11 - 15 Physiology SBAs for the Primary FRCA

11 - 15 Physiology SBAs for the Primary FRCA
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Question 11

A 21 year old man has sustained a displaced open right tibial fracture dislocation, multiple rib fractures and haemopneumothorax as a result of a motorcycle accident and is brought into the Emergency Department. The dorsalis pedis pulse is not palpable in the right foot. The trauma team have performed a primary survey and reduced the fracture dislocation, with return of palpable pulses in the foot. The patient's respiratory rate suddenly increases to 40 breaths per minute and his oxygen saturations drop to 82%, requiring 15 litres of oxygen via a non-rebreathe mask. You also note a petechial rash spreading across his upper chest.

Which of the following is the most likely diagnosis?

  • Tension pneumothorax
  • Catastrophic haemorrhage
  • Fat embolism
  • Pulmonary embolism
  • Myocardial infarction


  • Fat embolism

The combination of an open tibial fracture and sudden respiratory compromise, topped off with a petechial rash is a textbook description of fat embolism syndrome.

The triad of fat embolism syndrome:

  • Neurological changes (drop in GCS or confusion)
  • Respiratory compromise
  • Petechial rash (chest, axilla or conjunctiva)

The others are all possible, but less likely and don't explain all the clinical features described here.