AWAKENING PROPOFOL CONCENTRATION WITH AND WITHOUT BLOOD-EFFECT SITE EQUILIBRATION AFTER SHORT-TERM AND LONG-TERM ADMINISTRATION OF PROPOFOLAND FENTANYL ANESTHESIA

Citation
T. Kazama et al., AWAKENING PROPOFOL CONCENTRATION WITH AND WITHOUT BLOOD-EFFECT SITE EQUILIBRATION AFTER SHORT-TERM AND LONG-TERM ADMINISTRATION OF PROPOFOLAND FENTANYL ANESTHESIA, Anesthesiology, 88(4), 1998, pp. 928-934
Citations number
15
Categorie Soggetti
Anesthesiology
Journal title
ISSN journal
00033022
Volume
88
Issue
4
Year of publication
1998
Pages
928 - 934
Database
ISI
SICI code
0003-3022(1998)88:4<928:APCWAW>2.0.ZU;2-R
Abstract
Background: The propofol awakening concentration can vary. However, th e effect site awakening propofol concentration will be a fixed value. The purpose of this study was to determine the awakening propofol conc entrations obtained from infusion Schede using abrupt discontinuation of propofol (half-maximal effective concentration [EC50]) or a descend ing decrease in concentration to allow blood-effect site equilibration (EC(50)eq). Methods: Patients undergoing short-term (group 1) and lon g-term (group 2) elective surgery were anesthetized with computer-assi sted continuous infusion of propofol and fentanyl with both groups rec eiving the same propofol (3 mu g/ml) and fentanyl (1 ng/ml) concentrat ions 20-30 min before the end of surgery until the end. Then both grou ps were further divided into two subgroups: subgroup A abrupt disconti nuation, and subgroup B descending concentrations of propofol (15-min duration per concentration). In the A subgroups, the response to verba l command was evaluated every 30 s. In the B subgroups, the blood prop ofol concentrations just permitting and just preventing response to co mmand were averaged individually. The EC50 and EC(50)eq values were de termined by probit analysis. Results: The EC50 of group 1A was 1 mu g/ ml which was significantly less than the 1.6 mu g/ml of group 2A (P < 0.05). The awakening time of group 1A was 5.2 +/- 1.8 min, which was s ignificantly shorter than the 9.3 +/- 3.5 min of group 2A (means +/- S D). The EC(50)eq of both groups 1B and 2B was 2.2 mu g/ml. Conclusions : The EC(50)eq was independent of propofol infusion length, compared w ith the EC50. Thus the potential for hysteresis during emergence from propofol anesthesia was confirmed.