Minimum infusion rate and hemodynamic effects of propofol, propofol-lidocaine and propofol-lidocaine-ketamine in dogs.
ABSTRACT To evaluate the effects of a constant rate infusion (CRI) of lidocaine alone or in combination with ketamine on the minimum infusion rate (MIR) of propofol in dogs and to compare the hemodynamic effects produced by propofol, propofol-lidocaine or propofol-lidocaine-ketamine anesthesia.
Prospective, randomized cross-over experimental design.
Fourteen adult mixed-breed dogs weighing 15.8 ± 3.5 kg.
Eight dogs were anesthetized on different occasions to determine the MIR of propofol alone and propofol in combination with lidocaine (loading dose [LD] 1.5 mg kg(-1), CRI 0.25 mg kg(-1) minute(-1)) or lidocaine (LD 1.5 mg kg(-1), CRI 0.25 mg kg(-1) minute(-1)) and ketamine (LD 1 mg kg(-1), CRI 0.1 mg kg(-1) minute(-1)). In six other dogs, the hemodynamic effects and bispectral index (BIS) were investigated. Each animal received each treatment (propofol, propofol-lidocaine or propofol-lidocaine-ketamine) on the basis of the MIR of propofol determined in the first set of experiments.
Mean ± SD MIR of propofol was 0.51 ± 0.08 mg kg(-1) minute(-1). Lidocaine-ketamine significantly decreased the MIR of propofol to 0.31 ± 0.07 mg kg(-1) minute(-1) (37 ± 18% reduction), although lidocaine alone did not (0.42 ± 0.08 mg kg(-1) minute(-1), 18 ± 7% reduction). Hemodynamic effects were similar in all treatments. Compared with the conscious state, in all treatments, heart rate, cardiac index, mean arterial blood pressure, stroke index and oxygen delivery index decreased significantly, whereas systemic vascular resistance index increased. Stroke index was lower in dogs treated with propofol-lidocaine-ketamine at 30 minutes compared with propofol alone. The BIS was lower during anesthesia with propofol-lidocaine-ketamine compared to propofol alone.
Lidocaine-ketamine, but not lidocaine alone, reduced the MIR of propofol in dogs. Neither lidocaine nor lidocaine in combination with ketamine attenuated cardiovascular depression produced by a continuous rate infusion of propofol.
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ABSTRACT: To establish the correlation between the bispectral index (BIS) and different rates of infusion of propofol in dogs. Study design Prospective experimental trial. Eight adult dogs weighing 6-20 kg. Eight animals underwent three treatments at intervals of 20 days. Propofol was used for induction of anesthesia (10 mg kg(-1) IV), followed by a continuous rate infusion (CRI) at 0.2 mg kg(-1) minute(-1) (P2), 0.4 mg kg(-1) minute(-1) (P4) or 0.8 mg kg(-1) minute(-1) (P8) for 55 minutes. The BIS values were measured at 10, 20, 30, 40, and 50 minutes (T10, T20, T30, T40, and T50, respectively) after the CRI of propofol was started. Numeric data were submitted to analysis of variance followed by Tukey test (p < 0.05). The BIS differed significantly among groups at T40, when P8 was lower than P2 and P4. At T50, P8 was lower than P2. The electromyographic activity (EMG) in P2 and P4 was higher than P8 at T40 and T50. An increase in propofol infusion rates decreases the BIS values and EMG.Veterinary Anaesthesia and Analgesia 06/2008; 35(3):228-31. · 1.34 Impact Factor
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ABSTRACT: Objective To evaluate the effects of IV lidocaine (L) and ketamine (K), alone and in combination (LK), on the minimum alveolar concentration (MAC) of isoflurane (ISO) in goats.Study design Randomized crossover design.Animals Eight, adult mixed breed castrated male goats, aged 1–2 years weighing 24–51 kg.Methods Anesthesia was induced with ISO that was delivered via a mask. The tracheas were intubated and the animals ventilated to maintain an end-tidal carbon dioxide partial pressure between 25 and 30 mmHg (3.3–4 kPa). Baseline MAC (MACB) that prevented purposeful movement in response to clamping a claw was determined in triplicate. After MACB determination, each goat received one of the following treatments, which were administered as a loading (LD) dose followed by a constant rate infusion, IV: L (2.5 mg kg−1; 100 μg kg−1 minute−1), K (1.5 mg kg−1; 50 μg kg−1 minute−1), L and K combination or saline, and the MAC (MACT) was re-determined in triplicate. Plasma concentrations of L and K were measured around each MAC point and the values averaged.Results The least-squares mean MACB for all treatments was 1.13 ± 0.03%. L, K, and LK reduced (p < 0.05) MACB by 18.3%, 49.6% and 69.4%, respectively. Plasma concentrations for L, K, and LK were 1617 ± 385, 1535 ± 251 and 1865 ± 317/1467 ± 185 ng mL−1, respectively. No change (p > 0.05) occurred with saline.Conclusion Lidocaine and K caused significant decreases in the MAC of ISO. The combination (LK) had an additive effect. However, the plasma L concentrations were less than predicted, as was the MAC reduction with L.Clinical relevance The use of L, K and the combination, at the doses studied, will allow a clinically important reduction in the concentration of ISO required to maintain general anesthesia in goats.Veterinary Anaesthesia and Analgesia 01/2007; 34(2):125 - 131. · 1.34 Impact Factor
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ABSTRACT: Cardiovascular effects of high dose opioid together with low dose inhalant were compared with inhalant alone to determine whether opioid/inhalant techniques were less depressant on the cardiovascular system. The effects of positive pressure ventilation and increasing heart rate to a more physiological level were also studied. Cardiovascular measurements recorded during administration of enflurane at 1.3 minimum alveolar concentration (MAC; 2.89 +/- 0.02%) to spontaneously breathing dogs (time 1) and during controlled ventilation [arterial carbon dioxide tension at 40 +/- 3 mmHg (time 2)] were similar. At time 2, mixed venous oxygen tension and arterial and mixed venous carbon dioxide tensions were significantly decreased, while arterial and mixed venous pH were significantly increased compared to measurements at time 1. After administration of fentanyl to achieve plasma fentanyl concentration of 71.7 +/- 14.4 ng/mL and reduction of enflurane concentration to yield 1.3 MAC multiple (0.99 +/- 0.01%), heart rate significantly decreased, while mean arterial pressure, central venous pressure, stroke index, and systemic vascular resistance index increased compared to measurements taken at times 1 and 2. Pulmonary arterial occlusion pressure was significantly increased compared to measurements taken at time 2. After administration of atropine until heart rate was 93 +/- 5 beats/min (plasma fentanyl concentration 64.5 +/- 13.5 ng/mL) heart rate, mean arterial pressure, cardiac index, oxygen delivery index, and venous admixture increased significantly compared to values obtained at all other times.(ABSTRACT TRUNCATED AT 250 WORDS)Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire 11/1994; 58(4):248-53. · 1.19 Impact Factor