Muscle Oxygenation in Patients With COPD Exacerbation

Evaluation of Respiratory and Peripheral Muscle Oxygenation in Patients With Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is often complicated by acute exacerbations, which lead to functional impairments, increased dyspnea, and a rapid decline in lung function. During an exacerbation, impaired pulmonary gas exchange, systemic inflammation, and increased work of breathing significantly alter oxygen availability and metabolic demand in skeletal muscles. The aim of this study is to evaluate and compare respiratory and peripheral muscle oxygenation in patients with acute exacerbation of COPD (AECOPD) and patients with clinically stable COPD. By examining these physiological changes, the study seeks to determine the impact of exacerbations on muscle function and oxygenation efficiency

Study Overview

• Status: Not yet recruiting
• Conditions: COPD (Chronic Obstructive Pulmonary Disease); Muscle Oxygenation; Acute Exacerbation Chronic Obstructive Pulmonary Disease

Detailed Description

Chronic obstructive pulmonary disease (COPD) is characterized by recurrent acute exacerbations that negatively affect patients' quality of life and accelerate lung function decline. Severe exacerbations requiring hospitalization pose a significant mortality risk both during admission and in the following year.

During acute exacerbations, maximal pressure generation by respiratory muscles declines, and respiratory muscle efficiency-particularly of the diaphragm-is significantly reduced. Acute dynamic hyperinflation further shortens the inspiratory muscles, leading to functional muscle weakness. Consequently, accessory respiratory muscles are recruited maximally, often causing notable alterations in chest-wall and abdominal kinematics. Due to the requirement of spending a higher proportion of their maximum capacity with each breath, these patients face an elevated risk of developing respiratory muscle fatigue. Exacerbations lead to severe hypoxemia caused by impaired pulmonary gas exchange, driven primarily by ventilation-perfusion mismatch and increased tissue oxygen consumption. Acute hypoxemia exacerbates muscle weakness and impairs skeletal muscle function. Even after discharge from respiratory intensive care units following severe exacerbations, persistent respiratory muscle dysfunction is observed in more than a third of patients, requiring additional care and rehabilitation.

Physiological factors such as impaired gas exchange, reduced perfusion, and systemic inflammation during exacerbations substantially impact muscle oxygenation. Reduced arterial oxygen content diminishes oxygen availability to peripheral tissues and muscles. Simultaneously, the metabolic demands of both respiratory and peripheral muscles increase due to the heightened work of breathing and systemic stress.

This study aims to investigate respiratory and peripheral muscle oxygenation in patients with AECOPD and stable COPD, evaluating underlying physiological changes and assessing the impact of exacerbations on muscle function and oxygenation dynamics.

The aim of study is to investigate respiratory and peripheral muscle oxygenation in patients with AECOPD.

• Study Type: Observational
• Enrollment (Estimated): 40

Contacts and Locations

• Study Contact: Name: Aynur Demirel, PT, PhD, Assoc. Prof.; Phone Number: +90 554 529 5057; Email: aynur.demirel@hacettepe.edu.tr
• Study Contact Backup: Name: Alper kemal Gurbuz, PT, MSc.

Study Locations

• Turkey (Türkiye)
  • Ankara, Turkey (Türkiye)
    • Hacettepe University
    • Sub-Investigator: Hidaye Yamikan, PT, MSc.
    • Principal Investigator: Aynur Demirel, PT, PhD, Assoc. Prof.
    • Contact: Aynur Demirel, PT, PhD, Assoc. Prof.; Phone Number: +905545295057; Email: aynur.demirel@hacettepe.edu.tr
    • Sub-Investigator: Alper Kemal Gurbuz, PT, MSc.
    • Sub-Investigator: Irem Suzen, PT, MSc.
    • Sub-Investigator: Gulse Ozer, PT
    • Sub-Investigator: Aysu Yalman, PT, MSc.
    • Sub-Investigator: Oguz Karcioglu, MD, Assoc Prof.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population consists of adult patients aged 40 years and older diagnosed with Chronic Obstructive Pulmonary Disease (COPD) according to GOLD guidelines. The sample includes two distinct cohorts: patients admitted or presenting with an acute exacerbation of COPD (AECOPD), and patients in a clinically stable period (GOLD Grades 1-4) without exacerbations in the preceding 4 weeks.

Description

Inclusion Criteria:

Acute Exacerbation Group: 1. Diagnosis of Chronic Obstructive Pulmonary Disease (COPD) 2. Hospital admission or presentation due to an acute exacerbation of COPD 3. Age 40 years or older 4. Voluntary agreement to participate with signed written informed consent Clinically Stable Group: 1. Diagnosis of COPD (GOLD Stage 1, 2, 3, or 4) 2. Age 40 years or older 3. Clinically stable condition for at least the past 4 weeks without acute exacerbations 4. Voluntary agreement to participate with signed written informed consent

Exclusion Criteria: Acute Exacerbation Group: 1. Active participation in a formal pulmonary rehabilitation program 2. Co-existing neurological disorders 3. Heart failure classified as New York Heart Association (NYHA) Class III or IV 4. Unstable mental or cognitive status (Mini-Mental State Examination [MMSE] score ≤24) 5. History of surgical intervention within the past three months 6. Presence of malignant conditions .

Clinically Stable Group: 1. History of lung cancer, sarcoidosis, tuberculosis, and/or prior lung surgery 2. Known mental or cognitive impairment.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Acute copd patients; acute exacerbation of COPD
stable copd patients; clinically stable without any acute exacerbations for at least the past 4 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Muscle Oxygen Saturation	Muscle oxygen saturation (SmO_2) will be measured continuously using Near-Infrared Spectroscopy (NIRS) (Train.Red FYER) on the intercostal, deltoid, and dominant quadriceps muscles. The primary parameter ΔSmO_2 max represents the difference between the peak SmO_2 during functional tasks (30-second sit-to-stand test, 4-meter gait speed test, and upper extremity assessment) and the baseline resting	baseline (1 day)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
functional capacity	30-Second Sit-to-Stand Test: Assesses functional lower-limb muscle strength and exercise capacity. The total number of completed full stand-ups from a chair (height 43.2 cm) within 30 seconds will be recorded.	baseline (1 day)
Gait speed	4-Meter Gait Speed Test: Gait speed will be evaluated over a 4-meter course at normal walking pace. Gait speed is calculated in meters per second (m/s) by dividing 4 meters by the time taken	baseline (1 day)
Peripheral Muscle Strength	Maximal isometric handgrip strength will be measured in kilograms (kg) using a digital hand dynamometer (Baseline BIMS). The highest value of three trials for both dominant and non-dominant hands will be recorded	baseline (1 day)
pulmonary functions	Spirometry will be performed according to ATS/ERS guidelines. Values will be recorded.	baseline (1 day)
Dyspnea and Fatigue Perception	Dyspnea will be evaluated using the Modified Medical Research Council (mMRC) scale (grades 0-4) and Visual Analog Scale (VAS, 0-10 cm). Fatigue perception will be assessed using the Modified Borg Scale (0-10) before and after functional tests.	baseline (1 day)
Activities of Daily Living	Activities of daily living will be assessed using the London Chest Activity of Daily Living (LCADL) scale (score range 0-75).	baseline (1 day)

Collaborators and Investigators

• Sponsor: Hacettepe University
• Investigators: Study Director: Aynur Demirel, Hacettepe University

Study record dates

Study Major Dates

• Study Start (Estimated): August 30, 2026
• Primary Completion (Estimated): October 5, 2027
• Study Completion (Estimated): February 5, 2028

Study Registration Dates

• First Submitted: August 28, 2026
• First Submitted That Met QC Criteria: August 28, 2026
• First Posted (Actual): September 3, 2026

Study Record Updates

• Last Update Posted (Actual): September 3, 2026
• Last Update Submitted That Met QC Criteria: August 28, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pathologic Processes; Chronic Disease; Disease Attributes; Respiratory Tract Diseases; Lung Diseases; Lung Diseases, Obstructive; Pathological Conditions, Signs and Symptoms; Pulmonary Disease, Chronic Obstructive
• Other Study ID Numbers: FTREK25/189

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No