Abstract Rationale Portable oxygen concentrators (POCs) are widely used by patients requiring ambulatory oxygen therapy. Most devices on the market use pulsed or intermittent flow with claimed equivalency to continuous flow but few have been clinically validated. This study evaluates a new continuous flow ultra-portable POC compared head-to-head with an oxygen tank and examines breathing patterns to assess efficacy of oxygen delivery. Methods Patients with mild to moderate hypoxemia (SpO2 92% predicted) were recruited through a large Australian tertiary teaching hospital. Patients were fitted with a monitor recording nasal flow, respiratory effort and pulse oximetry. Two 6-minute walk tests were performed in randomised order with a C sized oxygen tank and a Juno (Roam Technologies Pty Ltd) POC. Both devices were set to deliver 2L continuous flow. Results 22 patients were recruited with 20 completing all study investigations. This was a mixed disease population and included both inpatients and outpatients and those with acute and chronic oxygen requirements. Analysis of respiratory effort and nasal flow during 6MWT demonstrated breathing pattern heterogeneity where 6/20 patients (30%) had periods where they switched from nasal to oral breathing. This was typically at the times of peak desaturation. This was not associated with a particular pathology (COPD vs ILD vs others) nor disease severity. While patients in the Juno arm achieved a statistically significantly higher walk distance (P 0.05) and had reduced dyspnea by BORG score (P 0.05), there was no correlation between supplemental oxygen device and breathing pattern, and patients who demonstrated periods of oral breathing did so with both devices. Conclusion Although all patients walked further with the POC, likely attributable to the lighter weight and more easily carried form factor over the tank, patients demonstrated significant breathing pattern heterogeneity. This was not predictable based on resting breathing patterns or even during light exertion, with the change from regular nasal to oral breathing only demonstrated during peak dyspnea and desaturation. This highlights the potential importance of continuous flow oxygen therapy, where patients who switch to mouth breathing will still accumulate oxygen in their dead space and receive a higher volume bolus of oxygen on their next nasal inhalation. Further research is required to validate this finding and confirm the above implications. This abstract is funded by: None
Flack et al. (Fri,) studied this question.