Aerosol delivery and humidification with the Boussignac continuous positive airway pressure device.

BACKGROUND

A simple method for effective bronchodilator aerosol delivery while administering continuing continuous positive airway pressure (CPAP) would be useful in patients with severe bronchial obstruction.

OBJECTIVE

To assess the effectiveness of bronchodilator aerosol delivery during CPAP generated by the Boussignac CPAP system and its optimal humidification system.

METHODS

First we assessed the relationship between flow and pressure generated in the mask with the Boussignac CPAP system. Next we measured the inspired-gas humidity during CPAP, with several humidification strategies, in 9 healthy volunteers. We then measured the bronchodilator aerosol particle size during CPAP, with and without heat-and-moisture exchanger, in a bench study. Finally, in 7 patients with acute respiratory failure and airway obstruction, we measured work of breathing and gas exchange after a β(2)-agonist bronchodilator aerosol (terbutaline) delivered during CPAP or via standard nebulization.

RESULTS

Optimal humidity was obtained only with the heat-and-moisture exchanger or heated humidifier. The heat-and-moisture exchanger had no influence on bronchodilator aerosol particle size. Work of breathing decreased similarly after bronchodilator via either standard nebulization or CPAP, but P(aO(2)) increased significantly only after CPAP aerosol delivery.

CONCLUSIONS

CPAP bronchodilator delivery decreases the work of breathing as effectively as does standard nebulization, but produces a greater oxygenation improvement in patients with airway obstruction. To optimize airway humidification, a heat-and-moisture exchanger could be used with the Boussignac CPAP system, without modifying aerosol delivery.