The effect of halothane anesthesia on heart function during normovolemia and hypovolemia in the dog.

The effects of halothane anesthesia on coronary circulation and cardiac work were studied in normovolemic and hypovolemic dogs, with aid of the radioactive microsphere technique. During normovolemia, halothane depressed the heart rate, cardiac output, arterial mean blood pressure and left ventricular work, with a simultaneous decrease in the coronary blood flow. During moderate hypovolemia, the arterial blood pressure was reduced as well as the coronary blood flow; whereas during hemorrhagic hypotension (severe hypovolemia), the arterial blood pressure was slightly increased and the coronary blood flow was unchanged with a reduced heart rate and increased stroke volume.