A. Wessen et al., CONCENTRATION-EFFECT RELATIONSHIPS OF PROPOFOL AFTER TOTAL INTRAVENOUS ANESTHESIA, Anesthesia and analgesia, 77(5), 1993, pp. 1000-1007
To evaluate the concentration-effect relationships of propofol during
recovery after total intravenous anesthesia, 20 female patients underg
oing lower abdominal surgery were studied. In 10 patients (Group B) th
e propofol infusion was supplemented with an epidural block with bupiv
acaine to evaluate the relation between the blood concentration of pro
pofol and various pharmacodynamic end-points. The remaining 10 patient
s (Group A) received an alfentanil infusion intravenously instead of t
he epidural block to assess the dynamic interactions of alfentanil and
propofol. Post-operative performances (drowsiness, amnesia, cooperati
on, and orientation) were evaluated by means of scoring scales. Critic
al flicker fusion threshold (CFF) also was used to assess the level of
postoperative alertness. A propofol blood concentration of 2.5 mug/mL
was required for satisfactory hypnosis during surgery and at 0.8 +/-
0.4 mug/mL, the patients were considered fully awake. A concomitant al
fentanil infusion reduced the propofol concentration required by 0.2-0
.4 mug/mL for the same degree of effect. Rapid recovery was seen in al
l patients, but in the group receiving alfentanil infusion there was a
shift to the left of the concentration-effect curve in regard to drow
siness and a statistically significant prolongation of recovery by CFF
-measurement which suggests a possible dynamic interaction with alfent
anil. We conclude that there is a good correlation between the blood c
oncentration of propofol and the pharmacodynamic responses during reco
very.