Crush Injury - REAL First Aid

When a limb becomes trapped (be it a tourniquet or entrapment) there is neither fresh supply of oxygen nor the removal of waste products due to the lack of circulation. What is traditionally taught is that these waste products accumulate to a toxic level and, should the limb be released, the waste products are released into the circulatory system and pumped to the heart which can cause cardiac arrest and IMMEDIATE DEATH!

As such, traditional UK First Aid guidelines including the current 10th edition of the Voluntary Ambulance Services First Aid Manual (1) state "If the casualty has been crushed for more thank 15 minutes…leave them in the position found. Offer comfort and reassurance."

This

Is

nonsense.

What is Crush Syndrome?

Crush syndrome refers to the complications following prolonged entrapment; the cause may be building collapse, fallen debris, vehicle entrapment, or simply the continued pressure exerted by the immobile casualty’s own body weight. (2-6)

Crush injury occurs when a body part is subjected to a high force or pressure, usually after being squeezed between two heavy objects. As a result of muscular compression, muscle cells (myocytes) are damaged, followed by the release of intracellular constituents into the systemic circulation. The process, called rhabdomyolysis, causes systemic organ dysfunction, such as acute renal failure, and is then called crush syndrome. (7-9)

The Royal College of Surgeons of Edinburgh’s Faculty of Pre-Hospital Care’s consensus view is (2):

“A crush injury is a direct injury resulting from crush. Crush syndrome is the systemic manifestation of muscle cell damage resulting from pressure or crushing”.

The likelihood of developing acute crush syndrome is directly related to the compression time, therefore victims should be released as quickly as possible, irrespective of how long they have been trapped. (2,3)

The principle complications of crush syndrome are the build up of toxins – rhabdomyolysis – and the lesser known, compartment syndrome. In this article we will look at both.

Tourniquets

The same mechanism of action occurs whether the limb is trapped or a tourniquet has been applied but the evidence for tissue damage points toward the order of magnitude of hours, rather than minutes (10-12).

Tourniquet use for less than 2 hours has proven safe. Tourniquets left in place for longer than 2 hours risk significant ischemic injury and should be converted.

Tourniquets in place longer than 6 hours should be left in place with an increased need for limb amputation.

Further Reading - Tourniquets

Rhabdomyolysis

As increasing pressure caused by a restriction (be it entrapment or a tourniquet) reduces circulation to the area the decrease in oxygen requires the cells to switch from aerobic respiration to anaerobic respiration. In this state cells attempt to produce energy from CO2 which generates large amounts of lactic acid and other damaging substances: