[Bronchodilator aerosol propellant interferes with an photoacoustic spectrophotometer respiratory gas analyzer].

A patient with bronchial asthma was scheduled for an operation under nitrous oxide-isoflurane anesthesia. We monitored isoflurane concentrations continuously using an anesthetic gas analyzer (BK 1304). Upon puffing procaterol hydrochloride aerosol for 4 times, the analyzer showed a rapid increase in end-tidal isoflurane concentration. The BK 1304 uses infrared photoacoustic spectrophotometry and it is susceptible to interferences caused by Freon propellants in bronchodilator aerosols. We should take care in monitoring inhalational anesthetics when using aerosols containing Freon propellants.