This study is a randomized clinical trial that compares two methods of non-invasive respiratory support in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) complicated by acute hypercapnic respiratory failure.

Eligible adult patients admitted with this condition will be randomly assigned to receive either High-Flow Nasal Insufflation (HVNI) or Non-Invasive Ventilation (NIV).

The main goal of the study is to evaluate changes in blood gas levels, especially carbon dioxide (PaCO2), after one hour of treatment. Secondary outcomes include the need for invasive ventilation, length of hospital stay, changes in breathing rate, and in-hospital outcomes.

The study aims to determine whether HVNI can provide a safe and effective alternative to NIV in this group of patients.

This study is a prospective randomized controlled trial conducted on adult patients diagnosed with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) complicated by acute hypercapnic respiratory failure (type II respiratory failure), admitted to the respiratory intensive care unit or emergency department.

COPD is a leading cause of morbidity and mortality worldwide, and acute exacerbations associated with hypercapnic respiratory failure represent a major cause of hospital admission and intensive care utilization. Non-invasive ventilation (NIV) is the standard of care in such cases; however, its use may be limited by patient intolerance, discomfort, and contraindications.

High-Flow Nasal Insufflation (HVNI) is an emerging non-invasive respiratory support modality that delivers heated, humidified oxygen at high flow rates, generating low levels of positive airway pressure, reducing dead space ventilation, and improving oxygenation and ventilation. It may offer improved patient comfort and tolerance compared to NIV.

In this study, eligible patients will be randomly assigned into two groups: Group I: High-Flow Nasal Insufflation (HVNI) Group II: Non-Invasive Ventilation (NIV) Baseline clinical data, arterial blood gases, and severity scores will be recorded. Patients will be monitored for clinical and laboratory response.

The primary endpoint is the mean difference in PaCO2 to evaluate the short-term effect of HVNI and NIV from baseline to one hour after randomization.

The secondary endpoints include the following outcomes:

Treatment change rates (switch to other ventilatory support modality due to clinical deterioration) Proportion of patients with PaCO2 worsening or reduction less than 10 mmHg from baseline, or no improvement in dyspnea Respiratory rate Changes in arterial blood gases Duration of mechanical ventilation (invasive and non-invasive) Length of hospital stay In-hospital mortality

Inclusion Criteria:

Adults aged ≥18 years Diagnosis of acute exacerbation of COPD (AECOPD) Acute hypercapnic respiratory failure (PaCO2 > 45 mmHg with acidosis or indication for ventilatory support) Indication for non-invasive ventilatory support Hemodynamically stable patients Ability to provide informed consent or legal representative consent

Exclusion Criteria:

Age <18 years Immediate need for invasive mechanical ventilation (e.g., apnea, respiratory arrest, severe respiratory distress) Severe hypoxemia (PaO2 < 55 mmHg despite oxygen therapy) Severe acidosis (pH < 7.25) with hypercapnia Neuromuscular disease Unstable hemodynamics (SBP < 90 mmHg or MAP < 65 mmHg despite resuscitation) Hypercapnic respiratory failure due to non-COPD causes Contraindications to HVNI or NIV (facial trauma, obstruction, severe agitation, etc.) Pregnancy BMI > 30 kg/m²