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

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.