(A&E) (Peri-Op & Anaesthesia)

Overview

• Acute or chronic inability of the respiratory system to maintain gas exchange. This can lead to failure to oxygenate the body and failure to eliminate carbon dioxide.
• Pulmonary Causes → acute exacerbation of asthma, PE, ARDS, pneumonia, pulmonary trauma, airway osbtruction, pneumothorax, chronic lung disease
• Extrapulmonary Causes → CNS depression (narcotic overdose or brain trauma), respiratory muscle weakness (MG, MND), decreased chest wall compliance, increased oxygen consumption or CO2 production (sepsis, cardiogenic shock), hypovalaemia, shock
• Type 1 (Hypoxaemic) → Low Oxygen (PaO2 <8kPa) + Normal CO2
• Type 2 (Hypercapnic) → Low Oxygen + High CO2 (PaCO2 >6kPa)
  • Respiratory muscle weakness due to neurological conditions is typically type 2. COPD exacerbation also type 2.

Making Diagnosis

Clinical Features:

• Hypoxia → tachypnoea, dyspnoea, cyanosis, pleuritic chest pain
• Hypercapnia → hypoventilation, headache, anxiety, papilloedema, asterixis

Investigtions:

• Arterial Blood Gas (ABG) → to confirm diagnosis

Management Plan