CARDIOTOMY SUCTION - A MAJOR SOURCE OF BRAIN LIPID EMBOLI DURING CARDIOPULMONARY BYPASS

Background. Brain injury remains a significant problem in patients und ergoing cardiac surgery assisted by cardiopulmonary bypass (CPB). Auto psy brain specimens of patients after cardiac operations with CPB reve al numerous acellular lipid deposits (10 to 70 mu m) in the microvascu lature. We hypothesize that these small capillary and arterial dilatat ions result from a diffuse inflammatory response to CPB or from emboli delivered by the bypass circuit. This study was undertaken to determi ne which aspect of CPB is most clearly associated with these dilatatio ns. Methods. Thirteen dogs were studied in four groups: group I (n = 3 ), right-heart CPB; group II (n = 2), lower-extremity CPB; group III ( n = 3), hypothermic CPB; and group IV (n = 5), hypothermic CPB with ca rdiotomy suction. All dogs in all groups were maintained on CPB for 60 minutes and then euthanized. Brain specimens were harvested, fixed in ethanol, embedded in celloidin, and stained with the alkaline phospha te histochemical technique so that dilatations could be counted. Resul ts. All dogs completed the protocol. The mean density of dilatations p er square centimeter for each group was as follows: group I, 1.77 +/- 0.77; group II, 4.17 +/- 1.65; group III, 4.54 +/- 1.69; and group IV, 46.5 +/- 14.5. In group IV (cardiotomy suction), dilatation density w as significantly higher than in group III (hypothermic cardiopulmonary bypass) (p = 0.04) and ail other groups (p = 0.04). Conclusions. Bloo d aspirated from the surgical field and subsequently reinfused into do gs undergoing CPB produces a greater density of small capillary and ar terial dilatations than CPB without cardiotomy suction, presumably bec ause of lipid microembolization. (C) 1998 by The Society of Thoracic S urgeons.