title: Delayed efficient anticoagulation with heparin in patients with a weight of 110 kg and more treated for acute coronary syndrome.
abstract: OBJECTIVE
  The use of a weight-based nomogram is considered as standard care for prescribing appropriate doses of unfractionated heparin (UFH). Because of the need for multiple other medications that may affect bleeding and that clinical data have relied on similar dosing algorithms, maximum initial bolus and infusion rates have been suggested (capped initial dose). Whether these weight-based heparin nomograms properly address therapeutic dosing in obese patients remains questionable.
  
  
  METHODS
  Thirty patients treated for acute coronary syndrome and weighing ≥110 kg were retrospectively compared with 90 controls (three groups of 30 patients, weighting 50-69.9, 70-89.9, or 90-109.9 kg), all treated with UFH, July 2008 to April 2009. The primary end point was the time required to obtain a threshold activated partial thromboplastin time (aPTT).
  
  
  RESULTS
  Mean time to achieve threshold aPTT was longer for obese patients weighing ≥110 kg than for controls (31.47 vs. 12.89 hours; P < 0.0001). At 24 hours, 63% of obese patients weighing ≥110 kg had not reached threshold aPTT vs. 7% of controls (P < 0.0001). However, threshold infusion rate did not differ between weight categories (13.0 vs. 13.1 U/kg/h; P = NS) and approximated the initial infusion rate recommended by nomograms without applying the dose cap (12 U/kg/h).
  
  
  CONCLUSIONS
  Adequate anticoagulation time doubled in patients weighing ≥110 kg, suggesting that these patients were not receiving appropriate heparin doses initially to achieve threshold aPTT rapidly. Using initial infusion rate recommended by a nomogram without capping for total body weight is suggested as acceptable in this study. This approach should be further evaluated in a prospective study.
authors: Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Canada.
authors: Sebastien X
authors: SX
authors: Joncas
authors: Paul
authors: P
authors: Poirier
authors: Jean-Luc
authors: JL
authors: Ardilouze
authors: Nathalie
authors: N
authors: Carrier
authors: Tania
authors: T
authors: Fayad
authors: Paul
authors: P
authors: Farand
mesh_terms: D054058:Acute Coronary Syndrome / Q000150:complications / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D001777:Blood Coagulation / Q000187:drug effects*; D001835:Body Weight; D016022:Case-Control Studies; D005260:Female; D006493:Heparin / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D010314:Partial Thromboplastin Time; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D000925:Anticoagulants; D006493:Heparin