What type of mask is best for a patient with mouth breathing who requires supplemental oxygen via nasal cannula (NC) at home, particularly for nighttime use?

From the Guidelines

For a patient who is a mouth breather and requires oxygen at night, a simple face mask would be the most appropriate option for home use. This mask covers both the nose and mouth, ensuring adequate oxygen delivery regardless of breathing pattern. The simple face mask typically delivers oxygen at 5-10 liters per minute, providing an oxygen concentration of approximately 40-60% 1. Unlike a nasal cannula which only delivers oxygen through the nostrils, the face mask creates a reservoir of oxygen around both the nose and mouth, making it ideal for mouth breathers. Some key points to consider when using a simple face mask include:

• The mask should be fitted properly to minimize leaks but shouldn't be too tight to cause discomfort during sleep.
• The patient should be instructed to clean the mask regularly with mild soap and water to prevent infection.
• Some patients may initially find the mask uncomfortable or claustrophobic, so a period of adjustment during waking hours before using it for sleep might be helpful.
• If the patient experiences significant discomfort or skin irritation, cushioned masks or periodic mask removal for short breaks might be necessary. It's also important to note that the upper range of oxygen delivery from nasal cannulae is a little lower than the output of a simple face mask, but the lower range goes a lot lower than a simple face mask which should not be used below a flow rate of 5 L/min (about 40% oxygen) 1.

From the Research

Types of Oxygen Masks

• Non-rebreather mask (NRB): provides a high concentration of oxygen, up to 95% 2, 3, 4, 5
• High-flow nasal cannula (HFNC): delivers heated and humidified oxygen at a high flow rate, typically 30-60 L/min 2, 6, 4
• Simple mask: provides a lower concentration of oxygen, typically 35-60% 3
• Partial rebreather mask: provides a higher concentration of oxygen than a simple mask, typically 60-80% 3

Comparison of Oxygen Masks

• A study comparing HFNC and NRB found that NRB resulted in a reduced device failure rate and higher survival among patients with acute hypoxaemic respiratory failure 2
• A simulation-based study found that the FIO2 delivery was significantly different for each device, with NRB providing the highest FIO2 3
• A study comparing HFNC and NRB in patients with mild carbon monoxide poisoning found that HFNC rapidly reduced blood COHb level 6
• A retrospective study found that NRB combined with low-flow nasal cannula was a viable alternative to HFNC in patients with COVID-19-related hypoxemic respiratory failure, with similar improvement in oxygenation at two hours and no significant differences in long-term outcomes 4

Considerations for Patient Use

• Patients with respiratory failure due to pulmonary disease using NRB for over 2 hours may have a higher mortality rate than patients not using NRB 5
• The choice of oxygen mask should be based on the patient's individual needs and medical condition, as well as the availability of resources 2, 3, 4