Aerosol Delivery to Simulated Spontaneously Breathing Tracheostomized Adult Model With and Without Humidification.

Abstract

Background: The optimal aerosol delivery methods for tracheostomized spontaneously breathing patients remain unclear. Thus, we aimed to assess the impact of nebulizer placement, flow settings, and interfaces on aerosol delivery using a vibrating mesh nebulizer (VMN) and jet nebulizer (JN) in-line with unheated humidification.Methods: An 8.0 mm tracheostomy tube (TT) was connected to the lung model simulating adult breathing parameters via a collecting filter. Albuterol sulfate (2.5mg/3mL) was administered via VMN and JN, which was placed in-line with unheated humidification provided by a large volume nebulizer (LVN) with FIO2 set at 0.28, with gas flows of 2 vs. 6 L/min. Nebulizers were placed in-line distal and proximal to the lung model, using trach collar (TC) and T-piece (TP). A conventional nebulization was tested using VMN and JN directly connected to TT without unheated humidification. Drug was eluted from the collecting filter, assayed with ultraviolet spectrophotometry (276 nm).Results: During in-line nebulizer placement with unheated humidification, inhaled dose was 2-4 times higher with gas flow of 2 vs. 6 L/min, regardless of nebulizer type, placement and interfaces (all P < .01). At 6 L/min, inhaled dose was higher with proximal than distal placement using both interfaces, but at 2 L/min the inhaled dose tended to be lower with proximal placement. With JN, the TC generated a higher inhaled dose at proximal placement compared to the TP, whereas TP gave a higher inhaled dose than TC with distal placement, regardless of the flow settings. Compared to conventional nebulization using VMN, in-line VMN with LVN at 2 L/min had an inhaled dose similar, regardless of nebulizer placement and interfaces. In contrast, in-line JN was influenced by both placement and interface.Conclusion: Aerosol delivery in-line VMN and JN with unheated humidification was affected by nebulizer placement, interface, and gas flow settings.