Chapter 11. Orotracheal Intubation

Airway control is the first and most critical action of the Emergency Physician. The “A” in the ABC's demands that no other action may take place until the airway is secure. Endotracheal (ET) intubation inserts an artificial airway connecting the respiratory system to the outside world and provides definitive control of the airway. Once the ET tube is in place, all methods of support can be applied. If the airway is not secure, nothing can help the patient. ET intubation can be accomplished by a variety of methods. The method of choice will be dictated by physician preference and experience, the patient's condition, and the available equipment. The most common method of ET intubation is orotracheal intubation. There are no good alternatives to intubation when oxygenation and ventilation are threatened. All actions should be focused on two objectives: to get the ET tube placed quickly and in the right location. The proper preparation, practice, and personnel can assure that the “nightmare airway” is an extremely rare event.1

For the purposes of intubation, our discussion of the anatomy starts at the lips and travels inward to end at the right mainstem bronchus. As you approach the patient, visualize the normal structures expected and match them with what is seen. Distortion occurs from edema or trauma. Structures may be hidden by vomit or blood. Airway structures are viewed upside down, from the position of standing over the head of the supine patient, and the potential for disorientation multiplies.

Begin at the face and move inward (Figures 11-1 & 11-2). The philtrum of the upper lip will be located at the 6 o'clock (bottom) position. Symmetrical swelling, carbon deposits, blistering, or signs of trauma to the lips can indicate that the inner anatomy of the airway may be altered and the intubation more difficult. Moving inward, open the patient's mouth and check the teeth for fractures, size, and the presence of removable dental devices. Large upper incisors and/or limited jaw opening will make orotracheal intubation more difficult. The tongue hangs down from the floor of the lower jaw (mandible) and ends with the tip against the upper (maxillary) incisors (Figure 11-2). Visualize the tongue as a hanging oval of tissue with two “tips.” The first is the anterior tip of the tongue proper. The second is the epiglottis. The anatomic “floor” of this view is formed by the hard and soft palates, which end at the palatopharyngeal arch (Figure 11-2). The uvula is located inferiorly and in the midline. The palatoglossal arch and palatopharyngeal arch form twin vertical pillars that lie posterior to the molars of the upper teeth (Figure 11-2). All of these structures are potential sources of obstruction and must be evaluated for swelling, deformity, or trauma. The “back wall” is the posterior wall of the pharynx (Figure 11-2).

At the posterior wall of the pharynx, the airway bends 90° to run almost parallel to the bed. Visualized from the perspective of the top of the patient's head, the root of the tongue and the lingual tonsils are located at the 12 o'clock position (Figures 11-3 & 11-4). The tongue continues into a blind pocket known as the vallecula. Following the vallecula posteriorly, it is continuous with the epiglottis. The epiglottis hangs with its tip pointing downward. Directly behind and protected by the epiglottis is the entry to the remainder of the airway (Figure 11-4). The esophagus lies at the 6 o'clock position. From the viewpoint of the intubator, the hypopharynx appears like the numeral 8. The top half is the airway and the bottom half the esophagus.

Under the epiglottis is the larynx (Figure 11-5). The vocal cords are located in the midline and form an “A” shape, with its apex superior and toward the epiglottis. Identifying the vocal cords is important, since the visualization of the ET tube passing between the cords is proof of a successful ET intubation. The arytenoid cartilages are paired structures. One lies at the posterior aspect of each vocal cord. The aryepiglottic folds are paired structures that span from the lateral edge of the epiglottis to the arytenoid cartilages. They contain the muscles that move the arytenoid cartilages, and subsequently open and close the vocal cords. The trachea bifurcates at the carina into the right and left mainstem bronchi. In some patients, the cartilaginous tracheal rings are visible through the vocal cords.

Any threat to oxygenation and/or ventilation is a relative indication for orotracheal intubation. If the threat is simple and easily removed, remove it. If there is uncertainty that the patient's airway patency, respiratory drive, or oxygenation cannot be maintained without intervention, orotracheal intubation is required. Time is of the essence. The decision to intubate early can make the difference between a controlled, successful procedure and a chaotic, “crashing” nightmare. Orotracheal intubation can be performed to administer resuscitation medications, ensure a patent airway, deliver oxygen, isolate the airway, reduce the risk of aspiration of gastric or oral contents, suction the trachea, ventilate the patient, and apply positive-pressure ventilation. Other indications for orotracheal intubation include altered mental status, head injury requiring hyperventilation, hypoxemia, hypoventilation, apnea, lack of a gag reflex, shock, and unconsciousness.

Orotracheal intubation is relatively contraindicated in patients who do not need it, who are likely to be injured by the procedure, or whose injuries make success unlikely. Spontaneous breathing with adequate ventilation and normal mental status may allow less invasive techniques such as continuous positive airway pressure (CPAP) in patients whose medical conditions are likely to respond quickly to interventions, such as cardiogenic pulmonary edema or pneumonitis.2 Trauma patients, with likely cervical spine injury or anterior neck wounds, as well as severely immobile arthritis patients may be injured by the manipulation required during orotracheal intubation.3 Severe orofacial injuries, bleeding, deep airway obstruction, or gross deformity of the head and neck may make successful intubation impossible. A quickly changing obstruction, such as edema or an expanding hematoma, may require a surgical airway if orotracheal intubation is delayed. Choose a surgical airway if the manipulation or time required for orotracheal intubation puts the patient at risk for spinal injury or hypoxia.4 Orotracheal intubation should not be performed by individuals unfamiliar with the equipment and technique.

• ET tubes, various sizes (Table 11-1)
• 10 mL syringe
• Water-soluble lubricant or anesthetic jelly
• Wire stylet, malleable type
• Laryngoscope handle
• Fresh batteries for the laryngoscope
• Laryngoscope blades, various sizes and shapes
• Supplemental oxygen with appropriate tubing and connectors
• Nonrebreather oxygen masks, various sizes
• Wall suction with appropriate tubing
• Yankauer suction catheter
• Bag-valve device, sizes: infant, child, adult small, adult medium, adult large
• Oral airways, sizes: infant, child, adult 3 to 5
• Nasal airways, various sizes
• Benzoin adhesive
• Tape
• Pulse oximeter
• Cardiac monitor
• Automatic sphygmomanometer
• End-tidal carbon dioxide (CO2) monitor/device
• Cricothyrotomy backup tray
• Crash cart
• Resuscitation medicines
• Personnel (respiratory technician, medication nurse, in-line stabilization assistant, and recorder)
• Medications (premedications, induction, anesthetics, paralytics), see Tables 11-1 to 11-2

Many institutions make their own “intubating/airway kit.” It contains all the commonly used equipment in a portable container or cart that can be moved wherever required in the Emergency Department. While differences will exist between institutions, the kit commonly includes adult and pediatric laryngoscope handles, various sizes and types of laryngoscope blades, various sizes of oropharyngeal airways, various sizes of nasopharyngeal airways, tongue blades, malleable stylets, various sizes of ET tubes, syringes, tape, and commercially available devices to secure the ET tube. Some institutions may have a single kit, or separate kits for adult and pediatric patients.

ET Tubes

The ET tube is a clear polyvinyl chloride disposable tube that is open on both ends (Figure 11-6). The proximal end contains a standard size (15 mm) connector that will attach to the bag-valve device, a ventilator, and other sources of positive-pressure ventilation. The distal end is beveled. It has a perforation, located approximately 0.5 to 0.75 cm from the tip and opposite the bevel, known as the Murphy eye. Printed on the tube are the size, a radiopaque line to aid in radiographic visualization, and 1 cm incremental marks beginning at the tip. An inflatable cuff is positioned proximal to the Murphy eye. A pilot balloon with an inflation port, to inflate the cuff, hangs from the proximal third of the ET tube. A syringe, filled with air, attaches to the inflation port to inflate and deflate the cuff.

The ET tube cuff is a high-volume, low-pressure balloon. It is designed to accommodate a high volume of air before the intracuff pressure rises. This is an extremely important feature. If the intracuff pressure rises, it is transmitted to the delicate tracheal mucosa where it can cause pressure necrosis and ischemia.

The choice of ET tube size will vary based on the patient's age, anatomic anomalies, body habitus, and airway anatomy (Table 11-1). The ET tube is sized based on the internal diameter (ID) measured in millimeters. The size is printed onto the surface of the ET tube for reference. The sizes begin with 2.5 mm and increase in 0.5 mm increments. Some generalities hold true in most patients. Adult males usually require a size 7.5 to 9.0 cuffed ET tube. Adult females usually require a size 7.0 to 8.0 cuffed ET tube.

ET tube selection in children can be made by one of several methods. A Broselow tape will identify the proper size tube. Visually select a tube with an ID that matches the size of the width of the nail of the patient's little finger, the width or diameter of the fifth finger, the diameter of the distal phalanx of the third finger, or the external nares luminal diameter. All these visual methods will approximate the same size ET tube. The following formula may be used to confirm the uncuffed ET tube size: (16 + child's age in years)/4. Tables based on the child's age, length (Broselow tape), or weight may be used to estimate the proper ET tube size. An uncuffed ET tube should be used in children under 28 days of age to prevent the complications of subglottic and tracheal stenosis. After determining the proper size ET tube, also select and prepare a tube that is one size smaller in case the patient's airway is smaller than expected.

Traditional teaching holds that cuffed ET tubes increase the risk of ischemic damage to the tracheal mucosa due to compression between the cuff and the cartilaginous rings, resulting in the old mandate to use uncuffed ET tubes in children younger than 8 years of age. There have been numerous advances in modern ET tubes that are changing this orthodoxy.41 Current American Heart Association Guidelines now recommend, but do not require, a cuffed ET tube for children older than 28 days of age. In the first 28 days of life, the cricoid narrowing functions as a cuff. For children over 28 days of age, the cuffed ET tube is just as safe as an uncuffed ET tube.25,26 The high volume, low pressure cuffs found on new ET tubes allow the cuff to produce a seal at much lower pressures. The use of cuffed ET tubes is becoming more common in pediatric ICUs and Emergency Departments. Several studies have shown no increase in postintubation stridor or reintubation when cuffed ET tubes are used in controlled settings with regular cuff pressure monitoring.

In addition to providing some protection from aspiration, other potential benefits resulting from the use of cuffed ET tubes in children include allowing ventilation at higher pressures, maintenance of more consistent ventilatory parameters, and fewer changes of inappropriately sized ET tubes. Cuffed ET tube size can be calculated using the equation (age in years/4) + 3, or by use of an ET tube one-half size smaller than the calculated uncuffed ET tube size.7,21

All ET tubes should be examined for defects before use. Attach a 10 mL syringe filled with air to the pilot balloon inflation port. Inject the air to inflate the cuff. The cuff should inflate symmetrically and have no air leak. Deflate the cuff completely. Leave the syringe attached to the pilot balloon in order to inflate the cuff after the ET tube has been inserted into a patient's airway. If an ET tube is defective, discard it and open a new ET tube.

Laryngoscopes

The laryngoscope is a handheld device that is used to elevate the tongue and epiglottis to expose the glottis. It is a device that is held in the left hand regardless of which hand of the user is dominant. It consists of a handle (Figure 11-7) and a blade (Figures 11-8 & 11-9). The handle contains the battery for the light source. The distal end of the handle has a fitting where the handle connects to the blade. A transverse bar indicates where the indentation on the proximal blade attaches to the handle. There are many types of laryngoscope handles. They all have the same basic design, but are available in a variety of diameters and lengths (Figure 11-7). Smaller diameter (thinner) laryngoscope handles may be better suited for use with the smaller sized pediatric laryngoscope blades. Shorter, “stubby” laryngoscope handles may offer an advantage when proceeding with intubation of obese or barrel-chested patients, especially in cases where the neck cannot be manipulated. The shorter handle will not catch on the chest wall during attempts to place the laryngoscope blade in the patient's mouth.

The laryngoscope blade may have a removable bulb attached to its distal third. A fiberoptic bundle within the blade transfers power from the handle to the bulb. Other laryngoscope blades only contain fiberoptic bundles which transmit light, with the light source located within the handle. The choice of the type and size of laryngoscope blade will vary with physician experience and preference. The best blade is one that the intubator feels comfortable and confident using. The curved Macintosh blade is most commonly used (Figure 11-8). It is the easier blade to use for those with little experience with orotracheal intubation. Many feel that it requires less forearm strength to use as compared to the straight blade. The large flange allows for easier control of the tongue and the flat curved shape of the spatula fits the natural curve of the tongue. The straight Miller blade is often reserved for those experienced with the blade and with orotracheal intubation (Figure 11-9).

The tip of the curved Macintosh blade fits into the vallecula and indirectly lifts the epiglottis to expose the vocal cords (Figure 11-10). A size 2 blade is used for 3 to 6 year olds. A size 3 blade is used for children starting at about age 6, for women, and for small to average-size males. A size 4 blade is usually reserved for large males.

The tip of the straight Miller blade goes directly under the epiglottis to lift it and the tongue to expose the vocal cords (Figure 11-11). Use the straight blade, if possible and the intubator is familiar with its use, to intubate patients under 2 years of age. A straight blade makes controlling the epiglottis and tongue easier than with a curved blade. It also makes visualization of the vocal cords easier due to its smaller flange profile. A size 0 blade is used for premature babies and neonates up to approximately 1 month of age. A size 1 blade is used for children from approximately 1 month of age to toddlers up to 2 years of age. A size 2 blade is used for children 3 to 6 years of age. Children between 6 and 12 years of age may require either a size 2 or 3 blade depending on their body size. A size 3 blade is used for adolescents, women, and average-size males. A size 4 blade is rarely used, and then primarily for large males.

If one cannot remember the proper blade size, it can be determined based on patient anatomy.20 Place the base of the blade, excluding the handle insertion block, at the level of the patient's upper incisor teeth. The tip of the blade should be located within 1 cm proximal or distal to the angle of the patient's mandible. Correct blade size allows for approximately 90% of first attempt intubations to be successful versus 57% if the blade is too small.20

There are a wide variety of laryngoscope blades commercially available. They tend to be variations of the curved Macintosh or Straight Miller blades. The McCoy blade is a curved blade with a hinged tip. The tip can be flexed by depressing a lever on the laryngoscope handle. This flexion augments indirect elevation of the epiglottis by stretching the hypoepiglottic ligament. The Flexiblade (Arco-Medic Ltd., Omer, Israel) laryngoscope also has a levering blade. The extra lift provided by these blades may improve visualization of the vocal cords.8,9 The Propper Flip-Tip laryngoscope blade (Propper Manufacturing Co., Long Island, NY) has a lever that elevates its tip up to 90° to lift the epiglottis. Other variations of the Macintosh blade include the incorporation of a variety of prism or mirror systems. These modifications allow for indirect visualization of otherwise obscured vocal cords. The Belscope (International Medical Inc., Burnsville, MN), Truvue EVO2 (Truphatek International Ltd, Netanya, Israel), Lee-Fiberview (Anesthesia Medical Specialties, Beaumont, CA), and Viewmax (Rusch, Duluth, GA) blades are examples of these types of modifications.8,10,11

There have also been many variations of the straight laryngoscope blade. Today, the Miller is the most popular straight blade. Other variants include the Phillips and Henderson blades. These modify components such as the cross section, the blade channel width, tip style, and light source placement. These modifications represent efforts to avoid such problems as dental trauma, laceration of the ET tube cuff, improve tongue displacement, minimize tip trauma, and obscuration of the light source by secretions.

In addition to traditional metal laryngoscope blades, plastic single-use blades are also available. These single-use plastic blades were developed, in part, to concerns regarding possible transmission of infectious agents by incompletely sterilized metallic blades. A study comparing plastic versus metallic Macintosh laryngoscope blades in 1177 patients found that metallic blades had higher first attempt intubation rates, fewer cases of difficult intubation, and used alternative airway interventions less often than when intubation was attempted with a plastic blade.12 Plastic blades cause less dental trauma when used on dental models.16 The rates of dental trauma in patients when compared to metal blades are not known. The use of single-use disposable plastic blades cannot be recommended at this time unless circumstances do not allow proper cleaning of metallic laryngoscope blades.

Stylets

The stylet is a semirigid piece of metal that is bendable (Figure 11-12). It is often plastic coated. It inserts into the lumen of the ET tube. It should be lubricated with a water-soluble lubricant or an anesthetic jelly prior to insertion into the ET tube. The tip of the stylet should be 1 cm proximal to the tip of the ET tube to prevent injury to the patient's airway. The ET tube, with a stylet, can be bent to maintain a specific shape. The stylet is used to facilitate passage of the ET tube through the vocal cords. It is commonly bent into a “hockey stick” or “J” shape for most intubations. A greater curvature is often used for intubations when the larynx is “anterior,” in difficult intubations, and in “blind” intubations.

A modification of the traditional stylet is the Parker Flex-It™ Directional Stylet (Parker Medical, Highlands Ranch, CO). This is a plastic articulating stylet that requires no prebending. The stylet has a built-in gentle curve. It has a button on its proximal end that extends from the ET tube. When pushed with the thumb, it allows the curvature of the ET tube to be continuously adjusted during intubation attempts.

Physician

Once the decision to intubate has been made, the Emergency Physician must use their training and experience to begin leading the team toward a successful intubation. Although the process must move quickly, the Emergency Physician must, by example, ensure a calm and orderly environment. Making the decision to intubate earlier allows the team to follow a shorter and easier time line. The Emergency Physician must visualize this time line and identify actions and potential problems before they occur. A backup plan should also be available in case orotracheal intubation is impossible. Any Emergency Department patient about to be intubated is a high priority, so do not be afraid to use resources liberally. Obtain assistants to help as soon as the decision to intubate is made.

Personnel

Shortly before the procedure begins, assemble the entire team near the bed and go over “the game plan” calmly and quickly. All personnel involved with the procedure should be gloved, gowned, and masked. Eye protection should be worn by all personnel to protect against splash injury from blood and secretions. Explicitly identify assistants and assign their roles early. Give instructions clearly and calmly before the procedure begins. It is helpful to write down medications and doses in the order that they will be given and to review them quickly with the medication nurse. Emphasize that it will be the nurse's job to draw up, label, and administer the medications, followed by a saline flush. Reinforce that during the procedure this will be a particular nurse's only job. The respiratory assistant has three important tasks: helping to ventilate the patient, applying cricoid pressure, and handing the ET tube to the intubator so that visual contact with the vocal cords is not lost. If cervical spine immobilization is needed, a third assistant should be explicitly instructed as to how and when the team leader would like the patient's neck secured.

Equipment

The mnemonic “SOAPME” can be used to help review the equipment required for intubation: Suction, Oxygen, Airway, Pharmacology, Monitoring, Equipment.13 Check that the room is ready and all equipment is within arm's reach. Turn on the suction and the oxygen. Confirm that both systems work. Attach the suction tip and check to see whether there is a small finger hole in the barrel that must be covered for the suction to work. If so, close it with a piece of tape so that the suction is “always on.” This is not a concern if a Yankauer suction catheter is being used. Ensure that the suction tubing is long enough to reach the center of the bed. Place the suction catheter under the mattress to the right of the patient's head and within easy reach. Place the spare suction tip nearby. Set the oxygen flow regulator to 15 L/min. Apply a nonbreather mask to the oxygen and the patient. Place the bag-valve device near the head of the bed and within easy reach. Confirm that the noninvasive blood pressure cuff, cardiac monitor, and pulse oximeter are working and attached to the patient. Confirm that the end-tidal CO2 monitor is nearby and working. If such a monitor is unavailable, a disposable in-line monitoring device should be available. Ensure that the patient has at least one working intravenous line.

Assemble the intubation equipment. Place the proper size laryngoscope blade on the handle. Open the blade and confirm that the light works. Close the blade into the ready position, flat against the handle, to keep the bulb cool and not drain the batteries. Take the ET tube and the backup smaller one and prepare them. Insert the 10 mL syringe into the inflation port of the pilot balloon for the ET tube cuff. Inject enough air to inflate the balloon. If there is no leak, deflate the balloon until it is completely flat against the ET tube. Leave the syringe attached. Liberally lubricate the stylet with a water-soluble lubricant. Insert the stylet into the ET tube until its tip is 1 cm proximal to the distal tip of the ET tube. Place a bend in the stylet as it enters the proximal end of the ET tube to keep the stylet from advancing. Bend the stylet/ET tube assembly into a curve roughly approximating a “hockey stick” or “J” (Figure 11-12). Lubricate the tip of the ET tube and the collapsed cuff. This prevents the ET tube from getting caught on the epiglottis and making its advancement through the vocal cords difficult. Place the assembly back into the ET tube package. Place the ET tubes, laryngoscope, backup laryngoscope handle and blades, oral airways, and tape on a tray within easy reach of the bed. Check the room lighting. Raise the bed to minimize excessive bending and better visualize the patient's airway.

If the patient is competent and awake, explain the procedure, clarify advance directives, and obtain consent. If time permits, a history is especially helpful. The mnemonic AMPLE can help to provide quick information: allergies, medications, past medical history, last meal, and events leading to the current problem.

Confirm again that the appropriate monitoring sources are working and attached to the patient. Confirm adequate intravenous access. Place the patient, with a normal neck, in the “sniffing” position, with the head extended at the atlantooccipital joint while the neck is relatively flexed. A folded towel under the occiput helps to gently raise and tilt the head back into the proper position (Figures 7-1, 11-1, & 11-13). Correct positioning is probably the most important preparation of the patient. Dentures should be left in place temporarily, as they help to stabilize the mouth and prevent occlusion during preoxygenation and bag-valve-mask ventilation.

To intubate the obese patient, place them into the head-elevated position using a ramp or pile of sheets under their head and shoulders (Figure 7-2). This position facilitates spontaneous ventilation, mask ventilation, and laryngoscopy.22–24 It also prolongs the patients oxygen saturation during and after rapid sequence induction.

If the patient is breathing spontaneously, begin preoxygenation for 5 minutes before the procedure (if time permits). Use a well-fitting nonrebreather mask with the oxygen flow regulator set at 15 L/min. This displaces nitrogen from the lungs and gives the patient a physiologic reservoir of oxygen for approximately 5 minutes while apneic. Remember: 5 minutes of preoxygenation provides 5 minutes of protection.5 If bag-valve-mask ventilation is required, have an assistant apply posteriorly directed cricoid pressure to minimize gastric distention and decrease the chance of vomiting and aspiration. Have assistants ready to turn the patient onto his or her left side to minimize the risk of aspiration if vomiting occurs. Monitor the pulse oximeter to assure good oxygenation and ventilation. It should rise to the high 90s and remain there. If not, check the O2 circuit from the wall to the patient and confirm that spontaneous breathing is still occurring.

The evaluation and preparation for orotracheal intubation are complex and essential. If done well, the intubation will hopefully be quick and anticlimactic. Position the respiratory assistant to the right side near the patient's head. The intubator should stand at the head of the bed. Adjust the bed to place the mattress level with the intubator's umbilicus. Pull the bed away from the wall at least 2 feet and clear a “maneuvering space” of tubes, lines, and equipment to prevent distractions. If in-line cervical immobilization is needed, the assistant should stand at the intubator's left hip, ready to remove the collar and hold the neck in position.

Grasp the laryngoscope with the left hand. It is a left-handed instrument regardless of the handedness of the intubator. Pull it open and lock the blade onto the handle. Confirm that the light is functioning. The tip of the laryngoscope blade should be pointed toward the patient's chin. Pass the prepared ET tube and suction catheter to the respiratory assistant, who will place them into your right hand when asked. This allows the intubator to maintain constant visual contact with the patient's airway during the procedure.

Induction of anesthesia is the final preparation for orotracheal intubation. The choice of drug sequence is based on the physician's experience and the patient's condition (Table 11-2). A typical sequence begins with a defasciculating dose of a nondepolarizing neuromuscular blocking drug. After 2 to 3 minutes, induce anesthesia with a sedative followed immediately by a paralytic agent (i.e., succinylcholine). Apply cricoid pressure. Once the patient's muscles are relaxed, perform the intubation as described below. Please refer to Chapters 8 and 10 regarding the complete details of the pharmacology of the induction agents and rapid sequence induction. Some patients, especially the old and sick, may stop breathing earlier than anticipated. Be prepared to intubate before the expected time of drug onset.

Observe the patient's chest. Watch it rise. When it stops, note the time. Place your right thumb on the patient's jaw. Gently pull down the lower lip and open the mouth. Reinspect the oral cavity. Remove any dentures or foreign bodies. Compare what you see with what you expect to see. Fix any problems as you go further into the airway. If blood or vomit is seen, ask for the suction catheter. Apply the suction catheter without removing your gaze from the patient's airway. When done suctioning, hold the suction catheter up for the assistant to take.

Intubating with the (Curved) Macintosh Blade

Firmly grasp the laryngoscope in the left hand (Figure 11-13A). Insert the tip of the Macintosh laryngoscope blade into the right side of the patient's mouth. Smoothly advance the blade inward while keeping slight upward pressure against the tongue. Use the blade to trap and push the tongue to the left as the blade is simultaneously moved to the midline, “clearing a path” for your gaze. Keep the left wrist firm. Use the forearm, wrist, and hand as a single unit and avoid bending or flexing the wrist. It is essential to move the patient's tongue up and to the left. The tongue will protect the mandibular teeth from being injured by the laryngoscope blade. It allows the laryngoscope blade to be moved away from the maxillary teeth. It also opens a path to visualize the patient's airway.

When the blade has been inserted all the way, lift the patient's airway up and forward exactly along the long axis of the laryngoscope handle, which should be aimed toward a point directly above the patient's chin (Figures 11-10, 11-11, & 11-13B). Do not “cock” or “crank back” on the laryngoscope handle with your wrist, or the back of the laryngoscope blade may break the patient's incisors. The epiglottis should be seen at the base of the tongue.

A variable amount of force is required to lift the mandible, tongue, and soft tissues to visualize the vocal cords. More force is required to visualize the vocal cords in patients who have a large tongue, are obese, have redundant pharyngeal soft tissue, or have trismus. Grasp the laryngoscope handle as close to its base as possible in these patients. The lower grasp provides more control of the laryngoscope and a mechanical advantage to apply more force without dental trauma.

Advance the tip of the laryngoscope blade into the vallecula—the space between the base of the tongue and the body of the epiglottis (Figures 11-10 & 11-13B). Lift the laryngoscope handle to raise the tongue, jaw, and epiglottis as a unit (Figure 11-10). Observe carefully as the epiglottis pivots upward and uncovers the glottis (Figure 11-5). The vocal cords should be visualized. Cricoid pressure (Sellick's maneuver) may make intubation more difficult. If the cricoid pressure is adversely impacting the view, it should be relaxed or even removed.14 The application of cricoid pressure by an assistant pressing the cricoid cartilage back, upward, rightward, and posteriorly (in this sequence) can help bring the vocal cords into view when the intubator cannot apply more lifting force due to lack of strength or reluctance to lift the airway, as in a suspected neck injury. This is known as the BURP maneuver.27

Another anterior neck manipulation maneuver known as optimal external laryngeal manipulation (OELM) or bimanual laryngoscopy may be applied.28 They differ from the BURP maneuver in that the intubator uses their right hand to manipulate the larynx into the optimal position while simultaneously viewing the patient's airway and controlling the laryngoscope with their left hand. An assistant then assumes control of the larynx, maintaining the same position as the intubator proceeds to insert the ET tube. Alternatively, to limit laryngeal movement during the hand-off, the intubator can use their right hand to manipulate an assistant's hand on the patient's larynx. When properly positioned, instruct the assistant to keep their hand still while the intubator removes their hand off the assistant's hand. A third variation uses the assistant to manipulate the patient's larynx while the intubator verbally directs them.

When the vocal cords are visualized, instruct the assistant to pass the ET tube into your right hand. This allows you to keep a “visual lock” on the vocal cords. Insert the ET tube into the right side of the patient's mouth. Advance the ET tube so that the tip reaches the vocal cords without letting the body of the tube block the view. Continue to advance the ET tube through the vocal cords until the cuff passes through them and into the trachea (Figure 11-13C). Advance the tube an additional 2 to 3 cm. The tip and cuff of the ET tube must be visualized passing through the vocal cords to assure placement in the trachea.

The fit of the ET tube through the vocal cords always seems to be tight, even in larger patients. A well-lubricated tip with the cuff completely collapsed is essential. Rolling the tube gently between the thumb and the index finger at the moment of insertion can also help pilot the tip between the vocal cords. If the ET tube is too large or the vocal cord opening narrow, ask the assistant to pass the smaller ET tube, which has already been prepared.

The average depth of insertion (in cm) of the ET tube starting from the patient's lips is listed in Table 11-1. It can also be calculated using one of the following formulas: ET tube ID (in mm) × 3, (age in years/2) +12 for patients over 2 years of age to a maximum of 18 years of age, or age + 10 for children less than 8 years of age.

Once the ET tube has been inserted, the intubator's right hand must hold the tube in place continuously until it is properly secured. The assistant should inflate the ET tube cuff with the attached 10 mL syringe of air (Figure 11-13D) and then remove the syringe and stylet. The intubator must hold the ET tube firmly to make sure that it does not become dislodged when the stylet is removed. The assistant should attach the end-tidal CO2 monitor and the bag-valve device to the ET tube. If symmetrical lung sounds are heard on auscultation and if pulse oximetry and CO2 monitoring appear appropriate, secure the ET tube in position in the right corner of the patient's mouth (Figure 11-13E).

Intubating with the (Straight) Miller Blade

Intubating with the straight blade is similar to the curved blade with a few differences. Insert the laryngoscope blade completely. If the epiglottis is seen, insert the tip directly under and slightly beyond it. Lift the epiglottis and airway as above by raising your hand along the long axis of the laryngoscope handle toward a point above the patient's chin (Figure 11-11). If neither the epiglottis nor the vocal cords are seen, the tip of the laryngoscope blade is in the esophagus. Locate the airway by lifting as above while slowly withdrawing the laryngoscope blade. As the tip slides back, it will “catch” the epiglottis and the airway should “fall down” into view. The BURP or OELM maneuver may now be applied if necessary. Some physicians use a variation of this to localize the epiglottis by inserting the blade deeply and lifting, then withdrawing while feeling for the “give” as the epiglottis tip falls off of the retreating blade, and then readvancing a small distance to “scoop up” the epiglottis, exposing the airway. The remainder of the technique is the same as described above.

In the Emergency Department, simple common-sense methods will quickly and accurately assess ET tube placement. The confirmation of ET intubation is briefly described in this section. Please refer to Chapter 12 for a more detailed discussion. The assessment must be made quickly! An ET tube in the wrong place, the esophagus, is as quickly dangerous as a properly placed one is lifesaving. Was the ET tube visualized passing through the “A frame” of the vocal cords? This is the most important assessment. If it was directly visualized being placed and continuously held in place, it is properly positioned. Is the pulse oximeter reading in the high 90s and steady or rising? Is the CO2 monitoring appropriate? Be familiar with the monitor in your institution. Electronic monitors will show a respiratory waveform and a numerical value. In-line colorimetric monitors connected between the ET tube and the respiratory circuit will change color with inspiration and expiration to indicate the flow of CO2 passed the device.

Evaluate the patient. Symmetrical upper chest rise without increasing abdominal size suggests proper placement. Persistent “fogging” or condensation inside the ET tube with each breath for at least six ventilations will also confirm proper placement. Auscultate lateral to the nipples for strong and symmetrical breath sounds during positive-pressure breaths. Avoid auscultating in the midline, where “normal” breath sounds can be heard from a misplaced ET tube in the esophagus. Auscultate at the lateral apices and bases of the lungs. Auscultate over the epigastrium. Correct placement will give strong, symmetrical breath sounds except in the epigastrium. If epigastric sounds are strongest or “gurgling” or vocalization is heard, assume incorrect ET tube placement. Breath sounds that are asymmetrical and stronger on the right indicate a right mainstem intubation. Deflate the cuff and gently withdraw the ET tube in 1 cm increments while auscultating. Continue to withdraw the ET tube until equal breath sounds are heard. Secure the tube and reinflate the cuff.

Obtain a chest radiograph after clinically confirming the placement of the ET tube. The tip of the radiopaque stripe of the ET tube should be over the third or fourth thoracic vertebra and 3 to 4 cm above the carina of the trachea. Always inspect the radiograph for any signs of a pneumomediastinum, pneumothorax, or hemothorax.

Clinical assessment of the ET tubes position should take less than 15 seconds. If you are unsure of the ET tube position, leave the first tube in place while applying cricoid pressure. If the patient's pulse oximetry reading is in the mid- to high 90s, reinsert the laryngoscope and look to see if the ET tube is passing between the vocal cords. Alternatively, the ET tube can be removed and intubation reattempted. If the pulse oximetry is low, remove the ET tube and ventilate the patient with a bag-valve-mask device for 30 to 60 seconds to allow the pulse oximetry to rise into the high 90s before making a second attempt at intubation. Do not ventilate the patient by a bag-valve-mask without the application of cricoid pressure. The stomach can inflate with air and increase the risk of aspiration.

Some physicians prefer to leave the misplaced ET tube in place. Leaving the first tube might seem to complicate subsequent intubation attempts but can serve to vent gastric vomit out of the oropharynx as well as to locate the esophageal entrance during the next attempt at direct visualization of the airway.

As long as ventilation is possible with the bag-valve-mask device and pulse oximetry can be maintained above 92% (PO2 = 60 mmHg), two or three attempts can be made at orotracheal intubation. If 30 seconds elapse or pulse oximetry falls to 92%, stop the intubation attempt and ventilate the patient for 30 to 60 seconds, as above. In training programs, the third attempt should be made by the most skilled person available. Three failed attempts define a “failed airway” and call for rescue intubation by an alternative method. Any patient in whom bag-valve-mask ventilation becomes impossible must be given a surgical airway.

The ET tube must be secured to prevent it from migrating distally or proximally. The traditional method of wrapping tape around the ET tube then around the patient's head is rarely used today. If used properly, tape functions just as well or better than commercially available ET tube holders.19 A variety of disposable, relatively inexpensive, and single patient use ET tube holders are commercially available. They are easy to apply, adjust, and reposition if necessary. The basic unit is a nonlatex plastic ET tube holder that positions over the patient's mouth, a cushioned neckband, and Velcro closures for a snug fit. There are many variations of this basic unit.

A nasogastric tube or orogastric tube is often placed after orotracheal intubation to remove air, fluid, and gastric juices from the stomach. This tube must also be secured. It is either taped to the patient's face or to the ET tube to prevent it from migrating distally or proximally. One specific ET tube holder is a novel device that deserves mention. The Intubix™ (Intubix LLC, Houston, TX) is an ET tube holder with a built-in bite guard and orogastric tube side port (Figure 11-14). It allows the blind passage of the orogastric tube through the side port as well as securing it in position.

Postintubation management should include pain control, sedation, and paralysis if indicated. The patient should be sedated, and possibly paralyzed depending on the situation, so they do not fight the ET tube and extubate themselves. The patient should never be paralyzed and not sedated so they are aware and but unable to respond. This is considered cruel. Administer an opioid analgesic as required for pain control. The patient may require repeated bolus dosing of these medications or a continuous infusion for analgesia, sedation, and/or paralysis depending on their condition.

Hypoxemia and Misplaced ET Tubes

Hypoxia is the most destructive complication. It often results from prolonged intubation attempts, with or without proper preoxygenation, and unrecognized misplaced ET tubes. Without adequate oxygenation, irreversible brain injury begins to occur within 2 to 3 minutes. Hypoxia can result in cardiac arrhythmias.

An unrecognized esophageal intubation will result in significant morbidity and mortality. After intubation, the proper ET tube placement should be confirmed by auscultation, chest rise, fogging in the ET tube, end-tidal CO2 monitoring, and chest radiography. Any manipulation or movement of the ET tube or the patient's upper body (head, neck, and torso) should be followed by an assessment of the ET tube position. It can easily become dislodged and migrate into the hypopharynx and esophagus. Other methods to confirm ET tube placement include inserting a fiberoptic bronchoscope through the ET tube and visualizing the tracheal rings and carina (Chapter 21) or inserting a lighted stylet and following the illumination into the trachea (Chapter 17).

Cardiovascular Complications

Bradycardia can be produced by pharyngeal manipulation. It may be especially pronounced in children because of their higher vagal tone. Pretreatment with atropine (0.02 mg/kg with a minimum dose of 0.15 mg) in children under 6 years of age can avoid this. It will also serve to decrease airway secretions.

Increased intracranial pressure can occur as a result of the direct laryngoscopy. The exact cause of this transient rise is unknown. Lidocaine has been postulated as being of benefit in blunting this but is so far unproven. A dose of 1.5 to 2.0 mg/kg IV may be used as a premedication if time allows and the patient's condition warrants its use.

Mechanical Complications

Direct mechanical complications from the laryngoscope include lacerations of the lips, trauma to the pharyngeal wall, broken teeth, or dentures that may be aspirated and require later removal. Vomiting can cause subsequent chemical and bacterial pneumonitis. A pneumothorax is a rarely seen complication of laryngoscopy. It is more often associated with positive-pressure ventilation. Laryngoscopy may cause apnea, bronchospasm, and/or laryngospasm due to prolonged stimulation of the pharynx.

Laryngospasm may result from insertion of the laryngoscope blade or attempts to advance the ET tube through the vocal cords. This occurs more often in patients who are awake, semiconscious, not paralyzed, and not anesthetized. It may be prevented by the application of nebulized lidocaine, topical anesthetic spray, transtracheal injection of lidocaine, or laryngeal nerve blocks. If laryngospasm occurs during intubation, remove the laryngoscope and begin positive-pressure ventilation. Positive-pressure ventilation will often overcome the laryngospasm. If not, consider paralyzing the patient immediately with succinylcholine or performing a surgical airway.

The ET tube and stylet can be a source of mechanical complications.15,17,18 A sore throat is a common and self-resolving nuisance. Uvular necrosis occurs when it is compressed between the ET tube and palate. This rare complication is self-limited and often heals within 2 weeks. Treatment includes antihistamines, steroids, and possibly antibiotics. The stylet protruding from the distal end of the ET tube can cause soft tissue contusions and lacerations, perforation of the vocal cords, hemorrhage into the airway, and perforation of the trachea. Proper stylet placement with its tip within the ET tube will prevent these complications. ET tube cuff overinflation can result in mucosal sluffing, pressure necrosis, and hemorrhage. Tracheal rupture is a rare but life-threatening complication.17,18 It may be due to cuff overinflation, a protruding stylet, intubation using more rigid and less pliable stylets, pushing through a weakness or defect, or from multiple intubation attempts. The complications associated with cuff overinflation can be prevented by using manometry, which is seldom used.

Air Leaks

A “leak” of air out from the patient's mouth or nose during ventilation signifies a mechanical problem with the ET tube. If the cuff is damaged, the ET tube must be removed and replaced. Check the position of the ET tube by direct laryngoscopy. If the cuff is located between or above the vocal cords, it will not secure the airway properly. Deflate the cuff, advance it through the vocal cords, and reinflate the cuff. If the cuff slowly deflates, there may be a leak in the pilot balloon. Reinflate the cuff and apply a hemostat to the tubing attached to the pilot balloon or attach a closed stopcock to the inflation port.

Aspiration

The risk of aspiration increases in patients with difficult airways or full stomachs. This includes obese and pregnant patients. The use of an awake ET intubation or rapid sequence induction with cricoid pressure may minimize the risk of aspiration. A properly placed ET tube with the cuff inflated will decrease, but not totally eliminate, the risk of aspiration.

The Utility of the Sellick Maneuver

The use of cricoid pressure was introduced in 1774 in its use to prevent gastric distention during artificial ventilation of drowning victims.29 Sellick reintroduced the application of cricoid pressure in 1961.30 Cricoid pressure theoretically causes an occlusion of the upper esophagus by trapping it between the cricoid cartilage and the vertebral bodies. It has since been used on a daily basis for rapid sequence induction by Anesthesiologists and Emergency Physicians. This maneuver was thought to prevent regurgitation and gastric insufflation during positive-pressure ventilation. The application of cricoid pressure was later termed the “Sellick maneuver.”

Sellick's original publications were small observational studies self-reporting on his technique. These studies were not blinded, controlled, or randomized. Several subsequent studies determined the amount of force required to occlude the esophagus on cadavers and patients. It is not practical or possible to measure the cricoid force applied during clinical care in the Emergency Department.

Multiple studies have found adverse effects associated with the Sellick maneuver.28,31–35 It can worsen the laryngoscopic view of the airway. Other complications include bruising, airway obstruction, cricoid cartilage fracture, goiter hemorrhage, subconjunctival hemorrhage, and esophageal rupture. Cricoid pressure decreases lower esophageal sphincter tone and may explain in part the cases of pulmonary aspiration prior to intubation.

Although the Sellick maneuver is considered a “standard of care,” very little evidence supports its use to prevent aspiration.33–35 This does not mean that the Sellick maneuver should not be performed! It may be of benefit to prevent aspiration, especially in the Emergency Department where patients often have “full stomachs.” If intubation or ventilation is difficult using the Sellick maneuver, slowly release cricoid pressure in an attempt to improve ventilation or airway visualization.

Endotracheal Cuff Pressure

Inflation of the ET tube cuff is required to adequately ventilate a patient without an air leak, provide positive-pressure ventilation, and prevent aspiration. There can be a fine line between proper cuff inflation and overinflation. One of the goals of any procedure is to prevent complications from the procedure itself. Overinflation of the ET tube cuff can result in mucosal necrosis, mucosal sloughing, hemorrhage, tracheal rupture, or subsequent tracheal stenosis. Physicians have traditionally palpated the pilot balloon to estimate cuff pressure and prevent any complications from overinflation. This method is not accurate.36,37

Measurement of the cuff pressure is a simple, quick, and inexpensive procedure. It should be considered whenever a patient is intubated.38 Cuff pressure should be measured if a patient is transported by air as the cuff pressure changes at elevated altitudes.39,40 A pressure of up to 20 cmH2O provides an adequate seal, without compromising mucosal blood flow and lowers the risk of subsequent subglottic stenosis. Tracheal mucosal blood flow shows a decline at 30 cmH2O, and is completely blocked at 45 cmH2O. An ET tube cuff pressure manometer is needed to measure these pressures accurately.

There are numerous methods to quickly assess cuff pressure. Palpation is not accurate and should not be used. The simplest method is to use a manometer. These devices (Cufflator, Posey Corp., Pasadena, CA or Rusch Endotest, Teleflex Medical, Research Triangle Park, NC) allow the simultaneous inflation of the cuff while monitoring the cuff pressure on a dial. These devices function similarly to those used to inflate a car tire. While simple to use, they can be cumbersome due to their shape and weight. An in-line device that attaches to the cuff inflation port is available (PressureEasy Cuff Pressure Controller, Smiths-Medical, Dublin, OH). The device has an indicator window that signals when the cuff pressure is maintained between 20 and 30 cmH2O. A third novel device is the Pressure Alert Endotracheal Tube (www.jamesdysonaward.org/projects/project.aspx?ID=598). This device is not yet commercially available. It incorporates a “pop-up” button into the pilot balloon that alerts the user when the cuff pressure is too high.

Orotracheal intubation is both common and lifesaving. It is the primary and preferred method of airway management. Every Emergency Physician must master this skill. With proper preparation, definitive control of the airway can be obtained. This assures that patients can be oxygenated and ventilated when they cannot do this on their own. Good team leadership skills are nearly as important as physical dexterity and assure an orderly and quick procedure. Rapid patient assessment is important to prevent complications. If orotracheal intubation is unsuccessful, another form of intubation or a surgical airway should be performed.