The purpose of this study is to determine if the use of a device called the BIS monitor in addition to the Richmond Agitation Sedation Scale will give better assessment of a subject's level of sedation.

Patients in the intensive care unit (ICU) who require a ventilator to help them breathe also require sedation in order to keep them comfortable and prevent injury. The national guidelines for sedation management include a daily interruption of sedation performed once each morning. To determine the amount of sedation needed, the current standard practice is to use a system called the Richmond Agitation-Sedation Scale (RASS). The patient is stimulated by calling their name or by tapping their shoulder until the patient's responses indicate that a satisfactory level of sedation has been achieved.

The purpose of this study is to determine if the use of a device called the BIS monitor in addition to the RASS will give better assessment of a subject's level of sedation. The BIS monitor is a sensor strip taped to the forehead and attached to a device that reads electrical activity from the brain. It is approved by the U.S. Food and Drug Administration (FDA) for monitoring patients under sedation.

Inclusion Criteria:

• patient in the ICU
• continuous IV sedation with propofol midazolam or dexmedetomidine
• age > 18
• expected to require mechanical ventilation for >=48 hours

Exclusion Criteria:

• prisoners
• no available space on forehead
• continuous electroencephalography(EEG) monitoring
• bifrontal brain injury
• barbiturate coma therapy
• known hypersensitivity to study medications
• high risk for ethanol (ETOH) withdrawal
• resuscitation from cardiac arrest without recovery of mental status
• moribund clinical state (death expected within 48 hours)