Retrospective comparison of three locoregional techniques for pelvic limb surgery in dogs.

OBJECTIVE: To retrospectively compare the efficacy and duration of effect of three commonly used locoregional blocks in dogs undergoing pelvic limb orthopaedic surgery. STUDY DESIGN: Retrospective clinical study. ANIMALS: A total of 236 dogs that underwent pelvic limb surgery and were administered a locoregional technique. METHODS: A total of 236 hospital records were reviewed and 230 included in statistical analysis. Dogs were grouped as following: electrostimulation-guided pre-iliac femoral and sciatic nerve block (group PFS, n = 70); ultrasound-guided saphenous and sciatic nerve block (group SS, n = 76); or lumbosacral epidural (group EPI, n = 84). In group EPI, bupivacaine 0.5% or ropivacaine 0.75% was used with morphine. Dogs were pain scored (short form of the Glasgow Composite Measure Pain Scale) hourly following recovery from anaesthesia. Analysed data included: time to first postoperative dose of methadone, pain score at that time, intraoperative rescue analgesia, intraoperative hypotension and ability to walk and urinate overnight. Separate analyses were performed including all pelvic limb surgeries and including only elective stifle surgeries. Kruskal-Wallis and Mann-Whitney tests were performed. A p value < 0.05 was considered significant. The median (range) is reported. RESULTS: For all pelvic limb surgeries, the time to first postoperative methadone was 530 (110-1337), 440 (140-1030) and 466 (135-1094) minutes in groups EPI, PFS and SS, respectively, and was not significantly different. Postoperatively, 10/84, 15/70 and 12/76 dogs in groups EPI, PFS and SS, respectively, did not require methadone (nonsignificant). Significantly fewer dogs in group EPI (18%) required intraoperative rescue analgesia compared with group SS (38%), but not compared with PFS (30%). Significantly more dogs in group EPI had hypotension intraoperatively (30%) and urinary retention postoperatively (62%). CONCLUSIONS AND CLINICAL RELEVANCE: Intraoperative analgesia may be superior with EPI than SS for some surgeries of the pelvic limb, but not for stifle surgeries. All three techniques provided similar requirement for postoperative analgesia, but EPI caused higher incidence of intraoperative hypotension and postopertive urinary retention.

Comparison of Brody's formula with respiratory gas analysis for estimating oxygen consumption in anaesthetized dogs.

OBJECTIVE: To determine agreement in oxygen consumption (V˙O2) values calculated using Sykes' formula V˙O2 = (FiO2 - Fe'O2) * V˙E (where Fi and Fe are the inspired and end-tidal fractional concentrations of O2, respectively, and V˙E is minute volume) with values derived using Brody's formula (V˙O2 = 10 kg3/4). It was hypothesized that the two methods would not yield statistically significant differences in calculated values. STUDY DESIGN: Prospective, clinical, pilot study. ANIMALS: A total of 22 client-owned dogs. METHODS: Dogs undergoing surgery were anaesthetized with either isoflurane or sevoflurane. The V˙E, FiO2 and Fe'O2 were measured during mechanical ventilation of the lungs (tidal volume 10 mL kg-1; respiratory rate: 8-12 breaths minute-1). Oesophageal temperature was maintained between 37.0 °C and 38.5 °C. Values for V˙O2 derived by Sykes' and Brody's methods were compared and agreement was determined using Bland-Altman analysis. RESULTS: Mean V˙O2 values were 4.67 ± 0.51 mL kg-1 minute-1 and 5.32 ± 1.69 mL kg-1 minute-1 calculated using Brody's formula and Sykes' equation, respectively. There was greater variability in the values obtained from Sykes' equation. The Bland-Altman plot revealed a proportional error with correlation but poor agreement between values. CONCLUSIONS AND CLINICAL RELEVANCE: Both methods yielded V˙O2 values of approximately 5 mL kg-1minute-1 with no statistically significant differences between the two methods.