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BACKGROUND Desflurane decreases the vasoconstriction and shivering thresholds disproportionately at high anesthetic concentrations. This result contrasts with the authors' previous report that isoflurane decreases the vasoconstriction threshold linearly. It is surprising that the basic shape of the concentration-response curve should differ with these two otherwise similar anesthetics. Therefore, the hypothesis that isoflurane produces a nonlinear reduction in the vasoconstriction threshold was tested. Because the effect of isoflurane on shivering remains unknown, the extent to which isoflurane reduces the shivering threshold also was determined. METHODS Eight men volunteered to be studied on four randomly ordered days: (1) a target end-tidal isoflurane concentration of 0.55%, (2) a target concentration of 0.7%, (3) control (no anesthesia) and a target end-tidal concentration of 0.85%, and (4) a target end-tidal concentration of 1.0%. Volunteers were surface-cooled until peripheral vasoconstriction and shivering were observed. We arithmetically compensated for changes in skin temperature using the established linear cutaneous contributions to control for each response. From the calculated thresholds (core temperatures triggering responses at a designated skin temperature of 34 degrees C), the concentration-response relation was determined. RESULTS Isoflurane administration produced a dose-dependent reduction in the vasoconstriction and shivering thresholds, decreasing each approximately 4.6 degrees C at an end-tidal concentration of 1%. Residual analysis indicated that the vasoconstriction and shivering thresholds were decreased in a nonlinear fashion during isoflurane administration. The vasoconstriction-to-shivering range was 1.5 +/- 0.8 degree C without isoflurane, and did not change significantly during isoflurane administration. CONCLUSIONS 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.
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
December 1995,
Anesthesiology,
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
June 1997,
Canadian journal of anaesthesia = Journal canadien d'anesthesie,
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
September 1993,
Anesthesiology,
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
August 1999,
Anesthesiology,
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
July 1998,
Anesthesia and analgesia,
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
May 1995,
Anesthesiology,
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
October 1997,
Anesthesiology,
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
October 1998,
Journal of applied physiology (Bethesda, Md. : 1985),
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
April 1994,
Anesthesiology,
J Xiong, and
A Kurz, and
D I Sessler, and
O Plattner, and
R Christensen, and
M Dechert, and
T Ikeda
January 2003,
British journal of anaesthesia,
