Does end-tidal capnography confirm tracheal intubation in fresh-frozen cadavers?
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 ETCO2levels 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 ETCO2was zero for 10 consecutive breaths. ETCO2and 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 ETCO2detected. For two cadavers, life-like ETCO2waveforms were achieved immediately after tracheal intubation, with maximum ETCO2achieved 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, ETCO2following tracheal intubation showed normal morphology which was sustained for 2 min. However, ETCO2was 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.
Greater Sydney Area Helicopter Emergency Medical Service, New South Wales Ambulance, Sydney, New South Wales, Australia.|Discipline of Emergency Medicine, Sydney University Medical School, Sydney, New South Wales, Australia.
Cliff
C
Reid
Greater Sydney Area Helicopter Emergency Medical Service, New South Wales Ambulance, Sydney, New South Wales, Australia.|Department of Emergency Medicine, Liverpool Hospital, Sydney, New South Wales, Australia.|South West Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.
Ian
I
Ferguson
Greater Sydney Area Helicopter Emergency Medical Service, New South Wales Ambulance, Sydney, New South Wales, Australia.|Discipline of Emergency Medicine, Sydney University Medical School, Sydney, New South Wales, Australia.
Brian
B
Burns
Greater Sydney Area Helicopter Emergency Medical Service, New South Wales Ambulance, Sydney, New South Wales, Australia.|Discipline of Emergency Medicine, Sydney University Medical School, Sydney, New South Wales, Australia.
Karel
K
Habig
Surgical and Anatomical Science Facility, University of Technology, Sydney, New South Wales, Australia.
Mohammed
M
Shareef
D001315:Australia; D002102:Cadaver; D019296:Capnography / Q000379:methods* / Q000706:statistics & numerical data; D004947:Esophagus / Q000473:pathology / Q000502:physiology; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000592:standards* / Q000706:statistics & numerical data; D008297:Male; D012121:Respiration, Artificial / Q000592:standards / Q000706:statistics & numerical data; D000066908:Simulation Training / Q000379:methods* / Q000592:standards* / Q000706:statistics & numerical data
airway; education