Awake flexible fiberoptic or video endoscopic intubation may be the best way to deal with an anticipated or actual difficult airway.
The technique depends on adequate local anesthesia which is discussed in previous posts. (1, 2, and 3)
There are a couple of caveats:
First, do not use the endoscope working channel to insuflate oxygen as it has been associated with serious complications. (4. 5)
Second, although uncommon, there is a risk of sudden and total airway obstruction in patients undergoing awake intubation with topical anesthesia. (6)
What follows is the method of MF Murphy and PMC DeBlieux as described in the Manual of Emergency Airway Management 4th edition. (7)
1. Gather all equipment (usually preassembled on a tray)
a. Topical airway anesthesia supplies and equipment, including three 5-ml syringes loaded with 4% lidocaine to inject into the airway through the scope as needed.
b. Endoscope, ETTs, airways, bite-blocks
c. Tonsil suction and antifog solution
d. Lubricant and antifog solution
e. Additional airway management equipment as indicated in case of patient deterioration and need for rapid intervention.
2. Obtain an able and knowledgeable assistant.
3. Prepare the patient
a. Antisialogogue, such as glycopyrrolate 0.01 mg per kg IM or IV allowing sufficient time for this to work (minimum of 10 minutes) if possible
b. Vasoconstrictor for the nose (if nasal route is chosen).
c. Local, topical airway anesthesia
d. Sedation as appropriate
e. Preoxygenate the patient as for rapid sequence intubation as much as possible
4. Lubricate the inside and outsice of the endotracheal tube because lubricating the scope makes it slippery and too hard to manipulate
5. Put a drop of slicone liquid (antifog solution) on the tip of the scope or place the tip of the fiber bundle in a bottle of warmed saline (usually available in the warming cabinets of most EDs) or in a warmed blanket for 1 minute to prevent fogging.
6. Insert a bite-block if the oral route is chosen or, preferably use an intubating guide such as a Berman intubating/pharyngeal airway. If a Berman guide is used, mount the ETT in the guide, ensuring that the tip of the ETT is at the end of the tubular portion of the airway before inserting the guide into the mouth, and then insert the endoscope through the ETT.
7. Stand up straight, either at the head of, the side of, or facing the patient. Operator positioning is mostly a matter of personal preference and patient tolerance.
8. Oral technique: Stay in the midline, stay in the midline, stay in the midline! The best way is to place the long or ring finger in the middle of the upper lip to maintain a reference point and hold the fiber bundle with the index finger and thumb. Gentle traction on the tongue by an assistant using a gauze bandage helps open the airway and prevent the patient from using the tongue to obstruct access to the airway. If the patient is supine, placing the patient in the upright sitting position (if possible) also makes the tongue less of an issue. Custom made airways such as the Berman intubating/pharyngeal airway and the ROTIGS, are helpful in keeping the scope in the midline and obviate the need for the tongue traction manuever. If such an adjunct is used, insert the ETT into the airway and then insert the scope through the airway/ETT combination, obviating the need to jam or tape the ETT connector onto the scope handpiece.
Nasal technique: Soften the nasotracheal tube by placing the ETT in a bottle of warmed saline or sterile water from the warming closet for 3 to 5 minutes before inserting the ETT through the nostril. It may be helpful to dilate the chosen anesthetized nostril by gently and slowly inserting and slowly inserting increasingly large nasopharyngeal airways or a lubricated and gloved small finger into the nostril as far as possible immediately before inserting the ETT. This allows the operator to choose the most patient nare. Advance the lubricated nasal tube to the level of the uvula in the nasopharynx, and then pass the scope thrhough the tube.
(9) Hold the body of the endoscope in the same hand as your dominant eye. This allows ont to turn slightly to the side when using the scope, an important detail in keeping the fiber bundle of the scope straight during the procedure for reasons described later. Some advocate holding the body of the scope in the left hand to facilitate clearance of the light source cable and suction tubing, which exit the body of the scope on its left side. Use your thumb to toggle the tip control lever up and down. The index finger can be used to depress and activate the suction feature. Flexing and extending the wrist moves the tip of the fiber bundle left and right, although the fiber bundle must be held straight with mild tension between the two hands to optimize this maneuver. Slackness in the fiber bundle will not permit wrist motion to rotate its tip. The nondominant hand advances, withdraws, and manipulates the fiber bundle, and maintains a midline oral position if the oral route is chosen. The operator should move the hands and arms, not the whole torso, to manipulate the fiber bundle into the airway.
(10) The assistant should have tonsil suction available to aspirate oral secretions and blood. The working channel of the scope may provide insufficient suction to clear the volume of secretions that may be present during the procedure. If the tip becomes soiled or fogged and obscures clear vision, bouncing the tip gently against the mucosa may be sufficient to clear it.
(11) Get your bearings. At the head of the bed, the base of the tongue is up; beside or in front of the patient it is down. Advance slowly while flexxing the tip up to pass over the back of the tongue.The epiglottis comes into view. Keep it above you. You will see the white cords opening and closing with respiration.
(12) It may be challenging to coordinate, but attempt to advance the scope through the vocal cords during inspiration, when the cords are open. It may be necessary to inject 1-2 ml of 4% lidocaine through the working channel onto the larynx to obtund the cough or closure reflex and permit entry into the trachea.
(13) If you get lost, withdraw to the oropharynx and find a landmark.
(14) Once the tip of the fiber bundle is through the vocal cords, advance the scope almost to the carina. Then slowly advance the ETT over the scope into the trachea, being careful not to king the scope. A conventional laryngoscope may be useful to straighten out the angle of the glottis, but rarely is required, except in the supine patient. Gentle rotation of the scope/tube unit through 180 degrees may be necessary if the ETT catches on the cords (usually on the arytenoids). Newer ETT tip designs may facilitate passage of the ETT through the cords (e.g., Parker tube).
(15) If coughing is a persistent problem, inject 5 ml of 2% acqueous lidocaine through the scope.
(16) After the ETT has been successfully passed into the trachea, the scope can be used to correctly position the ETT in the midportion of the trachea. Push the tip of the scope through the ETT until it is just distal to the end of the ETT and flex it gently forward. Grasp both the endoscope and the ETT, and move them together until light transilluminates the sternal notch. The light is shining forward immediately beyond the tip of the ETT, so this corresponds to the midtracheal position. Straighten the tip and remove the entire endoscope.
(1) Local Anesthesia for the Technique of Endoscopic Intubation—The Awake Intubation of the Difficult Airway, posted May 14, 2012 and available at https://www.tomwademd.net/2012/05/14/local-anesthsia-for-the-technique-of-endoscopic-intubation-the-awake-intubation-of-the-difficult-airway/.
(2) How to Do an Awake Intubation—Two Outstanding Videos, posted March 23, 2012 and availabe at https://www.tomwademd.net/2012/03/23/an-outstanding-video-on-how-to-do-an-awake-intubation/.
(3) More Details on Awake Intubation, posted March 26, 2012 and available at https://www.tomwademd.net/2012/03/26/more-details-on-awake-intubation/
(4) Gastric distention and rupture from oxygen insufflation during fiberoptic intubation, Anesthesiology, 1996;85:1479-1480 available at http://journals.lww.com/anesthesiology/Fulltext/1996/12000/Gastric_Distention_and_Rupture_from_Oxygen.30.aspx.
(5) Oxygen insufflation through the fiberscope to assist intubation is not recommended, Anesthesiology, 1997;87:183-184 available at http://journals.lww.com/anesthesiology/Fulltext/1997/07000/Oxygen_Insufflation_Through_the_Fiberscope_to.36.aspx.
(6) Total airway obstruction during local anesthesia in a non-sedated patient with a compromised airway, Canadian Journal of Anesthesia, 2004;51:838-841 available at http://www.springerlink.com/content/75122171v67614p5/fulltext.pdf.
(7) Manual of Emergency Airway Management 4 th ed., 2012. RM Walls and MF Muphy, pp. 170-172.