Lung Deposition of Nebulized Surfactant in Newborn Piglets

Background: It would be advantageous for the treatment of neonatal respiratory distress syndrome if effective amounts of surfactant could be delivered by nebulization. Objective: To investigate lung deposition and distribution of nebulized porcine surfactant using an investigational eFlow (R) neonatal nebulizer. Methods: While lying on one side, 1-day-old piglets inhaled 200 mg . kg(-1) of nebulized surfactant via mask, nasal prongs, or tracheal tube. The surfactant was diluted with normal saline to 40 mg . ml(-1) and labeled with (99m)technetium-labelled nanocolloid. Undiluted surfactant (80 mg . ml(-1)) was instilled tracheally in a fourth group. Each group had 8 animals. Lung deposition was measured by gamma scintigraphy, and deposition values were presented as a percentage of the nebulized or instilled dose. Results: The median lung deposition of inhaled surfactant was 5% (range 3-16) via mask, 14% (2-40) via prongs, and 45% (2556) via tracheal tube (p <0.05). It was 88% (71-96) with instillation. In all groups, the surfactant preferentially went to the dependent lung. Deposition ratios (upper lung/both lungs) were 0.32(0.13-0.58), 0.15 (0.05-0.58), 0.16 (0.11-0.23), and 0.08 (0.03-0.46). Conclusions: Using this nebulizer, the lung depositions of porcine surfactant were 45% via endotracheal tube and 14% via nasal-continuous positive airway pressure (prongs). These figures might be physiologically relevant, but still have to be confirmed in efficacy studies. (C) 2015 S. Karger AG, Basel