Elimination of fat microemboli during cardiopulmonary bypass

Background. Fat emboli have been implicated in cerebral dysfunction after cardiopulmonary bypass (CPB). We sought to identify the source of fat emboli during CPB and devise a technique for their elimination. Methods. Patients undergoing CPB were prospectively randomized to either cardiotomy suction (n = 7) or cell-saving suction device (n = 6). Blood was collected at various intervals during CPB, and the fat emboli were identified using oil red O stain. These emboli were grouped based on their diameter into 10- to 50-μm and more than 50-μm particles. The number of fat emboli per slide examined was graded according to the following scale: 1 (1 to 10), 2 (11 to 20), 3 (21 to 30), and 4 (> 30 emboli). In the second phase of the experiment, a 21-μm filter was attached in series, distal to the cardiotomy reservoir (n = 6), and fat emboli were quantified. Results. Blood from the pericardial well was saturated with fat emboli of both sizes. Patients randomized to the cardiotomy suction had a significantly higher number of fat emboli at the end of CPB when compared with those randomized to the cell-saving suction device and dual-filter group. Processed blood from both the cardiotomy reservoir and cell-saving device was noted to have an abundance of fat emboli when compared with blood processed through the dual filters. Conclusions. Processed blood from both the cardiotomy reservoir and cell-saving device appear to have an abundance of fat emboli that are completely eliminated by using a 21-μm arterial filter in series with the cardiotomy reservoir. This intervention could potentially reduce neurocognitive dysfunction associated with CPB.