Position of different nebulizer types for aerosol delivery in an adult model of mechanical ventilation

Background: The optimal positions of different types of nebulizer for aerosol delivery remain unclear. Methods: Three ICU ventilators employing three types of nebutizer were separately connected to a simulated lung to simulate nebulization during invasive ventilation. Assist/control-pressure control (A/C-PC) mode was utilized, with inspiratory pressure (Pi) set to 12 cmH(2)O and positive end expiratory pressure (PEEP) set to 5 cmH(2)O, and with a target Vt of 500 ml. The bias flow of all the ventilators was set to 2 L/min. The three nebutizers were the continuous jet nebutizer (c-JN), the inspiratory synchronized jet nebutizer (i-JN), and the vibrating mesh nebulizer (VMN). The five nebulizer positions were as follows: at the Y-piece (position 1) and 15 cm from the Y-piece (position 2) between the endotracheal tube and the Y-piece, at the Y-piece (position 3) and 15 cm from the Y-piece (position 4) in the inspiratory limb; and at the humidifier inlet (position 5). Aerosols were collected with a disposable filter placed at the simulated lung outlet (n = 3) and were measured by UV spectrophotometry (276 nm). The measurements were compared under different experimental conditions. Results: The aerosol delivery of c-JN, i-JN, and VMN was 5.33 +/- 0.49 similar to 11.12 +/- 0.36%, 7.73 +/- 0.76 similar to 13.75 +/- 0.46% and 11.13 +/- 56-30.2 +/- 1.63%, respectively. The higher aerosol delivery: for c-JN similar to Positions 2 (10.95 +/- 0.15%), fori-JN similar to Positions 1 or 2 (12.91 +/- 0.88% or 13.45 +/- 0.42%), for VMN similar to Positions 4(29.03 +/- 1.08%); the tower aerosol delivery: for c-JN-Positions 1, 3 or 5, fori-JN similar to Positions 4 or 5, for VMN similar to Positions 5. The highest aerosol delivery:For c-JN at Position 2 (10.95 +/- .15%), for i-JN at Position 1 or 2 (12.91 +/- .88% or 13.45 +/- .42%), for VMN at Positions 4 (29. 03 +/- 1.08%); the lower aerosol delivery: for c-JN at Positions 1, 3 or 5, for i-JN at Positions 4 or 5, for VMN at Positions 5. The highest aerosol delivery of c-JN was lower than that of i-JN while the VMN was the highest (all P < .05). However, no differences were observed between the highest aerosol delivery with c-JN and the lowest aerosol delivery with i-J N. Similar results were found between the lowest aerosol delivery with VMN and the highest aerosol delivery with c-JN /i-JN in the Avea ventilator. There were no differences in the highest aerosol delivery of each nebulizer among the different ventilators (all p > 0.05). Conclusion: During adult mechanical ventilation, the type and position of nebulizer influences aerosol delivery efficiency, with no differences between ventilators.

Automated summary

This study investigated the effect of different types and positions of nebulizers on aerosol delivery efficiency during adult mechanical ventilation. The results showed that the type and position of the nebulizer had an impact on aerosol delivery efficiency, but there were no significant differences between different ventilators.