The BIS Monitor (Aspect Medical Systems; Newton, MA) is one of the more recent attempts to simplify the monitoring of higher cerebral activity in a sedated patient. The initial assumption in the article in this issue of CHEST (see page 303) by Trope et al was that the bispectral index (BIS) met the goal of a reliable monitor for level of sedation in critically ill pediatric patients. They reference several studies that correlate the BIS with previously validated sedation scoring systems. The study by Crain et al7noted that there were favorable correlations between the BIS and the COMFORT (Calmness, Movement, Facial Tension, Respiratory Response, and Muscle Tone) scale in certain ranges but correlated less when comparing measurements at isolated moments during a prolonged pediatric ICU course. Courtman et al8 concluded that BIS scores correlated with COMFORT scores to a “moderate” degree. Lack of accuracy at some levels of sedation does not reject the BIS as a useful method to evaluate levels of sedation in critically ill children, especially those receiving neuromuscular blocking drugs. The many different scoring systems for sedation have advantages and disadvantages, but none detect changes in sedation over time. In pediatric patients, these sedation scores rely on variables that are impossible to measure in patients receiving neuromuscular blocking agents, often in use in the intensive care setting. Hence, the authors looked for a correlation between the BIS Monitor and changes in autonomic variables, the method most commonly used to assess sedation in patients receiving neuromuscular blocking agents, for lack of a better alternative. Another point to remember is that level of sedation does not necessarily correlate with level of comfort: a patient could be awake with a high BIS and be comfortable, or be sedated with a low BIS and be in pain.