SPECIAL CONSIDERATIONS

Cardiac Arrest
Mouth-to-mouth and BVM ventilation may suffice for out-of-hospital care with short transport times or for the initial few minutes of ventilation in cardiac arrest. However, optimal BVM ventilation during CPR is impossible. Mouth-to-mouth and BVM ventilation are adequate and effective in the anesthetized or paralyzed patient with an empty stomach in the absence of chest compression, but they are inadequate for prolonged ventilation in the patient in cardiac arrest.
Proper BVM ventilation is probably harder to master than tracheal intubation, and prolonged attempts during CPR usually only distend the stomach and give the uninitiated a false sense of security. Patients in cardiac arrest should be orotracheally intubated. Most cardiopulmonary arrests are not associated with cervical spine injury. When there is suspicion of cervical injury, the following precautions should be followed.

Potential Cervical Spine Injury
Any patient who has sustained a significant injury has the potential for cervical spine injury. Approximately 1.5 to 3.0% of initial survivors of all types of major trauma seen in emergency departments have significant cervical spine injury. It is interesting to note that this prevalence is not increased in the setting of significant head injury. Falls from heights and motor vehicle crashes are also common causes of spinal instability.
In patients with multiple injuries, the possibility of cervical spine injury warrants caution when considering tracheal intubation involving the use of the laryngoscope. It is prudent to provide adequate oxygenation while limiting neck extension until cervical spine injury is disproved. If the patient is severely hypoxic or apneic, immediate tracheal intubation may be necessary with in-line manual stabilization of the neck (without axial traction) by an assistant. When done cautiously, oral intubation of the unconscious spinal cord injured patient may be as safe as other techniques, including intubation with fiberoptic guidance.
Note that mouth-to-mouth and BVM ventilation frequently require some degree of neck extension to open the airway. A cadaver study demonstrated increased neck motion with BVM ventilation when compared to various intubation techniques, including oral intubation, lighted stylet guided oral intubation, and nasotracheal intubation. BVM techniques may, therefore, be less desirable than the other methods of securing the airway and ventilating the patient.
Many institutions and some out-of-hospital systems use pharmacologic adjuncts, in-line cervical stabilization, and orotracheal intubation before cervical spine films are initiated. In the patient who is comatose, combative, or in severe respiratory distress without definite evidence of spinal cord injury, this approach is advocated, because it may be life saving. Precautions during intubation of the patient with known cervical spine fracture or its potential should include in-line stabilization of the cervical spine with attempts to minimize traction or lateral neck motion during the intubation procedure. Clinical experience is accumulating that supports the safety of this approach.

Potential Epiglottitis/Supraglottitis
Epiglottitis is often considered a disease of children between the ages of 2 and 8 years, but it is being recognized in adults with increasing frequency. The typical presenting picture is that of an adult or child sitting upright, drooling, or spitting up oral secretions rather than swallowing. The voice may sound muffled. There is a history of a relatively abrupt onset of a sore throat that rapidly becomes more painful. Children commonly present with a high temperature, but adults usually are only mildly febrile. The disease is especially treacherous in children because of their small airways and their tendency to panic when an oral examination or insertion of an IV line is attempted.
Small children are most calm when allowed to sit on a parent's lap. An oxygen mask with oxygen flowing at 10 L/min can be held by the parent several centimeters from the child's face. If the child is using accessory muscles to breathe, every attempt should be made to keep the child calm. If a lateral radiograph of the neck taken on inspiration can be obtained without disturbing the child, it will often establish the diagnosis. On radiography, the inflamed epiglottis often appears thickened and rounded. The hypopharynx is dilated above the obstruction.
In cases of respiratory compromise, an epiglottitis protocol should be implemented rapidly. A preestablished protocol can save many minutes of time otherwise spent trying to reach all of the personnel needed to manage this critical emergency. When a child is suspected of having epiglottitis based on history and clinical presentation, the safest course of action to establish the airway should be pursued. The emergency physician should accompany the child at all times until the airway is secure and be prepared to intervene. Otolaryngologist notification should be included in the protocol because a tracheostomy may be necessary. When operating room space or personnel are not available immediately, emergency department personnel must be prepared to manage the airway.
If the child lapses into a coma or stops making ventilatory efforts, the first step is to attempt to force oxygen past the obstruction by using mouth-to-mouth respiration or a BVM apparatus. Because the obstruction is edematous supraglottic tissue and epiglottis, positive-pressure ventilation often can displace the edema enough to allow adequate ventilation. If this effort is unsuccessful, the emergency physician should attempt oral intubation. However, a normal larynx will not be visible because of the edema. The operator should attempt to pass an endotracheal tube through the slit-like opening that remains for the supraglottic airway. An assistant can compress the chest to force bubbles through the airway, as a means of locating the airway. The assistant can also palpate the larynx and the trachea to detect the tube's entry into the trachea. If orotracheal intubation fails, the intubator should go directly to transtracheal needle ventilation (TTNV) . The obstruction of epiglottitis is mainly inspiratory, so there should be no difficulty with chest hyperinflation with intermittent TTNV. This method should ease subsequent orotracheal intubation, because the path of the airway should be readily apparent as exhaled gases pass through it.
It is recommended that all children with acute epiglottitis receive tracheal intubation. If the child is not in distress, an IV line can be established before intubation for appropriate drug administration, although some operators prefer to delay IV placement until after inhalation anesthesia.
Adults and cooperative older children with suspected epiglottitis can be examined directly. It is good practice to visualize the epiglottis and the vocal cords of the stable older patient with laryngeal tenderness who is complaining of a severe sore throat or difficulty swallowing. A mirror, fiberoptic scope, or a right-angle scope can be used to do this. In epiglottitis, the pharynx and tonsils usually do not appear inflamed, a finding that might otherwise explain the symptoms. Adults with epiglottitis do not always
need to be intubated if rigorous monitoring can be accomplished, a skilled intubator is immediately available, and the patient is not in distress. Orotracheal intubation for epiglottitis is not as difficult in adults as it is in small children. Transtracheal needle ventilation can also be used in adults who are difficult to intubate.

Jaw Clenching
Hypertonus induced by neurologic dysfunction is a common complicating factor of airway management, especially in the patient with multiple injuries, drug overdose, or seizures. Jaw clenching may be a lethal complication when it prevents clearing of blood, vomitus, or foreign bodies in the airway. No more difficult airway problem exists than occlusion of the nasal and oral passages by vomitus while the patient's teeth are tightly clenched. Respiratory efforts may lead to severe aspiration, and although the hypertonus gradually gives way as the brainstem becomes progressively hypoxic, the cerebrocortical hypoxic insult sustained in the process may be irreversible. Various disease states can lead to a similar scenario in which the jaws are clenched in the presence of upper airway hemorrhage or the accumulation of secretions.
Jaw clenching and cervical spine injury can, of course, occur together. At times, the blind nasotracheal route of intubation may be adequate for airway management while minimizing the risk of further spine injury. However, at least a small degree of spontaneous air movement should be present for the blind nasotracheal approach to be successful. Although a serendipitous success may occur in the apneic patient, it is recommended that time not be wasted on this approach in the completely apneic patient.
Neuromuscular blocking agents are generally an effective means to overcome jaw clenching in the breathing patient. Both neuromuscular depolarizing and nondepolarizing agents may be administered IV to induce paralysis and allow orotracheal intubation.

Apnea with Airway Obstruction
Despite the many nonsurgical approaches to tracheal intubation discussed in this chapter, the patient who is apneic secondary to deep airway obstruction may be served best by a surgical airway. When maneuvers to relieve airway obstruction are unsuccessful and direct laryngoscopy is not possible or cannot rapidly alleviate the obstruction and permit ventilation, the operator should rapidly move to a surgical airway approach.

CONCLUSION
Airway management is the most fundamental aspect of emergency care. Every rescuer must know basic airway maneuvers and be able to use them instinctively. When basic maneuvers fail, airway management rapidly becomes more complex. Familiarity with the ingenious intermediate airway devices can often reverse a deteriorating situation and provide the rescuer with a temporary solution to an airway dilemma. When basic and intermediate maneuvers fail, complexity, risk, and exigency mount. Choices become more critical and complications more likely. Advance consideration of situations represented in the airway management algorithms is a wise practice for the emergency physician. It may hasten accurate decision-making when time becomes critical. In this chapter we have described basic and intermediate airway techniques and offered a logical schema for their use in the patient with an acutely compromised airway. Subsequent chapters deal with the more advanced airway techniques of tracheal intubation and cricothyrotomy.

INTERMEDIATE AIRWAYS

Intermediate airways are those interventions that go beyond the maintenance of a patent airway. They represent a midpoint between airway establishment and true airway control. Airway control is secured by maneuvers such as tracheal intubation and tracheotomy, in which an endotracheal cuff isolates the trachea. The devices described in this section occlude the esophagus and allow ventilation across the larynx. The devices discussed are the esophageal obturator airway (EOA), the esophageal gastric tube airway (EGTA), the laryngeal mask airway (LMA) and the esophageal-tracheal Combitube (ETC) airway (Sheridan Catheter Corp., Argyle, NY). Two are designed to occlude only the esophagus (EOA and EGTA), one (LMA) seals the larynx at the hypopharynx level, and one ETC offers the versatility of use whether placed into the esophagus or the trachea. Each is designed for use in the unconscious patient who requires positive-pressure ventilation. The esophageal cuff or seal built into these devices reduces gastric content aspiration. The EOA and EGTA have fallen into general disfavor in recent years due to the gravity of errors in placement. Complications including esophageal rupture and tracheal intubation have led many to prefer the ETC or LMA as an intermediate airway.
Esophageal Obturator Airway and Esophageal Gastric Tube Airway
The EOA and the EGTA maintain airway patency in ways similar to the oral and nasal airways, but they also protect
the airway by occluding the esophagus to reduce gastric distention and regurgitation. The face mask permits use of these airways as positive-pressure ventilating devices. Air insufflated through the airway traverses the upper airway before crossing the larynx and entering the trachea. Ventilation from the EOA exits the airway through numerous ports in its hypopharyngeal portion . Ventilation from the EGTA is identical to mask ventilation, with the addition of esophageal occlusion. A port is available on the EGTA to vent the stomach. The attractiveness of the EOA and the EGTA for use in the apneic patient stems from their retention of much of the simplicity of the artificial airway with the addition of an important feature of more complicated airways--some protection against regurgitation and reduction of gastric distention.

Indications and Contraindications
Speed and simplicity are advantages of the esophageal airway over tracheal intubation. Trained individuals can successfully place an esophageal airway in an average of 5 seconds, whereas the same individuals may need 20 seconds to perform a tracheal intubation. In one out-of-hospital study, failure to intubate was much higher with the endotracheal tube (19.4%) than with the EOA (1.7%). [19] Neck motion is not as necessary with the esophageal airway as it is with tracheal intubation. For these reasons, the EOA may be an effective adjunct in the management of the unconscious injured patient who requires respiratory assistance. Hypercarbia may occur more commonly with EOA ventilation as compared with endotracheal ventilation. The most difficult aspect of this form of ventilation is securing a tight fit with the mask. Dentures should be left in place to give support to the lips. Adequate tidal volume must be delivered to ventilate the lungs.
There are various contraindications to the use of the EOA and the EGTA. Because the airway is not protected from pharyngeal secretions, the presence of active oropharyngeal bleeding and excessive secretions represent a relative contraindication to EOA and EGTA use. Because of attendant discomfort, the devices cannot be used in the awake patient. Size specifications preclude their use in the pediatric patient; 16 years is the age usually cited as the lower limit for EOA and EGTA use. The actual limiting factors are the size of the esophagus and the face; an adult-sized 14-year-old would certainly tolerate an EOA or EGTA if necessary. However, a small adult may not receive an appropriate fit. Other contraindications include esophageal injury or conditions predisposing to perforation. A patient who has ingested a caustic agent or one with a known esophageal stricture should not undergo esophageal intubation. As a precaution against pressure-related complications, it is recommended that the device not be left in place for longer than 2 hours. It must be recognized that the EOA and the EGTA are temporary forms of airway control. This form of airway control is most often used in out-of-hospital care.

Placement of EOA/EGTA
The head is in the neutral position during placement of the EOA and the EGTA. Neck motion is unnecessary. The rescuer grasps and pulls the jaw forward. At this point, the rescuer inserts the assembled airway with the mask attached. The obturator tip is directed into the patient's posterior pharynx with gentle, steady pressure. The obturator is advanced down the esophagus until the mask rests flush against the face of the patient. Figure 1-9 (Figure Not Available) A illustrates the correct position at placement. The cuff should lie in the esophagus just distal to the carina of the trachea. The rescuer postpones inflation of the balloon until proper position is confirmed. The patient is ventilated with a tight mask seal on the face, and the lungs are auscultated. For effective ventilation, the mask seal must be tight. Breath sounds should be audible bilaterally. Unilateral breath sounds or failure of auscultation should lead the rescuer to reassess the airway placement. Pneumothorax or hemothorax may explain unilateral sounds, as may inadvertent main stem bronchus intubation. Tracheal intubation will result in the absence of breath sounds. The possibility of bronchial or tracheal intubation requires removal and replacement of the airway. Once satisfactorily placed, the esophageal balloon is inflated to 20 to 25 mL.

Complications
A 5% incidence of inadvertent tracheal intubation has been reported by Don Michael in experience with 29,000 placements. In a subsequent smaller sample, a 2.9% (5 of 170) incidence was reported with a 100% mortality among the 5 patients. One study comparing out-of-hospital EOA placement with endotracheal tube placement found that the occurrence rate for complications of the EOA that prevented resuscitation (tracheal placement, tube kinking) was nearly three times higher for the EOA (8.7% vs 2.6%). If not quickly rectified, tracheal intubation with the EOA or tube kinking are disastrous complications that produce occlusion of the patient's airway. Disciplined examination for bilateral breath sounds is critical.
Esophageal lacerations of undetermined depth were found in 8.5% of autopsies of patients in whom the EOA was used.Esophageal rupture has been found and reported in case histories. Since Scholl and Tsai first reported esophageal ruptures in 1977, the recommended balloon inflation volume was reduced from 35 to 20 mL. No further ruptures or leakage around the cuff have been reported. However, factors other than balloon inflation volume that theoretically can contribute to rupture include careless balloon removal without deflation and forceful attempts at placement when obstruction is met.
Tracheal intubation should be performed BEFORE removal of the EOA, because vomiting often occurs following deflation of the balloon and EOA removal. If the EOA cuff has been overinflated, it may partially occlude the trachea and make intubation difficult. In such cases, the balloon is partially deflated to facilitate tracheal intubation.

The Laryngeal-Mask Airway
The laryngeal-mask airway (LMA) (Intavent International SA, Henley-on-Thames, England) functions intermediately between an oropharyngeal airway and an endotracheal tube. It was developed for use in the operating room as an alternative for endotracheal intubation, but it has also been recommended for use in difficult intubations. It consists of a tube fitted with an oval mask, rimmed with an inflatable cuff. Contrary to usual mask design, the mask is intended to reside in the hypopharynx rather than on the face. It is inserted digitally until its tip meets resistance in the upper esophageal sphincter. The cuff is then inflated, forming a seal around the glottic opening. The result is a relatively secure airway. However, it cannot be considered to protect against gastric regurgitation. Leakage of the hypopharyngeal mask allows aspiration of emesis and gastric distention may occur with misplacement. Although the device may be used for prolonged periods under appropriate conditions, it is usually considered a temporary adjunct until tracheal intubation is established.

Indications and Contraindications
The LMA is indicated for patients requiring an airway who cannot be endotracheally intubated. The most frequently cited example is a patient whose anatomy prevents visualization of the larynx. Contraindications include the inability to open the patient's mouth and vomiting.

Placement of LMA
The LMA is first checked for possible air leaks by inflating and deflating the cuff. If the patient has a gag reflex, deep oropharyngeal topical anesthesia or conscious sedation must be administered. With the patient's head in the sniffing position, the mask is lubricated and oriented so the mask opening is facing the tongue. With the index finger of the dominant hand placed on the proximal aspect of the mask, the mask is inserted into the mouth, firmly against the hard palate. The index finger (or thumb) may also be used as a guide during advancement. With one smooth motion, the mask is advanced until resistance is encountered. With the tip of the mask thus seated in the upper esophageal sphincter, the cuff is inflated. The lungs are auscultated to confirm correct placement.
While the sniffing position is desirable, it has been shown that LMA placement was 95% successful when the patient was placed in the neutral position with in-line immobilization, simulating a trauma setting.
After successful placement of the LMA, several methods are available to achieve subsequent endotracheal intubation. The first method is simply to pass an appropriately sized endotracheal tube down through the lumen of the LMA, rotate the tube 90° so that the tip easily passes through the fenestrations, and advance it through the larynx to the trachea . This has been found to be successful in 90% of attempted cases. The second method involves the use of a tracheal tube exchanger. The exchanger is passed blindly down the lumen of the LMA and into the trachea. The LMA is then removed and an endotracheal tube is passed over the tracheal tube exchanger. This method of tube placement must be combined with confirmation of exchanger location, because it has been shown to pass into the esophagus in up to 70% of attempts. Confirmation of endotracheal tube location should be made . The third and most dependable method of intubation with an LMA in place is via a fiberoptic scope. A lubricated, appropriately sized endotracheal tube is mounted over a fiberoptic scope, and this combination is advanced through the lumen of the LMA out through the mask and through the larynx. The scope is then removed, but the LMA may be left in place with the cuff deflated. If the LMA must be removed after a tracheal tube has been successfully placed through it, pass a tracheal tube exchanger down the tube, remove the tracheal tube/LMA combination, and replace it with a tracheal tube.

Complications
Although the LMA works well in most cases, this airway has several significant drawbacks. Aspiration is always a possibility, because the cuff does not provide a watertight seal. Laryngospasm can occur if adequate anesthesia is not achieved. A significant air leak around the cuff may occur when high airway pressures exist, leading to poor ventilation. Finally, success rates in the operating room range from 94 to 98%; success rates in difficult emergency airway management are unknown, but they are undoubtedly lower.

Conclusion
The LMA is a blindly placed intermediate airway that should be considered in patients who require establishment of an emergency airway but cannot receive endotracheal intubation. The technique is quick and simple, requires a minimum amount of training, and appears effective in the hands of paramedics, nurses, and respiratory therapists.

The Esophageal-Tracheal Combitube
The ETC is a noninvasive airway device that is placed blindly. It allows for effective ventilation and oxygenation when placed in either the esophagus or the trachea. The device has two lumina running parallel to each other. One is perforated at the level of the pharynx and occluded at the distal end, similar to the EOA. The second lumen is open at the distal end, resembling an endotracheal tube. The device has two balloons: a proximal pharyngeal balloon that occludes the oropharynx by filling the space between the base of the tongue and the soft palate and a smaller, distal cuff that serves as a seal in either the esophagus or trachea . The Combitube has compared favorably with the endotracheal tube with respect to ventilation and oxygenation in cardiac arrest situations. It is also placed more rapidly.

Indications and Contraindications
The ETC is superior to other intermediate airways, because no face mask seal is necessary. It may be preferable to tracheal intubation in certain situations, because it can be placed blindly and is also effective in the esophageal or tracheal position. It is, therefore, more easily placed than an endotracheal tube and is indicated in situations in which tracheal intubation is difficult, neck motion is impossible, or the rescuers are not skilled in tracheal intubation.
The ETC should not be used in patients with an intact gag reflex and is not recommended in patients younger than 16 years or less than 5 feet in height. It is contraindicated in suspected caustic poisonings or proximal esophageal disorders.

Placement of ETC
The device is held in the dominant hand and gently placed caudally into the pharynx while the nondominant hand grasps the tongue and jaw between the thumb and index finger. The tube is passed blindly to a depth where the printed rings on the proximal end of the tube lie between the patient's teeth or alveolar ridge. The pharyngeal balloon is then filled with 100 mL of air, and the distal cuff is subsequently filled with 10 to 15 mL of air. The large pharyngeal balloon serves to both securely seat the ETC in the oropharynx and to create a closed system in the case of esophageal placement. Because approximately three-quarters of placements are esophageal, ventilation is begun through the longer (blue plastic) connector associated with the esophageal lumen. Chest rise and good breath sounds without gastric insufflation confirms effective placement in the esophagus. However, gastric insufflation without breath sounds and chest rise indicate a tracheal positioning of the tube and require changing the ventilation to the shorter (clear plastic) tracheal lumen. Auscultation of breath sounds over the lateral lung fields confirms endotracheal placement of the Combitube. If the tube is in the esophageal position, gastric suctioning can be accomplished by passing a catheter through the open lumen into the stomach while the patient is being ventilated via the other port.
An alternative method to identify position is to attach an aspirating device to the tracheal or clear plastic shorter tube. The inability to easily aspirate air confirms esophageal placement necessitating ventilation via the longer blue esophageal tube. In the patient with ventilatory effort, CO2 detector devices also may be useful.
A patient who has been successfully resuscitated with an ETC positioned in the esophagus should ultimately receive a definitive airway. The steps required to place a tracheal tube in this setting are detailed in Chapter 2 but consist generally of deflating the large pharyngeal balloon and, with the distal balloon still inflated, intubating around the ETC.

Complications
Inappropriate balloon inflation and incorrect ETC placement can lead to air leaks during ventilation. The most common placement error is an improper insertion angle. A more caudal, longitudinal direction is recommended, as opposed to an anteroposterior direction of insertion. Another caveat is that the ETC must be maintained in the true midline position during insertion to avoid blind pockets in the supraglottic area, which prevent passage of the tube. Attention to the ring markings on the tube at the level of the incisors ensures proper positioning of the tube. One must remember to first inflate the oropharyngeal balloon before inflating the distal balloon. Although unlikely, esophageal injury is theoretically possible with the overinflation of the distal balloon.

BAG-VALVE-MASK VENTILATION

Indications and Contraindications
Correctly performed, the BVM method of ventilation appears to be simple and effective. Still, it is fraught with difficulty and therefore deserves special mention. Bag-valve-mask ventilation should be used by experienced individuals who are able to ensure a tight mask seal in situations requiring positive-pressure ventilation. The BVM is often used with an oropharyngeal or nasopharyngeal airway in place.
Inexperience is a relative contraindication to the use of a BVM. A rescuer who is not skilled with the BVM will achieve much better ventilation with mouth-to-mouth or mouth-to-mask breathing than with a BVM. However, concern regarding transmission of infectious diseases has reduced the willingness of the lay public and health professionals to perform mouth-to-mouth ventilations. Although BVM ventilation may provide excellent respiratory support in the anesthetized, paralyzed patient in the operating room, the device frequently is of marginal value during cardiopulmonary resuscitation (CPR), during an ambulance run, or in the combative patient. A tight mask seal is mandatory to prevent loss of air volume during ventilation. Another hazard of BVM ventilation occurs when vomitus, blood, or other debris is present in the mouth or pharynx. The foreign material may be insufflated down the trachea if it is not cleared before ventilation. The three major problems encountered with BVM ventilation are inadequate tidal volumes, inadequate oxygen delivery, and gastric distention.

Ventilation Technique
Achieving adequate tidal volume with BVM ventilation requires a tight mask seal and adequate compression of the bag. Even trained paramedics practicing on manikins have difficulty delivering tidal volumes above 650 mL, which is well below the 10-15 mL/kg recommended by the American Heart Association. A variety of mask configurations are available to facilitate a tight seal, but none substitutes for the practiced skill of the rescuer. For the single rescuer, only one hand can be used to achieve the seal because the other must squeeze the bag. The rescuer's hand must be large enough
to apply pressure anteriorly while simultaneously lifting the jaw forward. The thumb and index finger provide anterior pressure while the fifth and fourth fingers lift the jaw. Care must be exercised to deliver an adequate tidal volume by full compression of the bag. Dentures generally should be left in place to help ensure a better seal with the mask.
It has been suggested that effective BVM ventilation during CPR requires two hands and, therefore, two rescuers. We suggest using the two-rescuer technique whenever it is practical. The presence on the BVM device of a pop-off valve may further frustrate ventilation efforts in the patient with reduced compliance.
All BVM devices should be attached to a supplemental oxygen source (with a flow rate of 15 L/min) to avoid hypoxia. A significant problem with the BVM method is the low oxygen saturation achieved with various reservoirs. The amount of delivered oxygen is dependent on the ventilatory rate, the volumes delivered during each breath, the oxygen flow rate into the ventilating bag, the filling time for reservoir bags, and the type of reservoir used. The commonly used corrugated tube reservoir is the least effective of those examined by Campbell and colleagues. [14] It is too sensitive to ventilatory technique and does not alert the clinician to changes in oxygen flow. A 2.5-L bag reservoir and a demand valve are the preferred supplementation technique during BVM ventilation.
Pediatric BVM devices should have a minimum volume of 450 mL. Pediatric and larger bags may be used for ventilation of infants with the proper mask size, but care should be taken to administer only the volume necessary to effectively ventilate the infant. Pop-off valves should be avoided because airway pressure under emergency conditions may often exceed the pressure of the valve.

Complications
Hypoventilation often occurs because of the difficulty of carrying out the technique properly. Three mechanisms can result in complications: poor mask seal, failure to achieve airway patency, and low tidal volume. Practiced skill development is necessary to avoid these errors. Gastric distention can also result from poor airway patency. Air is insufflated down the esophagus, which inflates the stomach. Consequently, the risk of regurgitation and aspiration increases. When assistance is available, the application of firm posterior pressure on the cricoid ring helps reduce gastric inflation during BVM ventilation. [15] [16] The technique must be used carefully in infants, whose airway is more pliable and subject to obstruction with excessive cricoid pressure. Even with proper BVM technique, aspiration can occur. The rescuer must be vigilant to recognize complications early and take corrective action.

ESTABLISHMENT OF AIRWAY PATENCY

The first concern in the management of a patient in critical condition is adequacy of the airway. Partial or complete airway obstruction must be overcome quickly. In some cases, such as an airway obstructed by a tongue, simple maneuvers will suffice. In other cases, particularly those in which myriads of obstructing agents are combining to block the airway, the task will be formidable. The tongue, dentures, swollen or distorted tissues, blood, and vomitus are common obstructing agents that make intubation difficult. Clearing obstructing agents may be made more difficult by muscular activity due to reflex stimulation or patient efforts to improve oxygenation. Moreover, the neck motion required for suction and intubation must be carefully managed in the face of potential cervical spine instability.
The wide availability of pulse oximetry monitors has greatly improved our ability to monitor oxygenation for patients at risk of airway or ventilatory compromise. Clinically subtle deterioration is much more quickly and easily recognized using the monitors. They have become standard equipment in emergency departments, intensive care units, and operating rooms to allow early recognition of patient deterioration.

Airway Maneuvers
Partial or complete airway obstruction resulting from lax musculature and tongue occlusion of the posterior pharynx may be overcome by a variety of maneuvers. The relative benefits of various airway-opening maneuvers have been examined. In a study of 120 anesthetized patients whose airways were obstructed by their tongues, Guildner compared the ease of performance of the neck-lift and head-tilt method, the jaw-thrust method, and the chin-lift method. He concluded that the chin lift was the easiest to perform and produced the greatest airway patency of the three methods tested. Besides offering greater patency, the chin-lift method has the additional advantage that neck extension is unnecessary.
Partial airway obstruction in the patient with a decreased level of consciousness is commonly due to posterior displacement of the tongue. This may be recognized readily in the presence of snoring or stridor, but an apneic patient or one who is moving minimal air may not exhibit any audible evidence of airway obstruction. Some type of jaw-thrust or chin-lift maneuver should be performed on every unconscious patient to ensure airway patency. When uncertain about cervical spine status, the neck must be maintained in the neutral position. If the patient was found with a flexed or extended neck, the neck should first be restored to neutral position with gentle longitudinal traction. The chin-lift or jaw-thrust method is then performed. A combination of these maneuvers usually clears airways obstructed as a result of the position of the neck itself. The neck-lift and head-tilt maneuver, as described in cardiac life support courses, should not be used when cervical spine injury is suspected, because the extension of the spine produced during the maneuver endangers the spinal cord.
Clearing the airway of foreign material requires more than a simple jaw thrust. The occasional patient who presents with complete airway obstruction secondary to food aspiration may be treated with abdominal thrusts as described in basic cardiac life support.
Partial or complete airway obstruction can be the result of upper airway hemorrhage, accumulation of the patient's own secretions, vomitus, or fractured dentition. When deciding on airway-clearing maneuvers, one must take these circumstances into account. Neck extension must be avoided or carefully minimized if the probability of a cervical spine injury is high. When stability of the spine is a concern, application of the abdominal thrust should be limited to the supine method described for unconscious victims. The abdominal thrust carries significant risks, compelling the rescuer to weigh the benefits of its application.

The Chin-Lift Maneuver
The rescuer places the tips of the fingers, volar surface superiorly, beneath the patient's chin. The jaw is lifted gently forward. The patient's mouth is opened by drawing down on the lower lip with the thumb of the same hand. Mouth-to-mouth resuscitation or other means of positive-pressure ventilation is provided if the patient is not ventilating spontaneously.

The Jaw-Thrust Maneuver
The jaw-thrust maneuver is the second choice, again because neck extension is not necessary. Forward traction on the mandible is achieved by using two hands to grasp the mandibular rami and pull them forward.

The Abdominal Thrust
The abdominal thrust is a method to relieve a completely obstructed airway. The technique was popularized by Dr. Henry Heimlich and is commonly referred to as the Heimlich maneuver. The technique is most effective when a solid food bolus obstructs the larynx. Although a subject of controversy, a role for the maneuver has not been found for the resuscitation of near-drowning victims.
The conscious patient with an obstructed airway exhibits increased respiratory effort, anxiety, aphonia, and, occasionally, cyanosis. In the conscious patient, the maneuver is performed with the rescuer positioned behind the upright patient. The rescuer's arms are circled about the patient's midsection with the radial side of the clenched fist placed in the epigastrium of the patient. Care is exercised to position the fist midway between the umbilicus and the xiphoid of the patient. After proper positioning, the rescuer grasps the fist with the opposite hand and delivers an inward and upward thrust to the abdomen. A successful maneuver will cause the obstructing agent to be expelled from the patient's airway by the force of air exiting the lungs.
An unconscious, supine patient must be handled differently: the rescuer kneels next to the patient's pelvis facing cephalad. The palmar bases of the hands are placed in an overlapping fashion on the epigastrium at the same spot as that used in the upright patient. Inward, upward thrusts are delivered in this fashion with the same objective.
Abdominal thrusts are relatively contraindicated in pregnant patients and others with protuberant abdomens. A chest thrust similarly to that delivered in closed chest massage may be used instead. The upright patient may be delivered a chest thrust by placing the fist over the sternum. Experimental primate models of infant airway obstruction show higher peak airway pressures with chest thrusts than with abdominal thrusts; a combined (simultaneous) chest and abdominal thrust produce even higher peak airway pressures. [6] Hence, a combined maneuver should be considered in the case of total airway obstruction that is unresponsive to simple abdominal thrusts.
Visceral injury can occur with the Heimlich maneuver. Excessive force may be responsible in such cases. In others, incorrect placement of the hands may play a role. Nonetheless, the technique can be life saving and should be used when needed. Attention to proper execution may limit complications.

Positioning
Positioning the patient who has sustained multiple trauma can be a problem. Spinal injury and airway access priorities dictate that the patient should be kept in the supine position while immobilized on a backboard. Turning the patient on the side allows upper airway hemorrhage, secretions, and vomitus to drain externally rather than to collect in the patient's mouth, which can lead to aspiration and airway obstruction.
Guidelines for patient positioning must take into account the status of the patient's spine and the use of gravity to enable secretions to drain rather than accumulate in the airway. The following is a judicious approach to airway management in a patient with spontaneous respiration:

1. Initial airway maintenance accomplished by the chin-lift maneuver and the application of cervical stabilization
2. Immobilization of the patient on a spinal backboard.
3. With the position of the neck controlled, transportation of the patient on the side to facilitate airway drainage.

Suctioning
Patient positioning and airway opening and clearing maneuvers are often inadequate to achieve the degree of airway patency desired. Ongoing hemorrhage, vomitus, and particulate debris often require suction to clear and maintain the respiratory passage. Three basic types of suctioning tips are available . Each is suited to different types of airway obstruction problems.
Dental tip suction is most useful for clearing particulate debris from the upper airway. Vomitus is most readily cleared with this tip because it is least likely to become obstructed itself by particulate matter. The tonsil tip (Yankauer) suction device is used most effectively to clear upper airway hemorrhage and secretions. Its design is intended to prevent the obstruction of its tip by tissue and clot. The rounded tip is also less traumatic to soft tissues.
Unfortunately, the catheter tip suction device is the one most readily available in many hospitals. Often it is the only type of suction available. This device is inferior to the other catheter tips for suctioning before the patient has been intubated. After intubation, it works well for suctioning the trachea and bronchi through the tracheal tube. The dental tip device should be used during the resuscitation period and should be ready at the bedside. The dental tip allows rapid clearing of both particulate matter and hemorrhage, thereby expediting airway control.
Optimally, stabilization of the patient with multiple injuries will involve use of all three types of suction tips. The tonsil or dental tip should be attached to the suction source during the interval between patient evaluations because it is most likely to be the one needed on short notice. Both the tonsil tip and catheter tip should be stored next to the suction source so they can be attached when needed. It is essential that all physicians and nurses know the location of suction equipment and know how to turn it on during an emergency. In the resuscitation rooms, the equipment should be connected and ready to operate and not kept in cabinets or wrapped in difficult-to-open packaging material . Interposition of a suction trap at the base of the dental tip suction device prevents clogging of the tubing with particulate debris. A trap that fits directly onto a tracheal tube has been described; use of this device allows effective suctioning during intubation.
Although no specific contraindications to airway suctioning exist, complications of incorrectly performed suctioning may be significant. Nasal suction is seldom required to improve oxygenation (except in infants), because most adult airway obstruction occurs in the mouth and oropharynx. Vigorous nasal suction can induce epistaxis and further complicate an already difficult situation. Suctioning that is prolonged may not be recognized during an emergency, but it should be avoided because it may lead to significant hypoxia, especially in children. Suctioning should not exceed 15-second intervals, and the provision of supplemental oxygen before and after suctioning should be routine . Basilar skull fractures can allow the inadvertent placement of nasal suction tubes in the brain. Extreme care should be exercised when a basilar skull or facial fracture is suspected, because communication between nasal and intracranial cavities may exist.
Generally, it is best to perform suctioning under direct visual inspection or with the aid of the laryngoscope. Forcing a suction tip blindly into the posterior pharynx can injure tissue or convert a partial obstruction to a complete obstruction.
Complications may be avoided by anticipating problems and providing appropriate care during suctioning maneuvers. Epistaxis may be avoided by limiting the force applied during suctioning. Vasoconstrictor drops or spray, such as 0.25% phenylephrine, constrict the nasal mucosa and reduce the injury potential in patients who require repeated nasopharyngeal suctioning. The rescuer must be aware that the patient may develop transient pupillary dilation if the vasoconstrictor solution drips into the conjunctival space. Naigow and Powasner found that suctioning induced hypoxia in dogs consistently and that it was best avoided by hyperventilating the animals before and after suctioning.

Artificial Airways
Indications and Contraindications
Once the airway has been established through various maneuvers and suctioning, the patient may require further temporary support to maintain airway patency. The semiconscious patient who is breathing with an adequate rate and tidal volume at the time of the chin-lift maneuver may develop hypoxia because of recurrent obstruction if the maneuver is discontinued. Oxygen supplementation and an artificial airway may be all the support that is necessary. The use of an artificial airway also allows more efficient use of rescuer skills and relief from fatigue that is caused by the continuous application of chin-lift or jaw-thrust maneuvers.
Positive-pressure ventilation with a bag-valve-mask (BVM) device may be necessary to bolster the patient's inadequate ventilatory effort or to provide total ventilation in cases of apnea. By maintaining airway patency, artificial airways facilitate spontaneous and bag-mask ventilation.

Airway Placement Technique
The simplest artificial airways are the oropharyngeal and nasopharyngeal airways . Both are intended to prevent the tongue from obstructing the airway by falling back against the posterior pharyngeal wall. The oral airway may also prevent teeth clenching. The oropharyngeal airway may be inserted by either of two procedures. In the first procedure, the airway is inserted in an inverted position along the patient's hard palate. When it is well into the patient's mouth, the airway is rotated 180° and advanced to its final position along the patient's tongue, with the distal end of the airway lying in the hypopharynx. The second procedure involves the performance of a jaw-thrust maneuver, either manually or with a tongue blade, and the simple advancement of the airway into the mouth to its final position. No rotation is performed when the airway is placed in this manner. Once inserted, the oral airway may have to be taped in place to prevent expulsion by the patient's tongue.
The nasopharyngeal airway is placed by gently advancing the airway into a nostril, directing the tip along the floor of the nose toward the nasopharynx. When in final position, the flared external end of the airway should rest at the nasal orifice. Either of these two airways provides airway patency similar to that in a correctly performed chin-lift maneuver, but the nasal airway may be better tolerated by the semiconscious patient.

Complications
Few complications are encountered in the use of these airways. The oropharyngeal airway may cause obstruction if during its placement the tongue is pushed against the posterior pharyngeal wall. Care in placement will prevent this occurrence. In the patient whose reflexes are intact, the gag reflex may stimulate retching and emesis, and the semiconscious patient may not tolerate the oropharyngeal airway. If gagging is a persistent problem, the airway should be removed and a nasal airway or tracheal intubation should be considered. If the patient with airway compromise is comatose and lacks a gag reflex, the oropharyngeal airway should not be used as a definitive airway; tracheal intubation should be used instead. The oropharyngeal airway will keep the mouth partially open if an orogastric tube is placed for gastric lavage or suction, and it will prevent clenching of the teeth, which can obstruct an orotracheal tube.
The nasopharyngeal airway may offer an advantage over the oropharyngeal airway in that the nasopharyngeal airway is less likely to induce gagging. The same considerations that apply to nasal suctioning apply to placement of the nasopharyngeal airway. That is, care must be exercised not to induce epistaxis, and extreme caution is indicated in patients with a suspected basilar skull fracture or facial injury. All patients with oral or nasal pharyngeal airways should be observed constantly, because these devices are temporary measures and cannot substitute for tracheal intubation.

DECISION-MAKING IN AIRWAY MANAGEMENT

The resuscitator must have many tools at hand to deal with the acutely compromised airway. Although proficiency may exist for all of the available maneuvers, the specific procedural choice often must be made in challenging circumstances. Rescuers should practice potential scenarios before facing actual airway management scenarios in the clinical situation. Failure to do so may lead to unnecessarily aggressive management in some situations or to irreversible hypoxic injury as a result of unnecessary hesitation in others.
Several parameters must be assessed quickly before an airway management choice can be made. The parameters to be considered are as follows:

1. Adequacy of current ventilation

2. Time of hypoxia

3. Patency of airway

4. Need for neuromuscular blockade (muscle tone, teeth clenching, severe obstructive pulmonary disease or asthma)

5. Cervical spine stability

6. Safety of technique and skill of operator

Consideration of these factors should guide a choice among those techniques described. This initial choice is often straightforward. Difficulty rises precipitously when the initial choice fails. Time becomes critical and safety of technique less important as the risk of irreversible hypoxic injury rises. Anxiety increases and error potential compounds under these circumstances. Forethought and practice are invaluable when making these decisions.
Now that the decision to manage the airway surgically has been made, one need only choose among three available options. Consideration of patient condition, security of the airway approach, and invasive nature of the procedure are factors to be weighed in the final decision.

Basic Airway Management

Airway management is widely preached as the first priority in the management of any seriously ill or injured patient. However, despite the lip service given to the importance of airway management, it is often overlooked and, consequently, can be a source of error in the care of the critically ill or injured patient. Although appropriate airway management is evident in all smoothly run resuscitations, inappropriate management often presages a cycle of patient deterioration and misguided therapeutic intervention.
Unfortunately, recognition of the need for airway management is only the first part of the problem in emergency resuscitation. Managing the airway may be one of the most difficult aspects of the entire resuscitation. Because of the sheer variety of airway difficulties possible, even the most skilled resuscitator can find the task challenging. Blood, loosened teeth, vomitus, swollen or distorted landmarks--all of these present formidable barriers to successful management. When obstruction occurs in conjunction with reflex clenching of the jaws and possible cervical spine injury, conventional airway management tools may be rendered useless. Time pressures imposed by the need to avoid cerebral anoxia force one to make difficult decisions concerning the use of risky maneuvers such as moving the neck, administering paralyzing agents, or using invasive procedures. Tools must be at hand, skills must be well practiced, and decision-making must be sharp if optimal emergency airway management is to occur.
Some solutions to the dilemmas faced in emergency airway management are presented in this and the following chapters. Decision algorithms are presented to help assemble the pieces of the airway management puzzle into a logical framework. Readers are encouraged to study the algorithms at their leisure to facilitate later decision-making when time is limited.