INDIVIDUAL VARIATIONS IN THE FIBRINOLYTIC RESPONSE DURING AND AFTER CARDIOPULMONARY BYPASS

The purpose of this study was to determine whether individual patients show different patterns of fibrinolytic response to cardiopulmonary b ypass (CPB) and whether preoperative or intraoperative parameters were predictive of these different patterns. Active t-PA, active PAI-1 and total t-PA antigen were measured in plasma samples obtained from 38 s ubjects, age 32 to 85 (median 69 years), before, during and after CPB. Four patterns of fibrinolytic response were noted: 1) 40% of patients showed the ''typical'' response, a rapid rise in active and total t-P A during CPB followed postoperatively by elevated PAT-1 and reduced t- PA, 2) 10% showed no change in t-PA or PAT-1 during or after CPB, 3) 2 4% showed no change in t-PA with an increase in PAT-1 postoperatively, and 4) 26% showed an increase in t-PA during CPB with no change in PA T-1 postoperatively. When present, the t-PA response was rapid, occurr ing within the first 30 min of CPB and was more common in patients und ergoing valve surgery than in coronary artery bypass grafting (p < 0.0 05). Increased levels of PAI-1 postoperatively were associated with is chemic times greater than 70 min (p = 0.003) but not with the total le ngth of CPB. Age, sex, CPB temperature, total CPB time and preoperativ e levels of t-PA and PAI-1 were not associated in the intra- or postop erative fibrinolytic response pattern. We conclude that the fibrinolyt ic response to CPB is heterogeneous. Further studies will be needed to determine whether different response patterns are clinically signific ant.