title: When is the best time to initiate peri-operative heparin therapy in general surgery patients? A risk-benefit dilemma.
abstract: We sought optimal timing for heparin therapy in general surgery (GS) patients. From 2001 to 2008, 95 GS patients with documented thromboembolic events (TE) were identified and compared with matched controls (age, gender, type of operation, date of operation, malignancy, and body mass  index [BMI]). Timing of heparin therapy, characteristics of TE or bleeding events, and risk factors for TE were collected. Mean age (57 years), BMI (33 kgM-2), gender (55% male), malignancy (53%), and duration of operation (204 vs 191 minutes, P = not significant) were similar  in both groups. Peri-operative (within 24 hours) heparin administration (study 56% vs control 64%, P = 0.2) was no different. Preoperative therapy was more common in the control group (77% vs 51%, P = 0.001). The regression model showed a protective effect for heparin  if given preoperatively (odds ratio = 0.37, P = 0.047) with no effect if started >10 hours from incision. Mean blood transfusion (97 and 106 mL) and hemorrhagic events (4.5% and 5%) were similar in both groups (P = not significant). Median (range) length of hospital stay and  mortality was higher in TE cases [19 (0-201) vs 6 (0-66) days, 11 vs 2 mortality in 100-person-years (P < 0.05)]. Heparin administration before GS is associated with >2-fold reduction in TE. The optimal time to start heparin seems to be 1 to 10 hours  before the time of incision.
authors.affiliation: Department of Surgery, College of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Nassir
authors.initials: N
authors.lastname: Rostambeigi
authors.forename: Susan M
authors.initials: SM
authors.lastname: Greenlee
authors.forename: Marianne
authors.initials: M
authors.lastname: Huebner
authors.forename: David R
authors.initials: DR
authors.lastname: Farley
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D016017:Odds Ratio; D011183:Postoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D011300:Preoperative Care / Q000379:methods / Q000592:standards*; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013514:Surgical Procedures, Operative; D013923:Thromboembolism / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D013997:Time Factors
chemical_list: D000925:Anticoagulants; D006493:Heparin