Hong Kong Emergency Nurses Association

High Flow Oxygen Therapy - EMERGENCY NURSING

High Flow Oxygen Therapy – Emergency Nursing

Author: CHOW Man Chun, HKECMED Nurse Consultant (Respiratory Care)

Acute hypoxemic respiratory failure is a common phenomenon for COVID-19 patients during the pandemic. It can cause respiratory muscle fatigue as well as the loss of airway cells that play a role in the physiological humidification of air, resulting in mucus plugs.

High Flow Nasal Oxygenation (HFNO) is an alternative modality to standard oxygen therapy which is the result of process to provide a system that could deliver both heated and humidified oxygen at high flows. It has a positive role in increasing ventilatory efficiency by a variety of mechanisms. It can constantly flush out carbon dioxide from the nasopharynx, which eliminates the dead space in proportion to flushed-out volume, increasing inspiratory fraction of oxygen (FiO2) (1-3). The effects of HFNO on positive end-expiratory pressure (PEEP) (4-7), which has the potential for application in ICU and perioperative settings as it prevents the cyclical opening and collapsing of alveoli. (8) The PEEP effect increases tidal volume and end-expiratory lung volume and decreases the respiratory rate and left ventricular afterload, while preserving minute ventilation. (9-11)

Easy set up and monitoring allow patients to stay in general unit for treatment. The connections of chamber kit set to sterile water and heated breathing tube to optiflow nasal cannula is the only set up for HFNO. There are three parameters in setting, i.e. Temperature (31℃, 34℃ & 37℃), Flow rate (10-60L/min) & Oxygen concentration% (21%-100%).

Usually, patients with respiratory failure required mechanical assisted ventilation, either invasive or non-invasive, to maintain oxygenation and adequate alveolar ventilation by reduction their work of breathing with pressure support.

There are reports that with the use of HFNO, reduction of intubation rate, reintubation rate and mortality rate when compare with face mask oxygen. (12-14) The need of mechanical ventilation support is also significantly reduced in recent studies on severe COVID-19 patients. (15-16) With the advantage of heating and humidification benefit, better patient comfort and tolerance of therapy leading to better therapeutic outcome. (13, 17)

High Flow Oxygen Therapy

High Flow Oxygen Therapy – Emergency Nursing


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