Feasibility of amikacin antimicrobial intravenous regional limb perfusion in canine pelvic limbs.

Objective: To use contrast venography and intravascular pressure monitoring to determine optimal perfusion volumes during IV regional limb perfusion (IVRLP) and to determine systemic, articular, and osseous concentrations of amikacin achieved following IVRLP in dogs.

Methods: Animals were anesthetized and had lateral saphenous vein catheters placed. Incremental IV contrast venography with pressure monitoring was performed on one limb with a tourniquet proximal to the stifle to estimate vascular filling volume. Intravenous regional limb perfusion was performed on the contralateral hindlimb using 5 mg/kg amikacin, IV, diluted to the total filling volume. Systemic blood samples and synovial fluid were collected prior to infusion and immediately prior to and 30 minutes after tourniquet removal. Tibial bone marrow aspirates were collected after tourniquet removal. Samples were analyzed for amikacin concentration.

Results: Contrast IVRLP perfused the pelvic limb distal to the tourniquet with a median volume of 10 mL (range, 6 to 16 mL) and perfusion pressure of 77.5 mm Hg (range, 37 to 130 mm Hg). The median systemic amikacin concentration with the tourniquet in place was low (0.6 μg/mL) and increased to 11.5 μg/mL following removal. The amikacin concentrations in synovial fluid and bone marrow were 109.8 and 49.7 μg/mL, respectively, with high interdog variability.

Conclusions: Contrast venography and tissue amikacin levels suggest that IVRLP is feasible in the canine pelvic limb as the amikacin concentrations in 75% of synovial fluid and 33% of bone marrow samples exceeded 10 times the MIC required to inhibit 90% of isolates (MIC90) reported for Staphylococcus pseudintermedius.

Clinical relevance: This study offers a baseline protocol for canine IVRLP for use in limb infections. Further studies should focus on drug delivery optimization and clinical application.