Feasibility of the pre‐operative measurement of fractional exhaled nitric oxide and respiratory mechanics to predict respiratory outcomes in children undergoing general anaesthesia

Summary Introduction Peri‐operative respiratory adverse events remain a major cause of morbidity and mortality in children undergoing general anaesthesia; those with asthma are at higher risk. The aim of this feasibility study was to determine whether pre‐operative measurements of fractional exhaled nitric oxide and the forced oscillation technique are feasible in children, and to explore whether these measurements can predict peri‐operative respiratory adverse events. Methods We assigned children into respiratory or control groups, according to the presence or absence of respiratory symptoms. We recorded pre‐operative measurements of fractional exhaled nitric oxide as well as respiratory mechanics, as determined by the forced oscillation technique. We then recorded the incidence of peri‐operative respiratory adverse events. Results We enrolled 120 children of which 116 were included. Fractional exhaled nitric oxide and respiratory mechanics (forced oscillation technique) were recorded in 106/116 (91%) and 71/116 (61%), respectively. Peri‐operative respiratory adverse events occurred in 17/116 (15%) patients but there was no difference between groups (OR 2.11, 95%CI 0.74–6.55). Pre‐operative fractional exhaled nitric oxide levels did not predict the occurrence of peri‐operative respiratory adverse events. The measurement of respiratory mechanics using the forced oscillation technique did not predict peri‐operative respiratory adverse events. Discussion We have shown the feasibility of study enrolment and pre‐operative fractional exhaled nitric oxide measurement but had difficulty obtaining measurements of respiratory mechanics (forced oscillation technique). Neither test improved the prediction of peri‐operative respiratory adverse events reliably in this group of patients. A thorough pre‐operative clinical history combined with care by an experienced paediatric anaesthetist remains the most reliable means of reducing peri‐operative respiratory adverse events.