Respiratory Failure and Its Types

Respiratory Failure

• Respiratory failure occurs when pulmonary gas exchange fails to maintain normal arterial oxygen and carbon dioxide levels.
• Classified into types I and II, based on the absence or presence of hypercapnia (raised PaCO2).

Type I Respiratory Failure

• Occurs when disease impairs ventilation of part of a lung, resulting in hypoxic and CO2-laden blood entering the pulmonary veins.
• Increased ventilation of neighboring regions of normal lung can correct arterial CO2 to normal, but cannot augment oxygen uptake.
• Examples: asthma, pneumonia.

Type II Respiratory Failure

• Occurs when there is arterial hypoxia with hypercapnia, seen in conditions that cause generalized, severe ventilation-perfusion mismatch.
• Examples: conditions that reduce total ventilation, such as neuromuscular mechanisms of ventilation.

Management of Acute Respiratory Failure

• Type I: prompt diagnosis and management of the underlying cause, oxygen administration to maintain SaO2 (94%-98%).
• Type II: prompt diagnosis and management of the underlying cause, oxygen administration to maintain SaO2 (88%-92%) or safe PaO2 (>7.0 kPa or 52 mmHg) without increasing PaCO2 and acidosis.

Management of Chronic and 'Acute on Chronic' Type II Respiratory Failure

• Most common cause of chronic type II respiratory failure is severe COPD.
• Management: identify and treat the precipitating condition, achieve safe PaO2 (>7.0 kPa or 52 mmHg) without increasing PaCO2 and acidosis.
• Non-invasive ventilation (NIV) may be beneficial in conscious patients with adequate respiratory drive.
• Intubation and ventilation may be necessary for patients who are drowsy and have low respiratory drive.

Home Ventilation for Chronic Respiratory Failure

• Indications: spinal deformity, neuromuscular disease, central alveolar hypoventilation, and some patients with advanced lung disease (e.g. COPD and cystic fibrosis).
• Diagnosis: morning headache and fatigue, revealed by sleep studies or morning blood gas analysis.
• Treatment: home-based NIV overnight, often sufficient to restore daytime PCO2 to normal and relieve fatigue and headache.

Lung Transplantation

• Established treatment for carefully selected patients with advanced lung disease unresponsive to medical treatment.
• Contraindications: patients with chronic bilateral pulmonary infection, such as cystic fibrosis and bronchiectasis.
• Prognosis: improving steadily with modern immunosuppressive drugs, median survival for double lung transplantation is 7.8 years.

Learn about the definition and types of respiratory failure, including the differences between type I and type II, and how they affect blood oxygen and carbon dioxide levels.