Mark Enterprises

• Breathable FlexiTube™ minimizes troublesome mobile condensate compared to a standard oxygen cannula
• Kink-proof and crush-resistant FlexiTube
• Adhesive Wigglepads™ easily maintain cannulae stability on cheeks
• Easy-click connector rotates for convenient movement of patient and breathing circuit
• Color coded for easy size identification

The nasal cannula (NC) is a device used to deliver supplemental oxygen or increased airflow to a patient or person in need of respiratory help. This device consists of a lightweight tube which on one end splits into two prongs which are placed in the nostrils curving toward the sinuses behind the nose, and from which a mixture of air and oxygen flows.^[1] The other end of the tube is connected to an oxygen supply such as a portable oxygen generator, or a wall connection in a hospital via a flowmeter.^[2] The cannula is generally attached to the patient by way of the tube hooking around the patient's ears or by an elastic headband, and the prongs curve toward the paranasal sinuses. The earliest, and most widely used form of adult nasal cannula carries 1–3 litres of oxygen per minute.

Cannulae with smaller prongs intended for infant or neonatal use can carry less than one litre per minute. Flow rates of up to 60 litres of air/oxygen per minute can be delivered through wider bore humidified nasal cannula.

High-flow nasal cannula (HFNC) therapy is a respiratory support method that uses a breathing circuit comprising an air/oxygen blender, an active humidifier, a single heated circuit, and a nasal cannula. The circuit delivers adequately heated and humidified medical gas at up to 60 L/min of flow. This setup is designed to reduce anatomical dead space, provide a PEEP (positive end-expiratory pressure) effect, maintain a constant fraction of inspired oxygen (FiO2), and ensure good humidification.

The breathing circuit in HFNC therapy is distinct from non-invasive ventilation (NIV) systems. Unlike NIV, which can increase anatomical dead space due to its interface, HFNC interfaces actually decrease dead space. This is because HFNC operates in an open circuit where neither inspiratory push nor expiratory pull is effective, making it less capable of actively enhancing tidal volume (VT). However, it still helps chronic obstructive pulmonary disease (COPD) patients mainly by decreasing anatomical dead space and secondarily by improving alveolar ventilation.

HFNC therapy has been shown to decrease breathing frequency and work of breathing, which can reduce the need for escalating respiratory support in patients with various underlying diseases, such as hypoxemic respiratory failure, acute exacerbation of chronic obstructive pulmonary disease, post-extubation, pre-intubation oxygenation, sleep apnea, acute heart failure, and patients with do-not-intubate orders.

The high flow rates in HFNC therapy help to increase ventilation, allowing for the displacement of excess carbon dioxide (CO2) with excess oxygen (O2). This leads to an increased partial pressure of arterial oxygen (PAO2), creating a greater oxygen diffusion gradient and potentially improving patient oxygenation.