Protocol for intubation with introducer guide

If the vocal cords are visible:
Insert the introducer guide;
Feel palpable vibrations (or clicks);
Insert the endotracheal tube over the guide (without removing the laryngoscope);
Rotate the endotracheal tube 90° clockwise before passing by vocal cords (keeping the bevel of the tube posteriorly directed eases its positioning and prevents arytenoid injury);
Remove the guide, while maintaining the endotracheal tube positioned;
Confirm proper endotracheal tube position.

If the vocal cords are NOT visible:
Insert the introducer guide in a most anterior position possible, until palpable clicks are felt;
Advance the endotracheal tube by the guide, till it "locks" or with a maximum distance of 45 cm;
If no vibrations (or clicks) are perceived or any feeling of resistance after 20–40 cm (the "lock"), probably the introducer guide will be in the oesophagus;
Move the guide a few centimetres backwards before inserting the endotracheal tube;
Rotate the endotracheal tube 90° clockwise before passing by vocal cords (keeping the bevel of the tube posteriorly directed eases its positioning and prevents arytenoid injury);
Remove the guide, while maintaining the endotracheal tube positioned;

Confirm proper endotracheal tube position.
Remember that while the laryngoscopy and insertion of the guide are performed, an assistant must be prepared to advance the endotracheal tube over the guide (keeping its position).

Adapted from Ref. 4 and 11, and Kaushal (2011).