General Anesthesia, Middle Aged Patients, Sevoflurane
Conditions
Keywords
anaesthesia, middle aged, minimal alveolar concentration, sevoflurane, isoelectric EEG
Brief summary
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
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.
Interventions
DRUGSevoflurane
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.
Sponsors
Ministry of Health, China
National Natural Science Foundation of China
Huazhong University of Science and Technology
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
45 Years to 65 Years
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| MACie | 30min | Minimal Alveolar Concentration of sevoflurane inducing isoelectric electroencephalogram (EEG) in 50% of the subjects (MACie) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| MACbs | 30 min | Minimal Alveolar Concentration of sevoflurane inducing inducing burst suppression EEG (MACbs) in middle aged adults. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Hemodynamic parameters | 3 min | Hemodynamic parameters 2 min before and 3 min after skin incision |
| Use of phenylephrine | 30 min | Use of phenylephrine during induction and maintenance of anesthesia with sevoflurane. |
Countries
China
Outcome results
None listed