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What is nasal high flow (NHF) therapy?  [7 key facts]   

1. Firstly, it’s called many things, High flow nasal cannula (HFNC), high flow therapy (HFT), high flow oxygen / therapy (HFO/T), nasal high flow (NHF), high flow nasal prongs (HFNP), high flow oxygen (HFO), humidified, high flow nasal cannula (HHFNC), heated, humidified high flow nasal cannula (HHHFNC), humidified high flow therapy (HHFT), nasal insufflation or just plain high flow (HF).

Our preferred generic descriptor is nasal high flow (NHF) because it’s all about Nasal delivery of High Flows of humidified air.

Commercially, we call it Optiflow
, which can be delivered in several different ways.

2. It can deliver high levels of oxygen, but it is significantly more sophisticated than that – the higher rates of flow (independent of oxygen) confer benefits that oxygen alone cannot, i.e., reduction of dead space and dynamic, positive airway pressure, both of which are capable of increasing alveolar ventilation.

3. The high flow rates, greater than those seen with conventional oxygen delivery devices (and more than peak inspiratory airflow), are tolerable because the air is heated and humidified.

Optiflow High Flow airway hydration mechanism overview

4. It is a form of noninvasive respiratory therapy, but it is not a ventilator nor is it a CPAP device.


5. It is designed to treat spontaneously breathing people experiencing respiratory compromise. 

respiratory rate
Dyspnea High work of
Low SpO2 High PaCO2

6. It has been proven in an ever-growing number of RCTs to be superior to conventional oxygen therapy (COT) and non-inferior (in some studies) to noninvasive therapy (NIV). 

A clincial practice guideline from late 2020 "...synthesizes current best-evidence into four recommendations for [NHF] use...
- Rochwerg et al. Intensive Care Med. 2020. For an overview of this guideline click here. 


Nasal High Flow publications by year
Search query: nasal high flow
(as of 25th Jan 2021)

7. What sets NHF apart from COT devices and bi-level NIV is that it is delivered via a nasal cannula (sometimes a tracheotomy). This means a mask seal is not required, making setup a simpler process. This results in several benefits to patients, including (and most importantly) granting them better communication with caregivers and loved ones.