Summary
In two groups of dogs, uptake and elimination of halothane and isoflurane were studied using a closed-loop anesthesia system which automatically controlled end-tidal halothane or isoflurane partial pressure at minimal alveolar concentration (MAC) equivalent levels. Hemodynamic and respiratory variables were recorded and the anesthetic partial pressure was measured in the inspired and expired air, as well as in the arterial, cerebrovenous and mixed venous blood. Data were recorded during wash-in, hyperventilation, hypercirculation, hypotension and wash-out. For halothane, the controller delivered a higher inspired partial pressure than for isoflurane to compensate for the higher blood/gas partition coefficient. This was especially pronounced during the wash-in and the hypercirculation periods. Smaller differences between halothane and isoflurane partial pressures occurred during hyperventilation, hypotension and the wash-out period and could be explained by the lower solubility of isoflurane. These results show that even under unstable ventilatory and hemodynamic conditions, the inspired concentration of isoflurane has to be adjusted less often and to a smaller degree than that of halothane if end-tidal concentrations are to be maintained constant.
References
Cromwell, T. H., Eger, E. I., Stevens, W. C., and Dolan, W. M., Anesthesiology35 (1971) 401.
Eger, E. I., and Severinghaus, J. W., Anesthesiology25 (1964) 620.
Eger, E. I., and Bahlman, S. H., Anesthesiology35 (1971) 301.
Eger, E. I., Anesthetic Uptake and Action, vol. II. Baltimore 1974.
Halands, G. H., Greene, R., Iliff, L. D., and Nunn, J. F., Clin. Sci.38 (1970) 451.
Joas, T. A., and Stevens, W. C., Anesthesiology35 (1971) 48.
Lowe, H. J., Ohio Medical Anesthetics New Drug Application on Isoflurane, p. 625. 1975.
Sawyer, D. C., Eger, E. I., and Bahlman, S. H., Anesthesiology34 (1971) 230.
Shibuya, T., Hashimtoto, K., and Imai, S., J. cardiovasc. Pharmac.5 (1983) 538.
Steffey, E. P., and Howland, D., Am. J. vet. Res.38 (1977) 1833.
Westenskow, D. R., Zbinden, A. M., Thomson, D. A., and Kohler, B., Br. J. Anaesth.58 (1986) 555.
Yamamura, H., Anesthesia18 (1963) 427.
Zbinden, A. M., Frei, F. J., Funk, B., Thomson, D. A., and Westenskow, D., Br. J. Anaesth.57 (1985) 796.
Zbinden, A. M., Westenskow, D., Thomson, D. A., Funk, B., and Maertens, J., J. clin. Monitor. Comput.2 (1986) 151.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Frei, F.J., Thomson, D.A. & Zbinden, A.M. Influence of ventilatory and circulatory changes on the pharmacokinetics of halothane and isoflurane. Experientia 44, 178–181 (1988). https://doi.org/10.1007/BF01952208
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF01952208