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Does end-tidal capnography confirm tracheal intubation in fresh-frozen cadavers?
  1. Cliff Reid1,2,
  2. Ian Ferguson1,3,4,
  3. Brian Burns1,2,
  4. Karel Habig1,2,
  5. Mohammed Shareef5
  1. 1Greater Sydney Area Helicopter Emergency Medical Service, New South Wales Ambulance, Sydney, New South Wales, Australia
  2. 2Discipline of Emergency Medicine, Sydney University Medical School, Sydney, New South Wales, Australia
  3. 3Department of Emergency Medicine, Liverpool Hospital, Sydney, New South Wales, Australia
  4. 4South West Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia
  5. 5Surgical and Anatomical Science Facility, University of Technology, Sydney, New South Wales, Australia
  1. Correspondence to Dr Cliff Reid, Greater Sydney Area Helicopter Emergency Medical Service, New South Wales Ambulance, 670 Drover Road, Bankstown Airport, NSW 2200, Australia; reidcg{at}


Background Life-like end-tidal capnography (ETCO2) waveforms have been demonstrated in recently deceased and fresh-frozen cadavers following tracheal intubation, offering potential for high fidelity airway simulation training. As the mechanism for carbon dioxide production is not fully understood, it is possible that oesophageal intubation may also generate a capnograph. Our aim was to measure ETCO2 levels following (1) oesophageal and (2) tracheal intubation in fresh-frozen cadavers, and to observe the size, shape and duration of any capnographic waveform.

Methods Four fresh frozen cadavers underwent oesophageal intubation by an emergency medicine specialist with confirmation by a second specialist. Hand ventilation with room air via a self-inflating resuscitation bag was provided at 12 breaths per minute for 2 min or until ETCO2 was zero for 10 consecutive breaths. ETCO2 and waveform morphology were examined and video recorded. The oesophagus was then extubated and the process was repeated for tracheal intubation.

Results In no case was oesophageal ETCO2 detected. For two cadavers, life-like ETCO2 waveforms were achieved immediately after tracheal intubation, with maximum ETCO2 achieved by the second breath. In these cases waveform morphology was normal and persistent.

Conclusions Cadaveric oesophageal intubation did not result in a capnography waveform, simulating live patients. When present, ETCO2 following tracheal intubation showed normal morphology which was sustained for 2 min. However, ETCO2 was not present following tracheal intubation in all cadavers. These results represent instrumentation on the cadavers for the first time after thawing and further work should assess the repeatability of the findings with subsequent intubations.

  • airway
  • education

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