Blood Transfusions

RBC transfusion

Used in amenia, though there is no absolute number to determine when, or when not, transfusions are required. It is rarely necessary if Hg is greater than 90 g/L and is often necessary if it is under 60 g/L.

When to Use?

Everyone agrees these days that no or less blood is a great thing.

Consider:

• severity and rapidity of anemia
• potential to correct/control cause (ie, EPO, iron, vitamins)
• presence of cardiovascular disease

For total hip replacements, the rates of people receiving blood have gone from 75% to 10%.

This is due to:

• a lowered threshold of transfusion
• improved attention to surgical hemostasis
• autologous blood donation (less done these days)
  • must be done within 35 days
• acute normovolemic hemodilution
  • autologous donation done before surgery
  • saline administered as fluid replacement, so blood loss is of diluted blood
  • blood reinfused following surgery
• blood substitutes
  • volume expanders: pentaspan
  • red blood cells: fluorocarbons, cross-linked hemoglobin preparations
• blood salvage devices
  • cell savers
  • storage of blood lost to fixed space
  • blood is reinfused after hemodilution and clotting factor depletion
• drugs:
  • EPO
    
  • DDAVP: mild/moderate VWB, hemophilia, platelet function disorders
  • antifibrinolytics: reduces blood loss during cardiac surgery

A RCT comparing 30 day mortality in the two groups: maintenance of HgB at 70-90g/L, versus 100-120 g/L in an intensive care unit, found that more is not necessarily better. Physicians are now much more conservative.

Platelet transfusion

Used in thromobocytopenia if:

• less than 10x10⁹/L any time
• less than 50x10⁹/L for surgery or during active bleeding
• less than 100x10⁹/L for neurosurgery

Plasma transfusions

Fresh frozen plasma (FFP) contains 100% of all clotting factors

Frozen plasma contains all factors except VIII (perhaps 50%)

Use plasma transfusions in:

• massively bleeding patients
• coagulopathy in actively bleeding patient
• preoperatively in patients with coagulopathy not responsive to vitamin K (ie due to liver disease)

Cryoprecipitate

• Von Willibrand's factor (factor VIII)
• fibrinogen

Albumin

provides volume and oncotic support in situations of:

• hypovolemic shock
• burns
• cardiopulmonary bypass

a 5% solution is iso-oncotic with normal plasma, while a 25% solution is hyperoncotic

an alternative is crystalloid or pentaspan

Immunoglobulin preparations

High concentrations of antibodies used in immunodeficiency or autoimmune disorders. These are non-specific, pooled from many donors.

Some preparations have antibody specificity

• anti-D
• anti-CMV
• anti-Hepatitis B