A comparison of the effects of continuous ketamine infusion and halothane on oxygenation during one-lung anaesthesia in dogs.

It has been shown that a continuous infusion of ketamine during one-lung anaesthesia combined with a 50 per cent oxygen-curare anaesthetic technique will provide consistently lower shunt fraction and higher Pao2 compared with halothane under the same experimental conditions. Because no additional factor was observed which could account for these changes and because the responses of the animals to the two anaesthetic agents were similar--the only difference being a different initial set point--the experimental model may be considered adequate. In the authors' view the difference in shunt fractions may be attributed to a more stable hypoxic reflex during ketamine anaesthesia. Further experimentation will be necessary to fully exclude the possibility of sequence-related changes affecting some of these results and to determine whether or not certain groups of dogs respond in a qualitatively different fashion.