Long term oxygen treatment used for at least 15 hours a day improves survival in patients with chronic obstructive lung disease and respiratory failure.1,2 In 1989 prescriptions for oxygen for use at home, particularly oxygen concentrators, cost the NHS pounds sterling 18 million, and the number of such prescriptions has been increasing.3 There has never, however, been a completely reliable method for measuring compliance with domiciliary oxygen treatment. The most common method uses a clock incorporated into the oxygen concentrator, but patients may take off their nasal cannulas, and leaving the concentrator and clock running, or they may run the machine without wearing the delivery system.
We developed a method to assess compliance that uses plastic electrodes connected …