In the present paediatric case series methoxyflurane appears to be an efficacious analgesic with a low adverse events profile. In young children in particular it can briefly lead to deep sedation.

Background-Expiratory flow rate, soft palate closure, and dead space air may influence exhaled levels of nitric oxide (NO). These factors have not been evaluated in the reservoir collection of NO. Methods-Exhaled NO was collected into a reservoir during a single flow and pressure controlled exhalation. Results-NO collected in a reservoir containing silica gel was stable for 24 hours. Nasally delivered 4.8% argon measured by mass spectrometry did not contaminate exhaled argon levels (0.1 (0.02)%) in five volunteers during exhalation against a resistance (10 (0.5) cmH 2 O), hence proving an eVective soft palate closure. Exhaled NO in the reservoir was 11 (0.2) ppb, 8.6 (0.1) ppb, 7.1 (0.6) ppb, and 6.6 (0.4) ppb in five normal subjects and 48.3 (18) ppb, 20.3 (12) ppb, 16.9 (0.3) ppb and 10.1 (0.4) ppb in 10 asthmatic subjects at four studied expiratory flows (5-6, 7-8, 10-11, and 12-13 l/min, respectively), with NO levels equal to direct measurement (7.3 (0.5) ppb and 17.4 (0.5) ppb for normal and asthmatic subjects respectively, p<0.05) at the flow rate 10-11 l/min. Elimination of dead space proved necessary to provide NO levels comparable to the direct measurement. Exhaled NO collected into the reservoir without dead space during flow controlled exhalation against mild resistance provided close agreement (mean (SD) diVerence -0.21 (0.68), coeYcient of variation 4.58%) with direct measurement in 74 patients (NO range 1-69 ppb). Conclusions-Flow and pressure controlled collection of exhaled NO into a reservoir with silica gel provides values identical to the direct measurement and may be used to monitor asthma at home and where analysers are not on site. (Thorax 1998;53:775-779)

Seventy-one percent of patients undergoing ED procedural sedation and analgesia with N2O did not meet established fasting guidelines. In this series, there was no association between preprocedural fasting and emesis. There were no serious adverse events.

Adolescent mental health presentations to the ED require a high number of ED, mental health and inpatient service resources. Security incidents occur frequently. We propose changes to address identified problems. These include redesigning the physical structure of the ED, more mental health training and support for ED staff, better access to mental health records and crisis plans for adolescents at risk, and improved after-hours mental health services for children and adolescents.