Comparison of Greenfield filter and vena caval ligation for experimental septic thromboembolism

Septic thromboembolism resulting from the placement of infected autologous thrombi was studied in three groups of ten dogs each following vena caval ligation (VCL) or Greenfield filter (GF) placement with or without antibiotic treatment. All the dogs that did not receive antibiotic therapy died, and the shortest survival time was after acute VCL. Dogs with GF and with delayed embolism after VCL survived significantly longer than did the control animals. Antibiotic therapy consisting of ampicillin and clindamycin resulted in survival except for one control dog with lung abscess. Cultures of the GF and contained thrombus were negative after 2 weeks. However, after VCL, two died of sepsis and two survivors had caval abscess. In a group of six dogs with VCL and delayed embolism, there were four deaths from sepsis and one survivor found to have a caval abscess. To test secondary infection of a trapped thrombus, in 12 dogs with GF and a sterile thrombus we created an extremity abscess with a fecally contaminated sponge, which resulted in death from sepsis in six animals within 3 days. Surgical drainage and antibiotic treatment of the remaining six resulted in survival in five dogs. Cultures of filters and emboli showed heavy contamination in the untreated animals and in one treated dog that died within 24 hours. The remainder had sterile filters and emboli. The presence of sepsis does not preclude use of the Greenfield filter, which is well tolerated in the face of septic embolism and allows sterilization with antibiotic treatment. Prophylactic antibiotic therapy seems advisable for any patient with a filter during a procedure that may produce bacteremia.