Objective - To evaluate the effects of intravenous lidocaine (L) and ketamine (K) alone and their combination (LK) on the minimum alveolar concentration (MAC) of sevoflurane (SEVO) in dogs. Study Design - Prospective randomized, Latin-square experimental study. Animals - Six, healthy, adult Beagles, 2 males, 4 females, weighing 7.8-12.8 kg. Methods - Anesthesia was induced with SEVO in oxygen delivered by face mask. The tracheas were intubated and the lungs ventilated to maintain normocapnia. Baseline minimum alveolar concentration of SEVO (MACB) was determined in duplicate for each dog using an electrical stimulus and then the treatment was initiated. Each dog received each of the following treatments, intravenously as a loading dose (LD) followed by a constant rate infusion (CRI): lidocaine (LD 2 mg kg-1, CRI 50 g kg-1 minute-1), lidocaine (LD 2 mg kg-1, CRI 100 g kg-1 minute-1), lidocaine (LD 2 mg kg-1, CRI 200 g kg-1 minute-1), ketamine (LD 3 mg kg-1, CRI 50 g kg-1 minute-1), ketamine (LD 3 mg kg-1, CRI 100 g kg-1 minute-1), or lidocaine (LD 2 mg kg-1, CRI 100 g kg-1 minute-1)+ketamine (LD 3 mg kg-1, CRI 100 g kg-1 minute-1) in combination. Post-treatment MAC (MACT) determination started 30 minutes after initiation of treatment. Results - Least squares meanSEM MACB of all groups was 1.90.2%. Lidocaine infusions of 50, 100, and 200 g kg-1 minute-1 significantly reduced MACB by 22.6%, 29.0%, and 39.6%, respectively. Ketamine infusions of 50 and 100 g kg-1 minute-1 significantly reduced MACB by 40.0% and 44.7%, respectively. The combination of K and L significantly reduced MACB by 62.8%. Conclusions and clinical relevance - Lidocaine and K, alone and in combination, decrease SEVO MAC in dogs. Their use, at the doses studied, provides a clinically important reduction in the concentration of SEVO during anesthesia in dogs.
- anaesthesia anaesthetics drug combinations drug delivery systems inhaled anaesthetics ketamine lidocaine dogs anesthesia anesthetics inhaled anesthetics lignocaine sevoflurane Canis Canidae Fissipeda carnivores mammals vertebrates Chordata animals small mammals eukaryotes
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