NCT01705743

Minimum Alveolar Concentration of Sevoflurane With Nitrous Oxide Inducing Isoelectric EEG

Minimum Alveolar Concentration of Sevoflurane With 60% Nitrous Oxide Inducing Isoelectric EEG in Mid-aged Adults

• Status: Completed
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 76 (actual)
• Sponsor: Huazhong University of Science and Technology · Academic / Other
• Sex: All
• Age: 45 Years – 64 Years
• Healthy volunteers: Not accepted

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

Interventions

Type	Name	Description
DRUG	Sevoflurane+Nitrous oxide	60% nitrous oxide +40% oxygen+ Sevoflurane
DRUG	Sevoflurane	100% oxygen+ Sevoflurane

Timeline

• Start date: 2012-09-01
• Primary completion: 2013-09-01
• Completion: 2013-10-01
• First posted: 2012-10-12
• Last updated: 2014-02-04

Locations

1 site across 1 country: China