Lung deposition after inhalation with various nebulisers in preterm infants

Aim: To compare pulmonary deposition after inhalation with three different nebulisers in preterm infants under conditions relevant to practice. Methods: The relative lung deposition (bioavailability) was estimated by inhalation of the marker substance, sodium cromoglycate (SCG), and measurement of urinary excretion of SCG. Seventeen spontaneously breathing preterm infants received 20 mg of SCG as nebuliser solution by means of (a) an LC Star jet nebuliser- (b) an LS 290 ultrasonic nebuliser; and (c) a Projet ultrasonic nebuliser in a randomised three-period, crossover design. Serial urine samples were collected until about 12 hours after inhalations, and the excreted SCG was determined by high-performance liquid chromatography. Results: The mean (SD) total amounts of SCG excreted in urine measured after inhalation with the LC Star nebuliser (0.089 (0.036) mg) were significantly higher than those obtained with the LS 290 (0.055 (0.019) mg) or the Projet nebuliser (0.046 (0.025) mg). The average pulmonary deposition after inhalation using the LC Star, LS 290 and Projet devices was estimated as 0.89%, 0.55% and 0.46% of the nominal dose, respectively. Conclusion: Inhalation with the LC Star jet nebuliser producing the greatest proportion of droplets < 2 mu m yielded a higher lung deposition in preterm infants than the LS 290 and Projet ultrasonic nebulisers.