How can examination of the skin aid the assessment of the degree of physiological compromise? What clues to the differential diagnosis may be available?

A reduced CO vasoconstriction caused by increased sympathetic activity will divert blood away from the peripheral circulation leading to cool peripheries.

Capillary refill is a useful test in assessing dehydration in diarrhoeal illness in children and has some value in paediatric trauma but is of questionable value in adult patients [13-15].

Sweating as a result of increased sympathetic activity may produce clamminess (diaphoresis).

In distributive shock, the skin may be warm and dry:neurogenic shock (loss of sympathetic tone as a result of cord injury) leads to vasodilatation and an absence of sweating. In UK trauma patients, neurogenic shock occurs in about 20% of patients with cervical cord injuries (7% for thoracic and 3% for lumbar) at presentation [16].

Anaphylaxis is characterised by patchy or generalised erythema, urticaria and angioedema but skin or mucosal changes may be absent in up to 20% of patients [17].

The image displays urticarial rash (hives).