The patient circuit is the equipment required to set up a patient with COVID-19 on a ventilator (bilevel or continuous pressure ventilation).

Patient interface

• The patient interface is a full-face, non-vented mask which fits over the patient’s nose and mouth and secured using straps.
• Ensure the mask is not too loose or too tight; you should be able to pass your fingers either side of the straps.
• The elbow of the mask should be blue; this means that there is no exhalation valve which is important for infection control.

Antibacterial-viral filter

• The antibacterial-viral filter fits onto the elbow of the patient interface, and filters the air that the patient exhales.

Exhalation valve

• The valve attaches to the antibacterial-viral filter and ensures the patient does not re-breath excessive carbon dioxide.
• The exhalation valve MUST follow the antibacterial-viral filter in the circuit to prevent unnecessary aerosolisation of the patient’s exhaled breath.

Standard 22mm circuit tubing

• The standard 22mm circuit tubing attaches to the side of the ventilator.