Nebulizing poractant alfa versus conventional instillation: Ultrastructural appearance and preservation of surface activity.
BACKGROUND
Nebulized surfactant therapy has been proposed as an alternative method of surfactant administration. The use of a perforated vibrating membrane nebulizer provides a variety of advantages over conventional nebulizers. We investigated the molecular structure and integrity of poractant alfa pre- and post-nebulization.


METHOD
Curosurf® was nebulized using an Investigational eFlow® Nebulizer System. Non-nebulized surfactant ("NN"), recollected surfactant droplets from nebulization through an endotracheal tube ("NT") and nebulization of surfactant directly onto a surface ("ND") were investigated by transmission electron microscopy. Biophysical characteristics were assessed by the Langmuir-Wilhelmy balance and the Captive Bubble Surfactometer.


RESULTS
Volume densities of lamellar body-like forms (LBL) and multi-lamellar forms (ML) were high for "NN" and "NT" samples (38.8% vs. 47.7% for LBL and 58.2% vs. 47.8% for ML). In the "ND" sample, we found virtually no LBL's, ML's (72.6%) as well as uni-lamellar forms (16.4%) and a new structure, the "garland-like" forms (9.4%). Surface tension for "NN" and "NT" was 23.33 ± 0.29 and 25.77 ± 1.12 mN/m, respectively. Dynamic compression-expansion cycling minimum surface tensions were between 0.91 and 1.77 mN/m.


CONCLUSION
The similarity of surfactant characteristics of nebulized surfactant via a tube and the non-nebulized surfactant suggests that vibrating membrane nebulizers are suitable for surfactant nebulization. Alterations in surfactant morphology and characteristics after nebulization were transient. A new structural subtype of surfactant was identified.
['Minocchieri|Stefan|S|', 'Knoch|Stephan|S|', 'Schoel|W Michael|WM|', 'Ochs|Matthias|M|', 'Nelle|Mathias|M|']
D001688:Biological Products D007322:Instillation, Drug D046529:Microscopy, Electron, Transmission D009330:Nebulizers and Vaporizers D010743:Phospholipids D011663:Pulmonary Surfactants D013500:Surface Tension
nebulizer surface tension aerosol drug therapy neonatal respiratory distress syndrome pulmonary surfactant