Nasal cannula

Illustration of a nasal cannula

The nasal cannula (NC) is a device used to deliver supplemental oxygen to a patient or person in need of extra oxygen. This device consists of a plastic tube which fits behind the ears, and a set of two prongs which are placed in the nostrils. Oxygen flows from these prongs.^[1] The nasal cannula is connected to an oxygen tank, a portable oxygen generator, or a wall connection in a hospital via a flowmeter. The nasal cannula carries 1–6 litres of oxygen per minute. There are also infant or neonatal nasal cannulas which carry less than one litre per minute; these also have smaller prongs. The oxygen fraction provided to the patient ranges roughly from 24% to 35%.

The nasal cannula was invented by Wilfred Jones and patented in 1949 by his employer, BOC.

Applications

A nasal cannula can be used wherever small amounts of supplemental oxygen without rigid control of respiration are required, such as in oxygen therapy. It can only provide oxygen at low flow rates—up to 6 litres per minute (L/min)—delivering an oxygen concentration of 28–44%. Rates above 6 L/min can result in discomfort to the patient, drying of the nasal passages, and possibly nose bleeds (epistaxis).

The nasal cannula is often used in elderly patients or patients who can benefit from oxygen therapy but do not require it to self respirate. These patients do not need oxygen to the degree of wearing a non-rebreather mask. It is especially useful in those patients where vasoconstriction could negatively impact their condition, such as those suffering from strokes.

It may also be used by pilots and passengers in small, unpressurized aircraft that do not exceed certain altitudes. The cannula provides extra oxygen to compensate for the lower oxygen content available for breathing at the low ambient air pressures of high altitude, preventing hypoxia. Special aviation cannula systems are manufactured for this purpose.

See also

• Oxygen therapy
• Oxygen mask
• Hyperbaric oxygen therapy
• Space suit
• Oxygen tent
• Oxygen bar

References

1. ^ http://www.glasgowfirstaid.org/images/cannula.jpg

External links

• Nasal cannula
• Nasal cannula patent (GB618570)