The Influence of Age on Bispectral Index Associated With Propofol-induced Sedation

• Status: Completed
• Trial end date: 2013-11-01
• Target enrollment: 0
• Participant gender: All

Summary

The bispectral index (BIS) is commonly used in anesthesia to evaluate the depth of sedation. Numerous studies in adults have shown good correlation between bispectral index values and depth of sedation regardless of the hypnotic drug used. Requirements of intravenous and inhalational hypnotic agents to suppress consciousness decrease with age. A study showed that the loss of consciousness (LOC) was obtained with lower concentrations of sevoflurane in elderly than in young adults, but at identical BIS values, so that BIS would predict depth of sedation better than drug monitoring. This result incited the use of bispectral index monitoring to overcome the significant pharmacological variability, especially in elderly. Nevertheless, another research with a comparable methodology during propofol-induced anaesthesia provided higher BIS values at LOC in elderly compared to younger patients. In these two trials, LOC was defined differently: either by absence of verbal response corresponding to loss of eyelash reflex (LOER) or by absence of response to prodding [(OAA/S) <2)]. Otherwise electromyographic activity (EMG) was not taken in account. As high EMG level (greater than 50 decibels) could create subtle artifact signal pollution without necessarily being displayed as artifacts, this would be misinterpreted by the BIS algorithm as EEG activity and assigned a spuriously increased BIS value.

The main objective of our study was to specifically evaluate BIS values according to age during propofol-induced sedation. LOC was measured by obtaining an OAA/S score <2 (OAA/S2), or a deeper sedation criterion: loss of eyelash reflex (LOER). The secondary objective was to specify the influence of EMG on the displayed BIS values and its age-related modifications.

• Phase: Phase 3
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Centre Hospitalier Universitaire de Saint Etienne
• Treatments: Propofol

Criteria

Inclusion Criteria:

• patients over 18 years

• ASA I to III

• scheduled to undergo orthopaedic surgery under general anaesthesia

Exclusion Criteria:

• presence of heart, respiratory, hepatic or renal failure

• psychiatric or neurological pathology

• severe depression or dementia

• gastro-oesophageal reflux

• hiatal hernia

• drug addiction or chronic alcoholism

• obesity with a body mass index greater than 30