Evaluation of Mapleson systems for administration of inhaled nitric oxide.

To assess the safety of nitric oxide (NO) inhalation during manual-controlled ventilation using Mapleson A, D, and F systems, we examined nitrogen dioxide (NO2) production using a chemiluminescence analyzer. The NO concentration was changed from 0 to 19 parts per million (ppm), and at each level of NO the oxygen (O2) concentration was changed from 21% to 100%. The NO2 concentration was observed to increase when either the O2 or NO concentration was increased. The maximum NO2 concentrations (mean ± standard deviation) of the Mapleson A, D, and F systems were 0.20±0.03, 0.15±0.03, and 0.17±0.02 ppm, respectively, when the concentrations of NO and O2 were 19 ppm and 100%, respectively. The NO2 concentrations of the Mapleson A system were significantly higher than those of either the Mapleson D or F system at 4, 8, and 12 ppm NO and 100% O2, and than that of the Mapleson D system at 19 ppm NO and 100% O2. From the viewpoint of NO2 production, we suggest that the Mapleson D and F systems are safer than the Mapleson A system when manual-controlled ventilation is required.