Minimum Alveolar Concentration of Sevoflurane With Nitrous Oxide Inducing Isoelectric EEG

Phase 4

Completed

• Conditions: Middle Aged Patients; General Anesthesia
• Interventions: Drug: Sevoflurane+Nitrous oxide; Drug: Sevoflurane

• Registration Number: NCT01705743
• Lead Sponsor: Huazhong University of Science and Technology

Brief Summary

In order to investigate the effect of a combination effect of sevoflurane and nitrous oxide on cerebral electrical activity, the investigators determined the MAC of sevoflurane combined with nitrous oxide inducing isoelectric electroencephalogram (EEG) in 50% of the subjects (MACie) in middle aged subjects.

Detailed Description

Anaesthesia was induced by sevoflurane in oxygen. Cisatracurium 0.15 mg 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 of 2 L min-1. Anesthesia was maintained by sevoflurane or sevoflurane+60% nitrous oxide respectively. The surgical incision was performed at least 30 min after tracheal intubation, provided that the predetermined end-tidal sevoflurane concentration had been constant for at least 30 min and that the difference between inspired and end-tidal concentrations was less than 10%.

Brain electrical activity was measured using Narcotrend Monitor and S/5 Compact Anaesthesia Monitor, which displayed unprocessed EEG and burst suppression ratio, respectively. The design of the experiment is referred to the "Dixon up-and-down" method. To avid anaesthesia awareness, the first subject was designed to receive end-tidal sevoflurane concentration of 2.5 %. The presence or absence of isoelectric EEG (Entropy Module) of the preceding patient determined the end-tidal concentration of sevoflurane given to the next patient (with an increment size of 0.2%). The isoelectric EEG was considered as significant when the isoelectric state last for more than 1 min. The maximal burst suppression rate was recorded if isoelectric EEG was not reached.

Study Timeline

• Study Start: 2012-09
• Study First Submitted: 2012-10-10
• Study First Submitted QC: 2012-10-11
• Study First Posted: 2012-10-12
• Primary Completion: 2013-09
• Study Completion: 2013-10
• Status Verified: 2014-02
• Last Update Submitted: 2014-02-03
• Last Update Posted: 2014-02-04

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 76

Inclusion Criteria

• between 45 to 64 years old
• ASA physical status class 1 or 2
• elective abdominal surgery
• Informed Consent

Exclusion Criteria

• history of 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
• others judged inappropriate as subjects for the study by the Study Chair

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Group 1 Sevoflurane+Nitrous oxide	Sevoflurane+Nitrous oxide	-
Group 2 Sevoflurane	Sevoflurane	-

Primary Outcome Measures

Name	Time	Method
MACie	30min	Minimal Alveolar Concentration of sevoflurane and NO inducing isoelectric electroencephalogram (EEG) in 50% of the subjects (MACie)

Trial Locations

Locations (1)

Department of Anaesthesiology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology; 🇨🇳 Wuhan, Hubei, China