Question 30

Please note: Marks for the following questions are equally distributed.
a)    List five relative contraindications to the use of a heat and moisture exchange filter.
b)    List six precautions to consider when applying defibrillation pads.
c)    List five complications that may arise from use of an intraosseous needle.

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College answer


  • Haemoptysis, tenacious secretions
  • Patients with large air leaks 
  • ARDS where controlling dead space is important
  • Large minute ventilation (e.g. > 10L/min)
  • Need for frequent nebulised medications
  • Long term ventilation (needs changing every 3-4 days)


  • Avoid fluid – water, perspiration etc.
  • Avoid excessive hair
  • Avoid metal (metal-backed patches, piercings, jewellery) 
  • Do not place over bone
  • Roll on to the skin to avoid air pockets
  • Do not place over implanted pacemakers 
  • Avoid wounds / broken skin  Ensure oxygen not flowing over pads


  • Infection – cellulitis and osteomyelitis
  • Extravasation of blood / infusion fluid / drugs
  • Compartment syndrome secondary to extravasation
  • Bone fracture or through and through penetration
  • Damage to surrounding structures 


This question is a concatenation of Question 15.1 and Question 15.2 from the first paper of 2012. Apart from this, no previous questions have asked about the contraindications for the use of a HME.

Contraindications to the use of a HME include:

  • Conditions which demand minimsation of apparatus dead space
  • Large volume of secretions or froth 
  • Large minute volume ( over 10L/min) 
  • Large air leak, eg. bronchopleural fistula
  • Long term ventilation
  • Frequent nebulised medications

With the defib pads, avoid the following:

  • Water
  • Vomit
  • Sweat
  • Excessive chest hair
  • Piercings
  • Necklaces
  • Bony prominences
  • Air pockets (burns may occur)
  • Implanted devices
  • Subclavian lines
  • Wounds

With intraossesous needle devices, the following complications occur:

  • Osteomyelitis
  • Fracture
  • "through and through" penetration
  • Extravasation
  • Compartment syndrome due to extravasation
  • Injury to staff (slipped needle)
  • Damage to surrounding structures
  • Microscopic fat emboli

With sternal approach:

  • Mediastinal injury
  • Pneumothorax
  • Greater vessel injury