Diaphragmatic Function and Respiratory Drive in OSA and COPD

Recruiting

• Conditions: Obstructive Sleep Apnea

• Registration Number: NCT07003399
• Lead Sponsor: Nanjing Medical University

Brief Summary

This cross-sectional observational study aims to assess the diaphragmatic morphofunction and respiratory drive characteristics among patients with obstructive sleep apnea (OSA), chronic obstructive pulmonary disease (COPD), overlap syndrome (OS), and healthy controls. Using ultrasound imaging and surface diaphragm electromyography (EMGdi), the study will explore group differences in diaphragmatic morphology, function, and respiratory drive indicators, and evaluate their clinical significance in disease differentiation and severity assessment.

Detailed Description

This is a single-center cross-sectional study designed to compare the diaphragmatic morphofunction and respiratory drive among four groups: OSA, COPD, overlap syndrome (patients with both OSA and COPD), and healthy controls. Participants will undergo overnight polysomnography (PSG), spirometry, impulse oscillometry, and diaphragm ultrasound combined with surface EMGdi measurements. The study will analyze group differences in diaphragmatic thickness, excursion, thickening fraction, and EMGdi parameters including EMGdi-rest, EMGdi-max, and EMGdi%max. The relationships between diaphragmatic indicators and respiratory parameters (FEV1, FVC, AHI, R5-R20, etc.) will also be assessed. This study aims to provide objective evidence for diaphragmatic dysfunction characterization in OSA and COPD, as well as to explore its diagnostic utility in overlap syndrome.

Study Timeline

• Study Start: 2025-01-01
• Study First Submitted: 2025-05-15
• Study First Submitted QC: 2025-05-25
• Status Verified: 2025-06
• Study First Posted: 2025-06-04
• Last Update Submitted: 2025-06-24
• Last Update Posted: 2025-06-25
• Primary Completion: 2025-08-31
• Study Completion: 2025-08-31

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 80

Inclusion Criteria

1. Patients aged between 18 and 80 years.
2. For OSA Group: Diagnosed obstructive sleep apnea with AHI ≥ 5 events/hour based on overnight polysomnography.
3. For COPD Group: Diagnosed chronic obstructive pulmonary disease based on GOLD guidelines.
4. For Overlap Group: Diagnosed both OSA (AHI ≥ 5) and COPD.
5. For Control Group: Healthy volunteers with no known respiratory diseases or sleep disorders.
6. Ability and willingness to provide informed consent for participation in the study.

Exclusion Criteria

1. Severe cardiovascular diseases (e.g., unstable angina, heart failure NYHA III/IV).
2. Severe hepatic or renal insufficiency.
3. Neuromuscular diseases affecting respiratory muscles.
4. Recent upper airway or thoracic surgery (within 3 months).
5. Pregnancy or breastfeeding.
6. Participants who cannot complete assessments due to cognitive impairment or poor cooperation.

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Diaphragmatic electromyography (EMGdi-rest) at baseline	Baseline (at enrollment)	To assess resting diaphragmatic electromyographic activity (µV) across OSA, COPD, Overlap, and control groups using surface and esophageal EMG.
Diaphragmatic EMG during maximal inspiration (EMGdi-max)	Baseline (at enrollment)	To assess maximal inspiratory diaphragmatic EMG activity (µV) using voluntary effort tests with surface and esophageal EMG.
Relative inspiratory EMG effort (EMGdi%max)	Baseline (at enrollment)	To calculate the ratio of EMGdi-rest to EMGdi-max as a percentage, reflecting the relative inspiratory effort.

Secondary Outcome Measures

Name	Time	Method
Minimum oxygen saturation (SpO₂ min)	Baseline (at enrollment)	To capture the lowest oxygen saturation (%) during overnight monitoring.
Diaphragmatic excursion measured by ultrasound during deep breathing	Baseline (at enrollment)	To evaluate diaphragmatic mobility (cm) during deep breathing using standardized ultrasound protocols.
Respiratory impedance parameter R5	Baseline (at enrollment)	To compare small airway resistance (kPa·s·L-¹) between groups using impulse oscillometry.
Respiratory resistance at 20 Hz (R20)	Baseline (at enrollment)	To compare central airway resistance (kPa·s·L-¹) using impulse oscillometry.
Difference in resistance (R5-R20)	Baseline (at enrollment)	To evaluate small airway dysfunction by calculating the difference between R5 and R20 (kPa·s·L-¹) .
Forced expiratory volume in 1 second (FEV1)	Baseline (at enrollment)	To compare FEV1 (L) across groups and assess its relationship with diaphragmatic function.
Forced vital capacity (FVC)	Baseline (at enrollment)	To compare FVC (L) across groups and assess pulmonary capacity.
FEV1/FVC ratio	Baseline (at enrollment)	To evaluate airflow obstruction using the FEV1/FVC ratio (%).
Apnea-hypopnea index (AHI)	Baseline (at enrollment)	To evaluate sleep-disordered breathing severity (events/hour) in OSA and Overlap groups.
Oxygen desaturation index (ODI)	Baseline (at enrollment)	To assess oxygen desaturation frequency during sleep (events/hour) using PSG data.
Time below 90% oxygen saturation (T90)	Baseline (at enrollment)	To calculate the percentage of sleep time with oxygen saturation \< 90% (%).

Trial Locations

Locations (1)

The First Affiliated Hospital of Nanjing Medical University; 🇨🇳 Nanjing, Jiangsu, China