Evaluation of a local anesthetic delivery system for the postoperative analgesic management of canine total ear canal ablation--a randomized, controlled, double-blinded study.
OBJECTIVE
To determine if a constant rate local anesthetic delivery system is more effective than continuous intravenous (IV) morphine infusion for postoperative analgesia.


METHODS
Twenty client-owned dogs undergoing total ear canal ablation.


METHODS
Dogs were randomly assigned to the lidocaine group (LID) or the morphine group (MOR). The LID group received a constant rate infusion of lidocaine locally and a continuous IV infusion of saline, while the MOR group received a constant rate infusion of saline locally and a continuous IV infusion of morphine. The primary investigator evaluated each patient and determined a hospital behavior score, anesthesia recovery score, preoperative pain score, and serial postoperative pain and sedation scores over 38 hours. Pain and sedation observations were videotaped and scored by three additional evaluators. Evaluators were blinded to treatment assignments.


RESULTS
There were no significant differences in age, weight, hospital behavior scores or anesthesia recovery scores. The primary investigator's pain scores were not significantly different, but sedation scores were significantly lower for the LID group. Sedation and pain scores by the video evaluators were not significantly different between groups. Kappa agreement between observers was poor, but better agreement was noted between sedation scores than pain scores. Drug-related complications were significantly lower in the LID group (n = 0) compared with the MOR group (n = 5). Wound complications were not significantly different (LID = 4, MOR = 4). Intravenous delivery complications occurred in 12 (60%) patients. Local delivery complications occurred in five (25%) dogs. Delivery complications were not significantly different between groups.


CONCLUSIONS
Continuous incisional lidocaine delivery was an equipotent and viable method of providing postoperative analgesia compared with IV morphine. Lidocaine delivery resulted in a trend toward lower pain scores, significantly lower sedation scores, and no dogs requiring analgesic rescue. Wound complications secondary to local infusion were minor and self-limiting. Drug-related complications occurred only in the MOR group.
Wolfe
Tina M
TM
Cincinnati Animal Referral and Emergency Center, Cincinnati, OH 45249, USA. wolfetin@aol.com
Bateman
Shane W
SW
Cole
Lynette K
LK
Smeak
Daniel D
DD
D000701:Analgesics, Opioid / Q000627:therapeutic use; D000772:Anesthesia, Local / Q000662:veterinary*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000627:therapeutic use; D000818:Animals; D004283:Dog Diseases / Q000601:surgery*; D004285:Dogs; D004311:Double-Blind Method; D016503:Drug Delivery Systems / Q000662:veterinary*; D004424:Ear Canal / Q000601:surgery; D008012:Lidocaine / Q000008:administration & dosage* / Q000627:therapeutic use; D009020:Morphine / Q000627:therapeutic use; D010032:Otitis Externa / Q000601:surgery / Q000662:veterinary; D010149:Postoperative Pain / Q000188:drug therapy*
D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D009020:Morphine; D008012:Lidocaine