mL/minute
- duration times for transfusion
    + whole blood/PRBC, less than 4 hrs (start within 30 minutes of removing from refrigerator)
    + platelet concentrate, less than 30 minutes (start immediately)
- warmed blood is most commonly required for:
    + large volume rapid transfers
        * adults, more than 50mL/kg/hr
        * children, more than 15mL/kg/hr
    + exchange transfusions in infants
    + patients with clinically significant cold agglutinins (patient produces autoantibodies which cause agglutination of red cells at cold temperatures)
    + rapid infusion of blood products through central lines
- blood should never be warmed in a bowl of hot water as this could lead to hemolysis (i.e. rupture) of the red cells which could be life-threatening when transfused
- a radiant heater should never be used to warm the blood being transfused because of the risk of hemolysis
- volume per unit of:
    + whole blood, 450ml
    + PRBC, 220-350ml
    + plasma, 180-270ml
    + platelets, 35ml
- material properties of blood
    + density 1.05g/ml (1050 kg/m^3)
    + specific heat 3490 J/kg*K
- medical tubing materials
    + polyvinyl chloride (PVC), most common (approx 30% of market)
    + polyethylene, second most common
    + thermoplastic elastomers (TPE)
    + nylon
    + silicone
- blood transfusion IV tubing catheter size 
    + adults, 18 gauge (nominal inside diameter 0.838 +/- 0.038mm)
    + pediatric, 22 gauge minimum (nominal inside diameter 0.413 +/- 0.019mm)
- infusion/transfusion line diameter
    + outside diameter 4 to 7mm
- warming blood to temperatures greater than 42degC may cause hemolysis
- nominal capacity of a standard 12V car battery is approximately 45Ah