Introduction: Prior studies found significant improvements in aerosol delivery using a prototype inspiration-synchronized vibrating mesh nebulizer (VMN) during mechanical ventilation. This study aimed to evaluate the effect of ventilator settings and lung mechanics on aerosol delivery using this VMN. Methods: Three adult lung models simulating normal lung mechanics, COPD, and ARDS, were connected to a ventilator via an 8.0mm endotracheal tube (ETT) with exhaled humidity in the circuit. Albuterol (2.5mg/3mL) was delivered using a small-particle, inspiration-synchronized VMN placed at the Y-piece and synchronized to the first 50% of the inspiration. Normal and COPD models were tested at tidal volume (Vt) 6 mL/kg with respiratory rate (RR) 16 breaths per min (bpm), and Vt 8 mL/kg with RR 12 bpm; ARDS model was tested at Vt 6 mL/kg with RR 16 and 32 bpm. The Vt was adjusted for ideal body weights (IBW) of 50, 70, and 90 kg using PRVC mode with I:E ratio 1:2 and PEEP of 8 cmH2O. The aerosol captured on a filter at the ETT end was eluted and quantified via ultraviolet spectrophotometry at 276 nm. Results: At Vt 6 mL/kg and RR 16 bpm, the ARDS model yielded higher inhaled dose across all IBWs compared to COPD and normal models (all p≤.005). Pairwise comparisons confirmed greater delivery in ARDS vs. normal model at all weights (all p.05), ranging from 65% to 70%. Within-model comparisons revealed minimal effect of ventilator settings on aerosol delivery in the normal model and COPD model, except with COPD at RR 16 bpm only at 90 kg IBW (p=.032). In ARDS model, increasing RR from 16 to 32 bpm at 6 mL/kg significantly reduced delivery at all IBWs (p=.008), with inhaled dose dropping from 76.8% to 50.2% at 70 kg. Conclusions: Aerosol delivery was significantly affected by lung mechanics and ventilator settings. At lower tidal volumes (6 mL/kg), the ARDS consistently showed higher inhaled doses compared to COPD and normal models, with differences reaching 10-15%. These differences were not observed at Vt 8 mL/kg.
Albuainain et al. (Sun,) studied this question.