In the United Kingdom, trauma kills 14,500 people annually and is the commonest cause of death in those under 40 years. The advanced trauma life support (ATLS) course (American College of Surgeons Committee on Trauma 2004) provides a basic framework onto which hospital specialists can build their individual skills. The ATLS course focuses on the initial management of patients with major injuries during the so-called ‘golden hour’. The golden hour reflects the importance of timely treatment. A severely injured patient who is hypoxic, in haemorrhagic shock, or who has an expanding intracranial haematoma, for example, will need rapid, effective resuscitation. The aim is to restore cellular oxygenation before the onset of irreversible shock.

Pathophysiology of trauma and hypovolaemia

Several mechanisms are involved in the development of cellular injury after severe trauma. The commonest is haemorrhage, causing circulatory failure with poor tissue perfusion and generalised hypoxia (hypovolaemic shock). Myocardial trauma may cause cardiogenic shock, while spinal cord trauma may cause neurogenic shock. Severe trauma is a potent cause of the systemic inflammatory response syndrome (SIRS) and this may progress to the multiple organ dysfunction syndrome (MODS) and multiple organ failure.

Physiological responses to haemorrhage

Trauma compromises tissue oxygenation because haemorrhage reduces oxygen delivery and tissue injury and inflammation increase oxygen consumption.

Compensatory responses to haemorrhage are categorised into immediate, early and late. The loss of blood volume is detected by low-pressure stretch receptors in the atria and arterial baroreceptors in the aorta and carotid artery.