title: The prothrombotic paradox of severe obesity after cardiac surgery under cardiopulmonary bypass.
abstract: 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.
  
  
  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.
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France. Electronic address: michel.kindo@chru-strasbourg.fr.
authors: Michel
authors: M
authors: Kindo
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France.
authors: Tam Hoang
authors: TH
authors: Minh
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France.
authors: Sébastien
authors: S
authors: Gerelli
authors: Department of Public Health, University Hospitals of Strasbourg, France.
authors: Nicolas
authors: N
authors: Meyer
authors: Department of Public Health, University Hospitals of Strasbourg, France.
authors: Mickaël
authors: M
authors: Schaeffer
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France.
authors: Stéphanie
authors: S
authors: Perrier
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France.
authors: Jonathan
authors: J
authors: Bentz
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France.
authors: Tarek
authors: T
authors: Announe
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France.
authors: Arnaud
authors: A
authors: Mommerot
authors: Department of Surgical Intensive Care Unit and Anesthesiology, University Hospitals of Strasbourg, France.
authors: Olivier
authors: O
authors: Collange
authors: Department of Surgical Intensive Care Unit and Anesthesiology, University Hospitals of Strasbourg, France.
authors: Sandrine
authors: S
authors: Marguerite
authors: Department of Surgical Intensive Care Unit and Anesthesiology, University Hospitals of Strasbourg, France.
authors: Adrien
authors: A
authors: Thibaud
authors: Department of Surgical Intensive Care Unit and Anesthesiology, University Hospitals of Strasbourg, France.
authors: Hubert
authors: H
authors: Gros
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France.
authors: Philippe
authors: P
authors: Billaud
authors: Department of Cardiovascular Surgery, University Hospitals of Strasbourg, France.
authors: Jean-Philippe
authors: JP
authors: Mazzucotelli
mesh_terms: D000368:Aged; D001777:Blood Coagulation; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood*; D010976:Platelet Count; D019106:Postoperative Hemorrhage / Q000097:blood*; D011184:Postoperative Period; D011446:Prospective Studies; D011517:Prothrombin Time
keywords: Blood coagulation; Cardiopulmonary bypass; Fibrinogen; Hemorrhage; Obesity