An in vitro analysis of pulmonary deliverability of inhalable solutions and inhalable aerosol products dispersed in ventilator circuit

During mechanical ventilation, the influence of the ventilator on drug delivery when inhalable solutions and aerosol products are used is relatively understudied, with limited elucidation of the impact of potential factors. This study investigated the effect of device connection positions and product administration conditions on pulmonary delivery rates, while comparing inhalable solutions with inhalable aerosol products using an in vitro system. Examination of the pulmonary delivery of inhalable solutions by ventilators using a vibrating mesh nebulizer and an Andersen cascade impactor cooled for 90 min revealed significant effects on particle size distribution based on the nebulizer connection position. Connecting the nebulizer to the patient's airway side resulted in minimal loss and excellent delivery to the lungs, which was attributed to the absence of droplet deposition on the heater/humidifier surfaces. Connecting the nebulizer to the heater/humidifier/ventilator produced numerous small droplets, indicating a higher likelihood of drug delivery deep into the lungs. Larger drug volumes correlated with enhanced lung delivery. These findings suggest that connecting to a heater/humidifier may be a more favorable approach for systemic delivery to the alveoli. A comparison between the inhalable solutions and inhalable aerosol products applied to the ventilator revealed that inhalable solutions exhibited a higher pulmonary delivery rate, making them more suitable for drug administration. Additionally, the continuous delivery feature of the nebulizer offered the advantage of not requiring consideration of ventilator breathing timing. Our findings provide valuable insights into inhalation therapy in ventilator-connected patients and contribute to enhancing treatment effectiveness.