“High-flow nasal oxygen therapy in intensive care and anaesthesia” – Excerpts and A Link

I put these excerpts in just to have an academic publication I could review. Dr. Farkas’ posts on high flow nasal oxygen therapy, listed below in Resources,  are what you really need to understand the procedure and to use it effectively. See especially his post –  PulmCrit- Mastering the dark arts of BiPAP & HFNC, February 12, 2018 by Dr. Farkas

The following are excerpts from Resource (1) below:


Oxygen therapy is first-line treatment for hypoxaemic acute respiratory failure (ARF). High-flow nasal oxygen therapy
(HFNO) represents an alternative to conventional oxygen therapy. HFNO provides humidified, titrated oxygen therapy
matching or even exceeding the patients’ inspiratory demand. The application of HFNO is becoming widespread in Intensive Care Units (ICUs), favoured by increasing evidence based on numerous studies supporting its efficacy. The mechanisms of action and physiological effects of HFNO are not yet fully understood. . . . The emerging evidence suggests that HFNO is effective in improving oxygenation in most patients with hypoxaemic ARF of different aetiologies.

Body of the Text:

High-flow nasal oxygen therapy (HFNO) is an innovative high-flow system that allows for delivering up to 60 litres min-1 of heated and fully humidified gas with a FIO2 ranging between 21% and 100%. Recent trials conducted in Intensive Care Unit (ICU) settings indicate that compared with conventional oxygen
therapy, HFNO achieves better oxygenation,6e9 as well as
improving patient comfort.6,7,10,11 Nevertheless, indications
and contraindications for HFNO use in critically ill patients
have not yet been fully established and there are currently few
In this narrative review, we aim to: (1) describe the potential
applications of HFNO in different settings, and (2) provide
practical indications and recommendations for facilitating
HFNO use.

HFNO delivery systems: main technical

HFNO allows for delivering up to 60 litres min-1 of gas at 37  C
and with an absolute humidity of 44 mg H2O litres-1. In
contrast with all the other systems for oxygen therapy, HFNO
enables the administering of FIO2 up to 100%. The physiological
effects and action mechanisms of HFNO6,10,12e21 are illustrated in Table 1.

The administration of HFNO requires the following: high
pressure sources of oxygen and air, an air-oxygen blender or a
high-flow ’Venturi’ system (which permits delivery of an accurate FIO2 between 21% and 100%), a humidifying and heating system for conditioning the gas to optimal temperature (37 C) and humidity (44mg H2O litrese1), a sterile water reservoir, a non-condensing circuitry, and an interface.

The two most widely marketed HFNO systems are the
Precision Flow by Vapotherm and Optiflow by Fisher & Paykel
Healthcare Ltd. [See my post How To Use High Flow Nasal Oxygen Therapy – Manuals From Vapotherm.]

For details on the two different HFNO systems, see pp. 19 + 20 in the above section.

Current evidence and clinical applications

HFNO has been increasingly used to treat hypoxaemia inspontaneously breathing, critically ill patients.26,27 Severalstudies in adult patients demonstrate beneficial effects interms of reduction of respiratory rate and dyspnoea, greatercomfort and improved oxygenation [expressed as eitherpartial pressure of oxygen in arterial blood ðPaO2 Þ or arterialperipheral oxygen saturation ðSaO2 Þ, and reduction of accessory muscles recruitment].7,8,11 HFNO is generally welltolerated. . . .  The strengths and drawbacks of HFNO are reported in Table 2 [below]. Worth noting, compared with non-invasive ventilation (NIV), HFNO is much easier to implement, requiring minor technical skills, training and nursing workload. Some practical information to facilitate implementation and use of HFNO is provided in Table 3 [below].

Hypoxaemic (de novo) acute respiratory failure 

Several studies have shown that HFNO is superior to conventional forms of oxygen administration in improving arterial oxygenation and patient comfort, while reducing respiratory rate, dyspnoea and clinical signs of respiratory distress.

Post-extubation respiratory failure

Immediate post-extubation is a crucial moment in the transition
from mechanical ventilation to spontaneous breathing.
By guaranteeing adequate oxygenation, facilitating expectoration and reducing the breathing effort, HFNO has the potential to prevent post-extubation respiratory failure and thereby avoid re-intubation.

Other indications are discussed in the paper.

Do-not-intubate order and palliative care

In some terminally ill patients with dyspnoea, NIV may reduce
breathlessness.56 Patients with a do-not-intubate order may
also receive NIV as ceiling treatment of intervening ARF.57 If
proved capable of providing similar symptom relief, HFNO
could be an additional means for the management of these
patients. In fact, HFNO can be delivered continuously for protracted periods with few side-effects, which might allow more effective symptom palliation. In keeping with this premise,
Peters and colleagues9 applied HFNO before proceeding with
NIV, if needed, in 50 patients aged between 27 and 96 and
admitted to amedical ICU with ARF of different aetiologies and a do-notintubate order. Several patients suffered from end-stage pulmonary fibrosis, malignancies and COPD.9 Mean SaO2 improved from 89.1 to 94.7% (P<0.001) and the respiratory rate decreased from 30.6 to 24.7 breaths min-1 (P<0.001). Only 18% of patients progressed to NIV, while 82% were managed with HFNO alone, for a median duration of 30 h.9 Further studies are necessary to confirm these encouraging preliminary results.


Several studies indicate that HFNO is more effective than
conventional oxygen therapy in improving oxygenation in patients with hypoxaemic ARF. The patients most likely to
benefit from HFNO are those with mild-to-moderate forms of
hypoxaemic ARF. A stepwise approach has been proposed,
which reserves HFNO for patients in whom standard oxygen
fails and escalating to NIV prior to invasive mechanical
ventilation if HFNO also fails.17,40

Compared with standard techniques, HFNO improves
safety in patients with known or anticipated difficult airways
undergoing elective intubation, and it may help in avoiding or
limiting hypoxaemia during invasive diagnostic procedures,
making it advisable for operating theatres to have access to
this technique.


(1) High-flow nasal oxygen therapy in intensive care and anaesthesia [PubMed Abstract] [Full Text HTML] [Full Text PDF].  Br J Anaesth. 2018 Jan;120(1):18-27. doi: 10.1016/j.bja.2017.11.010. Epub 2017 Nov 21.

(2) PulmCrit- Mastering the dark arts of BiPAP & HFNC, February 12, 2018 by Dr. Farkas

(3) How To Use High Flow Nasal Oxygen Therapy – Manuals From Vapotherm
Posted on June 6, 2018 by Tom Wade MD

(4) High-flow nasal cannula to prevent post-extubation respiratory failure
July 16, 2014 by Josh Farkas

(5) PulmCrit – Optimizing the respiratory drive to avoid failure, December 4, 2017 by Dr. Josh Farkas.

(6) Pneumonia, BiPAP, secretions, and HFNC: New lessons from FLORALI
May 25, 2015 by Dr. Josh Farkas.

(7) PulmCrit- Top 10 reasons pulse oximetry beats ABG for assessing oxygenation
November 2, 2016 by Dr. Josh Farkas.

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