Respiratory mechanics during sevoflurane anesthesia in children with and without asthma

We studied lung function in children with and without asthma receiving anes thesia with sevoflurane. Fifty-two children had anesthesia induced with sev oflurane (up to 8%) in a mixture of 50% nitrous oxide in oxygen and then ma intained at 3% with children breathing spontaneously via face mask and Jack son-Rees modification of the T-piece. Airway opening pressure and flow were then measured. After insertion of an oral endotracheal tube under 5% sevof lurane, measurements were repeated at 3%, as well as after increasing to 4. 2%. Respiratory system resistance (Rrs) and compliance during expiration we re calculated using multilinear regression analysis of airway opening press ure and flow, assuming a single-compartment model. Data from 44 children we re analyzed (22 asthmatics and 22 normal children). The two groups were com parable with respect to age, weight, ventilation variables, and baseline re spiratory mechanics. Intubation was associated with a significant increase in Rrs in asthmatics (17% + 49%), whereas in normal children, Rrs slightly decreased (-4% +/- 39%). At 4.2%, Rrs decreased slightly in both groups wit h almost no change in compliance system resistance. We concluded that in ch ildren with mild to moderate asthma, endotracheal intubation during sevoflu rane anesthesia was associated with increase in Rrs that was not seen in no nasthmatic children. Implications: Tracheal intubation using sevoflurane as sole anesthetic is possible and its frequency is increasing. When comparin g children with and without asthma, tracheal intubation under sevoflurane w as associated with an increase in respiratory system resistance in asthmati c children. However, no apparent clinical adverse event was observed.