Differences between BIS and Neurosense are important. This study can be terminated.

The assessment of anesthesia depth was based, until recently, on the evolution of hemodynamic parameters. Nowadays it can be evaluated by several monitoring methods, derived from electroencephalogram analysis, namely the Bispectral Index (Aspect Medical Systems, Newton, USA). A new modality is currently under development: the NeuroSENSE (Cleveland Medical Devices Inc., Cleveland, OH 44103, USA). The goal of this study is to compare both monitoring modalities during anesthesia.

Inclusion Criteria:

• Patients requiring either intravenous anesthesia or balanced anesthesia (including sevoflurane)

Exclusion Criteria:

• Pregnant women,
• Allergy to propofol, remifentanil, morphine, muscle relaxant, or to a component,
• Hypersensibility to sufentanil, remifentanil or to a derivate of fentanyl,
• History of neurological disorder or central brain lesion, of muscle disease,
• Patient carrying a pacemaker,
• Patients receiving a psychotropic treatment or a morphine agonist-antagonist,
• Alcoholic patients and patients taking opiates,
• Surgery with extracorporeal circulation,
• Surgical position incompatible with an adequate positioning of the probe.

Surgical patients