Abstract
Background: Aerosol delivery may be enhanced by utilizing an inspiration-synchronized nebulization mode, where nebulization occurs only during inspiration. This study aimed to compare aerosol delivery of albuterol via a prototype of an inspiration-synchronized vibrating mesh nebulizer (VMN) versus continuous VMN during invasive mechanical ventilation. Methods: A critical care ventilator equipped with a heated-wire circuit to deliver adult parameters was attached to an endotracheal tube (ETT), a collection filter, and a test lung. The nebulizer was placed at the humidifier's inlet, inspiratory limb at the Y-piece, and between the Y-piece and ETT. Conventional VMNs producing standard size aerosol particles (Solo; Aerogen Ltd) were compared with prototype small-particle VMNs (Aerogen Pharma) in both inspiration-synchronization and continuous modes. In each run, 1 mL of albuterol (2.5 mg) was used (n = 5). The drug was eluted from the collection filter and assayed with UV spectrophotometry (276 nm). Results: The inhaled dose with inspiration-synchronization mode was 1.4 to 3.6 times that with the continuous mode, regardless of nebulizer positions (all p < 0.001). The small-particle VMN delivered an 8%-69% greater inhaled dose than the conventional VMN (Solo), regardless of the nebulizer placement or aerosol generation mode (all p < 0.001). The highest inhaled dose (50%-60%) with the inspiration-synchronized VMN was observed when it was placed at the ETT (all p < 0.001), whereas the continuous VMN performed better when positioned near the humidifier, with an inhaled dose of 21%-37% (p < 0.001). Conclusion: The inspiration-synchronized VMN delivered a greater inhaled dose than continuous VMN, irrespective of nebulizer placement. The prototype VMN producing smaller aerosol particles resulted in a greater inhaled dose than the conventional VMN (Solo), regardless of placement or aerosol generation modes. The inspiration-synchronized VMN achieved the highest delivery when placed close to the airway, whereas the continuous VMN delivered the most when positioned near the ventilator.