title: Identifying optimal heparin management during cardiopulmonary bypass in obese patients: A prospective observational comparative study.
abstract: BACKGROUND
  The heparin regimen providing anticoagulation during cardiopulmonary bypass (CPB) is usually adapted to total body weight (TBW), but may be inaccurate in obese patients in whom TBW exceeds their ideal body weight.
  
  
  OBJECTIVE
  The objective is to compare the effects of heparin injection based on TBW on haemostatic parameters between obese and nonobese patients during cardiac surgery and to calculate the optimal heparin regimen.
  
  
  METHODS
  Prospective comparative study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Two groups of 50 patients (BMI≥ or <30 kg m) were included in the study over a 9-month period in 2013. The study started on 27 February 2013.
  
  
  METHODS
  An unfractionated heparin (UFH) bolus of 300 IU kg TBW was injected before initiation of CPB followed by additional doses (50 to 100 IU kg) to maintain a target activated coagulation time (ACT) of at least 400 s.
  
  
  METHODS
  ACT and plasma heparin concentration were measured at different time points after initiation of, and weaning from CPB.
  
  
  RESULTS
  Obese patients received higher initial and total doses of heparin (P < 0.0001). Plasma heparin concentrations were significantly higher in obese patients at each time point (P < 0.001) and reached very high values after the initial bolus (5.90 vs. 4.48 IU ml, P < 0.0001). The relationship between plasma heparin concentration and ACT after the initial bolus was not linear and followed an asymptotic regression curve. Haemoglobin concentration decreased intraoperatively to a greater extent in the obese group (P < 0.001). No significant differences in postoperative bleeding or global transfusion requirements were observed.
  
  
  CONCLUSIONS
  The standard heparin regimen based on TBW in obese patients during CPB results in excessive plasma heparin concentrations and a significant intraoperative decrease in haemoglobin concentration. ACT monitoring was not accurate in identifying this excess dosage. An initial bolus of 340 IU kg ideal body weight would achieve a heparin concentration of 4.5 IU ml, similar to that observed in nonobese patients. Further investigations are warranted to confirm this heparin regimen.
authors.affiliation: From the Department of Anaesthesiology (EH, FF, FL, SD, OC, PMM, AS); Department of Haematology (LG); and Department of Cardiovascular Surgery, Strasbourg University Hospital, France (MK).
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Haas
authors.forename: François
authors.initials: F
authors.lastname: Fischer
authors.forename: François
authors.initials: F
authors.lastname: Levy
authors.forename: Su-Emmanuelle
authors.initials: SE
authors.lastname: Degirmenci
authors.forename: Lelia
authors.initials: L
authors.lastname: Grunebaum
authors.forename: Michel
authors.initials: M
authors.lastname: Kindo
authors.forename: Olivier
authors.initials: O
authors.lastname: Collange
authors.forename: Paul-Michel
authors.initials: PM
authors.lastname: Mertes
authors.forename: Annick
authors.initials: A
authors.lastname: Steib
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use*; D001777:Blood Coagulation / Q000187:drug effects; D001835:Body Weight; D002315:Cardiopulmonary Bypass / Q000379:methods*; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006493:Heparin / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D019990:Perioperative Care; D011446:Prospective Studies; D014914:Whole Blood Coagulation Time
chemical_list: D000925:Anticoagulants; D006454:Hemoglobins; D006493:Heparin