Equine Veterinary Journal Early View October 2015
By Heather Ferguson
Effect of emptying the vasculature before performing regional limb perfusion with amikacin in horses
Sole, A., Nieto, J.E., Aristizabal, F.A. and Snyder, J.R.
This study set out to determine whether exsanguination of the distal limb prior to intravenous regional limb perfusion (IVRP) increases antimicrobial concentrations in synovial fluid.
Eight sound horses underwent IVRP with amikacin sulphate on two occasions; once with prior distal limb exsanguination and once without. The pneumatic tourniquet was placed approximately 10 cm proximal to the accessory carpal bone and exerted a standardised amount of pressure (450 mmHg).
A solution containing 2 g amikacin sulphate in 60 ml sterile saline solution was infused over a period of one minute into the cephalic vein distal to the tourniquet and the tourniquet was left in place for 30 minutes after the infusion. Venous blood samples were also taken one minute before tourniquet removal. Synovial fluid was obtained from the radiocarpal and metacarpophalangeal joints at 5 minutes and 24 hours. Concentrations of amikacin in synovial and blood samples were determined using an immunoassay.
Concentrations of amikacin sulphate in the metacarpophalangeal joint at 5 minutes were significantly higher in the exsanguination group than in the non-exsanguination group. This difference was no longer present at 24 hours. There was no significant difference in the amikacin concentrations in plasma or in radiocarpal joint fluid at either time point.
The authors postulate that the higher concentration of amikacin in exsanguinated limbs immediately after IVRP may be the result of decreasing the blood volume in the limb, resulting in the amikacin being less diluted by the blood and therefore reaching higher concentrations in the vasculature. This may be important when employing concentration-dependant antimicrobials such as amikacin. Emptying of the vasculature may also result in faster diffusion of antimicrobial solution and reduced risk of leakage of the solution under the tourniquet. Further study is required to determine whether these effects are also observed in horses with diseased or inflamed joints.
Empyting the distal limb vasculature using an Esmarch bandage prior to IVRP increases the immediate amikacin concentrations in the synovial fluid of the metacarpophalangeal joint.