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.