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Sequential landmarks and tube delivery with a Miller blade
Note the position of the blade all the way to the right (right of the right nostril), and tube delivery using the extreme right corner of the mouth.
Effective control of the tongue is critical for straight blade use. The small flange height prevents any ability to sweep the tongue. Proper position is achieved with straight blades by deliberately directing the blade to the right paraglossal space. No tongue should be present to the right of the blade. Full insertion of the blade should occur through the right lateral mouth, over the molar dentition, and while the distal blade may then be directed medially, the proximal blade should never be brought back towards the midline, otherwise it will hit the central incisors.
After the epiglottis edge is identified, the handle must be tilted forward (e.g., the tip moves backward, toward the posterior hypopharynx). The blade is then inserted slightly farther (~1-2 cm), and the tip passed under the epiglottis. Once the epiglottis is “trapped” under the blade tip, the blade is rocked slightly backward (handle brought slightly more upright) and then the lifting force increased.
The distal tip of the Miller blade is invisible to the operator when viewed down the long axis (because it is upturned). Often the laryngoscopist does not know if the blade has been advanced far enough to trap the epiglottis until the blade is rocked backward; sometimes the tip of the epiglottis is not trapped, and the advancement and tilting maneuver needs to be repeated.
Bimanual laryngoscopy and head elevation are both helpful in straight blade laryngoscopy. Bimanual laryngoscopy helps by moving the larynx posteriorly into the operator’s line of sight (it has no mechanical effect on the epiglottis, since the epiglottis is already trapped under the tip of the straight blade). Tube delivery should be done using the extreme right corner of the mouth, and come up from below the line of site. An adult tube will not fit through the lumen of a Miller blade (and should not be attempted). |
The epiglottis is the physical and visual bridge from the tongue (where laryngoscopy starts) to the glottic opening (the goal). It is the most superior aspect of the laryngeal inlet. The next structures seen after the epiglottis will be the posterior cartilages and the interarytenoid notch. The glottic opening and vocal cords are more anterior inside the larynx.
