The aim of the present study was to investigate the sensitivity of AEP (auditory evoked potentials) to muscular artefacts using sedation and local anesthesia.

Spontaneous or evoked electrical brain activity is increasingly used to monitor general anesthesia. During alertness, surgery and anesthesia the quality of AEP recordings may be reduced by artefacts. This poses the question to what extent AEP are sensitive for muscular artefacts. High frequency artefacts can have its seeds in muscles and in technical instruments in the operating room. Therefore, the study will take place under the terms of laboratory.

The present study was designed to measure the influence of muscular artefacts on AEP under propofol sedation with or without local anesthesia in the area of the electrodes.

If artefacts influence AEP, which are used to measure anesthesia, it is particularly interesting with regard to clinical application. AEP as a measure of "anesthetic depth" may not only reflect brain, but also muscular and high frequency activity. Therefore, while using muscle relaxants, the AEP of an awake patient may indicate deep anesthesia, because muscle signals are absent.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status 1-2

Exclusion Criteria:

• drugs that effect the central nervous system
• neurological or psychiatric deceases
• contraindications against use of propofol or local anesthesia