Cricothyroidotomy describes a group of techniques where an airway is passed through the cricothyroid membrane. The device used can either be narrow (<2 mm diameter) or wide (>4 mm diameter).

The device chosen must be matched with a suitable means of achieving adequate ventilation and safe expiration.

Narrow cannulae have a high resistance to gas flow and require a high pressure source to achieve ventilation, whereas wide bore devices can be used with normal low pressure sources of ventilation such as a self inflating bag.

Expiration is only possible via a wide bore device – try breathing through a 16 G cannula and then a 5.0 ETT to convince yourself of these differences.

The DAS plan shown recommends using a narrow bore kink resistant cannula.