The prothrombotic paradox of severe obesity after cardiac surgery under cardiopulmonary bypass.

BACKGROUND: Obesity is suggested to reduce postoperative bleeding in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) but perioperative hemostasis variations have not been studied. Therefore, we investigated the effects of severe obesity (body mass index [BMI] ≥35kg/m(2)) on chest tube output (CTO) and hemostasis in patients undergoing cardiac surgery with CPB. MATERIALS AND METHODS: We prospectively investigated 2799 consecutive patients who underwent coronary and/or valve surgery using CPB between 2008 and 2012. 204 patients (7.3%) presented a severe obesity. RESULTS: In the severe obesity group, the 6-h and 24-h CTO were significantly reduced by -21.8% and -14.8% respectively (P<0.0001) compared with the control group. A significant reduction of the mean number of red blood cell units transfused at 24h was observed in the severe obesity groups (P=0.01). On admission to the intensive care unit, a significant increase of platelet count (+9.2%; P<0.0001), fibrinogen level (+12.2%; P<0.0001) and prothrombin time (+4.1%; P<0.01) and a significant decrease of the activated partial thromboplastin time (-4.2%; P<0.01) were observed in the severe obesity group compared with the control group. In multivariate analysis, severe obesity was significantly associated to a decreased risk of excessive bleeding (24-h CTO >90th percentile; Odds ratio: 0.37, 95% CI: 0.17 to 0.82). No significant differences were observed regarding postoperative thromboembolic events between the two groups. CONCLUSIONS: Severe obesity is associated with a prothrombotic postoperative state that leads to a reduction of postoperative blood loss in patients undergoing cardiac surgery with CPB.

Plasma fibrinogen level on admission to the intensive care unit is a powerful predictor of postoperative bleeding after cardiac surgery with cardiopulmonary bypass.

INTRODUCTION: Evidence regarding the behavior of fibrinogen levels and the relation between fibrinogen levels and postoperative bleeding is limited in cardiac surgery under cardiopulmonary bypass (CPB). To evaluate perioperative fibrinogen levels as a predictor of postoperative bleeding in patients undergoing cardiac surgery with CPB. MATERIALS AND METHODS: In this prospective, single-center, observational cohort study of 1956 patients following cardiac surgery with CPB, fibrinogen level was measured perioperatively. Excessive bleeding group was defined as patients with a 24-h chest tube output (CTO) exceeded the 90th percentile of distribution. RESULTS: The median 24-h CTO was 728.6±431.1ml. A total of 189 patients (9.7%) were identified as having excessive bleeding. At admission to the intensive care (Day 0), the fibrinogen levels were 2.5±0.8g/l and 2.1±0.8g/l in the control and excessive bleeding groups, respectively (P<0.0001). The fibrinogen level on Day 0 was significantly correlated with the 24-h CTO (rho=-0.237; P<0.0001). Multivariate analysis demonstrated that the fibrinogen level at Day 0 was the best perioperative standard laboratory test to predict excessive bleeding (P=0.0001; odds ratio, 0.5), whereas preoperative fibrinogen level was not a predictor. Using receiver operating characteristics curve analyses, the best Day 0 fibrinogen level cutoff to predict postoperative bleeding was 2.2g/l. CONCLUSIONS: In this large prospective study, the fibrinogen level upon admission to the intensive care unit after CPB predicted the risk of postoperative bleeding. Our data add to the concern regarding the fibrinogen level threshold that might require fibrinogen concentrate infusion to reduce postoperative blood loss.