SNAP II EEG data will be recorded continuously during the sedation and intermittently compared to routinely monitored parameters of sedation adequacy including vital signs, patient movement, grimacing, verbal complaints, and patient responsiveness to verbal and tactile stimuli. Following surgery, patients will be questioned to determine recall or memory of discomfort.

A portable EEG monitor (SNAP II EEG System, Everest -St. Louis) is unique in that it monitors both low frequency EEG signals (1-40 Hz), which are typically used, and high frequency EEG signals (80-420 Hz), which are not usually used, and calculates a derived EEG parameter (the SNAP Index). The SNAP Index ranges from 100 (completely awake) to 0 (no brain activity) and has been shown in a few studies to correlate with increasing sedation and loss of consciousness in human volunteers and patients receiving general anesthesia during surgery.

The SNAP Index is a derived EEG (electroencephalogram) parameter (from the SNAP II EEG System) ranging from 100 (completely awake) to 0 (no brain activity). The Observer's Assessment of Alertness/Sedation Score (OASS) is a score derived from motor and sensory functions between 0 and 5 where 0 is unresponsive and 5 is awake.