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Updated: Jul 6, 2026
Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method
Published on: February 2, 2024
Comparing supplementary oxygen benefits from a portable oxygen concentrator and a liquid oxygen portable device
Jacek Nasilowski1, Tadeusz Przybylowski, Jan Zielinski
1Department of Internal Medicine, Pneumology and Allergology, Medical University of Warsaw, Banacha 1a, 02-097 Warsaw, Poland. jnasilek@amwaw.edu.pl
Background:
Differences in oxygen delivery between portable oxygen concentrators (POC) and liquid oxygen (LO) portable units, pose a question if POCs are equally effective as LOs in reducing exercise-induced hypoxaemia.
Design:
Randomized, single-blind clinical trial.
Patients:
Thirteen COPD patients (means: age 66+/-11 year, FEV(1) 35.2+/-13.7% predicted) and respiratory failure (means: PaO2 52+/-5mmHg, PaCO2 51.3+/-7.5mmHg).
Methods:
All patients underwent a series of 6-min walk tests (6MWT) carried out in random order among one of the three devices: POC, LO cylinder and cylinder with compressed air (CA). Oxygen supplementation was 3lpm for LO and an equivalent to 3lpm in a pulse flow system for POC.
Results:
The mean SpO2 was equally improved at rest: 92.9+/-2.8% with POC and 91.7+/-2.0% with LO compared to CA-87.8+/-2.7% (POC and LO vs. CA p<0.05). POC and LO significantly improved oxygenation during 6MWT (mean SpO(2) was 84.3+/-5% and 83.8+/-4.2%, respectively) compared to breathing CA-77.6+/-7.4%, p<0.05. Mean 6MWT distance increased with LO (350+/-83m) and POC (342+/-96m) when compared to CA (317+/-84m), however, these differences were not statistically significant. Dyspnoea score assessed at the end of the exercise (Borg scale) was significantly lower when breathing oxygen (4.2+/-1.2 with POC and 4.1+/-1.7 with LO vs. 5.4+/-1.9 with CA, p<0.05).
Conclusions:
Effectiveness of oxygen supplementation from a POC did not differ from the LO source during 6MWT in COPD patients with respiratory failure. Oxygen at 3lpm flow was not sufficient to prevent hypoxaemia during strenuous exercise.
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