Correlation Between Diaphragmatic Excursion and Exercise Tolerance Improvement Following Pulmonary Rehabilitation in Patients with Chronic Obstructive Pulmonary Disease-Obstructive Sleep Apnea Overlap Syndrome

Abstract

Purpose

We assess the predictive value of diaphragm excursion (DE) in enhancing exercise tolerance following pulmonary rehabilitation (PR) among patients with COPD-OSA overlap syndrome.

Material and Methods

This prospective cohort study enrolled 63 patients diagnosed with COPD-OSA overlap syndrome who actively participated in a PR program from January 2021 to May 2023. Among these, 58 patients successfully completed the 20-week PR program, with exercise tolerance assessed through the measurement of six-minute walk distance (6MWD), and DE evaluated by ultrasonography. The responder to PR in terms of exercise ability was defined as a patient who showed an increase of >30m in 6MWD. The cutoff value for predicting PR response based on DE was determined using receiver operating characteristic (ROC) curves.

Results

Following the PR program, significant improvements were observed in mMRC, 6MWD, DE during deep breathing, and diaphragm thickness fraction (DTF). Of the participants, 33 patients (57%) were classified as responders, while 25 patients (43%) were considered non-responders. Baseline values of FEV₁% predicted, 6MWD, DE during deep breathing, DTF, and PaO₂ exhibited a significant elevation in responders as compared to non-responders. The changes of 6MWD were positively associated with the baseline values of DTF and DE during deep breathing, FEV₁% predicted and PaO₂, while negatively correlated with baseline value of mMRC. The predictive performance in terms of the area under the ROC curve for determining responder’s DTF was found to be 0.769, accompanied by a sensitivity of 85% and specificity of 68%, using a cutoff value at 17.26%. Moreover, it was observed that DE during deep breathing could predict the area under the ROC curve for responders to be 0.753, with a sensitivity of 91% and specificity of 56% at a cutoff value of 3.61cm.

Conclusion

Diaphragm excursion serves as a valuable predictor for determining the enhancement of exercise tolerance following PR in patients with COPD-OSA overlap syndrome.

Trial Registration

ChiCTR1800020257, www.chictr.org.cn/index.aspx.

Keywords:

• pulmonary rehabilitation
• COPD-OSA overlap syndrome
• diaphragm excursion
• diaphragm thickness fraction
• six-minute walk distance

Data Sharing Statement

The datasets generated and/or analysed during the current study are available from the corresponding author upon reasonable request.

Ethical Statement

It has therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki (Revised in 2013). The study received approval from the Ethics Committee of The Fourth Rehabilitation Hospital of Shanghai (SP202002), and written informed consent was obtained from all participants. All methods were carried out in accordance with relevant guidelines and regulations.

Author Contributions

All authors have made significant contributions to the reported work, encompassing conception, study design, execution, data acquisition, analysis and interpretation. They have also participated in drafting, revising, or critically reviewing the article. Furthermore, they have provided final approval for the publication of this version and agreed upon its submission to the journal. Additionally, they acknowledge their accountability for all aspects of the work.

Disclosure

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

The National Natural Science Foundation of China (NSFC81770085, NSFC82070095). 2020 Jing’ an District Medical Research Project (face project 2020MS20).