IVRP: does it really fight infection?

Intravenous regional limb perfusion with antimicrobials (IVRP) has become a common adjunct therapy for the treatment of orthopaedic infections in horses. Numerous studies have described regional drug concentrations achieved after IVRP with a variety of antimicrobials in healthy horses. Results of these studies suggest that those antimicrobials concentrations should be effective for the treatment of horses with limb infections^1-12. However, those studies also describe large variation of tissue antimicrobials concentrations, and tourniquet efficacy is frequently questionable in some horses. Variation of tourniquet types, tourniquet applications, tourniquet times, horses’ weights, antimicrobial doses, antimicrobial combinations, and perfusate volumes preclude direct comparisons among studies.

Single antimicrobial or their combinations can be administered by IVRP; however, drug interactions may have negative effects on antimicrobial concentrations and activity in regional tissues.^8,9 Irritant antimicrobials or high antimicrobial doses can be associated with complications^13-15 Both time- and concentrationdependent antimicrobials can be administered. The high concentration peak achieved after IVRP makes this technique more suitable for concentrationdependent antimicrobials, although the maintenance of antimicrobial concentrations above the MIC for a prolonged time-period also makes IVRP applicable to time-dependent antimicrobials. Based on studies on healthy horses, antimicrobial concentrations in regional tissues remain above the MIC for periods of time up to 36h¹⁰ . [...]