Major Trauma

How does trauma cause the "terrible triad" of conditions?

Acidosis = if a patient is unable to breathe due to airway obstruction, unconsciousness or damage to the chest wall, cells become hypoxic. They respire anaerobically, producing lactate which lowers blood pH. Metabolic acidosis results (H+). Hypothermia = vasoconstriction and slowing of heat-releasing reactions results in low body temperature. Coaguloapathy = impaired function of the clotting cascade, which results from the other 2 conditions. Blood takes longer to clot, resulting in massive haemorrhage.

How do the 3 conditions of the "terrible triad" interact?

Acidosis reduces perfusion, causing peripheral vasoconstriction which contributes to hypothermia. Acidosis denatures enzymes essential for blood clotting, resulting in coagulopathy. Hypothermia causes coagulopathy because low body temperatures slow down enzymatic reactions essential for clotting. Coagulopathy worsens acidosis.

What is ATLS and what are the key principles?

Advanced Trauma Life Support - simple standard approach to trauma care. Principles = Airway and c-spine control Breathing Circulation Disability and neurology Exposure - other injuries Always treat greatest threat to life first.

What is major trauma?

Any injury with the potential to cause prolonged disability or death.

Why is clear fluid resuscitation NOT recommended in "terrible triad" patients?

Clear fluids worsen acidosis because resus fluid is more acidic than normal blood. Clear fluids also worsen coagulopathy because they do not contain the clotting factors lost in the blood (dilutional coagulopathy). Lost blood? Restore circulating volume with blood products, not clear fluids.

Physiological responses to trauma

Endocrine = Release of stress hormones e.g. cortisol and catecholamines. Reduction in insulin effects, so glucose utilisation is reduced and fatty acids used instead. Metabolic = Decreased metabolism followed by hypermetabolism. Hypotension due to hypovolaemia. Immunological = Pro-inflammatory cytokines produced.

What is the "terrible triad"?

Lethal group of 3 conditions which are recognised as a significant cause of death amongst trauma patients: 1. Acidosis 2. Hypothermia 3. Coagulopathy They are induced by haemorrhage and tissue damage, and worsen one another until eventually death results.

What is the injury severity score (ISS)?

Score of 0-75 used to determine the severity of trauma and help prognosticate. Worst AIS injury for each body area is scored, then the 3 most severe injured regions have their scores squared and added together.

What is the abbreviated injury score (AIS)?

Score of 1-6 used to classify severity of the injury. 1 = minor 6 = unsurvivable