Events related to microembolism during extracorporeal perfusion in man: effectiveness of in-line filtration recorded by ultrasound.

Microparticle generation during cardiopulmonary bypass was monitored continuously in 60 adult patients who underwent open-heart operations. Echo-ultrasound transducers of 5 mHz frequency were interposed in a bubble oxygenator arterial line proximal and distal to a commercially available micropore filter. Ordinary perfusion events correlated with an increase in embolic counts and were recorded graphically. Calculation of filter efficiency revealed that all filters decreased measurable embolic counts. Platelet and leukocyte determinations and plasma hemoglobin values were not altered beyond limits ordinarily encountered during perfusion without filters. No patient in any filter group experienced postoperative respiratory distress, diffuse pulmonary infiltrate, or low PaO2. The 20 mu woven nylon mesh filter and the Dacron-wool filter showed greater than 90% effectiveness in removing recorded particles. Insertion of a cardiotomy filter did not appreciably alter recorded embolic counts distal to the arterial line filter.