Iloprost is a selective pulmonary
vasodilator approved for inhalation by the Food and Drug Administration.
Iloprost has been increasingly used in the management of
critically ill neonates with hypoxic
lung disease. This in vitro study was designed to test the hypothesis that
aerosol drug delivery could be effectively administered to infants with both conventional ventilation and high-frequency oscillatory ventilation (HFOV). A neonatal test lung model configured with newborn lung mechanics was ventilated with a conventional
ventilator and an HFOV with standard settings. A vibrating-mesh
nebulizer was placed (1) proximal to the patient airway in the inspiratory limb between the
humidifier probe and patient
wye (conventional) as well as between the vent circuit and the endotracheal tube (ETT) for HFOV and (2) between the
ventilator and
humidifier (distal).
Iloprost was nebulized in three separate runs using three new
nebulizers in each of the circuit locations. A collecting filter was placed at the distal end of the ETT for each trial.
Iloprost was quantified using high-performance liquid chromatography. The percentage of nominal dose delivered was greater with the
nebulizer placed proximal to the airway for conventional ventilation (10.74% ± 2%) and HFOV (29% ± 2%) than with it placed in the distal position (2.96% ± 0.2% vs. 0.96% ± 0.8%, respectively; P < 0.05). Drug delivery in proximal position was nearly threefold greater during HFOV than during conventional ventilation. In conclusion,
iloprost drug delivery was best achieved when the
nebulizer was placed proximal to the patient airway during neonatal
mechanical ventilation. Drug delivery appears to be more efficient during HFOV than during conventional ventilation.