A new pendant storage oxygen-conserving nasal cannula

With increasing interest in reducing the cost of oxygen therapy, we recently designed an oxygen-conserving cannula. It reduces the oxygen supply flow necessary to achieve adequate oxygen saturation, but because it requires the use of a reservoir situated under the nose, some patients find it obtrusive. We therefore designed a similar system but displaced the reservoir away from the face and onto the anterior chest wall where it could be hidden from view by the patient's clothing. We evaluated this pendant conserving nasal cannula (PNC) in seven hypoxemic patients with chronic obstructive pulmonary disease. We compared oxygen saturations achieved using the PNC vs the standard steady flow nasal cannula (SNC) at 0.5 through 4 L/min. The mean improvement in oxygen saturation using the PNC vs the SNC was 3.3 percent at 0.5 L/min, 4.3 percent at 1 L/min and 3.1 percent at 2 L/min. These differences were statistically significant (p less than 0.001). The saturation achieved by the PNC at 0.5 L/min was equivalent to that achieved by the SNC at 1.8 L/min. We conclude that the PNC provides effective oxygen delivery to patients at supply flows substantially less than the SNC. The device is aesthetically acceptable to patients and its widespread use in patients requiring chronic oxygen therapy could bring about significant financial savings.