Once the catheter is threaded, the needle is withdrawn from the skin and fixed to the adaptor at the free end.
A syringe containing sterile saline or a multiple electrolyte solution (1 ml/5 lb) is attached to the catheter.
Aspiration on the syringe should yield air if the catheter is in the airway lumen. The solution is injected into the catheter and followed by 1 ml of air.
Injection of the solution usually induces a mild coughing response.