Plasma concentrations and cardiovascular influence of lidocaine infusions during isoflurane anesthesia in healthy dogs and dogs with subaortic stenosis

• Published in: Veterinary surgery 1998-09, Vol.27 (5), p.486-497
• Main Authors: Nunes de Moraes, A, Dyson, D.H, O'Grady, M.R, McDonell, W.N, Holmberg, D.L
• Format: Article
• Language: English
• Subjects: Anesthesia, Inhalation - veterinary; Anesthetics, Inhalation; Anesthetics, Local - administration & dosage; Anesthetics, Local - blood; Anesthetics, Local - pharmacology; Animals; Anti-Arrhythmia Agents - administration & dosage; Anti-Arrhythmia Agents - blood; Anti-Arrhythmia Agents - pharmacology; aorta; Aortic Stenosis, Subvalvular - blood; Aortic Stenosis, Subvalvular - physiopathology; Aortic Stenosis, Subvalvular - veterinary; blood chemistry; blood pressure; Cross-Over Studies; Dog Diseases - blood; Dog Diseases - physiopathology; dogs; Dogs - blood; Dogs - physiology; dosage; dose response; Electrocardiography - veterinary; Female; Fluorescence Polarization Immunoassay - veterinary; heart rate; Hemodynamics - drug effects; Infusions, Intravenous - veterinary; Isoflurane; lidocaine; Lidocaine - administration & dosage; Lidocaine - blood; Lidocaine - pharmacology; Male; resistance; stenosis
• ISSN: 0161-3499; 1532-950X
• DOI: 10.1111/j.1532-950X.1998.tb00161.x

Objective—To determine the plasma concentrations and cardiovascular changes that occur in healthy dogs and dogs with aortic stenosis that are given an infusion of lidocaine during isoflurane anesthesia. Study Design—Phase 1, controlled randomized cross‐over trial; Phase 2, before and after trial Animals—Phase 1, 6 healthy dogs (4 female, 2 male) weighing 23.8 ± 7.4 kg; Phase 2, 7 dogs (4 female, 3 male) with moderate to severe subaortic stenosis (confirmed by Doppler echocardiography) weighing 31.1 ± 14.5 kg. Methods—After mask induction, intubation, and institution of positive pressure ventilation, instrumentation was performed to measure hemodynamic variables. After baseline, measurement at an end‐tidal isoflurane concentration of 1.9% (phase 1) or 1.85% (phase 2), a loading dose infusion of lidocaine at 400 μg/kg/min was given. Phase 1: Maintenance doses of lidocaine were administered consecutively (40, 120, and 200 μg/kg/min) after the loading dose (given for 10, 10, and 5 minutes, respectively) in advance of each maintenance concentrations. Measurements were taken at the end of each loading dose and at 25 and 35 minutes during each maintenance level. The same animals on a different day were given dextrose 5% and acted as the control. Phase 2: Dogs were studied on a single occasion during an infusion of lidocaine at 120 μg/kg/ min given after the loading dose (10 minutes). Measurements occurred after the loading dose and at 25 and 35 minutes. A blood sample for lidocaine concentration was taken at 70 minutes. Data were compared using a one‐way ANOVA for phase 1, and between phase 1 and 2. Statistical analysis for phase 2 was performed using a paired r‐test with a Bonferroni correction. A P value ± .05 was considered significant. Results—Phase 1: Plasma lidocaine concentrations achieved with 40, 120, and 200 μg of lidocaine/kg/min were 2.70, 5.27, and 7.17 μg/mL, respectively. A significant increase in heart rate (HR) (all concentrations), central venous pressure (CVP), mean pulmonary areterial pressure (PAP), and a decrease in stroke index (SI) (200 μg/kg/min) were observed. An increase in systemic vascular resistance (SVR) and mean PAP, and a decrease in SI also followed the loading dose given before the 200 μg/kg/min infusion. No other significant differences from the control measurements, during dextrose 5% infusion alone, were detected. Phase 2: Plasma lidocaine concentrations achieved were 5.35, 4.23, 4.23, and 5.60 μg/mL at 10, 25, 35, and 70 min