DEEP VENOUS THROMBOSIS FOLLOWING TOTAL HIP-ARTHROPLASTY - EFFECTS OF PROLONGED POSTOPERATIVE EPIDURAL-ANESTHESIA

The authors studied the use of epidural anesthesia prolonged to 48 hou rs of epidural analgesia in 120 total hip arthroplasty patients in a c ase-control fashion. One half of the patients received prolonged epidu ral anesthesia, while the other matched half received general endotrac heal anesthesia. Venograms were obtained after surgery and graded in b lind fashion by a single radiologist. The overall incidence of deep ve nous thrombosis in the epidural versus general anesthetic groups was 2 3 (14 of 60 patients) versus 40% (24 of 60) (P <.05). There was an ide ntical incidence-8.3% (5 of 60 patients)-of proximal thrombosis in the two groups, and all of the difference in the overall rates of thrombo sis occurred in the calf. Fifteen percent (9 of 60 patients) of the ep idural patients and 31.6% (19 of 60) of the general anesthetic patient s demonstrated this finding (P <.05). Of the 10 proximal clots, 8 (80% ) were found in the operative leg, while only 29 (59.2%) of the 49 cal f clots were found in the operative leg. Prolonged epidural anesthesia significantly decreases the incidence of deep venous thrombosis after total hip arthroplasty, with its most apparent benefit on calf vein t hrombosis secondary to its hyperkinetic effect on lower limb blood flo w. The observation that it has no demonstrable effect on the preventio n of proximal thrombosis and our finding that the majority of proximal clots are in the operative leg suggest that thrombi in the thigh may be the result of a different primary pathogenic mechanism that is more related to endothelial injury than to changes in viscosity or blood f low. Epidural anesthesia alone does not address prevention of proximal thrombosis and therefore proper prophylaxis after total hip arthropla sty necessitates the concurrent use of additional methods.