[The relationship of individual sensitivities to fentanyl and those to propofol].
BACKGROUND
Individual variation in the sensitivity to anesthetics induces the delayed awakening and the severe postoperative pain at an inappropriate dose. We designed the study to see the correlation of the individual sensitivity to fentanyl and that to propofol which have different mechanism.


METHODS
General anesthesia was induced using target controlled infusion system of fentanyl and propofol. Fentanyl effect-site concentration gradually increased towards a target plasma concentration of 3 ng x ml(-1) until the appearance of the subjective symptom such as dizziness, a sensation of warmth and other reactions. After this, propofol effect-site concentration gradually increased towards a target plasma concentration of 4 microg x ml(-1) until loss of consciousness (LOC). The effect-site concentrations of fentanyl at the symptom and propofol at loss of consciousness were measured.


RESULTS
The correlation between the estimated effect-site concentration of fentanyl and propofol is not significant in the whole patient. However, a positive correlation between fentanyl and propofol was found in patients from 50s to 70s years of ages (r = 0.59).


CONCLUSIONS
The correlation of the individual sensitivity to fentanyl and propofol was found in older age groups.
Ueta
Kazuyoshi
K
Department of Anesthesia, Japan Labor Health and Welfare Organization, Kansai Rosai Hospital, Amagasaki 660-8511.
Nougawa
Rika
R
Amano
Masaru
M
Mashimo
Takashi
T
Nagata
Osamu
O
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D005283:Fentanyl / Q000494:pharmacology*; D006801:Humans; D007206:Individuality; D008875:Middle Aged; D015742:Propofol / Q000494:pharmacology*
D018686:Anesthetics, Intravenous; D005283:Fentanyl; D015742:Propofol