Are nasal cannulas the best way to deliver oxygen to patients with COPD?

Expert comment

The use of nasal cannulas is common for patients with chronic obstructive pulmonary disease (COPD). This is often patient choice, as cannulas allow them to eat, drink and speak, and are often more comfortable than masks when they are receiving oxygen for long periods of time. Cannulas can also feel less claustrophobic, which is an important consideration for a patient experiencing breathlessness.

A note of caution however. Nasal cannulas may not be suitable in acute exacerbations of COPD. Oxygen administration is described as controlled or uncontrolled. Nasal cannula, simple face masks and non-rebreathe masks are uncontrolled, while fixed high-flow concentration masks such as Venturi deliver controlled oxygen.

The amount of oxygen a patient receives from an uncontrolled device depends on variables including depth and rate of breathing, which can alter during acute episodes and produce unexpectedly high concentrations of inspired oxygen. This issue is important, especially for patients with chronic hypercapnia, and can lead to serious or even fatal consequences. These patients require controlled oxygen therapy during an acute phase. This allows oxygen of a known concentration to be delivered and titrated according to the patient’s oxygen saturation (target saturation 88-92%) irrespective of breathing pattern, without the risk of hyperoxia and worsening hypercapnia (BTS, 2008). Nasal cannulas can be substituted once the patient has stabilised.

Carol Kelly is a senior lecturer at Edge Hill University, Lancashire.