Diethylenetriaminepentaacetic acid labeled with 1 millicurie (37 MBq) of Technetium-99m (DTPA-Tc99m) in 0.9% saline to a total volume of 1 mL was administered via vibrating mesh nebulizer (VMN: Aerogen Solo, Aerogen Ltd., Galway, Ireland) placed at the inlet of a passover humidifier filled with sterile water and attached to a corrugated heated wire tubing and medium-sized adult nasal cannula (OptiflowTM; Fisher&Paykel Healthcare, Auckland, New Zealand) (Figure 2 ).
Oxygen was dispensed from a calibrated back pressure compensated flowmeter at 10, 30, and 50 L/min. Gas passed through the nebulizer connector, carrying aerosol into the inlet of the humidifier filled with water. For heated humidity, the water in the humidifier and circuit were heated to 34–36 °C. For unheated conditions, water in the humidifier was room temperature (20–22 °C) and the circuit was unheated.
After device setup and temperature stabilization, subjects were seated and nasal cannula prongs were placed in the nostrils. An orofacial mask with filter (Vital Signs, San Diego, California, USA) was placed over the cannula and lightly sealed to the face. Subjects were instructed to breathe normally and allotted 2 min to acclimate to the setup prior to dosing. The 1 mL dose was placed in the nebulizer reservoir and administered to completion.
Oxygen was dispensed from a calibrated back pressure compensated flowmeter at 10, 30, and 50 L/min. Gas passed through the nebulizer connector, carrying aerosol into the inlet of the humidifier filled with water. For heated humidity, the water in the humidifier and circuit were heated to 34–36 °C. For unheated conditions, water in the humidifier was room temperature (20–22 °C) and the circuit was unheated.
After device setup and temperature stabilization, subjects were seated and nasal cannula prongs were placed in the nostrils. An orofacial mask with filter (Vital Signs, San Diego, California, USA) was placed over the cannula and lightly sealed to the face. Subjects were instructed to breathe normally and allotted 2 min to acclimate to the setup prior to dosing. The 1 mL dose was placed in the nebulizer reservoir and administered to completion.