Nasal Cannula
The nasal cannula (NC) is a tool utilized for providing additional oxygen or
airflow to individuals requiring respiratory assistance. It comprises a
plastic tube that loops behind the ears and two prongs inserted into the
nostrils, through which oxygen is delivered.
This apparatus is linked to a source of oxygen, whether it be an oxygen
tank, a portable oxygen generator, or a hospital wall connection, via a
flowmeter. Oxygen is dispensed through the nasal cannula at a rate of 1–5
litres per minute.
For infants or neonates, specialized nasal cannulas are available,
delivering less than one litre per minute and featuring smaller prongs. The
oxygen concentration provided by the nasal cannula typically ranges from 24%
to 35%, although it may simply deliver humidified air.
Nasal cannulas are generally employed when modest amounts of supplementary
oxygen are needed, without stringent control of respiration, as seen in
oxygen therapy. Most cannulas are designed to deliver oxygen at low flow
rates, up to 5 litres per minute, resulting in an oxygen concentration of
28–44%. Higher flow rates exceeding 5 L/min may cause discomfort, nasal
dryness, and potentially nosebleeds (epistaxis).
Elderly patients or those benefiting from oxygen therapy but not reliant on
it for respiration commonly use nasal cannulas. These individuals don't
require the high oxygen levels necessitated by non-rebreather masks. Nasal
cannulas prove especially advantageous for patients vulnerable to
vasoconstriction, such as stroke victims. They are also employed by pilots
and passengers aboard small, unpressurized aircraft operating within
specific altitude parameters to counteract hypoxia caused by reduced oxygen
levels. Aviation-specific cannula systems are crafted for this purpose.
In situations necessitating a high volume of oxygen therapy, nasal cannulas
can administer high flows of an air/oxygen blend accurately. Respiratory gas
humidification enables comfortable delivery of these high flows through the
cannula. Nasal high flow therapy serves as an alternative to face mask
oxygen, enabling patients to engage in activities like talking, eating, and
drinking while receiving therapy.
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