Practical procedure - Cricothyrotomy (figure 3a & b)

A 12 or 14 gauge cannula with a syringe attached is introduced through the cricothyroid membrane until air can be aspirated. The cannula is then advanced off the needle down the trachea. The hub of the cannula is connected to an oxygen supply. (It is important that all connections are tested beforehand). The patient can be oxygenated in this way, but ventilation to remove CO2 cannot be achieved and respiratory acidosis will ensue. Spontaneous respiration is impossible through a needle cricothyrotomy.

A needle cricothyrotomy will ensure a supply of oxygen for a maximum of 10 minutes and it should be converted to a surgical cricothyrotomy to allow adequate ventilation. A horizontal incision is made through the membrane and a small (size 5.0-6.5) endotracheal or tracheostomy tube inserted.