Performance testing of a novel Continuous Powder Aerosolizer (CPA) for inhalative administration of surfactant to preterm neonates

The surfactant Continuous Powder Aerosolization (CPA) technology is intended for continuous administration of an aerosol for inhalation by preterm neonates on non-invasive ventilatory support. The CPA allows efficient aerosolization of dry surfactant powder, generating an aerosol of high concentration. In a subsequent humidification step, aerosol particles are heated and covered with a surface layer of water. The wet surfactant aerosol is then conducted via a tube to the patient interface (e.g., nasal prongs). Performance testing of nebulizers currently follows DIN EN 13544-1. Since this norm applies to nebulizers designed for adults, a new test strategy for the special requirements of a device for neonates had to be implemented. In particular, these requirements had to take into consideration neonatal respiratory physiology and operation of the CPA system in a ventilatory circuit under elevated temperatures. With the newly developed test rig, performance of the CPA can be characterized by measuring the aerosol output and output rate at the exit of the aerosol tube as well as at the outlet of the nasal prongs. Performance at the outlet of the nasal prongs is measured making use of an artificial lung with a hard-coded breathing profile of a preterm neonate. Results obtained with the test rig show that 50 to 60% of the surfactant leaving the aerosolizer as dry powder reach the exit of the aerosol tube as humidified with a temperature of 37 grad C. Total delivery of surfactant at the prong exit is about 20% when applying the hard-coded breathing profile.