Minimal Alveolar Concentration of Sevoflurane Inducing Isoelectric Electroencephalogram

NCT ID: NCT01662622

Last Updated: 2012-08-14

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

PHASE4

Total Enrollment

31 participants

Study Classification

INTERVENTIONAL

Study Start Date

2012-03-31

Study Completion Date

2012-07-31

Brief Summary

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Sevoflurane can abolish movement or adrenergic response to noxious stimulus. In order to investigate the effect of sevoflurane on cerebral electrical activity, we determined the MAC of sevoflurane inducing isoelectric electroencephalogram (EEG) in 50% of the subjects (MACie) in middle aged subjects.

Detailed Description

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Patients received sevoflurane for anesthesia induction and maintenance at preselected concentrations according to an 'up and down' design, with 0.2% as a stepsize. General anesthesia was induced and maintained with sevoflurane, tracheal intubation was facilitated with cisatracurium. After a steady-state period of 30min without surgical stimulation, the state of isoelectric EEG was considered as significant when a burst suppression ratio of 100% last for more than 1 min. The haemodynamic responses to skin incision and the vasopressor requirement to maintain cardiovascular system were also analysed according to the EEG state.

Conditions

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Middle Aged Patients Sevoflurane General Anesthesia

Keywords

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anaesthesia middle aged minimal alveolar concentration sevoflurane isoelectric EEG

Study Design

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Allocation Method

NA

Intervention Model

SINGLE_GROUP

Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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Sevoflurane

Anaesthesia was induced by 8% sevoflurane. Cisatracurium 0.15mg kg-1 was administered after loss of the lash reflex, then ventilated manually until the amplitude of T1 decreased to 0. Intubation was performed and switched to mechanical ventilation with a fresh gas flow 2L min-1. Gas concentrations were analysed using a gas analyser.The end-tidal concentration of carbon dioxide was maintained at 4.7kPa; an esophageal temperature probe was inserted and a warming unit was used if necessary to maintain normothermia (35.5°-38.5°). The surgical incision was performed at least 30min after tracheal intubation. When arterial blood pressure (MAP) decrease exceeding 20% of baseline values. Phenylephrine 0.1mg was administered intravenously if necessary to maintained MAP and recorded.

Group Type EXPERIMENTAL

Sevoflurane

Intervention Type DRUG

The design of experiment is referred to the "Dixon up-and-down" method. The first subject was designed to receive end-tidal sevoflurane concentration of 1.7%. For each subject, 30 min interval time was given. The isoelectric EEG was considered as significant when the isoelectric state last for more than 1min. The maximal burst suppression rate was recorded if isoelectric EEG was not reached. Heart rate and MAP, were recorded 2 and 1min before and 3 min after skin incision. Adrenergic reflexes positive cases were counted.

Interventions

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Sevoflurane

The design of experiment is referred to the "Dixon up-and-down" method. The first subject was designed to receive end-tidal sevoflurane concentration of 1.7%. For each subject, 30 min interval time was given. The isoelectric EEG was considered as significant when the isoelectric state last for more than 1min. The maximal burst suppression rate was recorded if isoelectric EEG was not reached. Heart rate and MAP, were recorded 2 and 1min before and 3 min after skin incision. Adrenergic reflexes positive cases were counted.

Intervention Type DRUG

Eligibility Criteria

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Inclusion Criteria

* 45-65yr
* upper abdominal surgery in general anaesthesia
* ASA physical status classification of I or II

Exclusion Criteria

* neurological disease
* received central nervous system-active drugs
* cardiac ejection fraction less than 40%
* history of difficult intubation or anticipated difficult intubation
* daily alcohol consumption
* obesity, defined as a body-mass index of more than 30
* without informed consent
Minimum Eligible Age

45 Years

Maximum Eligible Age

65 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Ministry of Health, China

OTHER_GOV

Sponsor Role collaborator

National Natural Science Foundation of China

OTHER_GOV

Sponsor Role collaborator

Huazhong University of Science and Technology

OTHER

Sponsor Role lead

Responsible Party

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Wei Mei

AssociateProfessor

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Yuke Tian, MD.

Role: STUDY_CHAIR

Department of Anaesthesiology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology

Locations

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Department of Anaesthesiology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology

Wuhan, Hubei, China

Site Status

Countries

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China

Other Identifiers

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TJMZK20120301

Identifier Type: -

Identifier Source: org_study_id