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Schultz A, Grouven U, Zander I, Beger FA, Siedenberg M, Schultz B. Age-related effects in the EEG during propofol anaesthesia. Acta Anaesthesiol Scand 2004; 48:27-34. [PMID: 14674970 DOI: 10.1111/j.1399-6576.2004.00258.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Age-related differences in the spectral composition of the EEG in induction and emergence times, and in drug consumption during propofol anaesthesia were investigated. METHODS The EEGs of 60 female patients between 22 and 85 years of age were monitored continuously during standardized induction of anaesthesia with 2 mg of propofol kg(-1)60 s(-1). The EEGs were visually assessed in 20-s epochs according to a scale from A (awake) to F (very deep hypnosis). Visual EEG classifications, spectral parameters, and induction times were compared between different age groups. Additionally, data of 546 patients included in a multicentre study with 4630 patients (EEG monitor Narcotrend, MT MonitorTechnik, Bad Bramstedt, Germany) were analyzed with regard to age-dependent changes of propofol consumption using target-controlled infusion (TCI). RESULTS During induction, patients older than 70 years reached significantly deeper EEG stages than younger patients, needed a longer time to reach the deepest EEG stage, and needed more time until a light EEG stage was regained. In patients aged 70 years and older, the total power, mainly in deep EEG stages, was significantly smaller due to a distinctly smaller absolute power of the delta frequency band. No single spectral parameter was able to reliably distinguish all EEG stages. During the steady state of anaesthesia, older patients needed less propofol for the maintenance of a defined stage of hypnosis than younger patients. CONCLUSION Older patients differ from younger ones regarding the hypnotic effect of propofol and the spectral patterns in the EEG. For an efficient automatic assessment of the EEG during anaesthesia a multivariable approach accounting for age-effects is indispensable.
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Affiliation(s)
- A Schultz
- Department of Anaesthesiology, Klinikum Hannover Oststadt, Hannover Medical School, Germany.
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102
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Goodwin N, Campbell AE, Hall JE, Plummer S, Harmer M. A comparison of 8% and 12% sevoflurane for inhalation induction in adults. Anaesthesia 2004; 59:15-9. [PMID: 14687093 DOI: 10.1111/j.1365-2044.2004.03481.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Sevoflurane is a non-pungent volatile anaesthetic agent with a low blood-gas solubility coefficient. It has been studied in concentrations of up to 8% for induction of anaesthesia. Previous work has suggested that there may be a ceiling effect with increasing concentration of sevoflurane above 6%, but there are no published studies using 12% sevoflurane. This study compared 8 and 12% sevoflurane to induce anaesthesia in adults. Sevoflurane was administered using two adapted datum vaporisers with the interlock removed. Induction with 12% sevoflurane compared to 8% sevoflurane produced a significant decrease in the time to achieve central pupils, corresponding to surgical anaesthesia and the third part of Guedel's stage 3 of anaesthesia (mean time (SD) 201 s (81) and 247 s (39), respectively, p < 0.05). Twelve-percent sevoflurane produced a similar stable cardiovascular profile to 8% sevoflurane, and there was no increase in respiratory complications.
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Affiliation(s)
- N Goodwin
- Department of Anaesthetics, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XW, UK.
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103
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Mustola ST, Baer GA, Toivonen JK, Salomäki A, Scheinin M, Huhtala H, Laippala P, Jäntti V. Electroencephalographic burst suppression versus loss of reflexes anesthesia with propofol or thiopental: differences of variance in the catecholamine and cardiovascular response to tracheal intubation. Anesth Analg 2003; 97:1040-1045. [PMID: 14500154 DOI: 10.1213/01.ane.0000080156.05749.17] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED The electroencephalographic burst suppression pattern (BSP) might indicate the brain's effect-site concentration of anesthetics more precisely than clinical signs and thus eliminate bias from studies on the reaction to tracheal intubation after different induction drugs. To test this hypothesis, we compared the catecholamine and cardiovascular responses and their variances to tracheal intubation when either BSP was induced by infusion of propofol (30 mg x kg(-1) x h(-1); n = 14) or thiopental (75 mg x kg(-1) x h(-1); n = 14) or anesthesia by repeated bolus doses until loss of reflexes (LR), initially of propofol 2.5 mg/kg (n = 15) or thiopental 5 mg/kg (n = 15). The standard deviations were more often smaller in the BSP than in the LR groups, but the results of Levene's test for differences of variance were insignificant. At the LR level, propofol attenuated catecholamine, arterial blood pressure, and heart rate responses to intubation better than thiopental, but at the BSP level, only the norepinephrine response was better attenuated. Cp50 concentrations of propofol and thiopental at the onset of BSP were 9.65 and 31.60 micro g/mL, respectively. IMPLICATIONS Our results did not support the hypothesis that the responses to tracheal intubation can be more accurately predicted when unconsciousness is controlled with the aid of an electroencephalographic burst suppression pattern. Significant differences were found in the reactions between propofol and thiopental. At the burst suppression level, the catecholamine response was abolished with propofol.
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Affiliation(s)
- Seppo T Mustola
- *Department of Anesthesia, South Carelia Central Hospital, Lappeenranta, Finland; †Department of Anesthesia, Tampere University Hospital, Tampere, Finland; ‡Department of Chemistry, Tampere University Hospital, Tampere, Finland; §Department of Pharmacology, University of Turku, Turku, Finland; ∥School of Public Health, University of Tampere, Tampere, Finland; ¶School of Public Health, Research Unit, Tampere University Hospital, Tampere, Finland; and #Ragnar Granit Institute, Tampere University of Technology, Tampere, Finland
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104
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Lallemand MA, Lentschener C, Mazoit JX, Bonnichon P, Manceau I, Ozier Y. Bispectral index changes following etomidate induction of general anaesthesia and orotracheal intubation. Br J Anaesth 2003; 91:341-6. [PMID: 12925471 DOI: 10.1093/bja/aeg175] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Etomidate-associated hypnosis has only been studied using standard clinical criteria and raw EEG variables. We conducted a BIS-based investigation of etomidate induction of general anaesthesia. METHODS Thirty hydroxyzine-premedicated ASA I patients were randomly allocated to receive etomidate 0.2, 0.3, or 0.4 mg kg(-1) intravenously over 30 s. The BIS was continuously recorded. A tourniquet was placed on a lower limb to record purposeful movements and myoclonia. Tracheal intubation was facilitated using rocuronium 0.6 mg kg(-1) when the BIS value was 50. The times to disappearance of the eyelash reflex, to a decrease in the BIS to 50, and to tracheal intubation were compared. The BIS values 30 s following tracheal intubation, and mean arterial pressure (MAP) and heart rate (HR) at all time points were also recorded. RESULTS The BIS value decreased to 50 for tracheal intubation with no purposeful movement in all but one patient in the 0.2 mg kg(-1) group. There was no difference between the etomidate groups (0.2, 0.3, and 0.4 mg kg(-1)) in regards to time to loss of the eyelash reflex (103 (67), 65 (34), 116 (86) s, P=0.2), or to a decrease in BIS to 50 (135 (81), 82 (36), 150 (84) s, P=0.1). Also, the BIS value 30 s after intubation (41 (10), 37 (4), 37 (4), P=0.4), and plasma etomidate concentrations (161 [29-998], 308 [111-730], 310 [90-869] ng ml(-1), P=0.2) did not differ between groups. The time to loss of the eyelash reflex was 12-140 s shorter than the time to a decrease in BIS to 50 in three patients in each group who received etomidate 0.2 and 0.4 mg kg(-1), and in four patients who received 0.3 mg kg(-1). No awareness was recorded. MAP and HR increases following tracheal intubation were comparable between groups. CONCLUSIONS Etomidate induction doses do not predict the time for BIS to decrease to 50 as this variable varies markedly following three etomidate dose regimen.
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Affiliation(s)
- M-A Lallemand
- Department of Anaesthesia and Intensive Care, University Paris V-René Descartes, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, F-75679 Paris Cedex 14, France
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105
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Steyn-Ross ML, Steyn-Ross DA, Sleigh JW, Whiting DR. Theoretical predictions for spatial covariance of the electroencephalographic signal during the anesthetic-induced phase transition: Increased correlation length and emergence of spatial self-organization. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:021902. [PMID: 14525001 DOI: 10.1103/physreve.68.021902] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2002] [Indexed: 05/24/2023]
Abstract
In a recent series of papers, the authors have developed a stochastic theory to describe the electrical response of a spatially homogeneous cerebral cortex to infusion of a general anesthetic agent. We showed that by modeling the GABAergic (propofol-like) drug effect as a prolongation of the inhibitory postsynaptic impulse response, we obtain a prediction that there will be a hysteretically separated pair of first-order phase transitions in the population-average excitatory soma voltage, the first occurring at the point of induction of unconsciousness, and the second at the point of emergence from unconsciousness. In the present paper we generalize our earlier "zero-dimensional" homogeneous cortex to a one-dimensional (1D) line of cortical "mass," thus allowing for the possibility of spatial inhomogeneities in neural activity. Following the spirit of our earlier adiabatic ("slow membrane") philosophy, we impose a spatioadiabatic approximation that permits us to compute analytic expressions for changes in EEG (electroencephalographic) correlation length and EEG spatial covariance as a function of anesthetic effect. We establish that the correlation length of the EEG fluctuations is expected to increase at the approach to the transition points, and this finding is consistent with both the homogeneous-cortex prediction of increased correlation time ("critical slowing down") near transition, and the recent, comprehensive anesthetic study by John et al. [Conscious. Cogn. 10, 165 (2001)] reporting an increase in EEG coherence near the points of loss and recovery of consciousness. In addition, we find that if the long-range (corticocortical) excitatory-to-inhibitory connectivity in the 1D cortex is stronger than the long-range excitatory-to-excitatory connectivity, then the spatioadiabatic system can organize itself into large-amplitude spatial patterns ("dissipative structures") consisting of giant stationary quasiperiodic voltage fluctuations distributed along the cortical rod.
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Affiliation(s)
- Moira L Steyn-Ross
- Department of Physics and Electronic Engineering, Private Bag 3105, University of Waikato, Hamilton, New Zealand
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106
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Naguib M, Schmid PG, Baker MT. The electroencephalographic effects of IV anesthetic doses of melatonin: comparative studies with thiopental and propofol. Anesth Analg 2003; 97:238-43, table of contents. [PMID: 12818973 DOI: 10.1213/01.ane.0000065545.58026.23] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED We have demonstrated that large-dose IV melatonin can exert hypnotic effects similar to those caused by thiopental and propofol. In this study, we compared the electroencephalographic (EEG) effects of melatonin with those of thiopental and propofol. Sprague-Dawley rats were assigned to receive equipotent bolus doses of thiopental (23.8 mg/kg), propofol (14.9 mg/kg), or melatonin (312 mg/kg). EEG effects were recorded at periodic intervals over 10 minutes. Of eight processed EEG variables analyzed, only relative total power (rTP), relative spectral edge 95% (rSE95), and relative approximate entropy (rAE) were altered by all drugs compared with their control vehicles. Drug administration decreased the values relative to baseline, with subsequent return toward baseline during the 10-min time course. Thiopental significantly increased rTP, whereas propofol and melatonin did not. All drugs significantly decreased rSE95. However, the time course of peak effect and duration differed for each, with melatonin exhibiting a slower onset and a more sustained EEG effect. All drugs significantly decreased rAE, with similar time courses for thiopental and propofol and a slower onset/longer duration for melatonin. Melatonin produced effects on processed EEG variables similar to those of thiopental and propofol, specifically a decrease in the rSE95 and a decrease in the rAE. IMPLICATIONS Anesthetic doses of melatonin produced effects on processed electroencephalographic variables similar to those of thiopental and propofol.
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Affiliation(s)
- Mohamed Naguib
- Department of Anesthesia, University of Iowa College of Medicine, Iowa City 52242, USA.
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107
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Johnson KB, Egan TD, Layman J, Kern SE, White JL, McJames SW. The influence of hemorrhagic shock on etomidate: a pharmacokinetic and pharmacodynamic analysis. Anesth Analg 2003; 96:1360-1368. [PMID: 12707134 DOI: 10.1213/01.ane.0000055804.30509.69] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED We studied the influence of hemorrhagic shock on the pharmacology of etomidate in swine. Sixteen swine were randomly assigned to control and shock groups. The shock group was bled to a mean arterial blood pressure of 50 mm Hg and held there until 30 mL/kg blood was removed. Etomidate 300 micro g x kg(-1) x min(-1) was infused for 10 min to both groups. Fifteen arterial samples were collected until 180 min after the infusion began to determine drug concentration. Pharmacokinetic variables for each group were estimated by using a three-compartment model. The bispectral index scale was used as a measure of drug effect. The pharmacodynamics were characterized by using a sigmoid inhibitory maximal effect model. The raw data revealed a 25% increase in the plasma etomidate concentration at the end of the 10-min infusion which resolved after termination of the infusion in the shock group. The pharmacokinetic analysis revealed subtle changes in the variable estimates between groups. The etomidate infusion produced a similar Bispectral Index Scale change in both groups. These results demonstrated that, unlike the influence of hemorrhagic shock on other sedative hypnotics and opioids, moderate hemorrhagic shock produced minimal changes in the pharmacokinetics and no change in the pharmacodynamics of etomidate. IMPLICATIONS Hemorrhagic shock produced minimal changes in the pharmacokinetics and no change in the pharmacodynamics of etomidate in swine. These results suggest that, unlike other sedative hypnotics and opioids, minimal adjustment in the dose of etomidate is required to achieve the same drug effect during hemorrhagic shock.
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Affiliation(s)
- Ken B Johnson
- Department of Anesthesiology, University of Utah School of Medicine, Salt Lake City, Utah
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108
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Erhan E, Ugur G, Gunusen I, Alper I, Ozyar B. Propofol - not thiopental or etomidate - with remifentanil provides adequate intubating conditions in the absence of neuromuscular blockade. Can J Anaesth 2003; 50:108-15. [PMID: 12560298 DOI: 10.1007/bf03017840] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
PURPOSE Administration of remifentanil followed by propofol provides adequate conditions for tracheal intubation without muscle relaxants. Other hypnotic drugs have not been thoroughly investigated in this regard. Intubating conditions with remifentanil followed by propofol, thiopentone or etomidate are compared in this study. METHODS In a randomized, double-blind study 45 healthy males were assigned to one of three groups (n = 15). After iv atropine, remifentanil 3 microg x kg(-1) were injected over 90 sec followed by propofol 2 mg x kg(-1) (Group I), thiopentone 6 mg x kg(-1) (Group II) or etomidate 0.3 mg x kg(-1) (Group III). Ninety seconds after the administration of the hypnotic agent, laryngoscopy and intubation were attempted. Intubating conditions were assessed as excellent, good or poor on the basis of ease of ventilation, jaw relaxation, position of the vocal cords, and patient response to intubation and slow inflation of the endotracheal tube cuff. RESULTS One patient in Group I, three patients in Group II and five patients in Group III could not be intubated on the first attempt. Clinically acceptable intubating conditions were observed in 93.3%, 66.7%, 40.0% of patients in Groups I, II and III, respectively. Overall conditions at intubation were significantly (P < 0.05) better, and the frequency of excellent conditions was significantly (P < 0.05) higher in the propofol group compared with the thiopentone and etomidate groups. No patient was treated for hypotension or bradycardia. CONCLUSION Propofol 2 mg x kg(-1) was superior to thiopentone 6 mg x kg(-1) and etomidate 0.3 mg x kg(-1) for tracheal intubation when combined with remifentanil 3 microg x kg(-1) and no muscle relaxant.
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Affiliation(s)
- Elvan Erhan
- Department of Anesthesiology and Reanimation, Ege University, Faculty of Medicine, Izmir, Turkey
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109
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Morse Z, Kaizu M, Sano K, Kanri T. BIS monitoring during midazolam and midazolam-ketamine conscious intravenous sedation for oral surgery. ORAL SURGERY, ORAL MEDICINE, ORAL PATHOLOGY, ORAL RADIOLOGY, AND ENDODONTICS 2002; 94:420-4. [PMID: 12374913 DOI: 10.1067/moe.2002.127587] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The purpose of this study was to determine whether the bispectral index scale (BIS) would provide added benefit to established methods of monitoring conscious sedation with midazolam (M group) or midazolam supplemented with ketamine (MK group). STUDY DESIGN BIS was prospectively and blindly examined in 22 patients receiving outpatient oral surgery with conscious sedation supplemented with local anesthesia. RESULTS The average midazolam dose in the midazolam group over the treatment period was 0.01 mg/kg/h, and the average midazolam plus ketamine dose was 0.01 and 0.05 mg/kg/h, respectively. Mean BIS values throughout the sedation study period were 90 for the midazolam group and 94 for the midazolam plus ketamine group. The addition of ketamine did not lower BIS. BIS values did not alter significantly over time except for an expected transient drop after the midazolam bolus induction. CONCLUSION BIS levels remained close to baseline levels, suggesting that BIS would not provided any additional benefit to currently established methods of monitoring patient consciousness during conscious sedation for oral surgery.
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Affiliation(s)
- Zac Morse
- Department of Anesthesiology, The Nippon Dental University at Niigata, Hamaura-cho, Japan.
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