Chest
Volume 96, Issue 3, September 1989, Pages 467-472
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Clinical Investigations
Efficacy of a Pulsed Oxygen Delivery Device during Exercise in Patients with Chronic Respiratory Disease

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The ability of a pulsed oxygen delivery system (Puritan-Bennett Companion Oxygen Saver (COS-5)) to track respiratory rate during exercise and the oxygenation achieved during the exercise while oxygen was being delivered by this system was compared to that attained while oxygen was delivered continuously in six patients with chronic obstructive pulmonary disease (COPD) and six patients with idiopathic pulmonary fibrosis (IPF). The COS-5 appeared to respond appropriately at respiratory rates between 15 and 45, even when there were minimal pressure changes at the nose. There was an excellent correlation in PaO2 at equivalent flow settings during the exercise in the patients with COPD and IPF. There were six instances (in four patients) of the 31 comparisons in which the PaO2 differed by more than 5 mm Hg. The PaO2 was higher with continuous oxygen delivery on two occasions in a patient with COPD who utilized pursed-lip breathing during the exercise. The PaO2 was higher with COS-5 delivery on two occasions in a patient with IPF who was breathing at the highest respiratory rates (44 and 45/min) during the exercise.

Section snippets

COS-5

The COS-5 device is an intermittent flow oxygen delivery device which can be used with both stationary and portable liquid oxygen systems as well as oxygen cylinders. The direction of the patient's respiratory flow is sensed via a standard nasal cannula, and the onset of inspiratory flow triggers a pulse of oxygen for a calculated period of time. The volume of oxygen delivered over a minute is approximately 40 percent of that which would be delivered during continuous oxygen delivery at the

RESULTS

The COS-5 was well tolerated by all patients, and they noted little difference from continuous flow delivery during exercise.

Figure 1 and Table 2 compare the arterial oxygen tensions achieved during continuous oxygen delivery and during demand delivery by the COS-5, at differing oxygen flow rates in patients with COPD (Fig 1 upper), and IPF (Fig 1 lower). As can be seen, there was an excellent correlation in PaO2 at equivalent flow settings while receiving continuous or COS-5 delivery of oxygen

DISCUSSION

Previous studies of pulsed demand oxygen delivery systems have reported equivalent oxygenation at rest in patients with pulmonary disease when oxygen is delivered by pulsed and continuous modes.12, 13, 14, 15, 16 However, since ambulation is essential for all patients with chronic pulmonary disease, it is important to ensure that these devices provide adequate oxygenation during exercise. We have previously found that the level of oxygenation achieved during exercise by another demand system

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