title: Anticoagulant effect at the time of epidural catheter removal in patients receiving twice-daily or once-daily low-molecular-weight heparin and continuous epidural analgesia after orthopedic surgery.
abstract: In patients who receive co-administered low-molecular-weight heparin (LMWH) and continuous epidural analgesia (CEA) after orthopedic surgery, there is concern about an increased risk of a spinal epidural hematoma. The practice of twice-daily LMWH dosing in North America might, in part, account for the greater number of epidural hematomas reports compared to Europe where once-daily LMWH is used. We performed a prospective cohort study in patients who had orthopedic surgery and received co-administered LMWH and CEA. We investigated the trough anticoagulant effect, as measured by an anti-Xa heparin level, at the time of epidural catheter removal in patients who received twice-daily or once-daily LMWH. Twenty-five patients who received enoxaparin, 30 mg twice-daily, and 25 patients who received dalteparin, 5,000 IU once-daily, had anti-Xa heparin levels measured on the second or third post-operative day at the time of epidural catheter removal. In patients who received twice-daily enoxaparin, or once-daily dalteparin, the anti-Xa heparin level was measured, on average, 10.4 h and 21.8 h, respectively, after the preceding LWMH dose. All 25 patients who received once-daily LMWH had an anti-Xa heparin level < 0.10 U/ml at the time of catheter removal. Of 25 patients who received twice-daily LMWH, the anti-Xa heparin level at the time of catheter removal was > or = 0.20 U/ml in 5 patients (P = 0.050), and > or = 0.10 U/ml in 7 patients (P = 0.009). We conclude that in patients who are receiving co-administered LMWH and CEA after orthopedic surgery, twice-daily but not once-daily LMWH administration is more likely to be associated with a clinically important anticoagulant effect at the time of epidural catheter removal.
authors.affiliation: Department of Medicine, McMaster University and St. Joseph's Hospital, Hamilton, Canada. jdouket@mcmaster.ca
authors.forename: James D
authors.initials: JD
authors.lastname: Douketis
authors.forename: Krystyna
authors.initials: K
authors.lastname: Kinnon
authors.forename: Mark A
authors.initials: MA
authors.lastname: Crowther
mesh_terms: D000368:Aged; D015360:Analgesia, Epidural / Q000379:methods*; D002408:Catheters, Indwelling; D015331:Cohort Studies; D017985:Dalteparin / Q000008:administration & dosage / Q000097:blood; D004359:Drug Therapy, Combination; D017984:Enoxaparin / Q000008:administration & dosage / Q000097:blood; D005170:Factor X / Q000037:antagonists & inhibitors*; D005260:Female; D006407:Hematoma, Epidural, Cranial / Q000139:chemically induced; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage* / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D011182:Postoperative Care; D011446:Prospective Studies
chemical_list: D017984:Enoxaparin; D006495:Heparin, Low-Molecular-Weight; D005170:Factor X; D017985:Dalteparin