The study is an observational, single-center, prospective cohort study aiming to evaluate respiratory mechanics data, as well as clinical and functional parameters commonly used in clinical practice in patients with COPD and hypercapnic respiratory failure. The study population consists of patients with COPD and hypercapnia requiring NIV. The primary objective of the study is to evaluate the association between the reduction in partial pressure of carbon dioxide in arterial blood (PaCO₂) levels at 6 and 12 months after initiating non-invasive ventilation (NIV) and the presence of nocturnal hypoventilation detected at baseline in patients with COPD and chronic hypercapnia. Secondary objectives of this study are the evaluation of the following parameters measured at baseline and/or after 6 and 12 months of NIV treatment in patients with COPD and chronic hypercapnia:
* Magnitude of esophageal pressure swing during nocturnal monitoring. * Diaphragm thickness and diaphragmatic thickening fraction assessed by thoracic ultrasound. * Presence of overlap syndrome (COPD + OSA). * Radiological classification of COPD subtypes to assess the association between radiological findings, functional profile, severity of nocturnal hypoventilation, and patterns of chronic hypercapnia. * Respiratory functional parameters, including FEV₁, FVC, FEV₁/FVC ratio, carbon monoxide diffusion capacity (DLCO), and airway resistance (R5 and R20). * Frequency of severe exacerbations and subsequent rehospitalizations during follow-up. * Rate of compliance with respiratory treatment.
Age ≥ 18 years
Patients with COPD and hypercapnia, defined as PaCO₂ > 50 mmHg either chronically or 4 weeks after an acute exacerbation requiring invasive or non-invasive mechanical ventilation
Provision of informed consent
Progressive neurodegenerative diseases
Diaphragmatic disorders
Severe hemodynamic instability (>1 vasoactive agent for at least 24 hours)
Acute coronary syndrome (unstable angina / myocardial infarction)
The study population consists of patients with COPD and hypercapnic respiratory failure who require NIV and who are evaluated in the outpatient clinic and/or inpatient unit of the Respiratory and Critical Care Unit of the IRCCS AOU of Bologna.
Cohort
Prospective
Not listed
The association between the reduction in PaCO₂ levels and the presence of nocturnal hypoventilation
The primary outcome is measured through arterial blood gas analysis (ABG) to determine PaCO₂ levels, and through transcutaneous monitoring of oxygen saturation and carbon dioxide (SpO₂ and TcCO₂) to assess the presence of nocturnal hypoventilation. Nocturnal hypoventilation is defined as an increase in PaCO₂ during sleep (TcCO₂ \>10 mmHg above daytime PaCO₂ with TcCO₂ \>50 mmHg for at least 10 minutes, or TcCO₂ \>55 mmHg for ≥25% of total sleep time).
Magnitude of esophageal pressure swing during nocturnal monitoring
Placement of a nasogastric respiratory mechanics catheter equipped with an esophageal balloon, and measurement of maximal inspiratory pressure swing (ΔPES).
Diaphragm thickness and diaphragmatic thickening fraction
Assessment of diaphragm thickness variation (TDi-exp, measured from pleural to peritoneal line at end-expiration; normal \<1.5 mm suggesting diaphragmatic weakness). Unit of measure: mm
Diaphragmatic thickening fraction
Thickening fraction will be measured with the following formula: TFdi = (inspiratory thickness - expiratory thickness) / expiratory thickness × 100). This outcome will be measure via thoracic ultrasound using a linear probe positioned sagittally along the axillary line at the 8th-9th intercostal space.
Presence of overlap syndrome (COPD + OSA)
Overnight cardiorespiratory monitoring
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