REASONS FOR PERFORMING STUDY : Antimicrobial i.v. regional limb perfusion (IV-RLP) is clinically performed on anaesthetised or sedated horses with or
without regional anaesthesia. To date, no scientific data are available on the clinical and pharmacokinetic effects of these anaesthetic protocols on
antimicrobial IV-RLP, which is believed to result in better tourniquet efficiency due to decreased movement.
OBJECTIVE : To determine the effects of regional or general anaesthesia on the clinical and synovial pharmacokinetic parameters of amikacin administered
by IV-RLP to horses.
STUDY DESIGN : Experimental crossover study.
METHODS : Eight healthy horses received 4 treatments of amikacin IV-RLP in a randomised, blinded, crossover design: standing sedation without regional
anaesthesia (CNT); standing sedation with i.v. regional anaesthesia; standing sedation with perineural regional anaesthesia (PNA); or general anaesthesia.
Synovial fluid amikacin concentrations were measured over 24 h and regional pharmacokinetic parameters calculated. Heart and respiratory rates, visual
analogue scale of discomfort, number of times the limb was lifted and number of additional sedations administered were recorded. Analysis of variance
crossover analysis was applied with significance level at P<0.05.
RESULTS : Amikacin concentrations and regional pharmacokinetic parameters did not differ significantly among treatments. Visual analogue scores
(mean ± s.d.) were significantly lower with PNA (19 ± 15) vs. i.v. regional anaesthesia (69 ± 36) or CNT (81 ± 13; P<0.001). Significantly less lifting of the limb
(mean ± s.d.) occurred with PNA (20 ± 20) vs. CNT (54 ± 22; P<0.04).
CONCLUSIONS : Perineural regional anaesthesia before IV-RLP was most effective in providing comfort to standing, sedated horses without significantly
affecting the regional pharmacokinetic parameters of amikacin. High variability of synovial amikacin concentrations was present. The use of general
anaesthesia for IV-RLP is not justified based on this study.