Research in veterinary science
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The effect of inhaling nitric oxide in the hypoxic pulmonary vascular response was measured in five calves anaesthetised with a combination of guaiacol, ketamine and xylazine. Alveolar hypoxia was induced by means of the inhalation of a gas mixture with an inspiratory oxygen fraction of 14-18 per cent. This alveolar hypoxia resulted in a pronounced pulmonary hypertension (mean pulmonary artery pressure in hypoxic animals: 30.2 mmHg). ⋯ A concentration of 40 ppm of nitric oxide fully abolished the hypoxia induced pulmonary hypertension (mean pulmonary artery pressure during inhalation of 40 ppm nitric oxide: 22.8 mmHg). Inhalation of nitric oxide had no effect on systemic arterial blood pressure nor on systemic vascular resistance. It was concluded that inhalation of 20 or 40 ppm of nitric oxide prevented a selective pulmonary vasoconstriction during alveolar hypoxia in calves, which may be helpful in the treatment of acute respiratory disorders in calves.
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Comparative Study
Cardiopulmonary effects of sevoflurane in cats: comparison with isoflurane, halothane, and enflurane.
The cardiopulmonary effects of sevoflurane (mean, 2.6, 3.8-3.9 and 5.2 per cent) were compared with those of halothane (1.2, 1.8 and 2.4 per cent), enflurane (2.4, 3.6 and 4.8 per cent) and isoflurane (1.6, 2.4 and 3.2-3.3 per cent) at end-tidal concentrations equivalent to 1, 1.5 and 2 minimal alveolar concentrations (MACs) during spontaneous or controlled ventilation (SV or CV) in 57 cats. Cats were assigned to four groups of nine animals each in SV trial and four groups of five or six animals each in CV trial. ⋯ During SV and CV, four anaesthetics decreased heart rate at 2 MAC when compared with control values, but there was no significant difference between anaesthetics. Sevoflurane, like halothane and isoflurane, induced hypotension at 2 MAC when compared with 1 MAC.