• Judith L Zier, Rod Tarrago, and Meixia Liu.
• Division of Pediatric Critical Care, Children's Hospitals and Clinics of Minnesota, Minneapolis, MN, USA. judy.zier@childrensmn.org
• Anesth. Analg. 2010 May 1;110(5):1399-405.

BackgroundNitrous oxide (N(2)O) delivered at a concentration <50% is accepted as a minimal sedation drug by both the American Society of Anesthesiologists and the American Academy of Pediatrics. The expected level of sedation at an N(2)O concentration >50% is less clear.MethodsWe conducted a retrospective chart review for all children receiving N(2)O for procedural sedation at Children's Hospitals and Clinics of Minnesota. Patient age, maximal N(2)O concentration, duration of N(2)O administration, completion of procedure, and adverse events were recorded. Level of sedation was assessed on a 0 to 6 scale.ResultsN(2)O was administered on 1858 occasions to 1585 patients younger than 18 years. Most administrations (91.3%) were N(2)O concentration >50%. Level of sedation scores were as follows: 6 (inadequate) = 1.3%; 5 (minimal) = 94.3%; and 4 (drowsy) = 4.3%; no patient reached a sedation score <4. Fifty-nine patients (3.3%) had adverse events of which 6 (0.3%) were atypical. There was no difference between N(2)O < or =50% and N(2)O >50% in the level of sedation or number of adverse events. More children < or =2 years (7.4%) achieved a sedation level of 4 than those older than 2 years (4%), but they experienced a similar rate of adverse events. There was no difference in the level of sedation by duration of N(2)O administration. Inadequately sedated patients were younger than the remainder of the group. Most procedures (94.1%) were completed with the patient calm and still.ConclusionsA significant number of children remain minimally sedated while receiving N(2)O at concentrations >50% via nasal hood using a system designed to titrate N(2)O concentration from 0% to 70%. Adverse event rates of patients receiving >50% N(2)O in this manner are similar to rates reported in large studies of 50% N(2)O administration.

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