Wednesday, October 19, 2016

Measurement of the 60 degree angle of the Glidescope Blade.

                                                   GlideScope Blade Angle
The measurement of the blade angle that is the key to success of the GlideScope Blade in management of Difficult Airway patients is carried out by comparison of what one sees when looking directly into the mouth when the GlideScope is inserted. Early experimentation clearly demonstrated that to get the 99.9% working view of the airway ( GSCL Grade 1 or 2 View ) it was necessary  to have a 60 degree angle . Lesser angles were shown clinically to be unable to get a working view in a few % of patients. The mission of the inventor was to provide a GSCL view that would permit intubation in 99.9 % of patients with the theory that if you could see it you could place the tube successfully.

Experience has shown that those users who used the GlideScope regularly could virtually always deliver the tube (especially with the highly controllable Verathon (Pacey) rigid steel stylet. Those who did not practice with the device sometimes failed to advance the ETT and blamed the tool for their performance. Because we have a large number of users who can always advance the tube when they get a good view we believe the tool is not the problem.

                                                    GSCL      Grades 1-4
Notes with respect to the Cormack - Lehane views are not relevant to video laryngoscopy and therefore I use the GSCL scale which is simply the GlideScope Cormack Lehane view scale. Because each device has its own performance characteristics this becomes relevant when transmitting patient information to future caregivers.

                                       Calculation of the 60 degree angle:
The black arrow is the line of sight when the GlideScope is inserted into the mouth.
The 60 Degree angle is thus measured.

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