Respiratory failure

Respiratory failure is a condition where the lungs fail to meet the body’s oxygenation or carbon dioxide (CO2) elimination needs.

• Type 1 (Hypoxaemic): PaO2 < 8 kPa with normal or low PaCO2. Primary failure of oxygenation.
• Type 2 (Hypercapnic): PaCO2 > 6.5 kPa. Failure of ventilation.

• Type 1: Pneumonia, pulmonary oedema, acute respiratory distress syndrome (ARDS), pulmonary embolism, asthma, interstitial lung disease.
• Type 2: COPD, neuromuscular disorders, chest wall deformities, obesity hypoventilation syndrome, drug overdose, central respiratory depression.

• Dyspnoea.
• Confusion/drowsiness.

• Use of accessory respiratory muscles.
• Cyanosis.
• Tachypnoea or bradypnoea.
• Altered consciousness or confusion (especially in hypercapnic).

• Arterial blood gas (ABG): determines type and severity of respiratory failure.
• Chest X-ray: to identify underlying causes (e.g., pneumonia, pneumothorax).
• Spirometry: especially in chronic conditions like COPD.
• Blood tests: FBC to rule out anaemia; inflammatory markers, e.g. CRP; U&E.

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• Supplemental oxygen: to correct hypoxaemia.
• Non-invasive ventilation (NIV): especially beneficial in hypercapnic respiratory failure, for example in COPD exacerbations.
• Invasive mechanical ventilation: in cases where NIV is contraindicated or has failed.
• Treat underlying cause (e.g. antibiotics for pneumonia, bronchodilators and steroids for asthma/COPD exacerbation).

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• Pneumonia.
• Acute respiratory distress syndrome (ARDS).
• Barotrauma (with mechanical ventilation).
• Death if respiratory failure not appropriately recognised/managed.

• Respiratory failure is either due to failure of oxygenation (Type 1) or ventilation (Type 2).
• There are multiple aetiologies which differ between the two types of respiratory failure.
• Early recognition and intervention are crucial as respiratory failure can be fatal.
• The main investigations include an ABG and chest X-ray to determine the type of failure and underlying cause.
• Management varies dependent on type, consisting of oxygen therapy, NIV and treatment of underlying cause.

• British Thoracic Society Guideline for the ventilatory management of acute hypercapnic respiratory failure in adults.
• British Thoracic Society Guideline for oxygen use in healthcare and emergency settings.