CL1N REV ALLERGY 3:25-36, 1985

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Emergency Management of the Patient with Upper Airway Obstruction Paul J. Donald

The most frightening and urgently demanding of all medical emergencies is the patient with acute airway obstruction. When true sudden obstruction exists, two etiologies should immediately spring to mind: an anyphylactoid reaction or foreign body aspiration. The foreign body aspirator can readily be distinguished from the individual who has a blockage of the upper esophagus or hypopharynx. These individuals are usually eating at a restaurant or cocktail party. However, the victim whose bolus is lodged in the upper food passageway may have some of the signs of the acute aspirator. Both are in acute distress, grabbing the anterior neck with one or both hands, retching, and heaving their bodies in an attempt to expel the foreign body, with faces florid and suffused. The major difference is that the patient who has aspirated cannot pass air or speak and the patient with pharyngoesophageal impaction can. The foreign body in the choking victim is usually lodged in the larynx. A swift employment of the Heimlich maneuver will rapidly discharge the foreign body and the patient will regain his ability to respire. The victim of pharyngoesophageal obstruction will usually either spontaneously retch up the obturating bolus or, w h e n he is able to relax his spastic cricopharyngeal sphincter, will then swallow the material. It is important to note that the Heimlich maneuver should not be done on these latter patients as it may result in esophageal or gastric rupture. Approximately 4000 persons die annually of foreign body aspiration. Most of these are in an age group of peak economic productivity, occurring typically in the middle-aged business man in the setting of the "caf6 coronary." Quick diagnosis and the effective application of the Heimlich maneuver can reduce this tragic wastage immeasurably. Management of the acutely obstructed airway in the atopic patient is an entirely different matter. Before considering the various methods of securing a patent airway in this group, it is prudent to review the relevant anatomy of the regions involved in the disease process as well as to highlight some of the anatomical danger areas that might ensnare the unwary physician as he attempts to save the patient's life.

From the Department of Otorhinolaryngo!ogy, University of California, Davis, Medical Center, Sacramento, California. Address correspondence and reprint requests to Paul J. Donald, M.D., Department of Otorhinolaryngology, University of California, Davis, Medical Center, 4301 X Street, Room 208, Sacramento, CA 95817. © Elsevier Science Publishing Co., Inc. 52 Vanderbilt Ave., New York, NY 10017

0731-8235/85/$03.30

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Paul J. Donald

Anatomy The most common culprit in atopic airway obstruction is the larynx. Although edema of the adjacent pharyngeal walls and tongue base can significantly contribute to this obturation, they rarely ever are the cause of the obstruction themselves (Fig. 1). The larynx has a cartigenous-osseous framework that contains only one structure, which is a complete ring: the cricoid cartilage. This is the narrowest part of the airway and is located in the subglottic region of the larynx (Fig. 2). The vocal cords themselves are housed within the thyroid cartilage, which has two large laterally disposed laminae fused in the midline and a central anterior prominence, the thyroid tubercle, commonly called the "Adam's apple." Above the thyroid cartilage resides the only osseous structure in the framework, the hyoid bone. This bone is the anchor of the tongue and is usually easily palpable at the point where the undersurface of the chin meets the anterior neck. The skeleton is b o u n d together by a tough fibroelastic membrane that forms two important fascial sheets, the thyrohyoid membrane above, between the hyoid bone and the thyroid cartilage, and the cricothyroid membrane below, between the thyroid and cricoid cartilages. The circothyroid membrane is the site of the cricothyrotomy operation. It is important to note that the cricothyroid artery, a branch of the superior thyroid artery, lies along the cricothyroid membrane and may be the source of vigorous hemorrhage if cut during tracheostomy.

Figure 1. Young woman with acute angioedema of her tongue secondary to a drug hypersensitivity. Although she could breathe through her nose without difficulty, a tracheostomy was done for safety's sake while her edema was treated medically.

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Figure 2. The skeletal framework of the larynx. Note that the cricoid cartilage is the only complete ring in the airway and is subglottically just above the first tracheal ring and below the vocal fold. Note the cricothyroid membrane, the site of the cricothyrotomy and the second, third, and fourth tracheal rings, the site of the tracheostomy. (Reproduced by permission from Romanes GJ: Cunningham's manual of practical anatomy, vol 3, head and neck and brain, 13th edition. London, Oxford Press, 1967, p 169.)

Figure 3 is a view of the larynx as seen from above by laryngoscopy. Because we commonly see the larynx depicted in a two-dimensional plane on an anatomical drawing, we tend to forget that it has depth. The epiglottis is approximately 35.5 cm long, and it's anchor, the petiolus, is another 1 cm above the anterior commissure area of the vocal folds. To safely and effectively perform a tracheostomy, a clear understanding of the paratracheal anatomy is essential. Figure 4A is a cross-sectional drawing done at the level of the third tracheal ring. Note the various layers the operator must pass through to gain access to the trachea. Deep to the superficial fascia under the subcutaneous layer is the anterior jugular venous arch. The anterior jugular veins are highly variable in their position, and the arch that joins them may occur at any level above the superior aspect of the manubrium sterni. Incision of this arch brings not only unwelcomed hemorrhage, but also the danger of air embolism. The most troublesome area in performance of tracheostomy is the thyroid isthmus (Fig. 4B). It usually covers the second to fourth tracheal rings, the precise site of desired entry into the trachea. Because of it's highly vascular nature, repetitive vigorous handling and retraction usually stimulates troublesome hemorrhage. The great vessels of the neck and the vagi are contained within the carotid sheath that lies directly against the lateral trachea. The recurrent laryngeal

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Figure 3. Laryngoscopic view of the larynx. (Reproduced by permission from Romanes GJ: Cunningham s manual of practical anatomy, vol 3, head and neck and brain, 13th edition. London, Oxford Press, 1967, p 175.) nerves lie more posteriorly in the tracheoesophageal grooves. The nerve is more laterally disposed on the right than the left. The cupulae of the lungs ascend into the root of the neck for a variable distance. They are particularly vulnerable in children, as they may even cover the dissected trachea upon deep inspiration. The risk of pneumothorax is so high in small children that a postoperative chest x-ray is mandatory after every tracheostomy. The last important anatomical hazard is the innominate artery. This large vessel crosses the trachea anteriorly at variable levels. It is most commonly encountered substernally, but in some cases, may present in the low neck and be at risk in patients who have had a low tracheostomy. The slow wearing away of the vessel wall by the tube as it rides up and down with each pulsation of this large vessel may result in the catastrophe of tracheoinnominate fistula and commonly death from hemorrhage or aspiration. Clinical P r e s e n t a t i o n Although airway obstruction can be rather acute and sudden in the atopic patient, usually there is some prodrome. The victim may develop a "hot potato" voice from edema of the tongue base. Hoarseness and stridor indicate the presence of laryngeal edema. The site of this edema is usually in the supraglottic portion of the larynx, where the mucosa is more loosely applied to the skeleton and a rich submucosa that can accumulate fluid exists. The vocal fold epithelium is more tightly approximated to the underlying vocal ligament, so that edema fluid does not suffuse it as readily. The key word in monitoring this process is progression: as laryngeal edema increases, stridor and hoarseness become more marked. Worsening of symptoms provides clear indication for airway control, and some form of intervention is essential. The sudden cardiorespiratory collapse of acute anaphylactic shock is an emergency situation demanding immediate intervention~ Securing a patent

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thyroid a.

:urrent al n.

Figure 4. (A) Cross-sectional view of the neck, depicting the relevant anatomy in the performance of tracheostomy or cricothyrotomy. (From Romanes GJ: Cunningham's manual of practical anatomy, vol 3, head and neck and brain, 13th edition. London, Oxford Press, 1967, p 113.) (B) Anterior view. (Reproduced by permission from Caldarelli DD, Holinger LD: Complications and sequellae of thyroid surgery. Otolaryngologic Clinics of North America 13:93, 1980.) airway and providing ventilatory assistance are an integral part of managing this catastrophe.

Management Intubation The most common and safest method of upper airway control is oroendotracheal intubafion which almost always requires a hospital setting. Unless the physician at that scene of an acute atopic episode carries an emergency bag equipped with a laryngoscope and endotracheal tube, one of the more invasive techniques will be required. Unfortunately, most of the emergency situations occur outside the hospital, and some form of operative intervention is usually necessary.

Paul J. Donald

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When endotracheal intubation is feasible, all physicians who may be required to perform this maneuver should prepare themselves by prior training. It is inexcusable for any physician w h o may some day be faced with an airway emergency not to familiarize himself with the use of the laryngoscope and avail himself of the training needed to safely pass an endotracheal tube. Fumbling, clumsy, rough intubations lead to laryngeal injury, pharyngeal lacerations, and worse, hypoxic brain damage and even death. Facility with the technique can be acquired by a rotation during training on an anesthesiology service and by practice on fresh cadavers in the autopsy room or on laboratory animals. Familiarization with equipment and technique by practical experience cannot be substituted by didactic, detailed explanations from texts or journal articles.

Large Bore Needle In the adult patient, a short No. 16 or 14 gauge needle can provide an adequate, albeit temporary, emergency airway. However, the use of this should be restricted to adults, because in children, the needle can slip from the larynx or trachea into an adjacent major cervical vessel. To insert the needle, the space between the inferior surface of the thyroid cartilage and the upper surface of the cricoid is palpated. The needle tip is then placed in the midline anterior neck over this site, and the needle is pushed through the skin, underlying soft tissue, and cricothyroid membrane (Fig. 5).

Figure 5. The technique of insertion of a large bore needle into the airway through the cricothyroid membrane.

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Extremely efficient ventilation can be established when the cannula is attached to a positive pressure source. A Saunder's type ventilatory apparatus delivering oxygen at 50 psi can maintain adequate respiratory exchange. This type of attachment is commonly used by the anesthesiologist to deliver anesthesia during bronchoscopy.

Cricothyrotomy The quickest, most efficient and effective method of obtaining an emergency airway is the cricothyrotomy. Rapid access to the airway with an eventration capacious enough to provide excellent respiratory exchange even with primitive equipment makes this the premier method of emergency airway management. Unfortunately, it has some short- and long-term complications that the operator must be aware of. For this procedure, the patient's head is acutely extended. This is provided by the placement of a bolster under the shoulders, either rolled up towels in a hospital situation or a rolled up jacket or tablecloth in the acute outside emergent case. The cricothyroid membrane is palpated between the cricoid and thyroid cartilages, and a puncture is made through the skin, underlying soft tissue, and the tough cricothyroid membrane (Fig. 6). The incision should be as close to the cricoid as possible to avoid injury to the superiorly located vocal folds. In the hospital, a scalpel with a No. 10 blade is most effective whereas in the extra-hospital situation, a pocket knife or even a scissors blade can be used. Once entry into the airway is made, the blade is twisted to open the space and allow free exchange of gas. Any type of tube can be inserted, a tracheostomy tube, endotracheal tube, or even the barrel of a ballpoint pen. If brisk hemorrhage ensues, it most likely indicates that the cricothyroid artery has been severed. Finger pressure or even pressure of the tube against the vessel is usually sufficient to reduce or stop the hemorrhage until a more

Figure 6. Technique of cricothyrotomy.

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orderly isolation and tying of the artery can be performed. It must be remembered that this technique is strictly an emergency one and that it must be converted into a tracheostomy at the soonest possible opportunity. The presence of a tube in the space between the thyroid and cricoid cartilages creates a considerable inflammatory response that will lead to later fibrosis and one of the most difficult conditions to reconstruct in head and neck surgery: subglottic stenosis. The sooner a cricothyrotomy is converted to a tracheostomy the better--preferably within 24 hr.

Tracheostomy The best method of airway divergence is tracheostomy. All physicians should know how to perform this vital operation. The principal drawbacks are that it takes some skill to perform and, unlike the cricothyrotomy, which takes seconds to accomplish, the tracheostomy can take 10-20 rain to complete. The surgery should be performed under operating room conditions. The days of doing this procedure in the emergency room or the hospital corridor is an anachronism. Quick control with an endotracheal tube or a large bore needle, or cricothyrotomy, will suffice until the patient can be taken to an operating room situation replete with good lighting, competent help, adequate equipment, and time to perform an orderly operative procedure. The patient's head is extended by the placement of a bolster under the shoulders. The neck is surgically prepared and the anterior neck draped. This necessitates placing a drape over the patient's face. An attendant is positioned at the head of the table to reassure the patient, who is extremely apprehensive due not only to his compromised airway, but because he is unsedated and having an operative procedure done while fully awake. Local anesthesia is usually used and infiltration of the incision site in the low anterior neck is clone using 2% lidocaine with 1/100,000 epinephrine. The injection is then carried deeper through the underlying muscular planes until the pretracheal fascia is infiltrated. This fascial layer is very pain sensitive and should be carefully anesthetized. The laryngeal skeleton is palpated and the space between the second and third tracheal tings identified. A horizontal incision is drawn with a marking pen in a natural skin crease about 1-2 finger breadths above the suprasternal notch (Fig. 7). The skin, subcutaneous fat, and platysma (when present) are incised. Care is taken to avoid the anterior jugular veins and arch. If they are unavoidable, they are ligated and transsected. Once the strap muscles are exposed, the direction of dissection changes from horizontal to vertical. The straps are separated in the midline and retracted (Fig. 8). Deep to these muscles lie the deep layers of deep cervical fascia that envelope the trachea and the thyroid isthmus. Access to the most desirable area of the trachea for tracheostomy (the second to fourth ring) is usually obscured by the thyroid isthmus. The isthmus can be handled in two ways. If dissection is easy and the thyroid gland readily mobilized, the isthmus may be retracted superiorly exposing the underlying tracheal rings. However, it is usually easier to transsect it. Once dissected from the trachea, the isthmus is cross-clamped and fled, usually with a 3-0 silk suture ligature.

Emergency Management

COMMONCAROTiDA.

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The tracheal lumen is now anesthesized by a transtracheal puncture with a 22-gauge needle and the instillation of 1 cc of 5% cocaine. This prevents the vigorous coughing spasms occasioned by the incursion into an unesthefized trachea. For short-term (2-7 days) tracheostomy, a transverse incision in the interspace between the second and third ring made with a No. 11 scalpel blade is simple and quite acceptable. A vertical incision through the third, or third and fourth rings, accompanied by the excision of a small elipse of trachea from this site is used for anticipated long-standing tracheostomies and is more commonly employed. The pretracheal fascia is cleaned from the proposed site of tracheal entry. A large stout hook is placed through the second ring, and the scalpel blade used to make the trachel opening (Fig. 9). Maintaining the opening during the passage of the tube is facilitated by a Trousseau dilator. The outer cannula of the tracheostomy tube, complete with the obturator (Fig. 10), is introduced into the trachea. The distal end of the tube in its initial passage is directed straight posteriorly, and then gently pushed with a curved motion inferiorly. The obturator is removed and the inner cannula inserted and locked into position. At this point, the patient may cough violently and the tube must be firmly held in place with finger pressure. Usually, however, the cocaine prevents this. Another unexpected event may occur the sudden cessation of respirations. Some patients, after prolonged hard, labored ventilatory effort, may suddenly stop breathing almost immediately following the creation of the tracheostomy. The precise mechanism for this is ill understood and vigilance to this event should be maintained so that intermittent ventflatory support can be provided until spontaneous respirations resume. The tie tapes to the tracheostomy tube are now secured. They should be comfortable yet tight enough to preclude coughing-out of the tube during a

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PLATYSMA M.

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Figure 8. (From Applebaum EL, Bruce DL: Tracheal intubation. Philadelphia, W.B. Saunders, Co 1976.) (A) Strap muscles are separated in the midline, exposing the thyroid isthmus and underlying trachea. (B) Isthmus of thyroid gland exposed over the second to fourth tracheal rings. (C) Isthmus incised in midline. (D) Trachea exposed and thyroid isthmus suture ligatured. tussive episode. Tying the tapes with some tautness with the head in the flexed position ensures this. Patients with fresh tracheostomies usually produce rather profuse tracheobronchial secretions. This is especially true of smokers, whose troublesome reflex bronchorrhea may persist for days. Suctioning, using sterile atraumatic technique, may be required as often as every 15-20 minutes in the first 36-72 hr. A drip pad made from a 4 x 4 gauze is placed under the flange of the tube to prevent skin irritation from secretions and to assist in overall hygiene. The pad may need frequent changes at first. Humidification of the trachea is essential, as the major warming and humidifying portion of the airway has been bypassed. Mist, preferably delivered by cupula, is necessary to prevent infection and to preclude the formation of tenacious mucus plugs that can obstruct the tube. A cataloguing of complications and a detailed description of their management is beyond the scope of this paper (Table 1 lists the surgical complications encountered in pediatric patients), however, an important caveat in reference to accidental tube displacement is appropriate. Outside of plugging

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Figure 9. A tracheostomy hook is used to engage and retract the second tracheal ring, and an incision is made in the anterior tracheal wall. (A) Horizontal incision. (B) Button of anterior tracheal wall removed. of the tube b y inspissated secretions, the most hazardous complication in the early days following t r a c h e o s t o m y is tube dislodgement. In the 5 days or so following the creation of the stoma, the tissue b e t w e e n the trachea and the skin is soft and loosely organized and w i t h o u t the fibrosis necessary to form a "track." If the tube is dislodged from the trachea, hasty a n d unskilled reinsertion m a y result in the accidental placement of the tube in the easily dissectable soft tissues of the anterior neck and into the mediastinum. If the laryngeal e d e m a originally requiring the tracheostomy persists, the patient is left w i t h o u t a p a t e n t airway. Patient mortality is high, especially in the pediatric age group. A good light, preferably a headlight, a t r a c h e o s t o m y hook, a n d a Trousseau dilator, as well as a spare tracheostomy tube of the same size, should be h a n d y at the bedside in the event of this complication. Mediastinal intubation is an inexcusable error in the tracheostomized patient and is a p o o r reflection on the skill of the attendants.

Figure 10. With the tracheal hook superiorly and the Trousseau dilator opening the tracheotomy, the tube is introduced.

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Table 1. Pediatric Surgical Complications Immediate Hemmorrhage Apnea; cardiac arrest Hypotension Obstruction; displaced tube Subcutaneous emphysema Pneumothroax, pneumomediastinum Aspiration and atelectasis Recurrent laryngeal nerve injury Tracheoesophageal fistula Aerophagia

Delayed Hemorrhage Obstruction Tracheifis Pneumonia Wound infection Subglotfic edema Tracheal stenosis Tracheoesophageal fistula Dysphagia Persistent tracheocutaneous fistula Difficult decannulafion Unsightly scar

From ApplebaumEL, Bruce DL: Tracheal lntubation. Philadelphia,W.B. Saunders, 1976, p 83, Table8-3.

To prevent tube plugging and avoid infection, the inner cannula should be removed and carefully washed frequently, especially in the first few days. Cleansing as often as every 1-2 hr is not uncommon initially, but is required only four times or so daily later on. The frequency is also usually dependent on the patient's smoking history and any underlying chronic pulmonary disease. Acute or subacute upper airway obstruction in the atopic patient is a highly emotionally charged, frightening situation for both patient and physician. It is vital that physicians equip themselves with the necessary skills and tools to handle this emergency situation.