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Airway management consists of clearing the upper airway, maintaining an open air passage with a mechanical device, and/or assisting respirations. There are many indications for airway control (see Table 1: Respiratory and Cardiac Arrest: Situations Requiring Airway Control). In most situations, a manual resuscitation bag and mask provides adequate temporary ventilation, allowing time to systematically achieve definitive airway control. When equipment is not available, mouth-to-mouth (or mouth-to-mouth-and-nose in infants) ventilation is effective if properly performed.

Table 1
Situations Requiring Airway Control Emergencies Urgencies Cardiac arrest Respiratory failure Respiratory arrest or apnea (eg, from CNS disease, drugs, hypoxia) Deep coma, when the tongue relaxes to occlude the glottis Acute laryngeal edema Laryngospasm Foreign body at the larynx (eg, the “cafe coronary”) Need for ventilatory support (eg, in acute respiratory distress syndrome, exacerbations of COPD or asthma, diffuse infectious or other parenchymal lung problems, neuromuscular diseases, respiratory center depression, extreme respiratory muscle fatigue) Need to relieve the work of breathing in patients in shock, with low cardiac output, or with myocardial stress that must be decreased Before gastric lavage in patients with an oral drug overdose and altered consciousness Very high O2 consumption (eg, in peritonitis, with limited respiratory reserves) Before bronchoscopy in patients with marginal respiratory status Before radiologic procedures in patients with altered sensorium, particularly if sedation is required Drowning Smoke or toxic chemical inhalation Respiratory burn (heat or chemical) Aspiration of gastric contents Upper airway trauma Head or high spinal cord injuries

Clearing and Opening the Upper Airway

Obstruction caused by relaxation of the soft tissues of the oropharynx may be relieved temporarily by neck extension (head tilt), chin lift, and thrusting the jaw forward (see Fig. 1: Respiratory and Cardiac Arrest: Expired air ventilation—adult.); these maneuvers stretch the anterior neck structures, lifting and drawing the tongue away from the posterior pharyngeal wall. Obstruction from dentures and oropharyngeal foreign material (eg, blood, secretions) may be removed by finger sweep of the oropharynx and suction, taking care not to push the material deeper (more likely in infants and young children, in whom a blind finger sweep is contraindicated). Deeper material can be removed with Magill forceps during laryngoscopy.

Fig. 1
Expired air ventilation—adult. Position to open airway alone. (Adapted from “Standards and Guidelines for Cardiopulmonary Resuscitation [CPR] and Emergency Cardiac Care [ECC],” in Journal of the American Medical Association 25:2956 and 2959, June 6, 1986. Copyright 1986, American Medical Association.)

Heimlich maneuver: The Heimlich maneuver (manual thrusts to the upper abdomen or, in the case of pregnant or extremely obese patients, chest thrusts) is the preferred initial method in the awake, choking patient and in the unconscious patient if the above methods are unsuccessful.

An unconscious adult is rolled into the supine position. The rescuer sits astride the patient above the knees with the heel of a hand in the upper abdominal area below the xiphoid process. To avoid damaging chest structures and the liver, the hand should never be placed on the xiphoid process or lower rib cage. The other hand is placed on top of the 1st and a firm upward thrust is delivered (see Fig. 2: Respiratory and Cardiac Arrest: Abdominal thrusts with victim lying (conscious or unconscious).). For chest thrusts, the hand is placed over the sternum similar to the position used for cardiac compression. With both techniques, 6 to 10 quick, firm thrusts may be necessary to dislodge a foreign body.

Fig. 2
Abdominal thrusts with victim lying (conscious or unconscious).

In conscious adults, the rescuer stands behind the patient with arms encircling his midsection. One fist is clenched and placed midway between the umbilicus and xiphoid. The other hand grabs the fist, and a firm inward and upward thrust is delivered by pulling with both arms (see Fig. 3: Respiratory and Cardiac Arrest: Abdominal thrusts with victim standing or sitting (conscious).).

Fig. 3
Abdominal thrusts with victim standing or sitting (conscious).

In older children, the Heimlich maneuver may be performed. However, in children < 20 kg (typically < 5 yr), very moderate pressure should be applied, and the rescuer should kneel at the child's feet rather than astride.

Infants < 1 yr should not have a Heimlich maneuver but should be held in a prone, head-down position, supporting the head with the fingers of one hand, while the rescuer delivers 5 back blows (see Fig. 4: Respiratory and Cardiac Arrest: Expired air ventilation—child.). Five chest thrusts should then be delivered with the infant in a head-down position with his back on the rescuer's thigh (supine). This sequence of back blows and chest thrusts is repeated until the airway is cleared.

Fig. 4
Expired air ventilation—child. Head-down position: dislodgment of foreign bodies from tracheobronchial tube. (Adapted from “Standards and Guidelines for Cardiopulmonary Resuscitation [CPR] and Emergency Cardiac Care [ECC],” in Journal of the American Medical Association 25:2956 and 2959, June 6, 1986. Copyright 1986, American Medical Association.)

Airway and Respiratory Devices

If there is no spontaneous respiration after airway opening, and no respiratory devices are available, rescue breathing (mouth-to-mouth or mouth-to-mouth-and-nose) is started. Exhaled air contains 16 to 18% O₂ and 4 to 5% CO₂, which is adequate to maintain blood O₂ and CO₂ values close to normal. Larger-than-necessary volumes of air may produce gastric distention with associated risk of aspiration.

Bag-valve-mask devices (BVMs) consist of a self-inflating bag (resuscitator bag) with a nonrebreathing valve mechanism. These devices do not maintain airway patency, so patients with soft-tissue relaxation require additional devices to keep the airway open. Supplemental O₂ delivers from 60 to 100% inspired O₂. Ventilation may be maintained for prolonged periods with a BVM, allowing time for careful nasotracheal or orotracheal intubation. However, if BVM ventilation is used for > 5 min, anterior cricoid pressure should be applied to prevent gastric insufflation and a nasogastric tube should be inserted to evacuate air, which is invariably introduced into the stomach during BVM ventilation. BVMs are also used with artificial airways, including endotracheal tubes and laryngeal mask airways. Pediatric bags have an adjustable pressure relief valve that limits peak airway pressures (usually at 35 to 45 cm H₂O); this valve must be closed when used with a mask to optimize ventilation.

An oropharyngeal airway or a nasal trumpet keeps soft tissues of the oropharynx from collapsing and blocking the airway. These devices facilitate BVM ventilation, although they produce gagging in fully conscious patients. The proper oropharyngeal airway size should be equal to the distance between the corner of the patient's mouth and the angle of the jaw.

A laryngeal mask airway can be inserted into the lower oropharynx to prevent airway obstruction by soft tissues; it contains a passage to allow easy BVM ventilation. Some models also have a channel that can guide an endotracheal tube into the trachea. This device causes minimal complications and has gained popularity because laryngoscopy is not needed for insertion, allowing use by minimally trained rescuers. Because it causes gagging, use is limited to obtunded patients and for short periods (hours).

Laryngeal Mask Airway (LMA). The LMA is a tube with an inflatable cuff that is inserted into the oropharynx. The deflated cuff is inserted into the mouth (A) and, with the index finger, is guided into place above the larynx (B). Once in place, the cuff is inflated (C).

A double-lumen esophageal/tracheal airway device with proximal and distal balloons (Combitube) may be used to occlude the pharynx and esophagus. It is inserted blindly, usually ending up in the esophagus, in which case ventilation is accomplished through one lumen. If it passes into the trachea, the patient is ventilated via the other lumen. Thus, insertion technique is easy to master, and the device is helpful for minimally trained rescuers. The device is not satisfactory for prolonged use and should be changed for an endotracheal tube as soon as practical. Use is limited to prehospital cases where endotracheal intubation is unavailable or in the emergency department following failed intubation.

An endotracheal tube is the definitive method to secure a compromised airway, prevent aspiration, and initiate mechanical ventilation and should replace BVM ventilation as soon as possible. It also permits suctioning of the lower respiratory tract. Placement typically requires laryngoscopy. It is indicated in comatose patients and others who need prolonged mechanical ventilation.

Airway Techniques

Most patients requiring an artificial airway can be managed with endotracheal intubation; a few require a surgical airway (eg, cricothyrotomy or tracheostomy).

Endotracheal intubation: Manual airway control, ventilation, and oxygenation are always indicated before attempting tracheal intubation. Orotracheal intubation is preferred in apneic and critically ill patients because it can usually be performed faster than nasotracheal intubation, which is reserved for awake, spontaneously breathing patients, in whom comfort has higher priority.

Larger endotracheal tubes have high-volume, low-pressure balloon cuffs that minimize risk of aspiration. Cuffed tubes are typically used only in adults and children > 8 yr, although cuffed tubes may be appropriate for selected infants and younger children. Most adults can accept tubes with an internal diameter ≥ 8 mm; these are preferable to smaller tubes because they have lower airflow resistance (reducing the work of breathing), facilitate suctioning of secretions, allow passage of a bronchoscope, and may aid in liberation from mechanical ventilation. The balloon cuff is inflated with air using a 10-mL syringe, and a manometer is used to verify that balloon pressure is < 30 cm H₂O. For infants and children ≥ 1 yr, tube size is calculated by (patient's age + 16)/4; thus, a 4-yr-old should have a 4 + 16/4 = 5 mm endotracheal tube. From birth to 6 mo, tube size is 3.0 to 3.5 mm; from 6 mo to 1 yr, 3.5 to 4.0 mm.

Before inserting an endotracheal tube, the cuff (if present) is checked for symmetric expansion and leaks. For conscious patients, a spray of lidocaine Some Trade Names
XYLOCAINE
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may make the procedure less uncomfortable. Sedation, vagolytic agents, and muscle relaxants should be considered in both children and adults (see Respiratory and Cardiac Arrest: Sedation and analgesia). Either a straight or curved laryngoscope blade can be used depending on the experience and preference of the operator; straight blades are preferred for children < 8 yr. Technique for exposing the glottis and vocal cords differs slightly for each blade, but in all cases the cords must be clearly visualized, or esophageal intubation is likely. Anterior cricoid or laryngeal pressure is often required for visualization. Some clinicians apply a water-soluble lubricant or insert a removable stylet in the tube to aid insertion (in pediatric patients, a stylet is always recommended). After orotracheal intubation, the stylet is removed, the cuff is inflated, a bite-block is inserted, and the tube is immobilized by taping it to the corner of the mouth and upper lip. Adapters connect the endotracheal tube to a resuscitator bag, T-piece supplying humidity and O₂, or mechanical ventilator.

When the tube is properly placed, manual ventilation should produce a chest rise and good breath sounds over both lungs and no gurgling over the upper abdomen. However, the most reliable way to determine tube placement is to measure end-tidal CO₂ using either a disposable detector that changes color in the presence of CO₂ or an infrared capnometer. Failure to detect CO₂ in a patient with intact circulation indicates esophageal intubation. (CO₂ also is not detected during cardiac arrest with no or ineffective CPR, but this situation should be apparent clinically.) Another tube must be immediately inserted into the trachea, following which the esophageal tube is removed (this may decrease the possibility of aspiration if the patient regurgitates following removal of the tube from the esophagus). If breath sounds are diminished or absent over one lung (usually the left), the cuff should be deflated and the tube carefully pulled back 1 to 2 cm (0.5 to 1 cm in infants) while listening over the chest for breath sounds to reposition it into the trachea. A rule of thumb for proper placement is that the centimeter mark of the tube at the gums or teeth is usually equal to 3 times the inner diameter of the tube (eg, for a 5.0 tube, the 15-cm mark should be at the teeth). A chest x-ray taken after tube insertion confirms tip position, optimally in the mid-third of the trachea with the balloon at least 2 cm below the vocal cords but above the carina. Some clinicians recommend daily chest x-rays to confirm proper tube position. In all patients, auscultation of both lung fields should be performed at regular intervals to exclude migration of the tube distally into a bronchus or cephalad.

Mechanical aids may assist in difficult cases (eg, patients with cervical spine injury or disease, massive facial trauma, airway abnormality). A lighted stylet is available; when the tube is properly positioned in the trachea, the skin overlying the larynx is illuminated. Alternatively, a guidewire may be inserted percutaneously through the cricothyroid membrane and passed retrograde out through the mouth. An endotracheal tube is then guided over the wire into the trachea. In another method, the endotracheal tube is slipped over a fiberoptic bronchoscope, which is inserted transorally or transnasally and then through the glottis, following which the tube is advanced over the scope into the trachea.

Nasotracheal intubation can be performed in spontaneously breathing patients typically without laryngoscopy, which may cause it to be preferred in patients with cervical spine injury. The tube is inserted through a nostril anesthetized with a topical agent (eg, benzocaine Some Trade Names
AMERICAINE
ANBESOL
HURRICAINE
ORAJEL BABY TEETHING
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, lidocaine Some Trade Names
XYLOCAINE
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) and advanced slowly to a position just above the larynx. As the patient breathes in, opening the vocal cords, the tube is promptly passed into the trachea. Because of airway anatomy, this technique is very difficult in children and is not recommended.

Surgical airway: If the upper airway is obstructed because of foreign body or massive trauma or if ventilation cannot be accomplished by other means, surgical entry into the trachea is required.

Cricothyrotomy can establish an emergency airway (see Fig. 5: Respiratory and Cardiac Arrest: Emergency cricothyrotomy.). The patient lies supine, shoulders raised by pillows or sheets, and neck extended. After sterile preparation, the larynx is grasped with one hand while a blade is used to incise the skin, subcutaneous tissue, and cricothyroid membrane precisely in the midline. An appropriately sized tracheostomy tube is advanced through the opening into the trachea. In an out-of-hospital, immediately life-threatening airway obstruction, a knife handle, disposable pen barrel, or other hollow object can be used to keep the airway open. If other equipment is unavailable, a 12- to 14-gauge IV catheter can be passed into the trachea through the cricothyroid membrane. The larynx is grasped with one hand while the sterile needle-catheter is inserted percutaneously through the precise midline of the cricothyroid membrane, pointing the needle tip slightly inferiorly, aspirating while advancing, and taking care not to perforate the posterior tracheal wall or to stray out of the midline into large vessels. Once tracheal position is confirmed by aspiration of air, the catheter is advanced into the trachea. A 3-way stopcock and an O₂ pressure source provide oxygenation but limited ventilation. Complications include hemorrhage, subcutaneous emphysema, and pneumomediastinum.

Fig. 5
Emergency cricothyrotomy. The patient lies supine with the neck extended. After sterile preparation, the larynx is grasped with one hand while a blade is used to incise the skin, subcutaneous tissue, and cricothyroid membrane precisely in the midline, accessing the trachea. A hollow tube is used to keep the airway open.

Tracheostomy is a more complex procedure involving surgical exposure and opening of the trachea. It is preferably performed in an operating room by a surgeon. In emergencies, the procedure has a higher rate of complications than cricothyrotomy and offers no advantage. It is, however, the preferred procedure for a long-term (> 48 h) surgical airway. Percutaneous tracheostomy is an attractive alternative for critically ill patients who should not be moved to the operating room. This bedside technique uses a simple skin puncture and single or multiple dilators to insert a tracheostomy tube.

Complications: Intubation can damage lips, teeth, tongue, and supraglottic and subglottic areas. Inappropriate tube placement in the esophagus results in a fatal failure to ventilate and also can cause gastric distention (rarely rupture) and aspiration of regurgitated gastric contents. Any translaryngeal tube injures the vocal cords somewhat; sometimes, ulceration, ischemia, and prolonged cord paralysis occur. Subglottic stenosis can occur later (usually 3 to 4 wk). Tracheostomy insertion can rarely cause hemorrhage, thyroid damage, pneumothorax, recurrent laryngeal nerve paralysis, injury to major vessels, or late tracheal stenosis at the insertion site.

Erosion of the trachea is uncommon. It occurs more commonly from excessively high cuff pressure. Rarely, hemorrhage from major vessels (eg, innominate artery), fistulas (especially tracheoesophageal), and tracheal stenosis ensue after intubation. Using high-volume, low-pressure cuffs with tubes of appropriate size and measuring cuff pressure frequently (q 8 h) to maintain it at < 30 cm H₂O decrease the risk of ischemic pressure necrosis, but patients in shock, with low cardiac output, or with sepsis remain especially vulnerable.

Drugs to Aid Intubation

A pulseless and apneic or severely obtunded patient can (and should) be intubated without pharmacologic assistance. Other patients receive pretreatment with sedating and paralytic drugs to facilitate intubation and minimize discomfort (termed rapid sequence intubation).

Pretreatment: If time permits, the patient prebreathes 100% O₂ for 3 to 5 min; this can maintain satisfactory oxygenation up to 4 or 5 min of apnea.

Laryngoscopy causes a sympathetic-mediated pressor response with an increase in heart rate, BP, and possibly intracranial pressure. To blunt this response, when time permits, some practitioners give lidocaine Some Trade Names
XYLOCAINE
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1.5 mg/kg IV 1 to 2 min before sedation and paralysis. Children and adolescents often have a vagal response (marked bradycardia) in response to intubation and are given atropine Some Trade Names
ATROPEN
ATROPINE-CARE
SAL-TROPINE
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0.02 mg/kg IV (minimum 0.1 mg in infants, 0.5 mg in children and adolescents) at the same time. Some physicians include a small dose of a neuromuscular blocker (NMB), such as vecuronium 0.01 mg/kg IV, in patients > 4 yr to prevent muscle fasciculations caused by full doses of succinylcholine Some Trade Names
ANECTINE
QUELICIN
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. Fasciculations may result in muscle pain on awakening and cause transient hyperkalemia; however, the actual benefit of such pretreatment is unclear.

Sedation and analgesia: Laryngoscopy and intubation are uncomfortable; thus, a short-acting IV drug with sedative or combined sedative and analgesic properties is mandatory immediately before the procedure. At this point, an assistant applies pressure over the cricoid cartilage (Sellick maneuver) to occlude the esophagus and prevent regurgitation and aspiration.

Etomidate Some Trade Names
AMIDATE
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0.3 mg/kg, a nonbarbiturate hypnotic, may be the preferred agent. Fentanyl Some Trade Names
ACTIQ
DURAGESIC
SUBLIMAZE
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5 μg/kg (2 to 5 μg/kg in children; Note: this is higher than the analgesic dose), an opioid (and thus with analgesic as well as sedative properties), also works well and causes no cardiovascular depression. However, at higher doses chest wall rigidity may occur. Ketamine Some Trade Names
KETALAR
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1 to 2 mg/kg is a dissociative anesthetic with cardiostimulatory properties. It is generally safe but may cause hallucinations or bizarre behavior on awakening. Thiopental Some Trade Names
PENTOTHAL
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3 to 4 mg/kg and methohexital Some Trade Names
BREVITAL SODIUM
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1 to 2 mg/kg are effective but tend to cause hypotension.

Paralysis: Skeletal muscle relaxation with an IV NMB markedly facilitates intubation.

Succinylcholine Some Trade Names
ANECTINE
QUELICIN
Click for Drug Monograph
(1.5 mg/kg IV, 2.0 mg/kg for infants), a depolarizing NMB, has the most rapid onset (30 sec to 1 min) and shortest duration (3 to 5 min). It should be avoided in patients with burns, muscle crush injuries > 1 to 2 days old, spinal cord injury, neuromuscular disease, renal failure, and possibly penetrating eye injury. About 1/15,000 children (and fewer adults) have a genetic susceptibility to malignant hyperthermia from succinylcholine Some Trade Names
ANECTINE
QUELICIN
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. Succinylcholine Some Trade Names
ANECTINE
QUELICIN
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should always be given with atropine Some Trade Names
ATROPEN
ATROPINE-CARE
SAL-TROPINE
Click for Drug Monograph
in children since pronounced bradycardia may occur.

Alternative nondepolarizing NMBs have longer duration of action (> 30 min) but also have slower onset unless used in high doses that prolong paralysis significantly. Drugs include atracurium Some Trade Names
TRACRIUM
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0.5 mg/kg, mivacurium Some Trade Names
MIVACRON

0.15 mg/kg, rocuronium Some Trade Names
ZEMURON
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1.0 mg/kg, and vecuronium 0.1 to 0.2 mg/kg injected over 60 sec.

Topical anesthesi: Intubation of an awake patient (typically not done in children) requires anesthesia of the nose and pharynx. A commercial aerosol preparation of benzocaine Some Trade Names
AMERICAINE
ANBESOL
HURRICAINE
ORAJEL BABY TEETHING
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, tetracaine Some Trade Names
PONTOCAINE NIPHANOID
PONTOCAINE
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, butyl aminobenzoate (butamben), and benzalkonium is commonly used. Alternatively, 4% lidocaine Some Trade Names
XYLOCAINE
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can be nebulized and inhaled via face mask.

Last full review/revision November 2005

Content last modified November 2005