Patient selection: Patients undergoing cardiopulmonary bypass for cyanotic congenital heart disease
Patients with polycythemia and cyanotic heart disease have evidence of a consumptive coagulopathy with changes including prolonged PT and aPTT, low fibrinogen, elevated fibrin degradation products, increased fibrinolysis, thrombocytopenia, and platelet dysfunction.
Goal: intraoperative hemodilution to a lower hematocrit
Data requirements:
(1) body weight in kilograms
(2) preoperative hematocrit
(3) intraoperative target hematocrit
Steps:
(1) Estimate the patient's blood volume based on body weight.
(2) Estimate the blood volume required to lower the hematocrit to the desired hematocrit (28% in the example).
(3) Determine the prime volume of crystalloid solution required.
estimated blood volume in mL =
= (body weight in kilograms) * (weight factor)
|
Body Weight in Kilograms
|
Weight Factor
|
|
< 10
|
80 mL/kg
|
|
10 - 20
|
75 mL/kg
|
|
> 20
|
70 mL/kg
|
where:
• These values are some of the standard factors used for estimated blood volume in infants, children and adults based on weights. Other approaches can be used including using different factors for men and women. See Chapter 2.
hemodiluted blood volume required in mL =
= (current hematocrit) / (desired hematocrit) * (estimated blood volume in mL)
prime volume of crystalloid in mL =
= (hemodiluted blood volume) - (estimated blood volume)
