RESUMO
OBJECTIVE: To evaluate induced hypothermia and rewarming times in Hispaniolan Amazon parrots (HAP; Amazona ventralis) anesthetized using isoflurane, sevoflurane or desflurane, and to describe selected cardiovascular and respiratory effects. STUDY DESIGN: Randomized, balanced, crossover experimental study. ANIMALS: A group of 12 adult HAP. METHODS: Parrots were premedicated with intramuscular butorphanol (0.5 mg kg-1) and anesthetized with the three inhalants with a 7 day washout period between events. Anesthesia was induced using isoflurane at 4 vol%, sevoflurane at 6 vol% or desflurane 12 vol% carried in oxygen, delivered via face mask. After orotracheal intubation, anesthesia maintenance was with end-tidal concentrations of 1.4-2% (Fe'Iso), 2.4-3% (Fe'Sevo) and 8.5-9.2% (Fe'Des). Hypothermia was defined as an esophageal temperature (BT) below 37.8 °C. External heat support was provided when BT dropped to 37.5 °C. Time for temperature decrease from 38.9 °C to 37.5 °C (T1), time to first increase in BT above 37.5 °C (T2) and time from external heat support to achieving 38.9 °C (T3) were recorded and compared via Friedman tests with post hoc Dunn's test. Heart rate, respiratory rate and end-tidal carbon dioxide, amongst other variables, were evaluated. RESULTS: All inhalants caused hypothermia (T1): isoflurane, 12 (2-37) minutes [median (range)]; sevoflurane, 12 (4-18) minutes; desflurane, 11.5 (6-24) minutes, with no significant differences between treatments (p > 0.05). T2 was significantly (p = 0.042) longer for sevoflurane than for desflurane but not isoflurane. Transient apnea was observed with all inhalants, including 25% of birds anesthetized with sevoflurane. Second-degree atrioventricular block and ventricular escape beats occurred with all inhalants with hypothermia potentially exacerbating cardiac arrhythmias. CONCLUSIONS AND CLINICAL RELEVANCE: Hypothermia rapidly developed in butorphanol-sedated HAP anesthetized using isoflurane, sevoflurane or desflurane. Sevoflurane prolonged warming time. Hypothermia may be associated with an increased likelihood of bradyarrhythmia in parrots anesthetized with inhalants.
RESUMO
The objective of this study was to describe the pharmacokinetics of intra-articular (IA) administered buprenorphine in horses with lipopolysaccharide (LPS)-induced synovitis. Radiocarpal synovitis was induced in six healthy adult horses with the IA injection of LPS (0.5 ng/joint) on two occasions in a randomized cross-over design. Treatments (IA buprenorphine (IAB) at 5 µg/kg plus intravenous saline; and intravenous buprenorphine (IVB) at 5 µg/kg plus IA saline) were administered 4 h following LPS injection. Concentrations of buprenorphine were assessed in plasma and synovial fluid (SF) at 0.5, 2, 6, 12, and 24 h after administration. Pharmacokinetic parameters after IVB and IAB in plasma and synovial fluid were calculated using a nonlinear mixed effects model. IAB was detectable in SF of all horses at 24 h [median concentration of 6.2 (3.46-22.6) ng/mL]. IAB resulted in a median plasma concentration of 0.59 (0.42-1.68) ng/mL at 0.5 h and was detectable in all subjects for up to 6 h and in two horses for up to 12 h. IVB resulted in SF concentrations detected up to 6 h in all horses [median concentration of 0.12 (0.07-0.82) ng/mL]. Results suggest that IA buprenorphine remains present in the inflamed joint for at least 24 h and systemic absorption occurs.
Assuntos
Buprenorfina , Doenças dos Cavalos , Sinovite , Animais , Buprenorfina/uso terapêutico , Doenças dos Cavalos/induzido quimicamente , Doenças dos Cavalos/tratamento farmacológico , Cavalos , Injeções Intra-Articulares/veterinária , Lipopolissacarídeos , Líquido Sinovial , Sinovite/induzido quimicamente , Sinovite/tratamento farmacológico , Sinovite/veterináriaRESUMO
OBJECTIVE: To investigate the cytotoxic effects of 2 different concentrations of buprenorphine and compare them with bupivacaine and morphine on healthy equine chondrocytes in vitro. SAMPLE: Primary cultured equine articular chondrocytes from 3 healthy adult horses. PROCEDURES: Chondrocytes were exposed for 0 and 2 hours to the following treatments: media (CON; negative control); bupivacaine at 2.2 mg/mL (BUPI; positive control); morphine at 2.85 mg/mL (MOR); buprenorphine at 0.12 mg/mL (HBUPRE); or buprenorphine at 0.05 mg/mL (LBUPRE). Chondrocyte viability was assessed using live/dead staining, water-soluble tetrazolium salt-8 (WST-8) cytotoxic assay, LDH assay, and flow cytometry. All continuous variables were evaluated with a mixed ANOVA with treatment, time, and their interactions as the fixed effects and each horse as the random effect. RESULTS: Buprenorphine showed a concentration-dependent chondrotoxic effect. The viability of chondrocytes was significantly decreased with exposure to HBUPRE and BUPI compared to CON, MOR, and LBUPRE. CLINICAL RELEVANCE: Negligible chondrotoxic effects were observed in healthy cultured equine chondrocytes exposed to 0.05 mg/mL of buprenorphine, whereas higher concentrations (0.12 mg/mL) showed a marked cytotoxic effect. Based on these results, low concentrations of buprenorphine appear to be safe for intra-articular administration. Further evaluation of this dose in vivo is needed before recommending its clinical use.