Pain on injection does not affect the effect site concentration of propofol at loss of consciousness

Growth hormone (GH) secretion is regulated by various hormones or neurotransmitters, including gamma-aminobutyric acid. The aim of this study was to determine the propofol requirement in patients with GH-secreting pituitary tumors undergoing transsphenoidal surgery. General anesthesia was induced in 60 patients with GH-secreting tumors (GH group, n = 30) or nonfunctioning pituitary tumors (NF group, n = 30) using an effect-site target-controlled intravenous propofol infusion. The effect-site concentrations were recorded at both a loss of consciousness and a bispectral index (BIS) of 40, along with the effect-site concentration after extubation, during emergence from the anesthesia. The effect-site concentration of propofol was higher in the GH group than in the NF group at a loss of consciousness and a BIS of 40 (4.09 ± 0.81 vs. 3.58 ± 0.67, p = 0.009 and 6.23 ± 1.29 vs. 5.50 ± 1.13, p = 0.025, respectively) and immediately after extubation (1.60 ± 0.27 vs. 1.40 ± 0.41, p = 0.046). The total doses of propofol and remifentanil during anesthesia were comparable between the groups (127.56 ± 29.25 vs. 108.64 ± 43.16 µg/kg/min, p = 0.052 and 6.67 ± 2.89 vs. 7.05 ± 1.96 µg/kg/h, p = 0.550, respectively). The propofol requirement for the induction of a loss of consciousness and the achievement of a BIS of 40 is increased during the induction of general anesthesia in patients with GH-secreting tumors.

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Performance of the ARX-derived Auditory Evoked Potential Index as an Indicator of Anesthetic Depth

Anesthesiology ◽

10.1097/00000542-200204000-00006 ◽

2002 ◽

Vol 96 (4) ◽

pp. 803-816 ◽

Cited By ~ 155

Author(s):

Michel M. R. F. Struys ◽

Erik Weber Jensen ◽

Warren Smith ◽

N. Ty Smith ◽

Ira Rampil ◽

...

Keyword(s):

Bispectral Index ◽

Evoked Potential ◽

Auditory Evoked Potential ◽

Noxious Stimulus ◽

Gynecologic Surgery ◽

Effect Compartment ◽

Loss Of Consciousness ◽

Anesthetic Depth ◽

Effect Site ◽

Effect Site Concentration

Background Autoregressive modeling with exogenous input of middle-latency auditory evoked potential (A-Line autoregressive index [AAI]) has been proposed for monitoring anesthetic depth. The aim of the current study was to compare the accuracy of this new index with the Bispectral Index (BIS), predicted effect-site concentration of propofol, and hemodynamic measures. Methods Twenty female patients scheduled for ambulatory gynecologic surgery received effect compartment controlled infusion of propofol. Target effect-site concentration was started at 1.5 microg/ml and increased every 4 min by 0.5 microg/ml. At every step, sedation level was compared with monitoring values using different clinical scoring systems and reaction to noxious stimulus. Results Bispectral Index, AAI, and predicted propofol effect-site concentration were accurate indicators for the level of sedation and loss of consciousness. Hemodynamic variables were poor indicators of the hypnotic-anesthetic status of the patient. BIS correlated best with propofol effect-site concentration, followed by AAI. Hemodynamic measurements did not correlate well. No indicators predicted reaction to noxious stimulus. Poststimulus, BIS and AAI showed an increase as a result of arousal. This reaction occurred more rapidly with the AAI than with BIS. Conclusion Bispectral Index, AAI, and predicted propofol effect-site concentration revealed information on the level of sedation and loss of consciousness but did not predict response to noxious stimulus.

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Comparison of Plasma Compartment versus Two Methods for Effect Compartment–controlled Target-controlled Infusion for Propofol

Anesthesiology ◽

10.1097/00000542-200002000-00021 ◽

2000 ◽

Vol 92 (2) ◽

pp. 399-399 ◽

Cited By ~ 186

Author(s):

Michel M. R. F. Struys ◽

Tom De Smet ◽

Birgit Depoorter ◽

Linda F. M. Versichelen ◽

Eric P. Mortier ◽

...

Keyword(s):

Time Course ◽

Drug Effect ◽

Peak Effect ◽

Effect Compartment ◽

Loss Of Consciousness ◽

Group Iii ◽

Time To Peak ◽

Effect Site ◽

Effect Site Concentration ◽

Plasma Effect

Background Target-controlled infusion (TCI) systems can control the concentration in the plasma or at the site of drug effect. A TCI system that targets the effect site should be able to accurately predict the time course of drug effect. The authors tested this by comparing the performance of three control algorithms: plasmacontrol TCI versus two algorithms for effect-site control TCI. Methods One-hundred twenty healthy women patients received propofol via TCI for 12-min at a target concentration of 5.4 microg/ml. In all three groups, the plasma concentrations were computed using pharmacokinetics previously reported. In group I, the TCI device controlled the plasma concentration. In groups II and III, the TCI device controlled the effect-site concentration. In group II, the effect site was computed using a half-life for plasma effect-site equilibration (t1/2k(eo)) of 3.5 min. In group III, plasma effect-site equilibration rate constant (k(eo)) was computed to yield a time to peak effect of 1.6 min after bolus injection, yielding a t1/2keo of 34 s. the time course of propofol was measured using the bispectral index. Blood pressure, ventilation, and time of loss of consciousness were measured. Results The time course of propofol drug effect, as measured by the bispectral index, was best predicted in group III. Targeting the effect-site concentration shortened the time to loss of consciousness compared with the targeting plasma concentration without causing hypotension. The incidence of apnea was less in group III than in group II. Conclusion Effect compartment-controlled TCI can be safely applied in clinical practice. A biophase model combining the Marsh kinetics and a time to peak effect of 1.6 min accurately predicted the time course of propofol drug effect.

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Effect-site Concentration of Propofol Target-controlled Infusion at Loss of Consciousness in Intractable Epilepsy Patients Receiving Long-term Antiepileptic Drug Therapy

Journal of Neurosurgical Anesthesiology ◽

10.1097/ana.0b013e31820a4f75 ◽

2011 ◽

Vol 23 (3) ◽

pp. 188-192 ◽

Cited By ~ 2

Author(s):

Eun Mi Choi ◽

Seung Ho Choi ◽

Min Huiy Lee ◽

Sang Hee Ha ◽

Kyeong Tae Min

Keyword(s):

Drug Therapy ◽

Antiepileptic Drug ◽

Intractable Epilepsy ◽

Loss Of Consciousness ◽

Effect Site ◽

Target Controlled Infusion ◽

Effect Site Concentration ◽

Antiepileptic Drug Therapy

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Automated Responsiveness Test (ART) Predicts Loss of Consciousness and Adverse Physiologic Responses during Propofol Conscious Sedation

Anesthesiology ◽

10.1097/00000542-200104000-00010 ◽

2001 ◽

Vol 94 (4) ◽

pp. 585-592 ◽

Cited By ~ 26

Author(s):

Anthony G. Doufas ◽

Maryam Bakhshandeh ◽

Andrew R. Bjorksten ◽

Robert Greif ◽

Daniel I. Sessler

Keyword(s):

Nitrous Oxide ◽

Conscious Sedation ◽

Predictive Accuracy ◽

Control Period ◽

Loss Of Consciousness ◽

Effect Site ◽

Effect Site Concentration ◽

Target Effect ◽

Physiologic Responses ◽

Initial Target

Background The authors evaluated a device designed to provide conscious sedation with propofol (propofol-air), or propofol combined with 50% nitrous oxide (N2O; propofol-N2O). An element of this device is the automated responsiveness test (ART), a method for confirming that patients remain conscious. The authors tested the hypotheses that the ART predicts loss of consciousness and that failure to respond to the ART precedes sedation-induced respiratory or hemodynamic toxicity. Methods The protocol consisted of sequential 15-min cycles in 20 volunteers. After a 15-min control period, propofol was infused to an initial target effect-site concentration of 0.0 microg/ml with N2O or 1.5 microg/ml with air. Subsequently, the propofol target effect-site concentration was increased by a designated increment (0.25 and 0.5 microg/ml) and the process repeated. This sequence was continued until loss of consciousness, as defined by an Observer's Assessment of Alertness/Sedation (OAA/S) score of 10/20 or less, or until an adverse physiologic event was detected. Results The OAA/S score at which only 50% of the volunteers were able to respond to the ART (P50) during propofol-N2O was 11.1 of 20 (95% confidence interval [CI]: 10.6-11.8); the analogous P50 was 11.8 of 20 (95% CI: 11.4-12.3) with propofol-air. Failure to respond to the ART occurred at a plasma propofol concentration of 0.7 +/- 0.6 microg/ml with propofol-N2O and 1.6 +/- 0.6 microg/ml with propofol-air, whereas loss of consciousness occurred at 1.2 +/- 0.8 microg/ml and 1.9 +/- 0.7 microg/ml, respectively. There were no false-normal ART responses. Conclusion The ART can guide individual titration of propofol because failure to respond to responsiveness testing precedes loss of consciousness and is not susceptible to false-normal responses. The use of N2O with propofol for conscious sedation decreases the predictive accuracy of the ART.

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