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

This study investigates how the volume of intravenous regional limb perfusion (IVRLP) impacts the concentrations of the antibiotic amikacin sulfate in the synovial and interstitial fluids of horses. It was found that larger volumes of IVRLP resulted in higher amikacin concentrations without leading to significant changes in local venous blood pressure.

Research Methodology

• Eight healthy adult horses were involved in the study.
• Each horse’s forelimb was randomly assigned to receive IVRLP with 4 mL of amikacin sulfate solution (250 mg/mL) in conjunction with 56 mL (total volume, 60 mL) or 6 mL (total volume, 10 mL) of lactated Ringer solution.
• Horses were anesthetized and baseline synovial and interstitial fluid samples were taken.
• A tourniquet was placed and the assigned treatment was administered through the lateral palmar digital vein.
• Venous blood pressure in the horse’s distal portion of the limb was recorded.
• Extra synovial fluid samples were collected 30 minutes and 24 hours after the IVRLP, with additional interstitial fluid samples taken at the 6-hour and 24-hour marks.

Results

• The findings show that 30 minutes after the start of the IVRLP, the mean amikacin concentration in the synovial fluid was significantly higher in the case of the large-volume treatment (459 μg/mL) than in the small-volume group (70 μg/mL).
• Similarly, six hours post-IVRLP, the mean concentration in the interstitial fluid was greater for the large-volume treatment (723 μg/mL) as compared to the small-volume treatment (21 μg/mL).
• The peak venous blood pressure following the large-volume IVRLP was significantly greater than after the small-volume IVRLP, however, the time taken for the pressure to return to baseline was the same for both treatment groups.

Implications of the Study

• The results suggest that large-volume IVRLP can transport more amikacin to the metacarpophalangeal joints of horses in comparison to small-volume IVRLP, with no clinically important impact on local venous blood pressure. This has the potential to make the treatment more effective.