Wound infiltration with ropivacaine or bupivacaine provides analgesic efficacy for 24 hours after feline injection sarcoma (FISS) surgery

In order to use multimodal and balanced analgesia, loco-regional techniques showed to be safe and efficient for postoperative pain control. Feline injection soft-tissue sarcoma (FISS) requests an extensive “en bloc” surgery, including infiltrated surrounding tissues and providing severe pain. Since new local anaesthetic drugs like bupivacaine (BVC) and ropivacaine (RVC) allowed prolonged effects respect those of the former ones, aim of the present study is to verify the analgesic efficacy of these drugs administered by a multihole indwelling catheter during postoperative pain control after FISS excision. General anaesthesia protocols included: morphine (0.1 mg kg-1 IM), atropine (0.03 mg kg-1 IM), acepromazine (0.05 mg kg-1 IM) preoperatively, propofol (4-6 mg kg-1 IV) for induction, and isoflurane in oxygen (100%). 12 cats (ASA-status II-III) were randomly treated by 2 mg kg-1 of RVC (6 cats) or BVC (6 cats) at timing 0, 6, and 12 hours after the end of the FISS excision by using a fenestrated catheter, placed prior to wound closure into subcutaneous or subfascial location. According with the surgeon, the catheter was adapted in spiroid or sinuous placement dependent upon the location of neoplasia. Boluses of local anaesthetics were diluted in 25% glucose solution and administered within 10 minutes. Analgesia was evaluated for 24 postoperative hours using numerical rating pain scale, adopted in Colorado Teaching Hospital. Data were analyzed by ANOVA and Mann-Whitney U test (P >0.05). Clinical results showed equivalent analgesic efficacy for both local anaesthetics, with the exception for the “interactive behaviour” (wound palpation) recording a significative difference for BVC. None patient required a rescue analgesic drug. Spiroid or sinuous placement of the catheter seems to be important for the successful analgesia. No morbidity related to the catheter was observed during the follow up period, as well as no sign of BVC or RVC toxicity was observed.