From the Guidelines
High flow heated oxygen therapy is generally preferred over standard nasal cannula for patients with moderate to severe respiratory distress or hypoxemia. High flow nasal cannula (HFNC) delivers oxygen at rates of 30-60 liters per minute with heated and humidified gas, while standard nasal cannula typically delivers only 1-6 liters per minute of dry oxygen. HFNC provides several advantages including more reliable oxygen delivery, reduced anatomical dead space, positive end-expiratory pressure of 2-5 cmH2O, improved patient comfort, and better mucociliary clearance due to proper humidification 1.
Key Benefits of HFNC
- More reliable oxygen delivery
- Reduced anatomical dead space
- Positive end-expiratory pressure of 2-5 cmH2O
- Improved patient comfort
- Better mucociliary clearance due to proper humidification
HFNC is particularly beneficial for patients with hypoxemic respiratory failure, post-extubation support, pre-oxygenation before intubation, and in patients with COPD exacerbations 1. However, standard nasal cannula remains appropriate for patients with mild hypoxemia, those requiring mobility, or when HFNC equipment isn't available.
Implementation of HFNC
- Start with flow rates of 30-40 L/min and FiO2 of 40-60%
- Titrate based on oxygen saturation goals and patient comfort
- Monitor for signs of respiratory deterioration, as delayed intubation in failing patients can worsen outcomes
The decision between these oxygen delivery methods should ultimately be based on the patient's clinical condition, oxygen requirements, and comfort. According to the American College of Physicians, HFNC is suggested over conventional oxygen therapy for hospitalized adults with postextubation acute hypoxemic respiratory failure 1.
From the Research
Comparison of High Flow Heated Oxygen Therapy and Oxygen Administration via Nasal Cannula
- High flow heated oxygen therapy, also known as high flow nasal cannula (HFNC), has been compared to conventional oxygen therapy (COT) and non-invasive ventilation (NIV) in several studies 2, 3, 4.
- HFNC has been shown to be effective in reducing dyspnea and improving oxygenation in patients with acute hypoxemic respiratory failure, and may be considered as an intermediate level of oxygen therapy between COT and NIV 4.
- Compared to COT, HFNC has been associated with superior comfort and patient tolerance, reduced work of breathing, and improved oxygenation in some studies 4.
- However, the need for mechanical ventilation was similar between HFNC and COT in a systematic review of patients with acute respiratory failure admitted to emergency departments 5.
- HFNC has also been shown to decrease respiratory rate compared to COT, but did not differ in terms of sensation of dyspnea, ED length of stay, and mortality 5.
- The use of HFNC in acute respiratory failure has been recommended as an alternative to COT and sometimes NIV, with strong recommendations for its use in hypoxemic respiratory failure and conditional recommendations for its use following extubation and in postoperative patients 3.
Mechanisms of Action
- HFNC reduces the anatomical dead space and improves carbon dioxide wash-out, reduces the work of breathing, and generates a positive end-expiratory pressure and a constant fraction of inspired oxygen 2.
- The heated and humidified oxygen provided by HFNC may also help to improve patient comfort and tolerance, and reduce the need for escalation of oxygen therapy 6, 4.
Clinical Applications
- HFNC has been used to treat a variety of clinical indications, including acute hypoxemic respiratory failure, exacerbation of chronic obstructive pulmonary disease (COPD), postintubation hypoxemia, and palliative respiratory care 2, 3.
- HFNC may also be considered for use in patients with chronic respiratory diseases, such as stable COPD, and in patients who require domiciliary treatment 2.