Minimum Alveolar Concentration of Sevoflurane With Nitrous Oxide Inducing Isoelectric EEG

NCT ID: NCT01705743

Last Updated: 2014-02-04

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: PHASE4
• Total Enrollment: 76 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2012-09-30
• Study Completion Date: 2013-10-31

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.

Conditions

Middle Aged Patients; General Anesthesia

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: DOUBLE

Study Groups

Group 1 Sevoflurane+Nitrous oxide

Group Type: ACTIVE_COMPARATOR

Sevoflurane+Nitrous oxide

Intervention Type: DRUG

60% nitrous oxide +40% oxygen+ Sevoflurane

Group 2 Sevoflurane

Group Type: ACTIVE_COMPARATOR

Sevoflurane

Intervention Type: DRUG

100% oxygen+ Sevoflurane

Interventions

Sevoflurane+Nitrous oxide

60% nitrous oxide +40% oxygen+ Sevoflurane

Intervention Type: DRUG

Sevoflurane

100% oxygen+ Sevoflurane

Intervention Type: DRUG

Eligibility Criteria

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

• Minimum Eligible Age: 45 Years
• Maximum Eligible Age: 64 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Huazhong University of Science and Technology

OTHER

Sponsor Role: lead

Responsible Party

Wei Mei

Associate Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Yuke Tian, MD.

Role: STUDY_CHAIR

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

Locations

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

Wuhan, Hubei, China

Countries

China

Other Identifiers

TJMZK20120903

Identifier Type: -

Identifier Source: org_study_id