Evaluation of regional limb perfusion with amikacin using the saphenous, cephalic, and palmar digital veins in standing horses

Abstract

Previous studies have shown that regional limb perfusion (RLP) using the palmar digital (PD) vein delivers therapeutic concentration of amikacin to the distal limb. Our hypothesis was that using the cephalic and saphenous veins for RLP will enable delivery of therapeutic concentrations of amikacin to the distal limb. Nineteen healthy horses participated in the study. The cephalic, saphenous, or PD vein was used to perfuse the limb with amikacin. Two grams of amikacin was used for RLP using the saphenous and the cephalic veins, and one gram was used in the PD vein. Synovial samples were collected from the metacarpo-/metatarsophalangeal (MCP/MTP) joint, and blood samples were collected from the jugular vein. Maximum concentration (Cmax) of amikacin in the MCP/MTP joint using the cephalic and the saphenous vein was 277 and 363 mg/L, respectively. The amikacin concentrations achieved in the synovial fluid of the MCP/MTP joint in the current study were between 69 and 91 times the minimally inhibitory concentration of common susceptible bacterial pathogens causing orthopedic infections in horses. To conclude, this study shows that use of the proximal veins for RLP to treat distal limb infections is a viable alternative to using the palmar or plantar digital vein.

Effects of regional limb perfusion volume on concentrations of amikacin sulfate in synovial and interstitial fluid samples from anesthetized horses

“…As previously mentioned, high pressures generated from large-volume perfusions can cause escape of the perfusate under the tourniquet (not observed in the present study) as well as leakage of perfusate from the venipuncture site or around the catheter used for injection. 1,2,4,9,10,15 Injection of a large volume in standing, sedated horses results in pain, leading to limb movement that leads to loss of tourniquet integrity, hematoma formation, and vasculitis. 1,3,4,16,17 Therefore, a greater degree of sedation than that used for small-volume perfusion is recommended for largevolume IVRLP.…”

“…However, injection of large volumes for IVRLP can lead to complications such as tourniquet failure and perfusate (antimicrobial plus diluent) leakage into systemic circulation. 1,2,4,9,10 In addition, injection of a large versus small volume for IVRLP in standing horses results in more severe signs of pain, resulting in horse movement and tourniquet displacement. 4 Both pressure and concentration likely play a role in antimicrobial distribution during IVRLP.…”

“…[1][2][3][4][5][6] These concentrations reportedly exceed 50 times the MICs of antimicrobials against common equine bacterial pathogens. 3,5,6 The MIC of amikacin against most equine bacterial pathogens is 16 µg/mL.…”

Evaluation of regional limb perfusion with chloramphenicol using the saphenous or cephalic vein in standing horses

“…Consequently, the cephalic and saphenous veins have been evaluated, both experimentally and clinically, and proved to be advantageous, alternative routes for performing RLP (Kelmer et al ., , ). Pharmacokinetic studies examining the disposition of drugs administered by RLP to the synovial structures of the distal portion of the limb of horses using proximal veins are scarce and only the disposition of amikacin and erythromycin was examined (Levine et al ., ; Kelmer et al ., ,b). There is, however, an ever‐growing problem of bacterial resistance to the commonly used antimicrobial drugs and there is an urgent need for use of newer and/or more effective ones.…”

Drug delivery to equine digital lamellar tissue

“…RLP was performed using peri-neural anaesthesia in the standing sedated horse as previously described (Chapter 4) (Parra-Sanchez, Lugo et al 2006;Kelmer, Bell et al 2013). The tourniquet was kept in place for 45 minutes following the injection.…”