Fig. 2.

Helmet interface and circuit set-up for CPAP and NIV. The helmet has a transparent hood and a soft collar that contacts the body at the neck and/or shoulders. It covers the head and neck without making direct contact with the patient’s face and it is fixed around the axillae. At least 2 ports are present, which are usually connected to two separate tubes for inhaled and exhaled gas (double-tube circuit). An antibacterial filter should be placed on the expiratory port