Terms used in the guideline

Continuous positive airway pressure (CPAP)

A type of non-invasive positive airway pressure that delivers a set pressure of airflow to the airways. This pressure is maintained throughout the respiratory cycle, both when the person is breathing in (inspiration) and breathing out (expiration). A CPAP device consists of a unit that generates airflow, which is delivered to the airway through a tight-fitting mask or other airtight interface.

High-flow nasal oxygen (HFNO)

Involves the delivery of warm and humidified oxygen (up to 70 litres per minute) through small nasal cannulae. The delivered gas flow is equal to or higher than the flow of air when the person is breathing in (inspiratory flow). This means that HFNO can deliver a higher and more stable concentration of inspired oxygen than conventional oxygen alone with nasal prongs. The higher flow also increases carbon dioxide washout in the upper airways and improves carbon dioxide clearance. Unlike CPAP, any positive pressure provided by HFNO is not measurable or sizeable.

Hospital-led acute care in the community

A setting in which people who would otherwise be admitted to hospital have acute medical care provided by members of the hospital team, often working with the person's GP team. They include hospital at home services and COVID-19 virtual wards.

Intermediate dose

Double the standard prophylactic dose of a low molecular weight heparin (LMWH) for medical patients.

Invasive mechanical ventilation

Any method of controlled ventilation delivered through a translaryngeal or tracheostomy tube, or other methods as defined by the Intensive Care National Audit & Research Centre definition of 'advanced respiratory support'.

Low-flow supplemental oxygen

Oxygen delivered by a simple face mask or nasal canula at a flow rate usually up to 15 litres/min.

Non-invasive respiratory support

A broad umbrella term for different types of respiratory support given through external interfaces, and includes HFNO, CPAP and non-invasive ventilation (NIV). These are more intensive interventions than conventional oxygen therapy alone. The different types of support are not, however, interchangeable because they have differing effects on a person's respiratory and cardiac physiology. So, they typically have different indications for their use.

Non-invasive ventilation (NIV)

Refers to a mode of positive pressure ventilation that delivers airflow to the airways through a tight-fitting mask or other airtight interface. Airflow is delivered at variable pressures that are higher than when the person is breathing in (inspiratory pressure) and lower than when the person is breathing out (expiratory pressure). NIV differs from CPAP by providing additional inspiratory pressure assistance. Most devices have an option of adding positive expiratory airway pressure that can fulfil a similar role to CPAP by maintaining a positive pressure in the airways to aid lung recruitment (opening of the airways).

Standard prophylactic dose

The prophylactic dose of an LMWH, as listed in the medicine's summary of product characteristics, for medical patients.

Treatment dose

The licensed dose of anticoagulation used to treat confirmed venous thromboembolism (VTE).