Background

An audit presented at the Winter British Thoracic Society (BTS) 2022 meeting found that, using a pre-established blinded treadmill protocol, BORG score (BS) may not be the most effective marker for assessing benefit from supplemental ambulatory oxygen in patients who are normoxic at rest (only 31% had a reduction in BS, 52% reported same BS, whilst 17% reported higher BORG scores).

It was hypothesised that ITHR may be a more robust objective marker than the subjective BORG.

Aim:

Can ITHR be used as an objective marker for demonstrating a positive improvement with ambulatory oxygen, using a pre-established blinded treadmill protocol?

Methods:

Test results, demographic and clinical data were collated for all patients referred for ambulatory Oxygen assessment over 2 years. ITHR was compared in patients who completed both walking tests (air and O2). T-tests were carried out to assess for statistical significance.

Results:

111 patients carried out ambulatory O2 assessment over 2 years.

52 included in analysis (46 patients no significant desaturation or SpO2 remained above 90%, with 13 excluded).

End of test BORG comparison on air and O2: 26 decreased (26/52 50%), 17 stayed the same (17/52 33%), 9 increased (9/52 17%).

Iso-time HR t-test result: p=<0.0001.

Effect size= 0.79, large effect size.

Conclusion:

ITHR may be used as an additional objective marker to demonstrate a positive improvement with ambulatory oxygen using a pre-established protocol. Although statistically significant, further investigation is necessary to establish clinical utility of ITHR.