LOW DOSE POST-OPERATIVE APROTININ ALTERS PATTERN OF MEDIASTINAL BLOOD LOSS IN PATIENTS AT HIGH RISK OF BLEEDING POST-CARDIAC SURGERY
JM Alvarez.*, LR Jackson, C Chatw in, JJ Smolich.
Cardiothoracic Surgery Unit, Monash Medical Centre; Centre for Heart and Chest Research, Monash Medical Centre and Department of Surgery, Monash University, Clayton, Victoria.
Although previous studies have shown that low dose post-operative aprotinin reduces mediastinal blood loss in patients at low risk of bleeding after cardiac surgery, it is unknown to what extent low dose post-operative aprotinin alters the pattern of blood loss in patients at high risk of bleeding. To address this question, 57 patients in whom aspirin was continued to within 48 hours of surgery were enrolled in a prospective, randornized, double-blind controlled trial to receive either placebo (n=29) or x106 kailikrein inactivator units (KIU) of aprotinin (n=28) at the time of closure of the sternal wound skin. Mediastinal blood loss was then measured in both groups at 2 hrly intervals over the course of the first post-operative day, and data analyzed with linear regression analysis.
Results: Patients in the aprotinin and placebo groups were of similar age (62±2 vs 62±2 yrs, mean±SE), and had a similar number of coronary grafts (3.3±0.2 vs 3.3±0.2) and duration of cardiopulmonary bypass (70±4 vs 76±4 min). The post-operative mediastinal blood loss- time relationships were highly linear in both the aprotinin (r2=0.96±0.01) and placebo groups (r2=0.95±0.01). The intercept of the blood loss-time relationship in the aprotinin group (278±27 ml) was 38% less than in the placebo group (448±48 ml, p<0.005). Furthermore, the average rate of mediastinal blood loss over the first post-operative day in the aprotinin group (28±3 ml/hr) was only 65% that of the placebo group (43±4 rnl/lhr, p=0.005).
Conclusions: These results suggest that post-operative, low dose aprotinin in patients continuing with aspirin up to 48 hrs before cardiac surgery reduces post-operative bleeding, and that this effect occurs not only via an immediate action, but also via a reduction in the rate of subsequent mediastinal drainage.
