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

Introducing the first F&P 'Micro Moments' Series. In this first series, we focus on high-flow therapy. Start with this quick animation (below) and then scroll down for more information.  


Nasal High Flow (NHF) is a form of noninvasive respiratory therapy, but it is not a ventilator nor is it a CPAP device.


NHF is called many things, High flow nasal cannula (HFNC), high-flow therapy (HFT), high-flow oxygen/therapy (HFO/T), nasal high flow (NHF), 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, i.e., there are several devices you can use to provide Optiflow NHF therapy.



It can deliver high levels of oxygen (from no added oxygen, i.e., 21% FiO2 up to 100%), but NHF therapy 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 can increase alveolar ventilation.

Mucociliary transport system


A critical element of NHF therapy is airway hydration, i.e., heated humidification.

Heating and humidifying not only makes high gas flows tolerable but also prevents desiccation of the airway epithelium and maintains and improves mucociliary clearance (MCT).

Your MCT system is fundamental in protecting your vulnerable airways and lungs - it's not just about comfort.  

Watch the MCT system in action on the right - audio on


What are the indications for NHF? Who is it for?

NHF treats spontaneously breathing people experiencing respiratory compromise. 

  • High respiratory rate
  • Dyspnea
  • High work of breathing
  • Low SpO2
  • High PaCO2

Please scroll down to see a list of patient groups for which there are published recommendations.

You might also be interested in how quickly NHF works. 



NHF has been proven to provide respiratory support to an increasing number of patient groups.

An ever-increasing body of evidence has allowed medical societies around the world (including AARC, ESICM, and ERS) to create guidelines and make recommendations for the use of NHF in comparison to other forms of NIV and conventional oxygen therapies:

The guidelines cover the use of NHF for:

  • Acute hypoxemic respiratory failure (AHRF)
  • Patients with severe or critical COVID-19
  • High-risk post-operative patients
  • Pre-oxygenation for peri-intubation patients
  • Low-risk, extubated patients
  • High-risk, extubated patients
  • NIV-rested AHRF patients
  • etc.



Compared with other NIV modalities, NHF has the distinct advantage of being delivered via a cannula (or tracheotomy), not a mask. 

There are several benefits:

1. a mask seal is not required, making setup a more straightforward process,

2. it's proven to be more comfortable, which may encourage therapy compliance

3. a smaller, less intrusive interface may facilitate better communication with caregivers and loved ones.