Association of Plasma Dilution with Cardiopulmonary Bypass-Associated Bleeding and Morbidity

OBJECTIVE:

To investigate the relationship of cardiopulmonary bypass-associated plasma dilution with blood product transfusion and postoperative morbidity.

DESIGN:

Retrospective chart review.

SETTING:

Single academic medical center.

PARTICIPANTS:

Five hundred forty adults undergoing cardiac surgery between January 4, 2005 and September 19, 2007.

INTERVENTIONS:

Records
were analyzed for demographics, blood volumes (BVs), and fluid balance.
Plasma protein concentrations (% of baseline) at the end of bypass
were calculated. The lowest and highest quartiles of plasma protein
concentration were correlated with blood product administration and
postoperative complications.

MEASUREMENTS AND MAIN RESULTS:

At the end of bypass,
calculated plasma protein concentrations ranged from a low of 10% to a
high of 111% of baseline. Concentrations below 45% of baseline were
associated with increased blood product administration, longer
ventilator support, and longer intensive care unit stay.

CONCLUSIONS:

Patient
morbidity and likelihood of transfusion were associated with calculated
plasma protein concentrations below 45% of baseline. Bleeding and
administered fluids decrease both hematocrit and plasma proteins.
Infusion of washed, salvaged blood or red blood cells raises hematocrit,
but further dilutes clotting factors. If this dilution is excessive,
coagulopathy may ensue. Patients with the smallest BVs are at greatest
risk, but dilution can negatively impact patients with large BVs as well
if the fluid used for cardiopulmonary bypass prime and anesthesia management represents a significant fraction of total BV.