Power analysis was based upon an assumed power of 80%, an effect size of 30% reduction in maximum cumulative daily dose of fentanyl, and historical data for maximum daily fentanyl dosing in the PICU at Children’s Medical Center Dallas (Between January and August 2002, the cumulative maximum daily fentanyl dose of 428 PICU patients was 79 mcg/kg with a standard deviation of ± 47 mcg/kg). Thus, the sample size was determined to be 62 per group (total N=124). The alpha criterion for significance was considered 0.05.