<P> Cannulae with smaller prongs intended for infant or neonatal use can carry less than one litre per minute . Flow rates of up to 60 litres of air / oxygen per minute can be delivered through wider bore humidified nasal cannula . </P> <P> The nasal cannula was invented by Wilfred Jones and patented in 1949 by his employer, BOC . </P> <P> A nasal cannula is generally used wherever small amounts of supplemental oxygen are required, without rigid control of respiration, such as in oxygen therapy . Most cannulae can only provide oxygen at low flow rates--up to 5 litres per minute (L / min)--delivering an oxygen concentration of 28--44% . Rates above 5 L / min can result in discomfort to the patient, drying of the nasal passages, and possibly nose bleeds (epistaxis). Also with flow rates above 6 L / min, the laminar flow becomes turbulent and the oxygen therapy being delivered is only as effective as delivering 5 - 6 L / min . </P> <P> 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 . </P>

The oxygen flow rate for a nasal cannula should not exceed