Isoflurane Produces Marked and Nonlinear Decreases in the Vasoconstriction and Shivering Thresholds

Abstract

The vasoconstriction-to-shivering range remained unchanged by isoflurane administration. In this regard, the effects of isoflurane are similar to those of desflurane, propofol, and alfentanil. The current data differ from the authors' previous report, in that the dose-dependence for vasoconstriction was nonlinear, with isoflurane reducing the threshold disproportionately at higher anesthetic concentrations. Differing dose-dependence in the two studies may result either because the current study's volunteers were not exposed to surgical stimulation and were given less isoflurane, or because of design limitations in the previous protocol.