Use of high-flow nasal cannula oxygenation in ICU adults: a narrative review

Abstract

Oxygen therapy can be delivered using low-flow, intermediate-flow (air entrainment mask), or high-flow devices. Low/intermediate-flow oxygen devices have several drawbacks that cause critically ill patients discomfort and translate into suboptimal clinical results. These include limitation of the FiO2 (due to the high inspiratory flow often observed in patients with respiratory failure), and insufficient humidification and warming of the inspired gas. High-flow nasal cannula oxygenation (HFNCO) delivers oxygen flow rates of up to 60 L/min and over the last decade its effect on clinical outcomes has widely been evaluated, such as in the improvement of respiratory distress, the need for intubation, and mortality. Mechanisms of action of HFNCO are complex and not limited to the increased oxygen flow rate. The main aim of this review is to guide clinicians towards evidence-based clinical practice guidelines. It summarizes current knowledge about HFNCO use in ICU patients and the potential areas of uncertainties. For instance, it has been recently suggested that HFNCO could improve the outcome of patients with hypoxemic acute respiratory failure. In other settings, research is ongoing and additional evidence is needed. For instance, if intubation is required, studies suggest that HFNCO may help to improve preoxygenation and can be used after extubation. Likewise, HFNCO might be used in obese patients, or to prevent respiratory deterioration in hypoxemic patients requiring bronchoscopy, or for the delivery of aerosol therapy. However, areas for which conclusive data exist are limited and interventions using standardized HFNCO protocols, comparators, and relevant clinical outcomes are warranted.

Non-invasive ventilation in hypoxemic acute respiratory failure: is it still possible?

“…In addition, high-flow nasal oxygen (HFNO) has been recently developed in adult ICUs [9,10]. A multicentre randomized trial conducted in hypoxemic ARF patients has shown that NIV, compared with standard oxygen therapy and HFNO, was related to higher intubation and mortality rates, particularly in more severely hypoxemic patients [11].…”

“…Finally, applying NIV in hypoxemic ARF is probably still possible in well-selected patients and experienced centres [18], provided ICU clinicians pay particular attention to the ventilator settings (expired tidal volume) [9,10,12] or, if experienced, possibly use a helmet as interface [15]. Under these conditions, the new HACOR score could be very useful to avoid unduly delaying the intubation time and increasing mortality, particularly in more severe patients.…”

Invited Review Series Introduction

“…The first two manuscripts will deal with the use of oxygen therapy outside the classical guidelines [4] and with the use a new technology [6]. Despite a relatively good evidence for benefits of LTOT in hypoxemic COPD patients in improving survival [4], the first review will highlight that similar benefits are not demonstrated in the majority of COPD patients who have moderate or intermittent hypoxia, either nocturnal or exerciseinduced, and in those with comorbidities.…”

“…The role of oxygen on relief of symptoms, such as dyspnoea, will be also addressed. The second review will discuss the role of high-flow nasal cannula (HFNC), a device able to deliver heated and humidified oxygen at high flows [6]. Potential benefits of HFNC are several and include the improvement of lung mucociliary clearance, the washout of upper airway dead space, the generation of a low level of positive airway pressure (PEEP effect) [6].…”

“…The second review will discuss the role of high-flow nasal cannula (HFNC), a device able to deliver heated and humidified oxygen at high flows [6]. Potential benefits of HFNC are several and include the improvement of lung mucociliary clearance, the washout of upper airway dead space, the generation of a low level of positive airway pressure (PEEP effect) [6]. Although there is a rationale for using HFNC in COPD patients even in stable condition [7,8], its use is still limited and its impact on long term outcomes has yet to be described.…”