Chapter 10. Compromised Airway

Securing the airway and assuring adequate ventilation are the first priorities in the resuscitation of any acutely ill or injured patient. Without a patent airway and adequate gas exchange, other resuscitative measures will usually be futile. Thus, attention to the airway must precede or occur simultaneously with any other type of management. The exception is the initial defibrillation in cardiac arrest due to ventricular fibrillation, if it can be performed immediately. (See Figure 10–1.)

Assess the Airway

First, determine the patient's level of consciousness and note the presence of respirations and grade respiratory effort. In patients with known or suspected cervical spine (C-spine) injury, all assessments and maneuvers should be undertaken with the C-spine immobilized in a neutral position to prevent cord injury.

Apneic, Unconscious Patients

If the C-spine is not injured, place the head in the sniffing position with the chin lift maneuver to open the airway (Figure 10–2). For patients with potential C-spine injuries, a jaw-thrust maneuver should be used. Clear the airway of obstructions, using a rigid suction catheter to remove any blood, vomitus, or secretions from the oropharynx. Remove any large obstructing foreign bodies from the oropharynx manually or with Magill forceps (see Chapter 9).

If the patient remains apneic, assist ventilation using a bag–valve–mask device (eg, Ambu bag) or mouth-to-mouth breathing (see Chapter 9). If adequate personnel and equipment are available, immediately perform endotracheal intubation.

Patients with Respiratory Effort

Administer high-flow oxygen. Clear and position the airway as described above. Identify evidence of upper airway obstruction. Prolapse of the tongue and accumulation of secretions, blood, or vomitus are common causes of obstruction. Signs may include wheezing, sonorous respirations, stridor, cough, and dysphonia. Upper airway obstruction should be removed if present. Back blows or the Heimlich maneuver may clear the obstruction. If not, use suction or direct visualization and a Magill forceps or finger. Blind finger sweep is contraindicated. Obstructions that recur or persist require endotracheal intubation, either orotracheally or via cricothyroidotomy, tracheostomy, or percutaneous transtracheal jet ventilation (PTTJV) (see also Chapters 7, 9, and 50).

Evaluate the effectiveness of the patient's respiratory effort. Helpful signs include respiratory rate, tidal volume, accessory muscle use, level of consciousness, skin color, upper airway sounds, and auscultated lung sounds. Further assessment may include pulse oximetry, arterial blood gas measurement, end-tidal CO2 capnography, and chest radiography. If intubation is indicated (Table 10–1), continue high-flow oxygen and assist ventilation as needed. Assemble all items necessary for the appropriate method of intubation (Table 10–2). Check for equipment malfunction. If the patient is alert, inform him or her of your plan.

Prepare for Intubation

High-Flow Oxygen

All patients with airway or ventilatory compromise require high-flow oxygen. Oxygen through a nasal cannula at flow rates up to 6 L/min provides a patient with 20–40% inspired oxygen concentration. A variety of masks are available that can accept oxygen flow rates of 5–15 L/min. Masks equipped with reservoirs and non-rebreathing valves can deliver oxygen concentrations close to 100% at flow rates of 10 L/min if an adequate seal can be maintained between the mask and face.

Before attempting intubation, preoxygenate the patient with 100% oxygen for 5 minutes or have the patient perform eight vital capacity breaths. In a ventilating patient, this should provide 6–7 minutes of protection against hypoxia if the patient becomes apneic. Caution should be exercised because this time interval can be significantly shortened in an ill patient. In an apneic patient, preoxygenation with a bag–valve–mask unit provides 2–3 minutes of protection against hypoxia.

Suction

A rigid-tipped suction catheter should be available at all times to keep the airway clear of blood and secretions. The suction device should be set at 120 mm Hg. After intubation, suction the tracheobronchial tree with a sterile, flexible catheter as necessary.

Oral and Nasal Airways

When the jaw thrust or chin lift is ineffective in airway opening, a nasal or oral airway may support collapsed oropharyngeal tissues and permit adequate ventilation. A range of sizes should be readily available in all areas of the emergency department (Figure 10–3).

The oral airway should only be used in an obtunded patient. It may be inserted over a tongue blade or positioned upside down as it enters the mouth and rotated after the tongue is cleared. The former is preferred in pediatric patients as to prevent trauma to the soft palate. Positioned correctly, it retracts the tongue upward and anteriorly. Care must be taken not to push the tongue backward into the pharynx, worsening the obstruction. An oral airway that is too long could potentially displace the epiglottis over the larynx, resulting in complete obstruction.

The soft, rubber, noncuffed nasopharyngeal tube tends to be better tolerated in a semiobtunded patient. Lubricate the tube with anesthetic jelly before insertion. Insert it through the least obstructed nostril, advancing it posteriorly along the floor of the nostril until it bypasses the tongue. If it is too long, it may enter the esophagus, resulting in ineffective positive pressure ventilation and gastric distention. Epistaxis may occur during insertion, and suction should be available.

In patients with intact airway reflexes, placement of either device may cause emesis, gagging, or laryngospasm. During and after placement, head position should be maintained to optimize airway patency. Where indicated, spinal precautions must be maintained. Evaluate breath sounds after placement of either device to ensure that obstruction has not occurred. Care must be taken to avoid trauma during placement.

Positive Pressure Ventilation

Following airway opening, positive pressure ventilation may be used to preoxygenate a patient before intubation. Occasionally it may be the only form of ventilation available in an apneic patient when an airway cannot be secured. In general, however, it is not recommended for prolonged ventilation owing to gastric dilatation and technical difficulty.

The bag–valve–mask unit is the device most commonly used to provide positive pressure ventilation in the emergency department. The bag–valve–mask unit has a self-inflating reservoir that accepts 15-L/min oxygen flows. A non-rebreathing valve permits this reservoir air to enter through a separate port from air that is being expired. At these flow rates, inspired air will approach 100% oxygen, provided adequate seal is established. The self-filling bag permits use with spontaneously breathing patients. The unit can usually be attached to an endotracheal tube (ET) after intubation for manual bag-assisted tracheal ventilation.

The procedure for using the bag–valve–mask unit is described in Chapter 7. Use of this device is difficult in the hands of a single operator because effective bag–valve–mask ventilation depends on a tight seal between the mask and face. Often this requires two hands and a second operator to compress the bag. Many circumstances of anatomic variation, facial hair, or maxillofacial trauma make a tight seal impossible. During bag–valve–mask ventilation, proper head position must be maintained to preserve airway patency. Monitor the effectiveness of ventilation closely by frequent assessments of chest wall movement, lung sounds, and gastric dilatation.

The positive pressure generated by bag–valve–mask ventilation leads to gastric dilatation and abdominal distention. This results in decreased lung compliance and significant risk of emesis and aspiration. A clear mask is recommended to identify emesis. Suction equipment must be available. In patients with unprotected airways, cricoid pressure (the Sellick maneuver) is recommended (Figure 10–4). To perform the Sellick maneuver, apply firm, direct pressure on the circumferential cricoid cartilage. This will compress the esophagus posteriorly, decreasing gastric dilatation and reflux. If emesis occurs, release pressure on the cricoid to prevent esophageal rupture and aggressively suction the hypopharynx. If bag–valve–mask ventilation must be prolonged for any reason, place a nasogastric tube to reduce gastric dilatation and its consequences. Because of operational difficulties and risks of aspiration, the bag–valve–mask is a temporizing measure under most circumstances. Patients who require bag-assisted ventilation should generally be intubated as soon as it can be accomplished safely and practically.

The mouth-to-mask technique is another method of providing positive pressure ventilation. This method may be easier for a single operator, because both hands can be used to seat the mask. Supplemental oxygen is provided via a port in the mask or via a nasal cannula worn by the operator.

Prehospital Airway Devices

Extraglottic devices can be used emergently, if no rapid sequence intubation (RSI) protocol exists or endotracheal intubation fails in the field. The esophageal tracheal Combitube (ETC) may even be potentially used as an ET if blind insertion results in tracheal placement, but this phenomenon is uncommon. Alternatively, the King LT airway is now becoming a popular device due to its ease of use and rapid deployment.

The ETC has found favor in prehospital and emergency department settings. It comprises two tubes that form a single double-lumen tube. A proximal balloon isolates the hypopharynx, whereas the distal balloon occludes the esophagus or the trachea, depending on its location. The tube is inserted blindly and is fairly stiff, so that it usually enters the esophagus. Tube 1 (larger tube) is closed distally with side holes for ventilation. Tube 2 (smaller tube) is open distally and gives a direct route to either the lungs or the stomach. Tube 1 is always ventilated first, when confirming placement of the tube. Advantages of the ETC include ease of placement, partial protection of the airway from aspiration, and lack of manipulation of the C-spine in the trauma patient.

The King LT airway is a single-lumen tube with two cuffs, but both are inflated simultaneously at a solitary site instead of the two required on an ETC. A ventilation port exists between the oropharyngeal and esophageal cuffs that provides ventilation toward the larynx. Insertion of King LT airway utilizes a similar technique as the ETC.

Esophageal tubes are contraindicated in semiobtunded patients, children, and patients less than 120 cm in height. Do not use them when there is known esophageal injury or ingestion of caustic substances. Complications are listed in Table 10–3. Because of reports of esophageal trauma, some authors recommend Gastrografin swallow or endoscopy after use of an esophageal obturator airway (EOA)-like device. Due to the established complication profile and the evolution of superior alternative devices, the use of esophageal tubes should be discouraged.

Patients intubated with an EOA in the field will need endotracheal intubation on arrival in the emergency department. If an ETC or King LT airway is in place, it may be used temporarily for continued resuscitation, but a premium should be placed in establishing a cuffed, endotracheal intubation.

Cuffed Oropharyngeal Airway

The cuffed oropharyngeal airway is a modified oropharyngeal airway with a large distal inflatable cuff. It is inserted like a traditional oral airway, and the cuff is then inflated in the supraglottic space. This device is useful in resuscitation because of its ease of insertion and the low level of skill required to place it. The disadvantage of the device is that it has no distal balloon and gastric contents may be more easily aspirated as compared to the ETC.

1This chapter is a revision of the chapter by Julia Nathan, MD, from the 4th edition.

These principles of intubation management apply to all methods of airway management described in this chapter. Airway positioning, suction, and administration of 100% oxygen must precede any attempt at advanced airway control. Keep protective gear with the airway equipment, and use it routinely.

Basic Orotracheal Intubation

Most patients can be intubated orally by direct laryngoscopic visualization of the cords. This is the method of choice, because the best assurance of correct tube placement is seeing the tube pass through the cords into the trachea. Please refer to Chapter 7 for complete discussion of basic laryngoscopy and orotracheal intubation technique.

When direct visualization is difficult (Table 10–4), various methods are available to improve visualization of the glottic opening. Backward, upward, rightward pressure (also known as the BURP maneuver) on the external larynx by an assistant to the intubator has been used with some success to increase the intubator's view of the glottic opening. An old technique that has resurfaced for use in the last few years, called external laryngeal manipulation (ELM), is probably even more successful at obtaining a better look at the glottis. This maneuver requires the intubator to use a bimanual technique for intubation. While attempting to visualize the glottis with the laryngoscope in the left hand, by traditional means, the intubator reaches around the anterior neck with the right hand and manipulates the external larynx in all directions while attempting to find a position in which the glottis can be better visualized. Once this position is noted, an assistant continues to hold the external laryngeal structures in this position while the intubator then passes the ET tube through the cords.

A head-elevated laryngoscopy position has also been found to be successful in increasing the view of the glottic opening. In patients who do not require C-spine immobilization, elevating the head so that the laryngeal structures are roughly level with anterior chest wall can also dramatically improve visualization of the glottic opening. This can be fairly easily accomplished with blankets, towels, or other material placed under the patient's head/neck, or by using the hand to help elevate the occiput. This maneuver is especially helpful in the obese patient with a large neck.

If the glottis is truly not visible after using these basic techniques, then other options are available. Blind intubation techniques, video laryngoscopy, fiberoptically assisted intubations, and surgical airways are all options in the difficult airway that cannot be intubated by direct means. These methods will be discussed in the next section.

Universal Precautions

Airway management presents many opportunities for exposure to patient secretions. Wear adequate protective clothing, including a gown, gloves, mask, and either a face shield or goggles, any time the airway is manipulated. When the intubator's fingers are in the patient's mouth (eg, digital intubation, lighted stylet), care must be taken to prevent bite wounds. Place a bite block or dental prod before initiating intubation. Alternatively, place several layers of gauze between the intubator's hand and the patient's teeth. If the patient wears dentures, remove them before airway manipulation.

Postintubation

After intubation, secure and assess the position of the ET by observing the chest wall for expansion. Auscultate both lung fields and the abdomen while ventilating. Inaudible lung sounds or the presence of abdominal sounds suggest esophageal placement. If breath sounds are louder on the right than on the left, suspect right mainstem intubation. Withdraw the tube 1–2 cm and auscultate again. Confirm the tube position by end-tidal CO2 detector and chest x-ray.

Intubating Laryngeal Mask Airway

The laryngeal mask airway (LMA) is a device that has proven to be useful as an alternative for bag–valve–mask ventilation and as a rescue option in the difficult airway. The LMA is a semirigid tube with a distal inflatable balloon mask that is inserted blindly into the hypopharynx. The mask lies over the larynx and seals around the glottic opening. The LMA does not protect against aspiration. This device has been demonstrated to be easy to insert with limited prior training. The LMA is appropriate for use in adults and pediatrics, including neonates weighing more than 2 kg. The intubating LMA (I-LMA) is a modification of the LMA that has been developed to act as a conduit to allow blind passage of the ET through the glottis. The I-LMA has a metal handle attached to it that allows the user to stand at the head of a patient and manipulate it similarly to using laryngoscope handle in order to reposition the device and tube as needed.

Lighted Stylet

Lighted stylet and light wand devices have been developed to aid in blind intubation. This method can be used when blood, secretions, or vomitus fill the hypopharynx. Because laryngoscopy need not be used, lighted stylets may be advantageous when the C-spine must remain immobilized. Blind intubation with a lighted stylet is most suitable for deeply comatose or apneic patients when there is little risk of stimulating protective reflexes or biting of the intubator's hand. Use a bite block or dental prod for protection. A lighted stylet can also be combined with direct laryngoscopy. Although there are no absolute contraindications to this technique, ambient lighting must be low to maximize its benefit. Obesity may diminish the intensity of transillumination. As for other blind techniques, avoid this method when direct laryngoscopy can be performed.

If necessary, one person can perform this technique unaided. These devices have a battery-powered light source at the top of a semiflexible stylet. A longer, floppy stylet is available for nasal intubations. The stylet is threaded into an ET. Aside from the lighted stylet, no special equipment is required.

Form the assembly of stylet and ET into a hook of slightly greater than 90°. The patient may be approached from the head if laryngoscopy is used. Otherwise, approach the patient from the right shoulder. While placing gentle traction on the tongue, pass the assembly into the mouth. When the epiglottis is reached, use a scooping or ladling motion to place the tip into the glottis. The appearance of transillumination at the neck indicates the position of the tube. Tracheal placement results in a bright, well-circumscribed area of transillumination at the cricothyroid membrane. The ET can then be advanced over the stylet into the trachea. Transillumination lateral to the midline indicates piriform sinus placement and need for repositioning. Esophageal placement causes little or no transillumination. The procedure is essentially the same for nasal intubation with a lighted stylet.

This procedure shares the same complications as other blind techniques: inadvertent malpositioning of the tube, hypoxia, and tissue damage.

Video Laryngoscopes

Over the last few years, video laryngoscopes have been added to the airway armamentarium that many emergency physicians have ready to assist in challenging airway problems. The video laryngoscope, as its name implies, is a device with a video camera situated at the end of a curved blade that allows visualization of the anterior aspect of the hypopharynx and glottis. Because of the curve of the device, visualization of the glottis occurs without out alignment of the oropharyngeal and laryngotracheal axes that is required for successful intubation using conventional direct laryngoscopy. These devices utilize indirect laryngoscopy and can be particularly useful in difficult airway patients including those airways complicated by large body habitus or limited neck mobility. Many emergency physicians now preferentially turn to one of these airway management tools when managing difficult airway patients. Similar to the limitations discussed below with fiberoptic laryngoscopy, video laryngoscopes are centered around conditions that can obscure the lens of the device such as excessive oropharyngeal secretions or blood in the hypopharynx. Suctioning the airway prior to the intubation attempt may improve the chance of a successful intubation using video laryngosopes.

Fiberoptic Intubation

Fiberoptic bronchoscopes may be used to locate the opening of the glottis when direct laryngoscopy cannot be used or is unsuccessful. The ET can then be advanced over the endoscope into the trachea. Although this procedure can be carried out without movement of the C-spine, it requires skill and practice. It can be performed either orally or nasally and oxygen can be insufflated during the procedure. It may be impossible when the hypopharynx is filled with blood or secretions. In addition, the equipment is expensive and easily damaged. Intubation via this method does require significant practice to become proficient.

Gum Elastic Bougie

Gum elastic bougie was designed as a tracheal tube introducer. It is made of woven polyester with resin coating and is meant to be reused, although disposable ones are available. It is 60-cm long and 5 mm in diameter with an angled tip. When the glottis is impossible to visualize, this introducer can be angled under the epiglottis. If it passes into the trachea, a series of clicks will be palpable as it passes over the tracheal rings. Because of the diameter of the tube, it will no longer advance past 40 cm if in the airway. Once you are certain that it is in the airway, a tracheal tube from 6 to 8 mm may be passed over it into the trachea. The introducer is then removed. The bougie should not be used if one is completely unable to visualize the epiglottis.

Nasotracheal Intubation

Please see Chapter 7 for description of method.

While this method of intubation is blind, it is relatively easy to perform in nonapneic patients. It is ideal in the patient who is awake and cannot undergo RSI or in those patients who have difficulty lying down secondary to severe shortness of breath (chronic obstructive pulmonary disease, congestive heart failure). It is contraindicated in the apneic patient and in those with severe facial trauma. This method has become less utilized in the recent years secondary to the use of RSI in most intubations. Prehospital providers occasionally still use it when RSI is not available to them.

Retrograde Intubation

Retrograde intubation is indicated when oral or nasal intubation is contraindicated or technically impossible owing to anatomic, pathologic, or traumatic abnormalities. The advantages of this technique include maintenance of the C-spine in a neutral position and the benefits of any blind technique. In addition, it requires less skill than does fiberoptic intubation. Disadvantages include its time-consuming nature and the need to have the patient ventilating adequately throughout. This method is contraindicated when the airway is obstructed at or above the level of the cords. If the patient is unable to open the mouth, the retrograde wire must be passed out the nose for nasal intubation, which can be difficult and suboptimal in some settings.

Retrograde intubation can be performed by one operator, although an assistant is extremely helpful. Special equipment includes a needle of sufficient caliber to accept a guide wire and a wire approximately 70 cm in length. A small clamp or hemostat and Magill forceps are also useful. Local anesthetic is recommended.

The principle of retrograde intubation involves entering the trachea at the cricothyroid membrane with a guide wire that is threaded out the mouth or nose and used as a guide for blind oral or nasal intubation. After appropriate preparation of the neck, identify the cricothyroid membrane and surrounding landmarks. Pass a needle through the skin, and puncture the inferior third of the cricothyroid membrane with the needle directed about 30° caudad. Aspiration of air confirms tracheal placement. Rotate the needle to about 30° cephalad, and reaspirate to confirm tracheal position. Introduce the wire through the needle. As the wire is threaded through the needle, it often exits spontaneously through the mouth. Occasionally, however, it must be retrieved with fingers or forceps. When the wire is in hand at the lips or nares, the needle is removed. Fix the wire at the cricothyroid membrane with fingers or a small clamp. Thread the proximal end of the wire into the ET through the side hole (Murphy's eye). It should pass up through the lumen of the tube, exiting at its proximal end. Advance the lubricated tube along the wire until resistance is met, indicating that the tube is in the trachea, below the cords, pulled tight against the fixed wire. Release the wire at the skin and pull it out through the proximal end of the tube. Advance the tube to the appropriate position, and confirm placement in the usual manner.

Only a small number of cases of retrograde intubation have been described. Few serious complications have been reported.

In cases of patients who cannot be oxygenated or intubated, bridging devices provide the ability to ventilate a patient until a secure airway can be obtained that may help prevent the need for a surgical airway. These devices and methods of ventilation, while lifesaving in many situations, are not considered secure airways and do not prevent aspiration nor do they provide the best means of oxygenation and ventilation. A secure airway defined as a one in which a cuffed ET is situated below the cords must ultimately be obtained. Some of the following bridge devices may be successfully used between intubation attempts in the initially difficult airway to prevent dangerous episodes of hypoxia.

Laryngeal Mask Airway

As stated in the section “Nonsurgical Devices and Techniques for Managing the Difficult Airway,” the LMA is a very useful device that allows rapid insertion of a tube with which to ventilate through but provides minimal protection against aspiration. Please see previous section for description of use.

Extraglottic Devices

As mentioned in previous sections, the ETC and King LT airway provide an excellent bridging device in hospital or prehospital failed airway situations. Please refer to the section “Prehospital Airway Devices” for description of use.

Percutaneous Transtracheal Jet Ventilation

(See also Chapter 7.) PTTJV is an alternative technique for oxygenating a patient who cannot be intubated. It is unique in that positive pressure is generated by high-pressure oxygen delivered as an intermittent jet through high-pressure tubing and a percutaneously placed large-bore tracheal catheter. No bag reservoir or non-rebreathing valve is employed. PTTJV is less invasive than cricothyroidotomy and less time consuming than retrograde intubation (see above). It is relatively easily learned. With attention to detail, there are few complications. It can be used in awake or obtunded patients. Other advantages include presumed protection of the C-spine and possible expulsion of a pharyngeal foreign body by expired air. In the emergency department it is regarded as a temporizing measure while other methods of airway control can be established. Indications for PTTJV are the same as for cricothyroidotomy. PTTJV has been proven useful in the pediatric population.

Disadvantages include the need for either makeshift or commercially available special equipment. With prolonged use, retention of carbon dioxide may develop. Contraindications include anterior neck trauma, where high delivered pressures may lead to severe tissue disruption, and complete airway obstruction, where expired air cannot escape through the glottis. PTTJV shares the relative contraindications mentioned above for all invasive methods of airway control. Prior unsuccessful attempts at catheter placement may lead to air leak or subcutaneous emphysema after a second, successful attempt.

Cricothyroidotomy

When there is complete upper airway obstruction or massive facial trauma that prohibits intubation from above, immediate access to the trachea can be obtained with cricothyroidotomy. In experienced hands, it is a rapid technique that maintains immobilization of the C-spine. It is a radical procedure with risk of significant short- and long-term negative outcomes. It is contraindicated whenever the airway can be secured by less invasive means. In children, cricothyroidotomy becomes technically more difficult as the landmarks become smaller. Patient age less than 10 years is a relative contraindication for inexperienced practitioners. In children younger than 5 years, PTTJV or a tracheostomy is preferable if possible. Other relative contraindications include preexisting laryngeal disease, coagulopathy, anatomic deformities of the neck due to trauma or other causes, and lack of familiarity with the procedure. The equipment and technique for cricothyroidotomy are described in Chapter 7. Kits that use over-the-wire techniques, progressive dilatation, and trocar placement are available.

Tracheostomy

Tracheostomy has little indication in emergency department management of the airway. Its only true indication is severe blunt trauma to the neck with fracture of the thyroid or cricoid cartilage, preventing access to the cricothyroid membrane. Tracheostomy is the preferred method of surgical airway management in the very small child when PTTJV is not possible. Because of the proximity of vascular, nerve, and visceral tissue, the risk of negative sequelae is high. A thorough knowledge of anatomy and careful surgical technique are critical to success. It should be performed only by surgeons experienced with the procedure.

Some patients in the emergency department can be intubated without the use of pharmacologic intervention other than oxygen. However, when pharmacologic adjuncts are indicated, their use may dramatically reduce the difficulty of intubation and speed control of the airway. The patient's overall condition and the goal of intubation determine the choice of agent. Local, topical, or regional anesthesias are usually not considered options for an emergently compromised airway. For a semiobtunded or combative patient, use of neuromuscular blockade with sedation, usually in an RSI protocol, provides rapid control of the airway while protecting against aspiration of gastric contents.

Drugs that induce apnea must be used by or under the direct supervision of experienced clinicians prepared to obtain a surgical airway in the event of failed intubation. Equipment necessary for intubation and surgical airway must be prepared in advance and be available at the bedside before the patient is sedated or anesthetized.

Rapid Sequence Intubation

General Considerations

Use of sedation alone to intubate a patient in the emergency department can be difficult and not without risk. Hypoventilation often occurs before the patient is adequately relaxed for intubation and prolonged bag–valve–mask ventilation may be required. Prolongation in airway control can delay other care and result in compromise of central nervous, cardiovascular, or pulmonary systems, further complicating the patient's postintubation course.

Every patient presenting with the need for an emergency airway should be approached as having a full stomach. These factors, combined with gastric distention due to bag–valve–mask ventilation, depressed airway reflexes, and the emetic effects of sedatives, raise the risk of aspiration.

The RSI protocol diminishes these difficulties in the awake patient who is agitated or who has altered mental status and requires oral intubation. A rapid-acting neuromuscular blocker is given to paralyze the patient. Though controversial, some protocols recommend a priming dose of a nondepolarizing neuromuscular blocker (such as vecuronium) to facilitate paralysis, reduce fasciculations, and limit elevations in intracranial pressure during laryngoscopy. Prior to administration of the paralytic, a short-acting sedative is added to decrease agitation and the noxious sensations associated with paralysis and intubation in awake or semiconscious patients. The patient is intubated immediately after paralysis. Further sedation and/or paralysis may then be necessary, as needed. During the short period when the patient is paralyzed and not intubated, the airway must be protected from aspiration with cricoid pressure.

The RSI protocol is generally unnecessary in a completely obtunded patient; however, if the patient has retained enough muscle tone to make intubation without paralytics difficult, RSI may facilitate a more rapid intubation. Because the RSI protocol will obscure the neurologic examination and physical manifestations of status epilepticus, only short-acting paralytics (such as succinylcholine) are recommended, or alternative plans to follow the neurologic condition of the patient must be made before inducing paralysis.

Equipment and Personnel Required

At least two individuals must be available to safely initiate the RSI protocol. Other than the drugs, no special equipment is required to induce neuromuscular blockade. Before giving any sedative or neuromuscular blocking agent, review the checklist in Table 10–5. The choice of sedative or anesthetic and neuromuscular blocking agent depends on the indication for intubation, patient condition, and user familiarity.

Procedure

Table 10–6 outlines the steps of the RSI protocol. The characteristics of the recommended drugs are mentioned in the section “Drugs Used During Intubation.”

Additional Drugs

Several agents may be added to the RSI protocol under specific circumstances.

Atropine

Atropine, 0.01–0.02 mg/kg (minimum 0.1 mg to prevent reflex bradycardia) given immediately before the sedative, attenuates the vagal bradycardia associated with succinylcholine. Children, who tend to be more sensitive to the bradycardic and hypotensive effects of succinylcholine, benefit from pretreatment with atropine. Therefore, all children younger than 5 years should be pretreated with atropine before succinylcholine is administered. Pretreat adults with bradycardia and those receiving a second dose of succinylcholine.

Lidocaine

Lidocaine, 1.5 mg/kg given 1 minute before intubation, may attenuate elevations in intracranial pressure associated with succinylcholine and intubation. It may have some protective effect against laryngospasm and ventricular arrhythmias during intubation, as well.

Analgesics

If pain control is part of the management plan, a narcotic such as morphine sulfate (0.1 mg/kg), fentanyl (1–2 μg/kg intravenously), or other analgesic should be added after intubation, because barbiturates have little analgesic effect and neuromuscular blockers have none.

Drugs Used during Intubation

Succinylcholine

Succinylcholine is a depolarizing neuromuscular blocking agent.

Dose

1.0–1.5 mg/kg in adults, 1.5–2.0 mg/kg in children.

Onset

60 seconds to complete relaxation.

Duration

5–10 minutes.

Indications and Advantages

1. Drug of choice for the RSI protocol under most circumstances owing to rapid onset, complete muscular relaxation, and short duration.

2. Single dose in emergency department setting, usually well tolerated if appropriate precautions are taken (see below).

Contraindications

1. Risk factors for hyperkalemia (see Adverse Effects and Precautions, below).

2. Hereditary pseudocholinesterase deficiency (1 in 2800 patients).

3. Penetrating ocular trauma or glaucoma.

4. Known family or personal history of malignant hyperthermia.

5. Hypersensitivity to succinylcholine.

Adverse Effects and Precautions

1. Cardiovascular effects include bradycardia and hypotension, ventricular arrhythmias, and tachycardia or hypertension. Use with care in the setting of an irritable myocardium.

2. Fasciculations (see above for sequelae).

3. Hyperkalemia occurs in settings of subacute burns, subacute crush injuries, upper and lower motor neuron disease, and tetanus. Levels in excess of 9 mEq/L have been reported, and cardiac arrest may occur. Use may worsen hyperkalemia in renal failure patients.

4. Pseudocholinesterase inhibition may occur in pregnancy, in renal or hepatic insufficiency, and with a variety of drugs.

5. Malignant hyperthermia occurs in 1 in 50,000 patients.

6. Histamine release may cause bronchospasm or anaphylactoid reaction.

7. Intraocular pressure is elevated during fasciculations.

8. Intracranial pressure may increase.

9. Intragastric pressure may increase; use cricoid pressure until ET cuff is inflated.

10. Always use sedation with alert patients; succinylcholine has no intrinsic analgesic or sedative effect.

Vecuronium

Vecuronium is a nondepolarizing neuromuscular blocking agent (NDNMB).

Dose

Standard dose is 0.1 mg/kg. To achieve rapid intubating conditions, 0.25 mg/kg may be used.

Onset

Dose dependent; standard doses achieve paralysis in 3–5 minutes, larger doses in 1–1.5 minutes.

Duration

Dose dependent; standard doses last 20–40 minutes and larger dose may prolong paralysis two to three times the usual duration.

Indications and Advantages

1. One of the NDNMBs that can be used when succinylcholine is contraindicated.

2. Relative short duration allows neurologic reevaluation and provides satisfactory paralysis for procedures such as computed tomography scan in an emergency setting.

3. Minimal cardiovascular effects at usual doses.

4. Reversible after partial recovery (evidence of head lift, respiratory effort, or muscle twitch response) with neostigmine, 0.04 mg/kg intravenously. Atropine, 0.02 mg/kg intravenously, must also be administered to prevent muscarinic side effects.

5. Does not cause fasciculations or elevate intracranial pressure.

Contraindication

Known hypersensitivity to vecuronium.

Adverse Effects and Precautions

1. Reduce dosage in patients with myasthenia gravis to avoid prolonged blockade.

2. Maintain cricoid pressure until inflation of ET cuff.

3. Must use sedation or anesthesia in awake patients.

4. Block is prolonged by aminoglycosides, lithium, quinidine, lidocaine, and propranolol and in hypermagnesemia, hyperkalemia, dehydration, hypothermia, and respiratory acidosis.

5. Use during pregnancy only if clearly indicated.

Rocuronium

Rocuronium is a rapid-onset, short-acting NDNMB.

Dose

0.6 mg/kg.

Onset

1–2 minutes.

Duration

30 minutes.

Indications and Advantages

Excellent choice for nondepolarizing neuromuscular blockade. Because of its rapid onset, rocuronium is a good alternative for use when succinylcholine is contraindicated.

Contraindication

Known hypersensitivity to rocuronium.

Adverse Effects and Precautions

1. Effects potentiated by electrolyte disturbances, neuromuscular diseases, and renal or hepatic failure.

2. Use in pregnancy only if clearly indicated.

Pancuronium

Pancuronium is a longer-acting NDNMB.

Dose

0.05–0.2 mg/kg.

Onset

1–3 minutes.

Duration

Dose dependent, averaging 60–90 minutes.

Indications and Advantages

1. Main use is prolonged blockade after intubation is complete.

2. Does not promote bronchospasm.

3. Reversible after partial recovery (see the section “Vecuronium”).

4. No elevated intracranial pressure or fasciculations.

Contraindications

1. Known hypersensitivity to pancuronium.

2. Cardiovascular instability or history of congestive heart failure.

Adverse Effects and Precautions

1. History of myasthenia gravis (see the section “Vecuronium”).

2. Cardiovascular effects include increased heart rate, increased afterload, and ventricular arrhythmias. Use with caution in the setting of irritable myocardium.

3. Blockade is prolonged by multiple drugs (see the section “Vecuronium”).

4. Duration profile is not optimal for use with the RSI protocol.

5. Maintain cricoid pressure until inflation of ET cuff.

6. Always use sedation or anesthesia in awake patients.

7. Use in pregnancy only if clearly indicated.

Etomidate

Etomidate is a short-acting sedative-hypnotic.

Dose

0.3 mg/kg intravenously.

Onset

Within 1 minute.

Duration

3–5 minutes.

Indications and Advantages

1. Alternative drug for sedation in RSI.

2. Little to no cardiovascular side effects.

3. Lowers intracranial and intraocular pressures.

Contraindication

Known hypersensitivity to etomidate.

Adverse Effects and Precautions

1. May cause hypotension in the hypovolemic patient.

2. May cause apnea, laryngospasm, hiccups, and cough.

3. May cause adrenal suppression with multiple doses.

4. Local pain on injection.

5. Skeletal muscle movements such as myoclonus.

6. No recommendations for dosing in children younger than 10 years.

7. May cause fetal malformation in pregnancy.

Midazolam

Midazolam is a short-acting benzodiazepine central nervous system depressant.

Dose

0.1–0.3 mg/kg.

Onset

Approximately 30 seconds, depending on rate of injection when given intravenously.

Duration

15–20 minutes.

Indications and Advantages

1. Alternative induction agent for sedation in the RSI protocol (may have prolonged sedative effect).

2. Minimal cardiovascular effects.

3. May produce amnesia for several hours.

4. Blunt intracranial pressure responses at high doses.

Contraindications

1. Known sensitivity to midazolam or benzodiazepines.

2. Acute narrow-angle glaucoma.

Adverse Effects and Precautions

1. Respiratory depression or arrest.

2. Cardiovascular effects usually minimal with bigeminy, premature ventricular contractions, and nodal rhythms.

3. Laryngospasm and bronchospasm, cough, and hives.

4. Local irritation at injection site.

5. Nausea and vomiting.

6. Potentiated by other central nervous system depressants; dose modifications recommended.

7. Dose modifications recommended in patients with chronic obstructive pulmonary disease or congestive heart failure, in elderly patients, and in patients with renal failure.

8. Possible increase in fetal malformations with pregnancy.

Fentanyl

Fentanyl is a short-acting narcotic anesthetic.

Dose

1–5 μg/kg intravenously.

Onset

60 seconds.

Duration

30–60 minutes.

Indications and Advantages

1. Alternative drug for sedation in the RSI protocol (sedation may be prolonged with thiopental).

2. Both analgesic and sedative effects.

3. No histamine release.

4. Blunts intracranial pressure response to intubation.

5. Reversible with naloxone, 1–4 mg intravenously.

Contraindication

Known sensitivity to fentanyl.

Adverse Effects and Precautions

1. Respiratory depression and apnea. Respiratory depression may persist beyond analgesic and sedative effects.

2. Muscle rigidity, which may occur with rapid injection of high doses.

3. Rare bradycardia or cardiovascular depression.

4. Nausea and vomiting.

5. Effects potentiated by other central nervous system or respiratory depressants.

6. Dose modifications recommended in patients with chronic obstructive pulmonary disease or congestive heart failure, in elderly patients, and in patients with renal failure.

7. Possible increase in fetal malformations. Consider alternative drugs in pregnancy.

Ketamine

Ketamine is a dissociative anesthetic agent.

Dose

1–2 mg/kg.

Onset

60 seconds.

Duration

5–10 minutes.

Indications and Advantages

1. Alternative drug for sedation and analgesia during the RSI protocol, particularly in hypotension.

2. Sedative of choice in status asthmaticus patients because it may cause bronchodilation.

3. Airway reflexes are usually maintained. Respiratory depression is usually minimal and transient.

4. Myocardial depression is uncommon.

5. Prominent analgesic effects.

Contraindications

1. Hypersensitivity to ketamine.

2. Head injury.

3. Severe hypertension.

Adverse Effects and Precautions

1. Elevated blood pressure and pulse rate are the most common cardiovascular effects. Hypotension, bradycardia, and arrhythmias have been reported. Use with caution if irritable myocardium is present or when hypertension would adversely affect patient course.

2. Respiratory stimulation and maintained airway most common, but apnea, respiratory arrest, and laryngospasm also have been reported.

3. Dysphoric emergence reactions.

4. Nausea and vomiting.

5. Local irritation at injection site.

6. Increased intracranial pressure.

7. Intraocular pressure may be increased.

8. Muscle rigidity or myoclonus.

9. Increased secretions. Consider pretreatment with atropine.

10. Possible prolonged recovery when used concurrently with narcotics or barbiturates.

11. Consider alternative drug in pregnancy and for patients younger than 2 months.

Management of the Pediatric Airway

Basic principles of airway management are similar for all age groups. However, anatomic and physiologic differences affect the emergency physician's equipment needs and management decisions when confronted with a pediatric airway emergency.

Unique Features

• In infants, the head is relatively larger in proportion to the body.
• The neck is more supple owing to a greater proportion of cartilaginous support tissue.
• The airway is smaller, resulting in increased resistance and susceptibility to obstruction due to edema, blood, or secretions.
• The mucosa is looser, permitting obstruction due to positioning and greater, faster distention from blood or edema.
• The adenoidal and tonsillar lymphatic tissues are larger and more friable than those of adults.
• The larynx is more cephalad and anterior.
• The epiglottis is larger and more floppy and protrudes into the airway more prominently.
• The narrowest portion of the airway in children younger than 5 years is the cricoid cartilage rather than the larynx, as in adults.
• The cricothyroid membrane is very small and does not lend itself to surgical manipulation.
• The carina branches symmetrically at 45°.
• The chest wall is thinner, and both airway and gastric sounds radiate easily, making auscultation less reliable.
• The chest wall is more pliable, and ventilation depends significantly on diaphragmatic movement.
• Oxygen consumption is 6–8 mL/kg/min in children, whereas adults usually consume about 3–4 mL/kg/min. Hypoxemia can occur more rapidly and is tolerated less well.
• Apnea occurs suddenly during a wide range of illnesses and injuries.
• Normal vital signs vary for different age groups (Table 10–7).

Equipment Required

All essential equipment (oxygen delivery systems, face masks, bag–valve–mask units, oral and nasal airways, laryngoscope blades, ETs, stylets, and suction devices) should be stocked in a variety of sizes to accommodate the anticipated population served by the facility (see Table 10–7). Oxygen should be humidified and warmed to prevent drying of secretions and subsequent airway obstruction. It has been classically taught that ETs for children younger than 8 years should be noncuffed to prevent damage to the cricoid ring. This notion has recently been challenged and many pediatric critical care specialists now routinely use modern high-volume, low-pressure cuffed ETs for intubation of all children. Correct tube size may be obtained from a table or gauged based on one of the following three methods:

1. The tube size should closely approximate the size of the child's small finger at the distal interphalangeal joint.

2. The tube size should closely approximate the size of the child's nares.

3. The tube size in millimeters is equal to (patient's age in years/4) + 4.

For patients younger than 4 years, a straight blade is preferred owing to the tendency of the epiglottis to protrude and cover the airway. In emergency departments where pediatric resuscitation is rare, precalculate the doses of commonly needed drugs, based on weights, and post them clearly in the resuscitation area or utilize length-based charts such as the Broselow–Luten tape.

Decision and Techniques

Evaluate for respiratory distress by assessing vital signs, skin signs, overall patient condition, use of accessory muscles, retractions, nasal flaring, and arterial blood gases or pulse oximetry. Since supplemental oxygen must be given and children often cannot tolerate a face mask, adequate oxygen supplementation can frequently be achieved by directing a stream of humidified 100% oxygen across the patient's face.

Airway positioning is essential. Alert patients will often choose the position of greatest airway patency and should not be forced to lie down. Infants and obtunded patients must be placed in the sniffing position (see Figure 10–2) unless C-spine injury is suspected or present. In this position, the neck is flexed slightly and the head is extended on the neck. The jaw thrust or chin lift is then used to lift the soft tissues out of the airway. Obstruction should be cleared.

Oral and nasal airways are less useful in children because they frequently stimulate laryngospasm or emesis when reflexes are intact. In addition, placement may traumatize the adenoidal or tonsillar soft tissues, resulting in significant bleeding, which can be difficult to control and may further complicate airway management.

In obtunded or paralyzed children, cricoid pressure should be used during positive pressure ventilation until intubation is confirmed. Bag–valve–mask ventilation is used initially for emergent oxygenation and ventilation in children because of the ease of attaining a seal and the smaller size of the chest cavity. Adequacy of ventilation is best assessed by observing chest wall motion, as auscultation is less reliable. Care should be taken to coordinate breaths with the bag–valve–mask unit with spontaneous ventilations, when present.

Definitive airway control involves oral endotracheal intubation. Blind nasal intubation is technically more difficult in children and is contraindicated in the emergency department. The increased adenoidal tissue is at risk for bleeding, and the anterior position of the larynx with the overlying epiglottis makes nasal tube placement more difficult. Until 5 years of age, children should be premedicated with atropine, 0.01–0.02 mg/kg (minimum 0.1 mg), to prevent bradycardia with intubation. Because auscultation can be unreliable, tube placement should be confirmed by a colorimetric end-tidal CO2 detector, observation of chest wall movement, skin color, and radiographs.

Surgical airways in young children and infants are extremely difficult. They should be performed only as a last resort by surgeons with experience in pediatric head and neck surgery. There are high failure and complication rates. Most airways will be adequately managed by bag–valve–mask or oral intubation techniques.

Epiglottitis and Croup

These illnesses may cause severe airway edema and sudden obstruction. Diagnosis is based on clinical features and, when necessary, anteroposterior and lateral neck soft tissue views.

Croup

Croup progresses more slowly than epiglottitis, causes subglottic swelling and a barking cough, and is often accompanied by signs of viral upper respiratory infection. It can rarely progress to bacterial tracheitis, an emergent airway infection. Unlike croup, which rarely requires intubation, bacterial tracheitis usually requires intubation, frequent suctioning, and antibiotics. When severe, croup requires treatment with racemic epinephrine, steroids, and observation.

Epiglottitis

Epiglottitis classically progresses rapidly with a toxic-appearing, drooling child sitting in the upright position with the neck hyperextended. Abrupt, complete airway obstruction can occur with minimal stimulation of the patient. When suspicion is high for epiglottitis, supplemental oxygen should be supplied and the patient transported with minimal disturbance to the operating room, where the epiglottis can be directly visualized. More than half of the patients with epiglottitis will require intubation, which is best done in the operating room by the most experienced intubator before airway obstruction occurs. If intubation fails, tracheostomy must be performed on an emergency basis, preferably by a pediatric otorhinolaryngologist. Treatment includes antibiotics and intravenous fluids after the airway is secured (see Chapter 50).

Management of Foreign Bodies in the Airway

Management of foreign bodies in the airway is dictated by the location of the object and the patient's age and condition. Most airway obstructions due to foreign bodies occur between the ages of 1 and 5 years. More than 3000 deaths annually are due to this disorder.

Assessment begins with observation for tachypnea, air movement, stridor, retraction, agitation or lethargy, and cyanosis. Auscultation and chest x-ray may be helpful. Examination of the oropharynx may reveal the foreign body. If the foreign body is visible, the airway may be cleared with a manual sweep. Blind sweep is not recommended. If the patient is coughing, do not interfere; the normal reflexes often clear the airway. Oxygen should be administered to all patients with foreign body aspiration.

If there is total obstruction, attempt the Heimlich maneuver in patients older than 1 year; in younger children, back blows and chest thrusts are recommended. If these methods are unsuccessful, position the airway to optimize patency. Attempt to remove the object under direct observation with a laryngoscope. If this is unsuccessful, a surgical airway may be necessary to relieve subglottic obstructions. Removal in the operating room with rigid bronchoscope may be the only option.

Management of the partially obstructed airway must be individualized. Bronchial obstructions often do not require intubation, and compromise may be subacute. If there is air movement and the object cannot be visualized on direct observation, the safest method for removal is under general anesthesia with the rigid bronchoscope. Take care not to cause complete obstruction while inserting the laryngoscope or bronchoscope.

Management of Airway in Trauma Patients

Patients with Unstable Cervical Spines or Facial Injuries

When airway control must precede definitive stabilization of the spine, oral intubation with RSI and in-line maintenance of the C-spine has been proved safe and effective. It is the method of choice in the trauma patient with suspected spinal injury. However, most large series report no bad neurologic outcomes with any technique that is carefully done. Other options for airway control include blind techniques such as nasal or digital intubation, use of lighted accessories, and transtracheal methods. The decision must be individualized based on the patient's level of consciousness and injuries, the urgency of the need for airway control, and the intubator's skill with various techniques.

Patients with severe facial and upper neck trauma present significant challenges to the emergency physician. If RSI techniques are attempted, the emergency physician should be prepared to switch immediately to a surgical airway or a bridge device to allow ventilation in the event that bag–valve–mask ventilation proves difficult or ineffective. If the airway is predicted from the beginning to be difficult, an awake intubation using topical anesthetics and intravenous sedation may be the best approach.

Patients with Head Trauma

Intubation of patients with severe head trauma (GCS ≤ 8) is indicated to treat hypoventilation and hypoxia and to protect and control the airway in patients who are unstable or combative and agitated enough to require paralysis for necessary studies and procedures. Additionally, it is the only way to hyperventilate the patient to a lower PCO2 as part of the treatment for severely elevated intracranial pressure and imminent herniation. Approach to the airway must take into account other potential traumatic injuries to the midface, C-spine, soft tissues of the neck, and respiratory tract. Oral intubation with the RSI protocol is generally recommended. If the RSI protocol is used, lidocaine, 1.5 mg/kg intravenously, may attenuate the rise in intracranial pressure. Although succinylcholine is reported to raise intracranial pressure, it remains the recommended agent for neuromuscular blockade in the setting of head trauma because it allows for rapid control of the airway and initiation of treatment. Other sedative options available to attenuate the rise in intracranial pressure associated with laryngoscopy include fentanyl and etomidate. Vecuronium, an NDNMB, is administered at 0.01 mg/kg as a small priming dose to eliminate muscle fasciculations associated with succinylcholine use.