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Cardiopulmonary and isoflurane-sparing effects of epidural or intravenous infusion of dexmedetomidine in cats undergoing surgery with epidural lidocaine
- Souza, Sérgio S., Intelisano, Tatiana R., De Biaggi, Christianni P., Moura, Cláudio A., Selmi, André L., Dias, Ricardo A., Cortopassi, Sílvia R.G.
- Veterinary anaesthesia and analgesia 2010 v.37 no.2 pp. 106-115
- cats, isoflurane, lidocaine, intravenous injection, spaying, analgesics, analgesia, anesthesia, general anesthetics, heart rate, breathing, blood pressure, body temperature, blood gases, muscle physiology, depth of anesthesia
- To compare the cardiorespiratory, anesthetic-sparing effects and quality of anesthetic recovery after epidural and constant rate intravenous (IV) infusion of dexmedetomidine (DEX) in cats given a low dose of epidural lidocaine under propofol-isoflurane anesthesia and submitted to elective ovariohysterectomy. Randomized, blinded clinical trial. Twenty-one adult female cats (mean body weight: 3.1 ± 0.4 kg). Cats received DEX (4 μg kg⁻¹, IM). Fifteen minutes later, anesthesia was induced with propofol and maintained with isoflurane. Cats were divided into three groups. In GI cats received epidural lidocaine (1 mg kg⁻¹, n = 7), in GII cats were given epidural lidocaine (1 mg kg⁻¹) + DEX (4 μg kg⁻¹, n = 7), and in GIII cats were given epidural lidocaine (1 mg kg⁻¹) + IV constant rate infusion (CRI) of DEX (0.25 μg kg⁻¹ minute⁻¹, n = 7). Variables evaluated included heart rate (HR), respiratory rate (fR), systemic arterial pressures, rectal temperature (RT), end-tidal CO₂, end-tidal isoflurane concentration ( e′ISO), arterial blood gases, and muscle tone. Anesthetic recovery was compared among groups by evaluation of times to recovery, HR, fR, RT, and degree of analgesia. A paired t-test was used to evaluate pre-medication variables and blood gases within groups. anova was used to compare parametric data, whereas Friedman test was used to compare muscle relaxation. Epidural and CRI of DEX reduced HR during anesthesia maintenance. Mean ± SD e′ISO ranged from 0.86 ± 0.28% to 1.91 ± 0.63% in GI, from 0.70 ± 0.12% to 0.97 ± 0.20% in GII, and from 0.69 ± 0.12% to 1.17 ± 0.25% in GIII. Cats in GII and GIII had longer recovery periods than in GI. Epidural and CRI of DEX significantly decreased isoflurane consumption and resulted in recovery of better quality and longer duration, despite bradycardia, without changes in systemic blood pressure.