ABSTRACT. Objective. In this successor to a preliminary retrospective study, we sought to confirm the apparent safety and efficacy of intravenous methohexital (MHX) for brief, unconscious sedation of pediatric hematology/oncology outpatients undergoing painful, invasive procedures.Methods. This prospective study was conducted in a children's hospital-based hematology/oncology clinic. Following published monitoring guidelines for deep pediatric sedation, MHX (1.0 mg/kg) was administered immediately before each procedure, 1% xylocaine was given locally, and additional MHX was titrated to maintain minimal response to pain during the procedure. For each patient, the procedural and physiologic response data reported below were recorded from the onset of sedation through recovery. Behavioral distress responses were measured using a standardized pediatric observational tool (Procedure Behavioral Checklist).Results. Two hundred and thirty-three procedures were carried out in 76 patients ranging .1 to 19.6 years of age. The mean cumulative MHX dose/procedure was 4.6 ؎ 2.9 mg/kg. The mean lengths of time from initiation of sedation until completion of the invasive procedure, attainment of patient arousability, discontinuation of monitoring, and attainment of patient alertness were 8 ؎ 5, 19 ؎ 8, 19 ؎ 9, and 22 ؎ 9 minutes, respectively. Relative to presedation values, mean arterial pressure (MAP), heart rate, and respiratory rate showed maximum mean percent changes of ؊16.6, ؉17. Invasive diagnostic or therapeutic procedures, such as lumbar punctures and bone marrow aspirations and biopsies, are required for the management of most children with cancer and serious hematologic disorders. The physical and emotional distress caused by these procedures are notable and have been well documented in behavioral studies of children with cancer. 1-3 Because procedure-related discomfort has been identified by children as the most negative aspect of their cancer treatment, efforts to improve their quality of life have included minimizing the acute distress associated with the procedures. 4 One such approach has been the use of brief sedation or anesthesia to reduce the anticipation and actual experience of pain during the invasive procedures.The selection of a sedation agent appropriate for that purpose is dependent upon several factors. These include the procedures, which vary in type, combination, duration, invasiveness, and frequency; the patients, who have variable coping capabilities; and the treatment setting, which is typically a busy outpatient clinic. Accordingly, desirable characteristics in a sedation agent for this patient population include rapid onset, predictable efficacy, controllable duration, and short recovery time, as well as convenient administration, manageable side effects, and feasibility relative to institutional resources.With the above in mind, since 1991 we have operated a joint sedation program staffed by our Divisions of Hematology/Oncology and Critical Care Medicine, in which children are routinely offer...