Aerosol Delivery With a Vibrating Mesh Nebulizer Across Tidal Volume-Based Pediatric Invasive Ventilation Models: An In Vitro Evaluation

CONTEXT: Despite the widespread use of vibrating mesh nebulizers (VMNs) for aerosol therapy during mechanical ventilation, there is limited pediatric evidence on how tidal volume (TV)-based ventilation models and commonly modified ventilator- and circuit-related factors affect aerosol delivery. HYPOTHESIS: We hypothesized that these ventilator- and circuit-related modifications would affect the efficacy of aerosol delivery with a VMN. METHODS AND MODELS: We conducted an in vitro experiment using six pediatric ventilation models with TVs set at 8 mL/kg (TV: 40–400 mL for 5–50 kg), representing children from infancy to adolescence. We nebulized salbutamol with a VMN positioned on the dry side of a heated humidifier, and quantified inhaled mass fraction by measuring the drug collected on a filter positioned distal to the endotracheal tube using a spectrophotometer. We evaluated the effects of TV-based models and variations in other settings, including endotracheal tube sizes, bias flows, inspiratory rise time, ventilator modes, circuit configurations, VMN positions, and drug concentrations. RESULTS: In the baseline model with a TV of 80 mL, the mean ± sd of inhaled mass fraction was 11.2% ± 0.3%. It increased progressively across the TV-based models: 3.5% ± 0.2% (TV: 40 mL), 7.9% ± 0.4% (TV: 56 mL), 15.7% ± 0.2% (TV: 120 mL), 19.4% ± 0.4% (TV: 160 mL), and 21.3% ± 1.7% (TV: 400 mL; all p < 0.001 vs. baseline). No significant differences were observed in variations of the other ventilatory, endotracheal tube-, or circuit-related settings. INTERPRETATION AND CONCLUSIONS: VMN aerosol delivery increased across TV-based ventilation models and was minimally affected by other ventilator settings, endotracheal tube size, and circuit-related modifications. Consistent aerosol delivery at a given TV suggests that TV is the dominant determinant of aerosol delivery efficacy.