Particulate Microembolism During Cardiac Operation

Abstract

In order to quantitate particulate microembolism during cardiac operations, particles 13 to 80 μ in size were measured, with a particle size analyzer, in the blood of patients before and during cardiopulmonary bypass. Venous particle measurements did not change. The volume of particles in arterial blood drawn from the bubble oxygenator (41.3 ± 4.4 × 10 3 μ 3/mm. 3, mean ± SE) was greater than that in venous blood (30.7 ± 4.1 × 10 3 μ 3/mm. 31987, p < 0.05) only during the first 10 minutes on bypass. In contrast, the volume of particles in blood drawn from the cardiotomy return line was markedly elevated (903 ± 121 × 10 3 μ 3/mm. 3). These microemboli remained elevated throughout the procedure, were most evident when extravasated blood was collected with the coronary suction line, and had a size distribution similar to platelet aggregates which could be induced in vitro in the patient's blood. The microemboli differed from platelet aggregates in that they were more resistant to deaggregation in vitro and a greater percentage (17%) floated into plasma after centrifugation. A Dacron wool filter removed 89% of these microemboli, while a 40 μ pore mesh filter and a polyurethane foam filter removed 58 and 64%, respectively. The data thus indicate that Dacron wool filtration of blood infused through the cardiotomy system would virtually eliminate particulate microembolism during cardiopulmonary bypass.