Cadaver study of oesophageal insufflation with supraglottic airway devices during positive pressure ventilation in an obstructed airway.
BACKGROUND
Supraglottic airway devices (SADs) play an increasing role in airway management in clinical anaesthesia and emergency medicine. Until now, no data exist concerning the extent of oesophageal insufflation when oropharyngeal leak pressures are exceeded.


METHODS
Laryngeal masks LMA-Supreme™ and LMA-ProSeal™, laryngeal tubes LTS-D and LTS II, Combitube™, and I-Gel were inserted into unfixed human cadavers. The oesophagus was connected to a volumeter, while the trachea was closed surgically to simulate complete airway obstruction. Volumes of oesophageal insufflation resulting from pressure-controlled ventilation at inspiratory pressures of 20, 40, and 60 mbar were measured.


RESULTS
No oesophageal insufflation could be detected at a ventilation pressure of 20 mbar in any device. Using inspiratory pressures of 40 and 60 mbar, oesophageal insufflation occurred in all devices, with significantly higher volumes of intraoesophageal air for both laryngeal tubes.


CONCLUSIONS
The use of SADs with inspiratory pressures of 20 mbar appears to be safe regarding the risk of intragastric insufflation. Higher inspiratory pressures should be strictly avoided.
Department of Emergency Medicine, Bundeswehrkrankenhaus Berlin, Scharnhorststraße 13, 10115 Berlin, Germany. willi-schmidbauer@web.de
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Schmidbauer
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Genzwürker
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Ahlers
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Proquitte
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Kerner
D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D004947:Esophagus; D005260:Female; D006801:Humans; D007327:Insufflation; D017214:Laryngeal Masks; D008297:Male; D011175:Positive-Pressure Respiration / Q000295:instrumentation*; D012121:Respiration, Artificial / Q000009:adverse effects*