[Isoflurane anesthesia in the Gottinger minipig. Hemodynamic and cardiac changes under controlled ventilation]

10 adult, female Göttingen minipigs were anaesthetized with isoflurane under controlled ventilation. A mixture of O2: N2O = 1:3 was used to vaporize isoflurane in an inspiratory concentration of 1.75-2.0 Vol%. Electrocardiogram, blood pressure, cardiac output and central venous pressure were continuously monitored. To determine the maximum rate of rise of intraventricular pressure (dp/dt max) as an indirect measure of myocardial contractility we placed a micro-tip manometer in the left ventricle before and during (30 min value) the experiment. Acid-base balance was controlled by collecting arterial blood samples anaerobically. We found a negative chronotropic and marked inotropic effect of isoflurane on the heart-muscle. This probably is the main cause for the depression of arterial pressure, though peripheral vasodilatation has some effect. All cardiovascular changes were fully reversible within a few minutes of completing anaesthesia. After only 15 min all animals were fully conscious and data values had returned to control levels. Because of its deficient metabolism and toxicity isoflurane seems to be well qualified for use in experimental medicine in minipigs, especially when the animals require long or multiple exposure. But we recommend the use of isoflurane in combination with a basic anaesthesia, for example NLA or Ketamine to reduce cardiovascular depression.