Dual-site pulse oximetry (finger and earlobe): During a single 6MWT, SpO2 and heart rate are recorded simultaneously at the finger (digital) and the earlobe (auricular) with two pulse oximeters, at eight timepoints (baseline, minutes 1 to 6, and a 2-minute recovery). No treatment is administered and routine clinical management is not modified; the procedure adds the simultaneous earlobe measurement for comparison with the finger.
Study summary
The OXISITE-ILD study is a prospective, multicenter, observational study designed to evaluate the agreement between finger (digital) and earlobe (auricular) pulse oximetry for measuring oxygen saturation (SpO2) during the six-minute walk test (6MWT) in patients with interstitial lung disease (ILD). In routine clinical practice, exercise SpO2 is usually measured at the finger; however, the finger reading can be unreliable in some patients, and there is currently no recommendation on the best sensor location in ILD. This study compares the two sensor locations, recorded at the same time, and evaluates whether any disagreement changes how exercise desaturation is classified and whether ambulatory oxygen is indicated.
All patients undergoing a 6MWT as part of routine ILD care are included consecutively to ensure a pragmatic, real-world representation of the ILD population. The primary objective is to measure the agreement between the two locations in the lowest SpO2 reached during the test, including the size and direction of any difference. Secondary objectives include the reclassification of patients at the clinical desaturation thresholds, the comparison between autoimmune and non-autoimmune ILD, the rate of invalid readings at each location, and the clinical, vascular and functional factors associated with disagreement.
Eligibility
Sex
ALL
Min age
18 Years
Max age
—
Healthy volunteers
No
Inclusion Criteria:
* Adults aged 18 years or older
* Confirmed diagnosis of interstitial lung disease (ILD) based on clinical, radiological and/or histological criteria
* Newly diagnosed or under follow-up for ILD
* Physically and cognitively able to perform the 6-minute walk test (6MWT)
* Signed informed consent
Exclusion Criteria:
* Inability to obtain a reliable, stable baseline pulse oximetry reading at the finger and/or the earlobe, preventing a valid paired baseline measurement and the calculation of agreement
* ILD exacerbation, decompensated comorbidity, or acute respiratory infection at the time of the test
Primary outcome measure(s)
Intraclass correlation coefficient for agreement in minimum SpO2 between sensor locations — Day 1 Absolute agreement in minimum SpO2 during the six-minute walk test between the finger and earlobe sensors, quantified with the intraclass correlation coefficient (two-way mixed-effects model, absolute agreement) and its 95% confidence interval. ICC values are interpreted as below 0.50 poor, 0.50 to 0.75 moderate, 0.75 to 0.90 good, and above 0.90 excellent agreement.
Bland-Altman agreement in minimum SpO2 between sensor locations — Day 1 Agreement in minimum SpO2 during the six-minute walk test between the finger and earlobe sensors, assessed with Bland-Altman analysis: mean bias (earlobe minus finger) with its 95% confidence interval and 95% limits of agreement, evaluated against a prespecified clinically acceptable difference of 3 percentage points. The direction of the bias is reported, as the finger is hypothesised to register lower values than the earlobe.
This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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