Q. What is high flow oxygen therapy (HFOT)?
HFOT is a form of therapy that administers heated and humidified air plus supplementary oxygen (FiO2 from 21% to 100%) through a nasal cannula at a continuous flow of up to 60 L/min
Q. What are the main clinical indications for HFOT?
- Non-hypercapnic acute hypoxemic respiratory failure1
- Post-extubation period2
Q. What are other potential clinical indications for HFOT?
- Patients undergoing bronchoscopy and other invasive procedures
- Emergency department
- Palliative care
- Acute heart failure
- Chronic airway disease
Q. What are the effects of HFOT?
- HFOT washes out carbon dioxide from the patient’s anatomical dead space of the patient3
- High flow oxygen creates an oxygen-enriched reservoir in the patient’s anatomical dead space while providing a flow to match or exceed the patient’s inspiratory demand. Thus, the patient’s work of breathing is reduced4
- High flow creates a small positive nasopharyngeal pressure5
Q. What are the advantages of HFOT?
- HFOT requires minimal technical skill to set up and apply – however, close monitoring is essential
- Allows patients to speak and to eat6
- Reduced sensation of respiratory distress7 and mouth dryness6
- Improving patient comfort and tolerance
- Heated and humidified gas flow preserves the mucociliary functions8
Q. Where is HFOT mainly used?
- HFOT has widespread hospital applications due to its various indications for use
- Most typical wards are:
- Intensive Care Units (ICUs)
- Emergency departments
Q. What is a typical hospital setup for delivering HFOT?
- Gas source with flow and FiO2 control
- Air/oxygen blender with flow meter (up to 60 L/min)
- Patient interface
- ResMed AcuCare HFNC
Q. Which parameters are set to provide HFOT?
- Flow: Continuous gas flow of up to 60 L/min
- To cover the patient's spontaneous breathing pattern
- FiO2 (fraction of inspired oxygen): from 21% to 100%
- To ensure correct patient oxygenation for treatment of hypoxemia
- Breathing gas humidity: ideally 100% relative humidity for a gas temperature between 34–37°C or (93–98°F)
- To avoid dryness, and to maximise patient compliance
Q. What are the contraindications for HFOT?
- High flow oxygen therapy is a form of positive airway pressure
- Contraindications for positive airway pressure apply:
- Pathologically low blood pressure
- Cerebrospinal fluid leak
- Recent cranial surgery or trauma
- Severe bullous lung disease
Q. What are the differences between HFOT and conventional low flow oxygen therapy?
- Conventional low flow oxygen therapy provides oxygen at flow rates up to 6 L/min when using standard low flow nasal cannulas, and a maximum of 15 L/min with non-rebreather masks
- Low flow oxygen supplies flow rates lower than the patient‘s inspiratory demand, thus a mix of supplemental oxygen and room air is entrained9
- No precise control of FiO2
- The gas supplied to the patient is typically non-conditioned to the patient, that is, not heated or humidified10
- Patient compliance might be reduced
Q. What are the differences between HFOT and non-invasive ventilation (NIV)?
- HFOT is NOT ventilation
- NIV can only be delivered by pressure or volume regulated ventilators
- The patient interface is typically a full face or a nasal mask, preventing unintentional leak between cushion and patient skin
- Ventilation is induced by several indications, such as chronic respiratory failure and acute respiratory failure with hypercapnic conditions
Q. Is an elevated noise level normal during HFOT?
- HFOT may be perceived as noisy due to its continuous high flow of up to 60 L/min
- When using an air/oxygen blender, ResMed recommends using a muffler between blender/flowmeter and humidifier to reduce the noise caused by the flow source
Maggiore SM et al. Nasal high-flow versus venturi mask oxygen therapy after extubation: effects on oxygenation, comfort and clinical outcome. American Journal of Respiratory and Critical Care Medicine 2014;190(3):282–8.
. Dewan, NA, Bell CW. Effect of low flow and high flow oxygen delivery on exercise tolerance and sensation of dyspnea. A study comparing the transtracheal catheter and nasal prongs. Chest 1994;105(4):1061–5.