Seek and you shall find--but then what do you do? Cold agglutinins in cardiopulmonary bypass and a single-center experience with cold agglutinin screening before cardiac surgery.

Cardiopulmonary bypass (CPB) during cardiac surgery can involve deliberate hypothermia of the systemic (22-36 °C) and coronary circulations (as low as 8-12 °C). Adverse sequelae of cold-active antibodies have been feared and reported under such conditions, and some centers thus elect to screen for cold agglutinins before CPB. We reviewed the literature on cold agglutinins in cardiac surgery and described the yields and effects of cold agglutinin screening (CAS) in 14,900 cardiac surgery patients undergoing CPB over 8 years at a single institution. Cold agglutinin screening was positive in 47 cases (0.3%), at an annual testing cost of $17,000 CAD. The response of the surgical team to the preoperative discovery of a cold agglutinin was variable, with CPB modified to avoid hypothermia in approximately one-third of cases. In patients discovered to have a positive CAS, postoperative intensive care unit and hospital length of stay were marginally increased (54.6 vs. 42.8 hours, P = .02; 7 [6-14] vs. 7 [5-9] days, P = .04). However, the composite of mortality or severe morbidity (stroke, myocardial infarction, dialysis, low output syndrome, sepsis, and deep vein thrombosis) was not significantly different (14.9% vs. 9.2%, P = .2). Antibody verification found that only 43% of positive CAS patients had true cold agglutinins (20 patients). Furthermore, the rate of adverse events was low in both CAS-positive and true-positive cold agglutinin patients undergoing CPB and cardiac surgery. Finally, modification of CPB to attenuate hypothermia did not decrease adverse events. Based upon historical and local data, preclinical CAS is cost-substantial and nonspecific. Cold agglutinin screening does not promote an algorithm of care that meaningfully improves patient CPB outcomes.