S401 Introduction: Recovery from general anesthesia can be a tumultuous time for both patients and caretakers. The etiologies of agitated behavior during recovery from anesthesia are difficult to ascertain in young children; however, the treatment for pain differs from that for anxiety or delirium. The purpose of this pilot study was to identify characteristics of emergence behavior that differentiate emergence delirium from pain in the pediatric population. Methods: We developed a pediatric emergence agitation scale (PEAS) from adult agitation scales designed for use in nursing home settings. [1,2] The tool was observational so pre-verbal children could be assessed. The variables were: restlessness, thrashing, repetitive vocalizations, screaming, restraint, altered sensorium. Each category was rated on a scale of 1-3 (none, present, severe). The Toddler-Preschooler Postoperative Pain Scale [3] was used to assess pain and allow a test of discriminative validity of these two scales. With IRB approval, 30 patients, ages 1 - 8 years old were observed as they entered the post-anesthesia care unit (PACU). Two research assistants (RAs) independently observed each of the patients for 15 min. Patient assessment took place for one-min intervals at time 0, 5, 10, and 15 min. The RAs were blinded to the type of anesthetic used. At the conclusion of the observation period, the following data was recorded: age, sex, procedure, anesthetic used, premedication, anesthetic complications, and co-morbid states (seizures, mental retardation, ADHD). The nurses assessment of the patient (agitation, pain, both, neither) was also recorded. Statistical instruments used were Kolmogorov-Smirnov 2-sample test, and Intraclass Correlation Coefficient (ICC). Results: The study sample comprised 17 males and 13 females. Mean age was 5.9 yrs (SD 2.6 yrs). Seven (23.3%) of the patients were noted by PACU nurses to be agitated, 17 (56.7%) to be caim or asleep and 2 (6.7%) to be both agitated and in pain. There were no patients noted to be in pain but not agitated. Therefore, discriminative validity of these scales could not be assessed. The interrater reliability of the PEAS tool assessed by ICC was 0.78, and of the TPPPS was 0.77 (perfect agreement = 1.0). Both scales correlated well with a nursing assessment of agitation (TPPPS p<0.01; PEAS p<0.01). Discussion: The results of this preliminary study point out several important aspects of analysis of emergence behavior in children. First, it appears to be very difficult for an observer to differentiate between pain and agitation. Yet, there are a number of relatively recent articles remarking on the relative rates of agitation or excitement in children recovering from different anesthetics. [4,5] If these studies have not employed validated measures which discriminate between pain and agitation, the results are confounded. Second, PACU nurses may base their assessment on factors such as patient response to voice, touch, parental presence or other data not measured by current scales. Future scales will need to account for emotional state of the child and response to non-pharmacologic intervention. Thirdly, the interrater reliability of the Toddler-Preschooler Postoperative Pain Scale was supported. In summary, the preliminary analysis of the PEAS tool, although limited, serves as an initial step in the differentiation of emergence agitation behaviors from pain behaviors. Refinement of the scale may lead toward more precise evaluation and treatment of undesirable recovery behaviors in children.