BJA Advance Access originally published online on September 29, 2009
British Journal of Anaesthesia 2009 103(6):891-895; doi:10.1093/bja/aep264
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Comparison of different methods of ventilation via cannula cricothyroidotomy in a trachea–lung model
1 Department of Anaesthesia, Critical Care and Pain Management, University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester LE1 5WW, UK
2 Department of Cardiovascular Sciences, Clinical Division of Anaesthesia, Critical Care and Pain Management, University of Leicester and University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester LE1 5WW, UK
* Corresponding author. E-mail: neil.flint{at}uhl-tr.nhs.uk
Background: Cannula cricothyroidotomy is recommended in recent guidelines as a rescue intervention in the ‘cannot-intubate cannot-ventilate’ scenario. Several methods of providing ventilation via a cannula cricothyroidotomy have been described, but there are no data comparing these methods and using cannulae of differing diameters.
Methods: Using a bench-top trachea–lung model (comprising a Siemens test lung attached to commercially available breathing system tubing), we compared delivered minute volumes (MVs) for five methods of ventilation administered through cannulae of diameters 20, 16, 14, and 13 G. The ventilation methods were: an ENK oxygen flow modulator, a Manujet, a self-inflating resuscitation bag, the oxygen flush of an anaesthetic machine, and oxygen from a wall-mounted flow meter attached via a three-way tap to the cannula. All experiments were performed with and without a proximal 2.5 mm diameter constriction to simulate partial upper airway obstruction.
Results: MVs increased with increasing cannula diameter. In the absence of a proximal constriction, MVs delivered via a 20 G cannula were <1 litre min–1 with all devices; only the Manujet delivered MVs >2 litre min–1, at cannula sizes of 
16 G. MVs were greater in the presence of a proximal constriction, but did not exceed 4 litre min–1 using the low-pressure devices.
Conclusions: Extrapolated to the clinical situation, these data suggest that low-pressure devices will not deliver adequate MVs via a cannula cricothroidotomy and should no longer be advocated. Purpose-made devices should be available in all areas where anaesthesia is administered or airway interventions are performed.
Keywords: airway, obstruction; equipment, breathing systems; ventilation, transtracheal
Presented in part to the Anaesthetic Research Society Meeting, Loughborough, UK, November 2005.
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