GlideScope Intubation

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Editor(s): Lee A. Fleisher, MD, FACC, FAHA Lee A. Fleisher, MD, FACC, FAHA

Robert Dunning Dripps
Professor and Chair
Department of Anesthesiology and Critical Care

Professor of Medicine
University of Pennsylvania School of Medicine
| Robert Gaiser, MD Robert Gaiser, MD

Professor of Anesthesiology and Critical Care
Department of Anesthesiology and Critical Care
University of Pennsylvania School of Medicine

Contributor(s): Ashish Sinha, MD, PhD Ashish Sinha, MD, PhD

Assistant Professor of Anesthesiology and Critical Care, Hospital of the University of Pennsylvania
University of Pennsylvania School of Medicine
| Elizabeth Watson, MD Elizabeth Watson, MD

Post-Doctoral Fellow, Department of Anesthesiology and Critical Care
Hospital of the University of Pennsylvania
| Acknowledgements Acknowledgements

VIDEO EDITOR
Jeremy D. Kukafka, MD
Faculty
Department of Anesthesiology and Critical Care
Univ of Pennsylvania School of Medicine
Philadelphia, PA

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Supraclavicular Nerve Block: Ultrasound-Guided Technique


MEDICAL WRITER
Gail A. Van Norman, MD
Clinical Associate Professor
Department of Anesthesiology
Univ of Washington
Seattle, WA

MEDICAL AND VIDEO EDITOR AND SUBJECT MATTER EXPERT
Elizabeth J. Watson, MD
Post-Doctoral Fellow
Department of Anesthesiology and Critical Care
Univ of Pennsylvania School of Medicine
Philadelphia, PA

VIDEO COORDINATOR
Liang Xue, BS
Research Assistant
Department of Anesthesiology and Critical Care
Univ of Pennsylvania School of Medicine
Philadelphia, PA

PRE-PROCEDURE
INDICATIONS
  • Patients with poor direct laryngoscopic view
  • Bariatric patients
  • Challenging airways (inability to view the vocal cords on direct view) due to anatomic variation or distortion
  • Small mouth opening (< 3 cm)
  • Limited neck extension
  • Excessive secretions in the airway (the GlideScope has an anti-fogging heat lamp to enable views in the presence of excess/bloody secretions)
  • Video-guided tube exchange
CONTRAINDICATIONS

Absolute Contraindications

  • None—in an emergency resuscitation in which an airway cannot be obtained by means of direct laryngoscopy, using a GlideScope to obtain a secure airway has no absolute contraindications.

Relative Contraindications

Relative contraindications may be overlooked in the true emergency situation because it is more important to resuscitate.

  • Limitations to mouth opening (< 3 cm)
  • Major trauma/fractures to the face (maxilla, mandible) or neck
  • Neck abscess (retropharyngeal) can cause difficulty with tracheal intubation.
  • Neoplasm of the upper airway that may distort airway anatomy
  • Nasal intubation required for surgical procedure (e.g., oral surgery)
  • Jet ventilation
EQUIPMENT
  • The GlideScope (GS) videolaryngoscope or other similarly equipped/manufactured video laryngoscope. A color or black and white image is displayed on a portable screen. In addition, the camera output can also be viewed on other devices or recorded using a standard video output port (NTSC).
  • Bag-valve face mask with oxygen supply
  • Yankauer catheter attached to wall suctioning unit
  • Stethoscope
  • Correctly sized, GlideScope-specific endotracheal tube
  • Endotracheal tube (ETT) stylet
  • 10-mL plastic syringe for cuff inflation
  • Capnograph
  • Tape to secure ETT after placement
  • Gloves and protective eyewear
ANATOMY

The goal of using a GlideScope is to place an ETT through the vocal cords and into the trachea approximately 1-2 cm beyond the vocal cords. Familiarity with the oral, pharyngeal, and laryngeal anatomy is important to physicians using the GlideScope as a means to correctly and safely place an ETT. Patients present with a number of anatomic variations of the upper airway so thorough knowledge of airway structures is a requirement for the GlideScope operator. A complete airway examination (in an elective intubation) will aid the physician in becoming acquainted with normal anatomic structures and will also help to identify anatomic variations that may be predicted to present difficulty during intubation. Examine neck flexion/extension, temporomandibular mobility, artificial/loose or damaged teeth, visualization of the uvula (Mallampati score and thyromental distance. Review the medical records for possible prior intubations, a description of the patient’s airway, and/or any difficulties that were encountered. Information describing past techniques that were used to successfully intubate the patient will aid the physician, especially in the case of a challenging airway. In addition, identification and removal of any personal ornamentation, such as tongue piercing ornaments, should occur before undertaking airway manipulation, to avoid aspiration of the ornament or trauma and edema in the oropharynx.


The internal anatomy important for intubation can be divided into three sections—the mouth, the pharynx, and the larynx.

Mouth

The size of the mouth opening, size and distribution of teeth, and size of the tongue play important roles in ease of laryngoscopy and intubation.

Pharynx

The oropharynx includes the structures of the upper airway from the soft palate to the level of the hyoid bone. The oropharynx opens anteriorly into the mouth, is bounded laterally by the two palantine arches and tonsils, and includes the posterior tongue. The laryngopharynx includes the epiglottis and larynx, which in turn consists of the vocal folds and vocal cords, the thyroid, cricoid and arytenoid cartilages, and the intrinsic muscle of the larynx. The larynx begins where the upper airway divides to form the laryngeal inlet and the upper esophagus. The epiglottis is a cartilaginous flap attached to the posterior tongue, which forms a protective flap between the trachea and the upper esophagus. During swallowing, the hyoid bone is elevated, pulling the larynx upward and folding the epiglottis downward over the laryngeal inlet, diverting material into the upper esophagus.


Many major nerves contribute to pharyngeal and laryngeal function. Pharyngeal function is governed by cranial nerves IX, X (pharyngeal plexus), and XI (pharyngeal branch), which control elevation and shortening of the pharynx, alterations in palate position, the size of the pharyngeal lumen, and bolus transport of food in the esophagus. Motor innervation of the larynx is via the external and recurrent laryngeal branches of cranial nerve X. In addition, the facial nerve (7th cranial nerve) and cervical spinal nerves (C1-3) contribute to motor function of the upper airway via actions of the mylohyoid muscle on the hyoid bone to pull the larynx up and the infrahyoid muscles, which pull the larynx down. Mandibular action during phonation is also controlled by the mandibular branch of the trigeminal nerve. Sensory innervation of the larynx is via the internal laryngeal branch of the vagus nerve (cranial nerve X) above the vocal folds and the recurrent laryngeal branch of the vagus nerve below the vocal folds.


Important internal landmarks involved in laryngoscopy and intubation include the epiglottis, the vallecula, the intrinsic cartilages of the larynx (arytenoids, thyroid, cricoid), the true and false vocal cords, and the hyoid bone.

External Anatomic Features

The external anatomy of the larynx is also important in airway management. Operators should be able to identify the external landmarks of the mental protuberance of the mandible, thyroid cartilage, hyoid bone, and cricoid cartilage. Anatomic features of direct relevance to laryngoscopy include extent of mouth opening, extent of jaw subluxation, ability to flex and extend the neck, neck circumference, tongue size and protrusion, ability to visualize the uvula or soft palate with mouth opened and tongue protruded in the sitting posting without phonation (Mallampati score), mandibular size, mento-hyoid distance, thyromental distance, and protuberant dentition. The sensitivity and specificity of any of these measures to predict limited view on direct laryngoscopy is limited. Taken together, limitations of movement, low Mallampati score, and short anatomic distance may warrant alternative strategies to endotracheal intubation. Each of these aspects has been studied extensively in conjunction with radiologic investigations of airway anatomy in awake and unconscious patients. The reader is encouraged to consult the considerable literature on the subject for a more thorough discussion.


There continues to be considerable discussion in the field of airway management as to the optimal position for intubation based on anatomic principles. It is generally accepted that for direct laryngoscopy to be successful, three anatomic axes—oral, pharyngeal, and laryngeal—must be at least partially aligned. Toward this end, flexibility of the cervical spine and stability of the atlanto-occipital joint, full mouth opening, jaw subluxation around the temporomandibular joint, and tongue mobility are each important. It appears that maximization of the atlanto-occipital-axial angle is one of the most important factors in glottic visualization. With the GlideScope®, direct visualization is not necessary, and a more neutral head position is possible.


PROCEDURE
Sample excerpt does not include step-by-step text instructions for performing this procedure
The full content of this section includes:
  • Step-by-step text instructions for performing the procedure
  • Clinical pearls providing practical clinical tips from medical experts
  • Patient safety guidelines consistent with Joint Commission and OHSA standards
  • Links to medical evidence and related procedures

POST-PROCEDURE
CARE
  • After placement of the endotracheal tube, the cuff should be inflated with the minimum volume of air to prevent a leak at the peak pressures required for effective ventilation (usually less than 30 cm H2O).
  • Check tube position by auscultating the chest and monitoring an in-line capnography or colorimetry device while administering several slow breaths.   Rapid, large tidal volume ventilation may increase aspiration risk if the tube is malpositioned in the esophagus. If these procedures indicate incorrect placement of the endotracheal tube, the tube should be promptly removed with suction available and mask ventilation resumed.
  • Once proper placement has been determined, position of the endotracheal tube at the incisors should be noted and tube secured with adhesive tape. The dental guard should be removed and teeth and mouth inspected for injury.
Clinical Pearls: When the airway will be positioned away from the anesthesiologist or in the prone position for surgery, it may be useful to use additional adhesive (such as benzoin) and a covering layer of waterproof tape to ensure maintenance of endotracheal tube position.

Clinical Pearls: In average-height persons (173 ± 4 cm for men; 162 ± 3 cm for women), securing the endotracheal tube at 23 cm and 21 cm at the teeth or gums, respectively, has been shown to reliably avoid endobronchial intubation, even with flexion of the neck.
COMPLICATIONS

Common General

  • Dental injury
  • Minor bleeding
  • Lip, gum, or tongue trauma

Common Cardiovascular Consequences

  • Tachycardia
  • Hypertension

Uncommon General

  • Eye trauma/corneal abrasion
  • Major bleeding
  • Airway edema
  • Temporomandibular joint dislocation
  • Vocal cord paralysis
  • Laryngospasm
  • Bronchospasm
  • Hypoxemia
  • Esophageal intubation, particularly if undetected
  • Endobronchial intubation

Uncommon Cardiovascular Consequences

  • Bradycardia, particularly in children
  • Myocardial ischemia as a result of tachycardia in a susceptible patient

Rare

  • Esophageal perforation from malpositioned endotracheal tube
  • Arytenoid dislocation
  • Aspiration
  • Cervical spine injury
  • Tracheal perforation
  • Elevated intracranial pressure (especially in patients with already elevated pressure)
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