The optimal position to maximize laryngoscopic visualization of the larynx is:
The head extended.
The neck flexed.
The base of the ear is aligned with the sternal notch (see Fig. 22.10).
The facial plane is horizontal, parallel to the ceiling (see Fig. 22.10).
The facial plane should be positioned between the laryngoscopist’s xiphoid process and umbilicus (see Fig. 22.14).
Correct Intubating Height. Optimal height for intubation is typically when the plane of the patient’s face is between the intubator’s umbilicus and xiphoid process. (Photo contributor: Lawrence B. Stack, MD.)
This position most closely replicates in a supine posture which the patient would assume sitting up. For very large individuals or those with significant morbid obesity, this may require creation of a textile ramp of blankets, sheets, or towels to raise the head and shoulders to proper elevation and alignment.
Preoxygenation and Passive Apneic Oxygenation
Preoxygenation, when possible, should be used to create an oxygen surplus in the blood and tissue which permits a period of apnea to occur without arterial oxygen desaturation. This process hopefully begins in the prehospital setting with the placement of a nonrebreather mask with high-flow oxygen on the patient. This should continue in the ED in the event intubation is required. In addition, a nasal cannula on high flow (15 L/min) should also be placed when the patient arrives in the ED if there is a high likelihood of intubation. High-flow oxygen delivered by nasal cannula provides passive apneic oxygenation during the apneic phase of endotracheal intubation.
A stylet should be used with all oral intubations in which a laryngoscope is employed. The laryngoscopist will typically fashion an inexpensive stylet, essentially a malleable wire, into a shape of their preference, to permit control of the distal endotracheal tube (ETT) tip. One should take care not to place too much bend or curvature to the stylet, because such a configuration can actually impair the glottic view and control of the ETT tip. Optimal stylet configuration has been described as “straight to the cuff” and then a gentle anterior bend of 30 degrees.
Preoxygenation and Passive Oxygenation. In preparation for intubation, simultaneously placing an NRBM (preoxygenation before induction) and nasal cannula (passive oxygenation after paralysis) at 15 L/min will help prolong tissue oxygenation during the apneic phase of intubation. (Photo contributor: Lawrence B. Stack, MD.)
Even with a correct bend on the stylet, it may be difficult to advance the styletted ETT into the trachea. The tip of the left-sided beveled tube can impact and catch on the anterior tracheal cartilages, preventing advancement. This can often be remedied with a generous clockwise or rightward rotation of tube and stylet, which acts to rotate the bevel anteriorly and depress the ETT tip.
Holding the laryngoscope handle and blade where the proximal end of the blade is in the palm of the hand creates a natural extension of the forearm and provides fine control of the blade tip. The left thumb should run parallel to the axis of the handle. Effort mechanics are more efficient with this grip. Placing the elbow close to the body requires less effort and more mechanical control than if the elbow abducted from the body. A memory aid for these concepts are “Thumb up-Wing in.”
Stylet Shape. Straight to cuff with a 30-degree bend is the optimal stylet shape as this offers the most ETT tip control and view of the glottic opening. (Photo contributor: Lawrence B. Stack, MD.)
Laryngoscope Grip. The laryngoscope should be gripped as low as possible and the thumb extended. This makes a natural extension of the forearm. (Photo contributor: Lawrence B. Stack, MD.)
The scissor technique places the laryngoscopist’s right thumb on the occlusive surface of the patient’s lateral mandibular teeth or gum and long or index finger on the maxillary teeth or gum. A scissoring motion opens the mouth allowing blade insertion. The fingers should be removed once the blade is adequately inserted. An alternative technique is to place the laryngoscopist’s right thumb on the nasal bridge and long finger between the mental protuberance and alveolar margin. The thumb and long finger are moved away from each other, causing the mouth to open.
Laryngoscope Biomechanics. Keeping the elbow close to the body requires less effort and more control during laryngoscopy. (Photo contributor: Lawrence B. Stack, MD.)
The blade is initially inserted just to the right of midline with the handle pointed toward the patient’s feet. As the tip of the blade advances downward along the tongue base and into vallecula, the tongue is swept slightly to the left to increase the amount of workspace. When fully inserted into the vallecula, the angle of the handle is now approximately 40 degrees from horizontal with lifting forces directed upward and forward.
Mouth Opening Techniques. The traditional “scissor” technique (A) and the “clean hand” technique (B) for opening the mouth during endotracheal intubation. (Photo contributor: Lawrence B. Stack, MD.)
The key to using the laryngoscope to optimally visualize the glottic opening is to first visualize and control the epiglottis, a relatively fixed anterior structure. Pulmonary secretions, blood, and/or vomitus that pools in the posterior pharynx may obscure the posterior laryngeal structures, dependent with gravity. The epiglottis itself may be camouflaged in this pool of muck (see Fig. 22.20). One should carefully insert the laryngoscope blade with a goal of adequately visualizing and controlling the epiglottis. Failure to do so risks inserting the laryngoscope blade too deeply, and often results in displacing the larynx anteriorly to expose the esophagus, which, as a consequence of anterior-ward tension on the laryngoscope blade, may then look like a glottic opening begging for a tube. By carefully controlling the epiglottis, the intubating clinician will be able to locate important airway landmarks. Be careful to displace the tongue to the left side as you insert the blade. If the bulk of the tongue wraps around the blade, it can both impair your view and impede insertion of the ETT.
Epiglottic Camouflage. Vomitus, blood, and pulmonary secretions may pool in the posterior pharynx and obscure the gravity-dependent epiglottis. Elevating anterior laryngeal structures will expose the epiglottis. (Photo contributor: Lawrence B. Stack, MD.)
Progressive visualization of laryngeal structures is predictable:
Uvula and posterior pharynx (see Fig. 22.21A)
Epiglottis (see Fig. 22.21B)
Posterior arytenoids cartilages and interarytenoid notch (see Fig. 22.21C)
Glottic opening (see Fig. 22.21D)
Vocal cords (see Fig. 22.21E)
Esophagus (see Fig. 22.21F)
Progressive Visualization—Uvula. The uvula and posterior pharynx are the first structures visualized during correct laryngoscopic technique. (Photo contributor: Lawrence B. Stack, MD.)
Progressive Visualization—Epiglottis. The key to first-pass intubation is finding and identifying the epiglottis laryngoscopy. Following epiglottis will take one to the glottic opening. (Photo contributor: Lawrence B. Stack, MD.)
Progressive Visualization—Interarytenoid Notch. The interarytenoid notch is a vertical cleft between the posterior cartilages. Above the notch lies the glottic opening. Below the notch is the esophagus. (Photo contributor: Lawrence B. Stack, MD.)
Progressive Visualization—Glottic Opening. The posterior glottic opening is seen before the vocal cords are visualized. (Photo contributor: Lawrence B. Stack, MD.)
Progressive Visualization During Laryngoscopy—Vocal Cords. The vocal cords have a distinct white appearance. (Photo contributor: Lawrence B. Stack, MD.)
Progressive Visualization During Laryngoscopy—Esophagus. The esophagus lies directly below the interarytenoid notch. (Photo contributor: Lawrence B. Stack, MD.)
Even with well-performed laryngoscopy, adequate visualization of the laryngeal structures may be difficult. Bimanual laryngoscopy (external laryngeal manipulation by the operator), where the laryngoscopist performs laryngoscopy while simultaneously manipulating the external larynx, facilitates optimal visualization. This eliminates any delay or miscommunication between an assistant and laryngoscopist. Once optimal position is found, an assistant can maintain that position. Alternatively, an assistant’s hand, placed on the laryngeal structures, guided by the laryngoscopist’s hand can maintain optimal position after the laryngoscopist removes his hand from the assistant’s hand.
Lip Commissure Retraction
The lip commissure is the junction of the upper and lower lips. Lateral retraction of the patient’s right lip commissure by an assistant facilitates visualization of oral structures and insertion of the ETT into the oral cavity. This creates an optimal workspace for tube delivery. After glottis visualization is achieved, an assistant places their right index finger in the patient’s right commissure and thumb against the maxilla. The index finger retracts the commissure laterally while applying an opposing force with the thumb to avoid excessive movement of the head. A memory aid of this concept is “pull out commissure, push on maxilla,” or “POC-POM.” Retraction of the lip commissure aids in keeping the ETT from blocking the view of the glottic opening during advancement of the ETT. Using the retracted lip commissure as a fulcrum or “toggle” gives optimal control of the ETT tip, especially when the stylet is in the “straight to cuff” shape. Retraction may also facilitate intubation by allowing clockwise rotation of the tube if the ETT tip becomes hung up on the proximal tracheal cartilages. A memory aid of this concept is “right on rings” or rotate the tube to the right or clockwise if it hangs up on the tracheal rings.
Bimanual Laryngoscopy. Laryngoscopist uses right hand to manipulate laryngeal structures for optimal visualization during laryngoscopy. Once optimal position is identified, an assistant maintains it during intubation. (Photo contributor: Lawrence B. Stack, MD.)
Commissure Retraction. An assistant retracts the right commissure to create a generous “workspace” to visualize and deliver the endotracheal tube. (Photo contributor: Lawrence B. Stack, MD.)
Endotracheal Tube Handling
The thumb, index, and long fingers provide the fine dexterity for the hand, and should be used to control the tube during endotracheal intubation. The ETT should be held like a “throwing dart” between the thumb, index, and long fingers midway along the tube for precise control during the procedure. A trained assistant should hand the tube to the laryngoscopist in this manner.
Endotracheal Tube Delivery
Obtain the best glottic view and have an assistant provide right lip commissure retraction. Introduce the ETT at the 3-o’clock position of the mouth. Advance the tube posteriorly in a manner that will not obstruct the direct view of the “target.” Advance the tube through the glottis. The last thing you should see is the tube going through cords. If resistance is met, it is most likely due to the bevel being caught on a tracheal ring. Turn the tube to the right or clockwise and attempt to advance the tube. Advance the tube to 22 cm at the lip, inflate the cuff, and confirm placement. Secure the tube in place (see Table 22.1).
Pull on Commissure-Push on Maxilla. When pulling on the commissure with the index finger, simultaneous pushing on the maxilla with the thumb will minimize head movement during intubation. (Photo contributor: Lawrence B. Stack, MD.)
Correct ETT Grip. Using the thumb, index, and long fingers to grip the mid-endotracheal tube like a “throwing dart” will provide the most precise control during tube deliver. (Photo contributor: Lawrence B. Stack, MD.)
TABLE 22.1Endotracheal Tube (ETT) Delivery Steps ||Download (.pdf) TABLE 22.1 Endotracheal Tube (ETT) Delivery Steps
Obtain best possible glottic view
Introduce ETT at 3-o’clock position of the mouth
Advance ETT posteriorly to avoid obstruction of “target” view
Advance ETT through glottis (last thing to see is ETT through cords)
If resistance is met (bevel against rings), rotate tube clockwise, then advance
Confirm tube placement (ETCO2, breath sounds, O2 saturation monitor)
The key to first-pass intubation success is identification and control of the epiglottis during direct laryngoscopy.
The glottic opening lies between the epiglottis and interarytenoid notch. Identification and passing the tube between these structures will improve first-pass success.
While most intubations are performed without difficulty, if a difficult airway is anticipated and there is time to prepare, optimize the patient’s ear-to sternal notch position.
Approximately 250 mL/min of oxygen will move from the alveoli into the blood during apnea, which may extend the period of adequate arterial oxygenation during intubation.
Incorrect ETT Grip. These ETT grips will provide a powerful force on the tube but will lack precise handling of the tube, critical to tube delivery. (Photo contributor: Lawrence B. Stack, MD.)
Tube Delivery. Obtain the best glottic view. Introduce the ETT at the 3-o’clock position of the mouth. Advance the tube posteriorly in a manner not to obstruct the view of the “target.” Advance the tube through the glottis. (Photo contributor: Lawrence B. Stack, MD.)