Effects of perineural administration of dexmedetomidine combined with ropivacaine 0.75% in sciatic and femoral nerve blocks guided by ultrasound and electrical nerve stimulation in dogs

Abstract

Combinations of local anesthetics and adjuvants have been studied with the aim to improve quality and safety of the peripheral anesthetic block. This study aims to evaluate the effects of dexmedetomidine, administered either perineurally or systemically, combined with femoral and sciatic nerve blocks with ropivacaine 0.75% in dogs. Seven healthy Beagle dogs, males and females, aged two to four years and weighing five to 15 kilos will be used. Each dog will participate in three experimental groups: perineural administration of ropivacaine 0.75% on the aforementioned nerves (0.1mL/kg/nerve) and intramuscular saline (0.2mL/kg) (GCON); perineural administration of dexmedetomidine diluted (1µg/mL) in ropivacaine 0.75% on the aforementioned nerves (0.1mL/kg/nerve) and intramuscular saline (0.2mL/kg) (GDPN); perineural administration of ropivacaine 0.75% on the aforementioned nerves (0.1mL/kg/nerve) and intramuscular dexmedetomidine diluted (1µg/mL) in saline (0.2mL/kg) (GDIM). The blocks will be performed under general inhalation anesthesia and guided by ultrasound and electrical nerve stimulation. Afterward, the dogs will be allowed to recover from general anesthesia. Heart rate, respiratory rate, systolic arterial pressure and rectal temperature will be evaluated before anesthetic induction (TB), at the beginning of anesthetic recovery (T0) and every 15 minutes until 240 minutes. Motor and sensory activities will be evaluated at TB, T0, five and 15 minutes after T0 and every 15 minutes until total recovery of motor and sensory activity. Central venous blood gas, blood lactate and blood glucose will be evaluated at TB and 30, 90, 165 and 240 minutes after T0. Twenty-four and 72 hours following T0, motor and sensory activities will be re-evaluated. (AU)