Seeing is believing but to much of a good thing can be bad as demonstrated in this view with the Glidescope where the image occupies most of the screen and the blade is over-rotated to look up at the anterior tracheal wall. Here you see the cricoid ring which Levitan kindly named the Kovacs sign in his ACEP piece entitled Tips for Using a Hyperangulated Video Laryngoscope. As a co-author for Adam Law's study comparing a restrticted view from full view using a hyperacute angled video laryngoscope I had to review all of the laryngoscopy videos. This is where it clicked for me in understanding why being too close caused challenges for the user. Seeing the pink/white rings of the anterior tracheal wall was more often associated with difficulty than observing the black hole of a view looking down the long axis of the trachea. This can be managed with tube manipulation however it is best to back off, lessening the blades rotation for a 50:50 view where the glottis occupies 50% of the screen and the POGO is less than 50%. The trachea then will appear as a black hole as the camera and blade are in-line with the long axis of the trachea.
