Ambulatory Long-Term Oxygen Therapy in Patients with Severe COPD: A Randomized Crossover Trial to Compare Constant-Minute-Volume and Constant-Bolus Systems

Abstract

Background and Methods

Constant-minute-volume and constant-bolus devices serve as two different means of portable oxygen conservation. A prospective randomised crossover study was conducted in COPD GOLD IV patients to investigate the effect of these two devices on dyspnea, oxygenation and 6-minute walking test (6MWT) distance. The primary endpoint was the final operating level required (operating level range 1–5 for both devices) by either device to meet the success criteria for mobile oxygen therapy, as outlined in the British Thoracic Society guidelines (SpO₂ ≥90% throughout 6MWT; ≥10% increase in walking distance from baseline; improvement in BORG of at least 1 point from baseline).

Results

Twenty-five patients were enrolled in the study and randomly assigned to one of two sequences involving the use of each type of portable oxygen conservation device. 14 female, 67.9 years (±7.8); FEV1: 27.3%pred. (±8.4); PaO₂ at rest without oxygen: 50.3mmHg (±5.9). For both systems, 24/25 patients (96%) were successfully recruited. The mean operating-level difference when success criteria were met was −0.58 in favor of the constant bolus device (95% CI: −0.88 to −0.28, P <0.001). Secondary endpoints (walking distance, respiratory rate and BORG dyspnea) showed no statistically significant or clinically relevant differences. An algorithm created especially for this study showed a high success rate in terms of titration for the required operating level.

Conclusion

Both portable oxygen-conserving devices met the success criteria in 96% of patients in the 6MWT when they were titrated to the correct level. The constant-bolus device required a significantly lower operating level to achieve the success criteria, hereby reducing energy consumption. Individual titration of the respective device is recommended, which can be facilitated by the novel titration algorithm described here.

Keywords:

• COPD
• LTOT
• ambulatory oxygen therapy
• portable oxygen conserving devices
• 6MWT

Data Sharing Statement

The authors do not intend to share individual deidentified participant data. The authors do only, without exception, share anonymized data with written permission given by each participant. The authors intend to publish an original contribution and will not share any other information concerning this trial on other platforms. The data will be accessible through the corresponding author Prof. Dr. Wolfram Windisch at [email protected] permanently.

Acknowledgments

We acknowledge all participants for the effort they devoted to this study.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The Cologne study group (F.S.M., D.K., M.Z., S.B.S., D.S.M., M.WS and W.W.) received an open research grant from Weinmann/Germany, Vivisol/Germany, Heinen und Löwenstein/Germany, GCE Ltd. UK and VitalAire/Germany Philips Respironics/Netherlands and Löwenstein Medical/Germany. F.S.M., and S.B.S. received personal travel grants from companies dealing with LTOT. W.W. received speaking fees from companies dealing with LTOT. MZ reports personal fees from Resmed, outside the submitted work. The authors report no other conflicts of interest in this work.

Additional information

Funding

A research grant was provided by GCE Healthcare (Malmö, Sweden). The authors state that neither the study design, results, interpretation of the findings, nor any other subject discussed in the submitted manuscript was dependent on financial support.