Minimal Alveolar Concentration of Sevoflurane Inducing Isoelectric Electroencephalogram

Huazhong University of Science and Technology31 enrolled

Overview

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.

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.

Study Type

INTERVENTIONAL

Allocation

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Middle Aged Patients Sevoflurane General Anesthesia

Interventions

SevofluraneDRUG

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.

Eligibility

Sex: ALLMin age: 45 YearsMax age: 65 Years

Medical Language ↔ Plain English

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

Locations (1)

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

Wuhan, Hubei, China

Outcomes

Primary Outcomes

MACie

Minimal Alveolar Concentration of sevoflurane inducing isoelectric electroencephalogram (EEG) in 50% of the subjects (MACie)

Time frame: 30min

Secondary Outcomes

MACbs

Minimal Alveolar Concentration of sevoflurane inducing inducing burst suppression EEG (MACbs) in middle aged adults.

Time frame: 30 min

Data from ClinicalTrials.gov

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