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.