[Perioperative failure of hemodialysis shunts: analysis of risk factors].

BACKGROUND: Because vascular access dysfunction results in substantial morbidity in patients undergoing chronic hemodialysis, this complication should be avoided. However, we experienced four patients whose hemodialysis shunts failed within 24 hours postoperatively. METHODS: We retrospectively analyzed operations performed under general anesthesia in our hospital for patients receiving hemodialysis shunts between May 2001 and October 2002. Comparisons between cases with and without perioperative shunt failures were performed using Mann-Whitney and Fishers exact tests. RESULTS: Spinal surgery (P<0.01) and surgery placed in prone or knee-chest positions (P<0.05) were significantly more frequent, and the operation times (P<0.01) and blood losses (P<0.05) were significantly greater, in the occluded group (n=4) than in the non-occluded group (n=12). CONCLUSIONS: Prone position might have impaired venous backflow from the shunt, thus promoting thrombogenesis. Additionally, moderate hemorrhage, with or without blood transfusion, may have induced a transient hypercoagulable state during the operation, which thus contributed to the acute shunt failure.