The 6 most frequently asked
questions about High Flow (HF) therapy

Optiflow usage: There is an ever–increasing body of clinical literature which may provide guidance on day–to–day application of HF therapy. Here are the 6 most frequently asked questions from clinicians.

  1. Is there a NHF protocol for AHRF patients?

  2. What flow rates and ranges are used?

  3. How much pressure is generated?

  4. When are the effects of Optiflow HF therapy seen?

  5. Is there a way to predict the outcome of HF?

  6. Who can benefit from Optiflow HF?



Is there a Nasal High Flow (NHF) alogrithm for AHRF patients? 

Ischaki 2017 European Respiratory Review

Ischaki 2017 European Respiratory Review
View the latest Flow Matters View the clinical summary View the Pubmed abstract
  1. Ischaki E, Pantazopoulos I, Zakynthinos S. Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device. Eur Respir Rev. 2017;26(145):170028.

Adapted from above original paper; used under Creative Commons licence 4.0. MV = mechanical ventilation; SOT = standard oxygen treatment. Please note: this
material is intended exclusively for healthcare practitioners and the information conveyed constitutes neither medical advice nor instructions for use. This material
should not be used for training purposes or to replace individual hospital policies or practices. Before any product use, consult the appropriate user instructions.


What flow rates and ranges are used for Optiflow HF therapy?

The following table lists starting flows and flow ranges used in clinical studies for Optiflow HF therapy.

Flow rate guidance
  1. Macé J, Marjanovic N, Faranpour F, Mimoz O, Frerebeau M, Violeau M, et al. Early high–flow nasal cannula oxygen therapy in adults with acute hypoxemic respiratory failure in the ED: A before–after study. Am J Emerg Med. 2019 Mar 5. [Epub ahead of print]
  2. Hernández G, Vaquero C, Colinas L, Cuena R, González P, Canabal A et al. Effect of Postextubation High–Flow Nasal Cannula vs Noninvasive Ventilation on Reintubation and Postextubation Respiratory Failure in High–Risk Patients. JAMA. (Oct) 2016; 316(15):1565–74.

How much pressure is generated? 

Average pressure increases approximately 0.5 - 1 cmH2O per 10 L/min.

Airway Pressure Graph

Pressure ranges are cannula and patient dependent. For illustrative purposes only. 

  1. Ritchie JE, Williams AB, Gerard C, Hockey H. Evaluation of a humidified nasal highflow oxygen system, using oxygraphy, capnography and measurement of upper airway pressures. Anaesth Intensive Care. 2011; 39(6):1103–10.

When are the effects of Optiflow HF therapy seen? 

Sztrymf associated Optiflow HF therapy with sustained beneficial effects on oxygenation and physiological
parameters for patients with acute respiratory failure. Similarly Rittayamai showed significant improvement
in post-extubation patients. These studies may provide guidance on patient responses to the therapy.

  1. Rittayamai N, Tscheikuna J, Praphruetkit N, Kijpinyochai S. Use of High-Flow Nasal Cannula for Acute Dyspnea and Hypoxemia in the Emergency Department. Respir Care. 2015; 60(10):1377–82.

Is there a way to predict the outcome of HF?

The validated ROX index predicts failure in adults with AHRF receiving NHF.

4 time intervals are observed: 2, 6, 12 and >12 hours. It's an easy-to-use dynamic bedside tool.

Calculating a ROX score
View the clinical presentation View the Pubmed abstract
  1. Roca O, Caralt B, Messika J, Samper M, Sztrymf B, Hernandez G, et al. An Index Combining Respiratory Rate and Oxygenation to Predict Outcome of Nasal High Flow Therapy. Am J Respir Crit Care Med. 2018 Dec 21. [Epub ahead of print]

The short answer is spontaneously breathing patients with, or at risk of respiratory distress.

Is your patient presenting with:






Respiratory Rate


Work of Breathing



The key to really understanding who can benefit from HF is in understanding the mechanisms of HF. 



What next?

F&P Optiflow™+ Nasal Cannula

AIRVO™ 2 Humidified High Flow System

Optiflow™ Nasal High Flow at the Royal Berkshire Hospital

Introducing Optiflow to the Royal Berkshire Hospital

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