Resumen de Postoperative comparison of four perioperative analgesia protocols in dogs undergoing stifle joint surgery
Objective—To compare 4 analgesic protocols in dogs undergoing stifle joint surgery.
Design—Randomized, blinded, prospective clinical trial.
Animals—48 client-owned dogs that underwent stifle joint surgery.
Procedures—Dogs undergoing tibial plateau leveling osteotomy were randomly assigned to receive a constant rate infusion of a combination of morphine, lidocaine, and ketamine; a lumbosacral epidural with morphine and ropivacaine; both treatments (ie, constant rate infusion and lumbosacral epidural); or only IM premedication with morphine. Indices of cardiorespiratory function and isoflurane requirement were recorded at 5-minute intervals during anesthesia. A validated sedation scoring system and the modified Glasgow composite measure pain score were used to assess comfort and sedation after surgery and anesthesia once the swallowing reflex returned and a body temperature of ≥ 36.7°C (98.1°F) was attained. Pain and sedation scores were acquired at 60-minute intervals for 4 hours, then at 4-hour intervals for 24 hours. Dogs with a postoperative pain score > 5 of 24 were given morphine as rescue analgesia.
Results—No differences in heart rate, respiratory rate, systolic arterial blood pressure, end-tidal Pco2, end-tidal isoflurane concentration, and vaporizer setting were detected among groups. No differences in pain score, sedation score, rescue analgesia requirement, or time to first rescue analgesia after surgery were detected.
Conclusions and Clinical Relevance—Pain scores were similar among groups, and all 4 groups had similar rescue analgesia requirements and similar times to first administration of rescue analgesia. All 4 analgesic protocols provided acceptable analgesia for 24 hours after stifle joint surgery.
Stifle joint surgery in dogs is associated with considerable postoperative pain.1–3 Opioids, N-methyl-d-aspartate receptor antagonists, local anesthetics, and NSAIDs are classes of analgesic drugs that have been administered to dogs both systemically and as part of a regional anesthetic technique (epidural) to provide relief from pain.4 Multimodal analgesia, the concurrent administration of multiple analgesic drugs and analgesic techniques, is a method of providing postoperative pain relief. Multimodal analgesia is purported to provide superior pain relief because the combination of drugs that act via different pathways has the potential to enhance efficacy.4,5 Morphine, an opioid analgesic, is used by a variety of routes and methods to produce analgesia.5,6 Morphine infusion alone and in combination with lidocaine and ketamine reduces the inhalation anesthesia requirement in dogs.7,8 The transfer of such studies to clinical medicine is difficult because the evaluation of the severity of pain in dogs is complex.9–20 The MGCMPS is a validated pain scoring system that uses multiple indices associated with orthopedic pain, including the patient's overall appearance, observation of gait, response to pressure on the surgical site, and overall demeanor of the patient.12,15 Interpretation of the MGCMPS is made more difficult because sedation can alter the perception of the dog's pain.
To our knowledge, no clinical study has systematically compared the postoperative sedation and analgesia associated with morphine administration alone with that of morphine administered epidurally along with a local anesthetic and morphine combined with lidocaine and ketamine as a CRI.2,21–24 The purpose of the study reported here was to determine whether the multimodal analgesic technique (ie, CRI of MLK and LE with MR) provides superior postoperative analgesia to that of IM administration of morphine alone (as a premedication), CRI of MLK alone, or LE with MR alone.
