High-flow nasal oxygen therapy in intensive care and anaesthesia

Abstract

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. Pharyngeal dead space washout, decrease in airway resistance, generation of a positive end-expiratory pressure, and enhanced delivery of oxygen are all alleged to be potential mechanisms. The emerging evidence suggests that HFNO is effective in improving oxygenation in most patients with hypoxaemic ARF of different aetiologies. Notwithstanding the potential benefit of HFNO in the management of hypoxaemia, further large cohort studies are necessary to clarify the indications, contraindications and factors associated with HFNO failure. HFNO may also be valuable in reducing the need for tracheal intubation in the management of post-extubation ARF. In addition, HFNO has been proposed to limit oxygen desaturation by prolonging apnoeic oxygenation during intubation both in ICUs and operating theatres.

How to use humidified high‐flow nasal cannula in breathless adults in the emergency department

“…HHFNC is seen as a useful therapy providing some degree of respiratory support, thus bridging the dyspnoea management gap between early oxygen therapy and non‐invasive ventilation (NIV) or intubation …”

“…The same groups advise against HHFNC for those patients in whom alveolar collapse is the main mechanism of dyspnoea, as the PEEP delivered by HHFNC is inferior to that delivered by full facemasks. This makes HHFNC of less use in obesity, acute pulmonary oedema or following abdominal surgery . It is also considered contraindicated in epistaxis, base of skull fracture, upper airway surgery or nasal obstruction because of the risk of mucosal ulceration from the nasal prongs, decreased access for certain surgical procedures and an unobstructed path to the HHFNC airflow …”

“…HHFNC is seen as a useful therapy providing some degree of respiratory support, thus bridging the dyspnoea management gap between early oxygen therapy and non-invasive ventilation (NIV) or intubation. [3][4][5] Current management of breathlessness in the ED is a sequential treatment ladder, progressing incrementally from low-flow nasal oxygen supplementation, via simple facemasks through non-rebreathing facemasks, to NIV and intubation (ETT) and/or front of neck access (FONA). Definitive treatments for the undifferentiated breathless patient are provided as indicated, with nebuliser therapy for bronchoconstriction, continuous positive airway pressure for pulmonary oedema, biphasic respiratory support or intubation for ventilatory insufficiency or FONA for obstruction.…”

“…HHFNC has been recommended for spontaneously breathing adults with hypoxemia, or discomfort from increased respiratory effort. 5,[8][9][10][11] It has been used in adults with acute respiratory failure, 12 pneumonia, 12 immunocompromise, 13 during airway procedures, 14 post-extubation 15 and palliative care. 3,16 The utility of HHFNC in hypercapnic respiratory failure is still uncertain.…”

“…This makes HHFNC of less use in obesity, acute pulmonary oedema or following abdominal surgery. 5,11,18 It is also considered contraindicated in epistaxis, base of skull fracture, upper airway surgery or nasal obstruction because of the risk of mucosal ulceration from the nasal prongs, decreased access for certain surgical procedures and an unobstructed path to the HHFNC airflow. 5…”