A previously fit and well 24 year old man sustained an isolated C5-C6 spinal injury following a diving accident resulting in a tetraplegia. The spinal fracture was surgically fixed the following day and the patient was extubated on Day 6 of his ICU admission. Within 4 hours of extubation, the patient developed respiratory distress requiring urgent rapid sequence induction and reintubation. The patient sustained a cardiac arrest soon after intubation.
18.1. List five (5) likely causes of cardiac arrest in this patient.
• Oesophageal intubation
• Hypoxic cardiac arrest (unrelated to oesophageal intubation due to delayed or unanticipated difficulty with intubation)
• Suxamethonium induced hyperkalemia
• Incidental PE
• Autonomic dysfunction from the spinal injury.
• Tension pneumothorax
This question relies on the candidate being able to generate a list of differential causes for cardiac arrest.
A good systematic framework for this is the "Four Hs and four Ts" mnemonic:
- Hypoxia (thus, oesophageal intubation or delayed oxygenation)
- Hypovolemia (thus, cardiovascular collapse due to vasodilation by an induction agent like propofol, or due to the autonomic dysfunction of spinal cord injury)
- Hyper/hypokalemia (thus, the effects of suxamethonium)
- Hyper/hypothermia (probably irrelevant in this case)
- Tension pneumothorax (due to overvigorous bag-mask ventilation, or due to tracheobronchial disruption by violent use of the bougie)
- Tamponade (unlikely in this setting)
- Toxins (eg. anaphylactic reaction to induction agents)
- Thrombus (eg. the PE which the college for some reason offer as a valid differential)