Filtration of shed mediastinal blood.

Re-infusion of shed blood carries the risk of re-infusing cellular debris. All re-infusion devices have some sort of integral filtration which is variably supplemented with a second intravenous filter. Using electron microscopy we have observed what debris is collected by secondary filtration. In 12 patients studied, nine out of 12 filters had significant amounts of cellular debris present, but not clearly related to increased rates of postoperative bleeding. Noncellular debris, silicon and strands of cellulose were also observed. Although we have not detected any clinically significant embolic phenomena from re-infusion of shed mediastinal blood, it seems prudent to include a second filter prior to re-infusion.