Which Nebulizer Position Should Be Avoided? An Extended Study of Aerosol Delivery and Ventilator Performance during Noninvasive Positive Pressure Ventilation.

BACKGROUND: Research on the effect of nebulizer location on aerosol delivery during noninvasive ventilation has reached inconsistent conclusions.

OBJECTIVE: To investigate the effects of nebulizer position on aerosol delivery efficiency and ventilator performance during noninvasive ventilation.

METHODS: The Active Servo Lung 5000 respiratory simulation system (ASL5000) was used to simulate a COPD patient. The noninvasive ventilator was set to the spontaneous breathing mode. Six nebulizer positions, 2 exhalation valve types (single-arch exhalation port and whisper swivel), 4 combinations of inspiratory and expiratory pressure, and 2 respiratory rates were used.

RESULTS: Significant differences between nebulizer positions existed in aerosol delivery (p < 0.05). Aerosol delivery efficiency was lower for nebulizer locations on either side of the exhalation valve and next to the ventilator outlet. When the nebulizer was located between the exhalation valve and the simulated lung, increased inspiratory pressure increased and increased expiratory pressure decreased delivery efficiency (both p < 0.05). When the nebulization device was located between the exhalation valve and the ventilator, no obvious trend was observed. Compared to baseline, nebulization lowered the air leakage volume displayed on the ventilator. There were no differences in ventilator performance between different nebulizer positions.

CONCLUSIONS: The closer the nebulizer was to the exhalation valves or ventilator, the lower the aerosol delivery efficiency. Nebulizer position had little clinically significant effect on ventilator performance.