To the Editor:--Pappert et al. described the use of nebulized prostacyclin (PGI2) versus inhaled nitric oxide in children with acute respiratory distress syndrome. We realize that the authors studied only three children and, as such, did not derive any conclusion from the study other than that PGI2may be an alternative to nitric oxide as a selective pulmonary vasodilator. From this paper, it is questionable whether the clinical benefits of PGI2may be offset by a rebound increase in pulmonary artery pressure. The baseline figures of pulmonary artery pressures did not greatly vary between increasing concentrations of nitric oxide. However, in two of the children, there was a marked increase in the pulmonary artery pressure during the interval between the different doses of PGI2. It would be interesting to know, after each dose of PGI2, how long the period was before measuring the baseline variables. We also wonder whether the variation of effects of different concentrations of PGI2may be due to the effect of positive end-expiratory pressure (PEEP) on the nebulizer. In Glasgow, we have been investigating benefits of nebulizing drugs in patients whose lungs are ventilated. We have had difficulty in obtaining an ultrasonic nebulizer that will perform well in the presence of PEEP. We wonder whether the authors assessed this before their study.
Dr. Gavin Fletcher, Senior Registrar
Dr. Malcolm Daniel, Senior Registrar, Department of Anaesthetics, Royal Infirmary, Glasgow G4 OSF, United Kingdom