Cell quality of salvaged blood after total knee arthroplasty. Drain blood compared to venous blood in 32 patients.

We used the ConstaVac drainage retransfusion system in 32 patients operated on with cemented tricompartmental knee arthroplasty. The mean total postoperative bleeding was 1.1 L of which 0.7 L was retransfused within 8 hours postoperatively. Samples were taken from the venous blood and drain blood at 2 hours and 6-8 hours postoperatively. The drain blood had low counts for leukocytes and thrombocytes as compared to venous blood, and fibrinogen was almost absent. Incubation at room temperature slightly lowered glucose and pH which made the erythrocytes swell. There was a slight hemolysis in the drain blood at 2 hours. At 6-8 hours the shed blood was closer to normal, especially with regard to hemolysis, but there was a further decrease in glucose. Within this time, there was no change in acidity and no further swelling of the erythrocytes. No clinical adverse reactions were observed and we consider the observed cellular and chemical changes to be of little importance. The quality of filtered drain blood within the analyzed time limit is considered acceptable for clinical use.