Near-Infrared Spectroscopy Measurements in Chronic Obstructive Pulmonary Disease

Prior treatment

• Patients were excluded from the study if they met any of the following criteria:
  • Acute Exacerbation: Evidence of an acute COPD exacerbation within four weeks prior to enrolment.
  • Other Respiratory Disorders: Coexistence of other chronic respiratory diseases such as asthma, interstitial lung disease, or bronchiectasis that might interfere with the assessment of COPD.
  • Renal Transplantation: History of kidney transplantation, as immunosuppressive therapy may affect disease progression and outcomes.
  • Uncontrolled Comorbidities: Presence of any uncontrolled comorbid conditions, including:
  • Cardiovascular instability or recent myocardial infarction (within six months).
  • Active malignancy (other than localized skin cancer).
  • Severe liver disease (e.g., cirrhosis with hepatic failure).
  • Pregnancy or Breastfeeding: Women who were pregnant or breastfeeding at the time of study enrolment.
  • Cognitive Impairment: Any condition that would impair the ability to provide informed consent or participate in study procedures, such as dementia or significant psychiatric disorders.

• To be eligible for the study, patients were required to meet all of the following criteria:
  • Age: Patients aged between 18 and 80 years.
  • COPD Diagnosis: A confirmed diagnosis of COPD according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria, including:
  • A post-bronchodilator forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) ratio of \<0.70.
  • Renal Failure: Evidence of CKD, defined as:
  • An estimated glomerular filtration rate (eGFR) of \<60 mL/min/1.73 m² (Stages 3-5 CKD) on at least two occasions three months apart, or a history of renal replacement therapy.
  • Stable Medical Condition: Clinically stable COPD, with no exacerbations or hospital admissions within the preceding four weeks.