Airway Skills 3:
Orotracheal Intubation
The following techniques help in the performance of expert orotracheal intubation:
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Position the patient. Ideally the head should be in the sniffing position, with a small cushion behind the occiput. In trauma situations, the cervical spine is a major concern, so you will be limited as to how much movement you can apply. Oftentimes the patient is in a hard cervical collar, further limiting motion. An assistant may apply in-line immobilization by kneeling at the head of the cart holding the patient's head between his or her hands. Another assistant may then open the anterior piece of the collar, allowing movement of the jaw. This assistant may then apply cricoid pressure during the procedure.
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Select a laryngoscope blade of the appropriate size. Curved Macintosh blades or straight Welch-Allyn-Miller 6804x series blades are optimal because of their wide flanges.
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Open the patient's mouth using the thumb and forefinger of your right hand as shown.
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Insert the larygoscope blade along the right side of the tongue, displacing the tongue to the patient's left side. Here is where the large flange of the Macintosh blade and the Welch-Allyn-Miller blade are great advantages. These blades allow maximum visualization of the glottis. Lean back as you do this instead of bending forward. This gives you binocular vision. Advance the blade to its correct position while lifting the handle of the laryngoscope toward the ceiling of the room at the patient's feet. The Macintosh blade is inserted into the valecula of the epiglottis so that it lifts the base of the patient's tongue. The straight Welch-Allyn-Miller blade is inserted past the epiglottis where it lifts the epiglottis directly. It may also be used as a Macintosh blade because it has a curved tip.
The arytenoid cartilages are seen well enough in this view to allow the
intubator to insert an ET tube introducer into the trachea
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Now insert the endotracheal tube introducer (ETI or bougie) as described in Vol II—Air Skills 1 Aids to Intubation. If you hold the ETI in your fingers like a dart and lean back, you may insert it very surely through the arytenoids and into the larynx. As it moves through the trachea, you will feel the tracheal rings like a washboard. Once you have assured yourself that you actually feel the rings, pull back the ETI until its black stripe is at the corner of the patient's mouth.
Alternatively, you may insert the ET tube with its contained stylus directly. However, oftentimes you will lose vision of the ET tube as it enters the glottis because the size of the ET tube and its cuff obstructs the view at the last critical moment. If the assistant who is applying cricoid pressure presses too hard, the ETI and the ET tube can meet resistance at the glottis. If this happens, simply easing up on the pressure will allow the instrument to pass. When you are unsure of what opening you are seeing, the assistant applying cricoid pressure may assist you by moving the cricoid cartilage from side to side. Oftentimes this brings a displaced glottis into view. -
Remove the laryngoscope from the patient's mouth and set it aside. Place the selected ET tube on the ETI and grasp the tip of the ETI that protrudes through the proximal end of the ET tube. Turn the ET tube 1/4 turn counterclockwise and advance it through the glottis into the trachea. Turning the tube in this way causes it to spread the arytenoids with its bevel rather than getting hung up, an effect called "railroading."
If the intubation of the glottis with the ETI was difficult because of patient anatomy resulting in a need to bend the ETI, leave your laryngoscope blade in place and ask an assistant to load the ET tube on the ETI and advance it into the trachea. -
Confirm correct placement of the ET tube by applying an esophageal intubation detector (EID) and determining if resistance to pulling the plunger indicates esophageal intubation. The alternative is to apply a CO2 detector to detect exhaled CO2 for confirmation. Listen for breath sounds beginning with the stomach so that esophageal insufflation is detected on the first breath. See Vol II—Air Skills 1 Aids to Intubation for more information about these devices.
It is not necessary to inflate the cuff of the ET tube prior to using the EID. Before inflating the cuff, adjust the depth of placement so that it is at the 21 to 23 cm mark at the corner of the mouth. Use 21 cm for women and 23 cm for men. This will place the tip of the ET tube at the mid-tracheal level in most adult patients. Listen for differences in breath sounds between the left and right lungs, indicating that the tube is in too far and is in the right or left main stem bronchus. A subsequent chest x-ray also confirms correct placement. -
Secure the tube. Someone must hold the ET tube firmly in place.
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Suction is a critical need in many situations. A Big Stick sucker tip is optimal because its opening at the tip is as large as the standard suction tubing. This tip should be at the patient's head where the intubator can reach it without taking his or her eyes off the target. There should be a bracket under the cart cushion to hold this suction tip. Because the aperture of the Big Stick tip is as large as suction tubing, the suction tubing itself can get plugged with vomitus. Many seconds of critical time can be lost trying to replace this suction tubing at the worst possible moment. A solution is to use a large cath-tip syringe full of tap water to clear the tubing.
PEDS: Pediatric intubation deserves special comment.
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Positioning the head of the small child or infant is important. Because of the relatively large occiput, a cushion should be placed behind the child's shoulders. This enables you to put the head in the sniffing position.
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The small mouth (and often a relatively large tongue) of an infant can make exposure of the glottis difficult. The anatomic position of the larynx is relatively anterior, also making visualization difficult. In addition, the very active reflexes in a small child or infant can cause the child to gag as the laryngoscope blade nears the glottis. Cricoid pressure is important in children to help overcome some of these problems. The BURP variation of cricoid pressure is effective.Vol II—Air Skills 5 Cricoid Pressure and the Burp Technique)
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Generally, a size 1 or 2 Miller blade is most useful for intubating infants or small children. This blade is not used to hold the tongue aside as in adults; rather, the epiglottis is approached in the midline. Ideally the glottis may be exposed without touching the epiglottis, obviating gagging and swallowing reflexes. Insert the uncuffed ET tube to the black line printed near its tip. This line should be at the vocal cord level to result in ideal placement. The RSI procedure can assist when gagging or larygospasm is severe. (Vol II—Air Skills 4 Rapid Sequence Intubation)
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The common fallback rescue airway in most adult emergencies is the combitube. Unfortunately, Combitubes™ are not available in pediatric sizes. Also, a standard ETI only fits through a 6.0 or larger ET tube, making it not useful in children under about 7 years of age. An 8 French pediatric ET tube exchanger (available from the Cook Co.) fits through a 3.0 ET tube and may be used instead.
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The EID is not reliable in children under 1 year of age, so other means of confirming correct placement must be used. Pediatric CO2 detectors are useful.
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Post a table showing tube sizes versus age on your airway cart.
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Securing an ET tube in an infant is a special problem. (Vol II—Air Skills 1 Aids to Intubation, Securing an ET Tube)
References
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Benumof JL. Conventional (layngoscopic) orotracheal and nasotracheal intubation (single lumen tube) in Airway management, principles and practice. Benumof JL, Ed. Mosby: St. Louis. 1996;261-276.
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Viswanathan S, Cambell C, Wood DG, Riopelle JM, et al. The Eshmann tracheal tube introducer. (Gum elastic bougie.) Anesthesio Rev. 1992;19:29-34.