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 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% (25-56) 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.