Rapid 1% increases of end-tidal desflurane concentration to greater than 5% transiently increase heart rate and blood pressure in humans.
BACKGROUND
Large (0.5-1.0 MAC), rapid increases of desflurane to concentrations greater than 5% can transiently increase heart rate, mean arterial blood pressure (MAP), sympathetic nerve activity, and plasma epinephrine concentration. We tested the hypothesis that small (1% = 0.14 MAC), rapid increases of desflurane concentration to greater than 5% do not increase heart rate, blood pressure, and plasma catecholamine concentrations.


METHODS
Anesthesia was induced with intravenous propofol, 2 mg/kg, in 13 healthy male volunteers, 19-33 yr of age, and ventilation was controlled to maintain normocapnia. We gave 4% end-tidal desflurane in oxygen for 32 min and then imposed successive 1% increases in end-tidal desflurane concentration, each new concentration maintained for 4 min, to a final concentration of 12%. We measured heart rate, MAP and plasma catecholamine concentrations in the awake state, after 4 min at each 1% step, and at times of peak increase of MAP (> or = 10% change).


RESULTS
Increases in heart rate and blood pressure of more than 10% occurred with 1% step-increases in only 1 volunteer at 5% desflurane but in 7-10 (MAP) and 8-12 (heart rate) of the 13 volunteers at higher desflurane concentrations. The 1% increases in desflurane concentration to greater than 5% also transiently increased plasma epinephrine concentrations but not vasopressin concentration or plasma renin activity in those volunteers in whom MAP increased.


CONCLUSIONS
Small (1%) increases in desflurane concentration to and greater than 6% can transiently increase heart rate, mean arterial pressure, and plasma epinephrine concentration. These data and those from a previous study indicate that these increases occur with a lesser frequency and magnitude than those associated with a single, rapid step from 4% to 12% end-tidal desflurane.
Moore
M A
MA
Department of Anesthesia, University of California, San Francisco 94143-0648.
Weiskopf
R B
RB
Eger
E I
EI
Noorani
M
M
McKay
L
L
Damask
M
M
D000328:Adult; D001127:Arginine Vasopressin / Q000097:blood; D001794:Blood Pressure / Q000187:drug effects*; D000077335:Desflurane; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000097:blood; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D007530:Isoflurane / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D008168:Lung / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000097:blood; D012083:Renin / Q000097:blood; D013268:Stimulation, Chemical; D013990:Tidal Volume
D001127:Arginine Vasopressin; D000077335:Desflurane; D007530:Isoflurane; D012083:Renin; D009638:Norepinephrine; D004837:Epinephrine