Open the reservoir of the bedside humidifier and add sterile, distilled water to the fill line; then close the reservoir. Keep all room windows and doors closed tightly to maintain adequate humidification.

The cascade bubble diffuser should be installed into the ventilator circuit according to the manufacturer’s instructions. Unscrew the cascade reservoir and add sterile, distilled water to the fill line. Screw the top back onto the reservoir. Plug in the heater unit and set the temperature between 95°F (35°C) and 100.4°F (38°C).

Unscrew the humidifier reservoir and add sterile, distilled water to the appropriate level. (If using a disposable unit, screw the cap with the extension onto the top of the unit.) Then screw the reservoir back onto the humidifier, and attach the flowmeter to the oxygen source. Screw the diffusion head humidifier onto the flowmeter until the seal is tight. Then set the flowmeter at a rate of 2 L/minute and check for gentle bubbling. Next, check the positive-pressure release valve by occluding the end valve on the humidifier. The pressure should back up into the humidifier, signaled by a high-pitched whistle. If this whistle doesn’t occur, tighten all connections and try again.