Context

The arterial blood gas (ABG) is one of the most useful investigations performed in the emergency department (ED). It takes mere minutes to perform and analyse on the machines most commonly kept in areas of acute care e.g. the resuscitation room, intensive care, high dependency and coronary care.

The most common sites from which to obtain a sample are radial and femoral arteries though it should be noted that sampling is often a painful procedure and local anaesthetic should be used in all conscious patients [1].

The results obtained from an ABG include:

• Acid-base balance and its component parts
• Partial pressures of oxygen (O₂) and carbon dioxide (CO₂) and O₂ saturation
• Several other anions and cations influenced by renal function
• Haemoglobin, haematocrit and carboxyhaemoglobin
• Glucose and lactate