Acute Upper Airway Obstruction

The new england journal of medicine

Review Article

Dan L. Longo, M.D., Editor Acute Upper Airway Obstruction

Antoine Eskander, M.D., John R. de Almeida, M.D., and Jonathan C. Irish, M.D.

From the Department of Otolaryngology– cute upper airway obstruction is a life-threatening emergency Head and Neck Surgery/Surgical Oncol- and requires immediate assessment and intervention with little margin for ogy (A.E., J.R.A., J.C.I.) and the Institute 1,2 for Health Policy Management and Evalu- error, making it a constant challenge for clinicians. Substantial advances ation (A.E., J.R.A.), University of Toronto, A have been made in preventive medicine, our understanding of the pathophysiology Sunnybrook Health Sciences Centre and of acute upper airway obstruction, and surgical and anesthetic technologies, but Michael Garron Hospital (A.E.), the Insti- tute for Clinical Evaluative Sciences (A.E.), management of the obstructed airway remains one of the most challenging emer- and Princess Margaret Cancer Centre gencies in clinical medicine. Arguably the largest effect on acute upper airway (J.R.A., J.C.I.) — all in Toronto. Address obstruction in the modern era has occurred through preventive medicine with the reprint requests to Dr. Irish at the De- partment of Otolaryngology–Head and widespread implementation of Haemophilus influenzae type B vaccination, a develop- Neck Surgery, University Health Network, ment that has resulted in marked declines in the incidence of and the mortality Princess Margaret Cancer Centre, 200 Eliza- related to epiglottitis and pneumonia.3-5 Epiglottitis, once a very common occur- beth St., 8NU-882, Toronto, ON M5G 2C4, Canada, or at jonathan.irish@uhn.ca. rence, is now exceedingly rare. Similarly, the public health campaign to widely implement and use epinephrine autoinjectors in persons with anaphylaxis has N Engl J Med 2019;381:1940-9. DOI: 10.1056/NEJMra1811697 successfully decreased the need for airway intervention in many cases. Copyright © 2019 Massachusetts Medical Society. Treating acute upper airway obstruction in the clinical setting is complicated and requires managing a sometimes chaotic environment, understanding the potentially multiple causes of disease (infectious, inflammatory, traumatic, mechanical, and iatrogenic), and having the technical ability to quickly secure a challenging airway. Each patient with acute upper airway obstruction is distinct. The treating clinician must consider several factors, including the patient’s age, coexist- ing conditions, ability to remain in the supine position, level and severity of obstruction, stability of the cervical spine, ability to ventilate, and level of anxiety. The historical algorithm for the management of acute upper airway obstruction was a stepped series of interventions that started with the administration of high- flow oxygen and the use of conservative measures and extended to bag-mask ventilation, intubation, and the surgical opening of the airway. This algorithm has been modified as our understanding of the pathophysiological underpinnings of the most common causes of acute upper airway obstruction has increased and the anesthetic and surgical technologies used have advanced. Here we review recent advances that have affected the management of acute upper airway obstruction.

Anatomy A brief overview of the anatomy of the upper airway is required for a thorough understanding of advances in the causes of obstruction and in emerging technologies for treatment (Fig. 1). Acute upper airway obstruction can occur at any one of several anatomical levels. In infants, who have historically been considered to be obligate nasal breathers, nasal or nasopharyngeal masses or obstructions can lead to airway distress, although in most cases not to airway obstruction, since open-mouth breathing can compensate for this level of obstruction. Obstruction at the level of the oropharynx (soft palate, palatine tonsils, posterior pharyngeal wall, and tongue base), larynx (including the supraglottic, glottic, and

1940 n engl j med 381;20 nejm.org November 14, 2019 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. Acute Upper Airway Obstruction

SAGITTAL SECTION OF THE HEAD The Pharynx

SAGITTAL SECTION

Paranasal sinuses Nasopharynx

Nasal cavity Soft palate Oropharynx Base of Soft palate Palatine tonsils the tongue Posterior pharyngeal wall Base of the tongue

Oral cavity Tongue

Hypopharynx

The Larynx

SAGITTAL SECTION POSTERIOR CORONAL SECTION Epiglottis

Supraglottic Epiglottis region Greater cornu of hyoid bone Thyrohyoid membrane Supraglottic region Quadrangular membrane

Vestibular fold Glottis (false vocal cords) Subglottic Laryngeal saccule region Glottic Laryngeal ventricle region Esophagus Thyroarytenoid muscle Trachea Subglottic Vocal fold region (true vocal cords) Trachea Thyroid cartilage Cricovocal ligament Cricoid cartilage Arytenoid cartilage

Glottis Vocal folds (true vocal cords) Vestibular folds (false vocal cords) Epiglottis

Closed TRANSVERSE SECTION Open Figure 1. Sagittal, Coronal, and Transverse Sections of the Upper Aerodigestive Tract.

n engl j med 381;20 nejm.org November 14, 2019 1941 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. The new england journal of medicine

subglottic subsites), and hypopharynx may lead score, in which a scale of 0 to 10 is used to indi- to acute upper airway obstruction. Historically, cate the likelihood of difficulty with intubation, the most common site for airway obstruction was with higher scores indicating greater difficul- the supraglottic larynx, which includes the epi- ty).10-12 The factors used in assessment include glottis, the aryepiglottic folds, the arytenoids, increased weight, decreased cervical spine mobil- and the ventricular folds (or “false cords”). Ob- ity, decreased jaw mobility, retrognathia, and struction can occur at the level of the glottis, or prominent incisors, all of which are associated “true” vocal cords. With adduction, the vocal with increased difficulty with intubation. Other cords allow for phonation and, more important, aspects of physical examination that can be used when effortful and strong, produce an effective to assess the likelihood of a difficult intubation cough, an important airway-protection maneuver. include the hyomental–thyromental distance, with The posterior aspect of the glottis carries the shorter distances indicating greater difficulty, largest cross-sectional area (Fig. 1) and is there- and the Mallampati score, which is used to as- fore responsible for the majority of airflow, sess the visibility of oropharyngeal structures which explains why lesions in the anterior glottis with the mouth opened maximally. For the lat- have less effect on the airway and greater effect ter, a scale of 1 to 4 is used, with higher num- on voice, with the opposite effects applying to bers associated with poorer visibility. Findings lesions on the posterior glottis.6 Distal to the from a recent systematic review suggest that the glottis is the subglottis, which is the narrowest best predictor is the inability to bite the upper portion of the airway in neonates, followed by lip with the lower teeth.13 However, no finding the cervical trachea. on physical examination and no specific risk factor consistently rule out a potentially difficult Pathophysiological Features intubation. In short, one should always be pre- pared to manage a difficult airway.13 Much of our current understanding of the pathophysiological features of acute upper airway ob- Advances in Treatment struction can be discerned from our understand- According to Cause ing of the neurophysiological modulation and pathophysiological features of obstructive sleep An anatomical approach to classifying the causes apnea. Apnea, whether acute or chronic, causes of acute upper airway obstruction is the most an increase in respiratory effort. Phrenic and practical (Table 1). Congenital causes are more sympathetic nerve activation from airway ob- common in children, and neoplastic causes are struction are largely driven by chemoreceptor more common in adults, particularly in patients afferents and glutamatergic neurotransmission with a substantial history of smoking or alcohol in the nucleus tractus solitarius.7 In acute upper abuse. Although chronic causes of airway ob- airway obstruction, severe hypoxemia can lead to struction are not the focus of this article, all cardiac arrest. Chronic obstructive sleep apnea is chronic causes can reach a point at which there associated with major cardiac events, hyperten- is patient decompensation, and what was once a sion, arrhythmias, congestive heart failure, and chronic problem is now acute. Thus, it is impor- stroke.8,9 tant to obtain a detailed history, even in patients with an acute presentation, to delineate the cause. Physical Examination Infection and inflammation are the most common causes of acute upper airway obstruction. One of the most important advances in airway management has been the development of physi- Croup cal examination grading scales to help predict a The parainfluenza viral infection of the supra- difficult airway. Some scales rely only on the glottis known as croup occurs in 3% of children visibility of the vocal cords on laryngoscopy 6 months to 3 years of age.14 Children with (e.g., the Cormack–Lehane grading scale, on croup have a barking cough, inspiratory stridor, which grades range from 1 to 4, with higher hoarseness, and respiratory distress, symptoms grades indicating poorer visibility), whereas others that typically have an abrupt onset at night.15 use prelaryngoscopic factors (e.g., the Wilson The mainstay of treatment is oral or inhaled

1942 n engl j med 381;20 nejm.org November 14, 2019 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. Acute Upper Airway Obstruction

glucocorticoids. Oral dexamethasone should be Table 1. Causes of Acute Upper Airway Obstruction administered in a single dose of 0.6 mg per kilo- According to Subsite.* gram of body weight. Nebulized dexamethasone Supraglottic should be administered in a dose of 160 μg, with a fill volume of 3 ml and the oxygen flow Croup set to 5 to 6 liters per minute. A Cochrane re- Supraglottitis, epiglottitis, or neck abscess view of 43 randomized clinical trials involving Ludwig’s angina 4565 children reported that glucocorticoids re- Angioedema duced symptoms at 2 hours and were associated Tumor with shorter hospital stays and lower rates of Foreign body return to the hospital than placebo or other pharmacologic treatments.16 Racemic epineph- Glottic rine and humidified cold air can also be useful Iatrogenic (bilateral vocal cord paralysis) adjuncts. Tumor Foreign body Epiglottitis and Supraglottitis Subglottic or tracheal Vaccination against H. influenzae type B has result- Foreign body ed in a lower incidence of epiglottitis and lower Subglottic stenosis mortality associated with epiglottitis and pneumonia in children.3-5 Supraglottitis, like epiglot- Tumor (extrinsic or intrinsic) titis, is also rare in adults. It is typically caused * Inhalation and traumatic (penetrating or blunt) injuries by infectious processes but may also result from can affect the airway at any level and are therefore not injuries from trauma or inhalation or from the included. ingestion of caustic substances. Patients with an aggressive disease course are typically male, have dyspnea or stridor, and present with edema in patients who receive early surgical drainage of the epiglottis or aryepiglottic folds. Elevated (26.3% vs. 2.9%).18 Immunocompromised pa- C-reactive protein levels and hyperglycemia are tients are at a higher risk for airway compro- also typical. These patients often have a history mise, other complications (e.g., sepsis and pneu- of recurrent episodes.17 The most common pre- monia), longer hospital stays, and death.19 Overall, senting symptoms are sore throat (79%) and the mortality associated with Ludwig’s angina is dysphagia (71%). Stridor (3.6%) and dyspnea approximately 8%.20 Therefore, the standard of (6.7%) are less common but are associated with care includes securing the airway followed by a increased need for airway intervention.17 formal incision and drainage of the sublingual and submandibular spaces. Ludwig’s Angina Patients with Ludwig’s angina have bilateral in- Angioedema fection of the sublingual and submandibular The condition angioedema is characterized as spaces that is characterized by submental and recurrent, nonpitting, nonpruritic swelling of submandibular induration, cellulitis, and a swol- the deep layers of the skin and mucosal tissues. len and tender floor of mouth, all of which result It may be hereditary, acquired, drug induced, or in a posteriorly displaced tongue. This displace- idiopathic.21 Hereditary angioedema, an autoso- ment ultimately leads to obstruction at the oro- mal dominant condition, results from deficiency pharyngeal and supraglottic levels and can be of the C1 esterase inhibitor, which may reflect life-threatening. The most common causes of inadequate levels (type I) or function (type II). Ludwig’s angina are dental infections, followed Deficiency of the C1 esterase inhibitor changes by sialadenitis, peritonsillar abscess, abscess in- activation of the complement and contact sys- volving the parapharyngeal space, traumatic in- tems and also affects the regulation of coagula- juries to the oral cavity, and mandibular fractures. tion and fibrinolysis, although to a lesser extent.21 Conservative management with intravenous anti- Table 2 summarizes the differences among he- biotics is associated with a risk of airway com- reditary angioedema, acquired angioedema, and promise that is nearly 10 times as high as that angioedema that is associated with angiotensin-

n engl j med 381;20 nejm.org November 14, 2019 1943 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. The new england journal of medicine

Table 2. Subtypes of Angioedema and Related Laboratory Abnormalities.*

Diagnosis C4 Level C1 Inhibitor Function C1 Inhibitor Level C1q Level Hereditary angioedema Type I Low Low Low Normal Type II Low Low Normal Normal Acquired angioedema Low Low Normal or low Low ACE-inhibitor–associated Normal Normal Normal Normal angioedema

* Adapted from Banerji et al.21 ACE denotes angiotensin-converting enzyme, and C1q a protein that is part of the classic complement pathway.

converting–enzyme (ACE) inhibitors. ACE inhibi- need for intubation or tracheostomy is increased tors are thought to cause angioedema through if the anterior tongue, base of the tongue, or an effect on the kallikrein–kinin system that larynx is involved and if drooling or stridor oc- reduces the catabolism of bradykinin and in- curred within 4 hours after symptom onset.26,27 creases its activity, leading to the inflammatory In such cases, fiberoptic intubation is the fa- effect seen in angioedema. vored approach.28,29 A recent change in guidelines recommends that patients carry on-demand treatment for Bilateral Paresis and Paralysis of the Vocal hereditary angioedema at all times and consider Cords short-term prophylaxis before undergoing proce- In paresis and paralysis of the vocal cords, the dures that can induce an attack.22 The revised vocal cords fail to adequately abduct. Bilateral guidelines recommend consideration of on- vocal-cord paresis and paralysis can result from demand treatment (with self-dosing of a C1 ester- tumor infiltration of the glottic larynx or both ase inhibitor) for all attacks, treatment of attacks recurrent laryngeal nerves, prolonged intubation affecting the upper airway, early treatment, and or placement of a nasogastric tube, and infec- initiation of treatment with a C1 inhibitor — tious and pathologic conditions affecting the either ecallantide (a kallikrein inhibitor) or icati- brain stem. In some instances, vocal-cord pa- bant (a bradykinin receptor antagonist).22 Ecal- ralysis can also result from complications dur- lantide should be administered subcutaneously ing thoracic and anterior neck surgery. Patients by a health care professional in three 10-mg can often abide a narrowed airway for some (1-ml) injections; if the attack persists, an addi- time, but further diminution of the airway cali- tional dose of 30 mg may be administered within ber, with inflammatory insults such as a viral in- a 24-hour period. The recommended dose for fection, may lead to airway compromise. For this icatibant is 30 mg injected subcutaneously in the reason, a tracheostomy should be considered abdominal area; additional doses may be admin- while the assessment for recovery is pending. If istered at intervals of at least 6 hours if the re- recovery is not achieved, surgical procedures can sponse is inadequate or if symptoms recur, but be used to improve the airway (leading to trache- no more than 3 doses may be administered in ostomy decannulation), but these interventions, any 24-hour period. The consensus guidelines including arytenoidectomy, with or without aryte- recommend screening children from families noid abduction, often affect voice quality. with a history of hereditary angioedema and all offspring of an affected patient.22 Because the Subglottic and Glottic Stenosis diagnosis is often delayed,23,24 a low threshold Cases of subglottic and glottic stenosis are rare for screening in the emergency department is and challenging; they most often result from recommended, particularly in patients with a prolonged or traumatic intubation but may also family history of angioedema.25 be congenital or idiopathic. Patients with granu- In patients who present to the emergency de- lomatosis polyangiitis and relapsing polychon- partment with angioedema, the likelihood of the dritis may also present with subglottic steno-

1944 n engl j med 381;20 nejm.org November 14, 2019 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. Acute Upper Airway Obstruction

sis.30,31 Mucosal inflammation and localized outcomes than those who have the procedure af- fibrosis are the main pathophysiological fea- ter management.36,37 Benign tumors of the thy- tures of the disease. Diagnosis is confirmed by roid, particularly when they extend substernally, means of laryngoscopy and bronchoscopy. Stan- can lead to substantial subglottic and tracheal dard treatment involves dilation of the airway, deviation and compression. In rare instances, commonly performed with the adjunctive use of thyroid cancers invade the airway, leading to lasers to radially incise the stenosis or of pres- both an extrinsic compression effect and an in- sure-controlled balloons to dilate the stenosis. trinsic narrowing related to intraluminal disease. Some surgeons consider injection of glucocorticoids or the topical application of mitomycin. Psychogenic Upper Airway Obstruction A sample dose of triamcinolone acetonide (40 mg Psychogenic presentations of upper airway ob- per milliliter) should be injected submucosally struction are rare. Most patients have para- in a circumferential pattern with the use of a doxical vocal-fold motion disorder, a conversion 25-gauge butterfly needle controlled with micro- disorder in which the vocal cords adduct on in- laryngoscopic alligator forceps. Usually no more spiration and abduct on expiration, leading to than 0.1 ml can be applied per quadrant. Mito- inspiratory stridor. Patient presentation is simi- mycin should be applied at the site of stenosis lar to that of patients with epiglottitis.38 The for 2 to 4 minutes with two lightly soaked cot- condition can also be induced by exercise and is ton pledgets at a dose of 0.4 mg per milliliter. associated with laryngopharyngeal reflux, aller- Neither the surgical technique used nor the grade gic and sinus problems, and obstructive sleep of stenosis alters surgical intervals; however, apnea.38,39 The diagnosis is often confused with mitomycin application is associated with exten- severe asthma. It is made by means of fiberoptic sion of the periods between subsequent endo- laryngoscopy when no other abnormalities of the scopic treatments.32 Although in-office gluco- upper aerodigestive tract are noted. Respiratory corticoid injections have been studied, long-term retraining and laryngeal control therapy are the outcomes have not yet been reported.33,34 mainstays of treatment, which is performed by a An international, prospective, pragmatic trial speech–language pathologist. The use of counsel- protocol published in 2018 compares three stan- ing and psychiatric assessment is in decline. dard surgical approaches to idiopathic subglottic stenosis at multiple international institutions.35 Inhalation Injury The primary end point is the time to recurrent Approximately 15% of patients with burn injuries operative procedure. Patients are being followed have inhalation injury, which, along with the for up to 36 months, and data on a number of total body-surface area of the burn, is an impor- secondary end points related to quality of life tant independent predictor of mortality.40,41 In are being collected. In patients with recalcitrant patients with recent injury from smoke inhala- stenosis who are unlikely to have a response to tion, intubation should be initiated if there are conservative surgical dilation, definitive crico extensive facial or neck burns, a decreased level tracheal resection and reconstruction of the of consciousness, or airway obstruction. In those stenotic segment can be considered when there with clinical signs and symptoms of inhalation is no active airway inflammation (e.g., active sub- injury, such as dysphonia, dysphagia, singed nasal glottic granulomatosis polyangiitis). hairs, sooty sputum, stridor, cyanosis, or neuro- logic symptoms, endoscopic assessment by an Neoplasms Intrinsic or Extrinsic otolaryngologist is warranted.42 Intubation is also to the Upper Aerodigestive Tract called for if erythema, edema, or sooty exudate Neoplasms can lead to acute upper airway ob- is detected. These patients are at a substantial struction. The most common intrinsic neoplasms risk for decline in the first 24 hours after inhala- associated with airway obstruction are glottic tion injury.42 and supraglottic cancers, most often squamous- Patients with inhalation injuries tend to have cell carcinomas. They are often caused by smok- long-term laryngological complications. Conse- ing and alcohol abuse, which act synergistically. quent to local inflammation and edema, patients Patients who require a tracheostomy before man- may have granulation tissue, scarring, webbing, agement of their laryngeal cancer have worse vocal-cord immobility, stenosis, and laryngeal

n engl j med 381;20 nejm.org November 14, 2019 1945 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. The new england journal of medicine

hyperfunction. The subglottis is particularly way device to cricothyroidotomy (Fig. 2). The sensitive, and patients with inhalation injuries guidelines highlight the role of video laryngos- have an earlier onset and more severe stenosis copy in difficult intubations and recommend than those whose subglottic stenosis is due to that all anesthetists be skilled in the use of these other causes.43,44 The earlier onset and greater devices. Nonetheless, the ultimate choice of the severity associated with subglottic stenosis in type of laryngoscope used should be based on these patients have led to calls for earlier use of the experience and training of the person per- tracheostomy.45 forming the intubation.

Traumatic Airway Injury Emerging Technologies Traumatic injury to the airway can be open (pene- and Simulation trating) or closed (blunt). A study examining the U.S. Nationwide Emergency Department Sample Several recent advances in airway instrumenta- from 2009 through 2011 showed that the major- tion have provided new tools to help manage the ity of injuries (91.4%) were closed.46 The majority challenging airway. Nasal high-flow oxygen ther- of patients had multiple injuries (76.2%), were apy (Optiflow, Fisher and Paykel Healthcare) is admitted to the hospital (71.9%), and had an an alternative to the standard face mask or nasal overall mortality of 3.8%. The rate of fiberoptic prongs used in patients who are in airway dis- examination was poor (1.9%), although this co- tress. This approach provides warmed, humidi- hort probably had a low rate of severe injury fied oxygen at high flow rate (1 to 60 liters per given the low frequency of both intubation minute, with 60 liters being the maximum), with (2.6%) and tracheostomy (0.1%). In a cohort study a linear relationship between airflow and airway of changes in airway management from 1995 pressures as well as lung impedance.50 Unlike through 2011, researchers in Alberta, Canada, a face mask or nasal prongs, nasal high-flow reported that increased use of computed tomog- therapy also provides some positive end-expira- raphy in the later years of the study was associ- tory pressure that may decrease the work of ated with a higher rate of intubation (27% in breathing, especially in patients with acute up- 1995 vs. 64% in 2011).47 It should be noted that per airway obstruction.51 This therapy has also patients in this cohort had more severe injury been described as being more comfortable than than those in most other studies that have ex- a face mask or nasal prongs.51 However, since very amined the management of difficult airways few studies have evaluated the specific indica- associated with trauma and that 56% of the pa- tions for nasal high-flow therapy, recommenda- tients in this cohort underwent surgical inter- tions regarding its use remain unclear. vention. In patients requiring a definitive airway for Classic signs and symptoms of a major injury mechanical ventilation, endotracheal intubation after open or closed neck trauma include a suck- should be considered, barring any contraindica- ing or bubbling neck wound, pharyngeal bleed- tions. On the basis of a recent systematic review ing, a large or expanding hematoma, subcutane- and meta-analysis, the first-pass success rate for ous emphysema, dysphagia, dysphonia, and emergency airway intubation is 84.1% (95% con- stridor. Vascular, pharyngeal, and laryngotracheal fidence interval, 80.1 to 87.4).52 However, over the injuries are managed simultaneously and require past decade, the use of video intubation technol- the expertise of a multidisciplinary team, prefer- ogy has increased, and there has been a sub ably at a specialized trauma center.48 sequent decrease in the use of direct laryngoscopy.53 Video laryngoscopes (e.g., the GlideScope Algorithm for Management [Verathon] and C-MAC [Storz]) provide indirect of a Difficult Airway visualization of the glottis, with a camera and lighting placed at the tip of the scope to facili- Guidelines for the management of unanticipated tate intubation. Similarly, the laryngeal mask difficult intubation from the Difficult Airway airway (e.g., LMA CTrach [The Laryngeal Mask Society49 include a flowchart that escalates from Company]) uses a screen, camera, and light laryngoscopy to supraglottic insertion of an air- source and has a large opening through which

1946 n engl j med 381;20 nejm.org November 14, 2019 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. Acute Upper Airway Obstruction

Plan A Perform face-mask ventilation Laryngoscopy Succeed Perform tracheal intubation and tracheal intubation Failed intubation

Plan B Maintain oxygenation Stop and Think and insert SAD SAD Succeed Options (consider risks and benefits) 1. Wake up patient Failed ventilation 2. Intubate trachea with SAD 3. Proceed without tracheal intubation 4. Perform tracheostomy or cricothyroidotomy

Plan C Attempt face-mask ventilation Final attempt at Succeed Wake up patient face-mask ventilation

CICO

Plan D Obtain emergency front-of-neck Cricothyroidotomy access

Figure 2. Guidelines for Difficult Intubation. CICO denotes can’t intubate–can’t oyxgenate, and SAD supraglottic airway device. Adapted from the Difficult Airway Society 2015 Guidelines for Management of Unanticipated Difficult Intubation in Adults.49

an endotracheal tube can be passed. Another cyclodextrin, was approved by the Food and such device is the Airtraq double-lumen video Drug Administration in 2015 for the reversal of laryngoscope, which has a channel that guides neuromuscular blockage induced by rocuronium insertion of the tube. One of the benefits of the or vecuronium. Sugammadex may be used in Airtraq is that it can be synced with a smart- patients who have already received a neuromus- phone. These devices are fairly new adjuncts to cular blockade and cannot be intubated or ven- direct laryngoscopy, the laryngeal mask, and fiber- tilated. A quick and early reversal can then allow optic intubation. the patient to breathe spontaneously and prevent During the past decade, video laryngoscopy the need for emergency anterior neck airway ac- has been associated with an increase in the success. This course of action should not be used as cess rates of first-pass intubation (first-pass suc- a substitute for good decision making regarding cess with video laryngoscope, 87.8 to 95.2%) and the type of neuromuscular blockade (short-acting a decline in the success rates of direct laryngos- vs. long-acting) used in emergency intubation, copy (90.8 to 75.5%).53 Overall, the use of video but it may be helpful for cases in which unantici- intubation technologies has improved intubation pated difficulty in establishing ventilation arises. rates in obese patients, but it has not necessarily Sugammadex has been associated with rare improved intubation times and in some cases has events of laryngospasm, which may be related to increased these times.54,55 However, since there is rapid and full return of muscle tone after deep a learning curve associated with the use of the neuromuscular blockade.59-61 As is the case with new technology, higher success rates would be medications that are somewhat new to the mar- expected over time.56 Many centers have moved ket, further assessment is required to determine toward video laryngoscopy for all intubations in its safety and suitability for broad application. It is nonemergency settings,57 such as the operating not yet known whether this agent will decrease room and the intensive care unit. In many coun- morbidity and mortality. For routine reversal, a tries the technology is not readily available in the dose of 4 mg per kilogram should be used. In the emergency department.58 exceptional situation of postoperative recurrence Sugammadex (Bridion, Merck), a gamma- of neuromuscular blockade, after an initial dose

n engl j med 381;20 nejm.org November 14, 2019 1947 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. The new england journal of medicine

of 2 mg or 4 mg per kilogram, a repeat dose of ing tracheostomy for those with more experi- 4 mg per kilogram is recommended. Patients who ence. Simulation of cricothyroidotomy in a skill receive a second dose of sugammadex should be laboratory with appropriate models is useful for monitored closely to confirm sustained return of training and recertification in what is a rarely neuromuscular function. used procedure.64 When available, a surgeon skilled in tracheostomy could perform the pro- Surgical Intervention cedure just as quickly as a cricothyroidotomy can — Cricothyroidotomy be performed. or Tracheostomy Conclusions When neither intubation nor oxygenation is pos- sible, the airway must be opened surgically. The The management of acute upper airway obstruc- preferred approach is a tracheostomy because of tion has been modified to incorporate advances the risks of dysphonia (50%) and subglottic ste- in our understanding of its pathophysiological nosis (2%) associated with cricothyroidotomy.62 features and causes. The traditional algorithm However, for clinicians who have not performed for management continues to call for high-flow a tracheostomy, a cricothyroidotomy may be the oxygen and conservative measures, bag-mask preferred (and lifesaving) approach to securing ventilation, intubation, and, if needed, a surgical the airway. Anesthesiology programs recommend opening of the airway. Advances in anesthetic training and ongoing retraining in this tech- and surgical technologies appear to be improv- nique.49 Although the emergency cricothyroidot- ing practitioners’ ability to secure the airway in omy kit can be used to perform a tracheostomy,63 patients with acute airway obstruction. practitioners who lack the experience and expertise required to locate the airway landmarks No potential conflict of interest relevant to this article was reported. used for tracheostomy are better off using the Disclosure forms provided by the authors are available with kit as intended for cricothyroidotomy and leav- the full text of this article at NEJM.org.

References 1. Golzari SE, Khan ZH, Ghabili K, et al. sufficiency. JAMA Otolaryngol Head Neck The Rational Clinical Examination Sys- Contributions of medieval Islamic phy- Surg 2017;143:1141-5. tematic Review. JAMA 2019;321:493-503. sicians to the history of tracheostomy. 7. Ferreira CB, Cravo SL, Stocker SD. 14. Johnson DW. Croup. Am Fam Physi- Anesth Analg 2013;116:1123-32. Airway obstruction produces widespread cian 2016;94:476-8. 2. Szmuk P, Ezri T, Evron S, Roth Y, Katz J. sympathoexcitation: role of hypoxia, ca- 15. Smith DK, McDermott AJ, Sullivan JF. A brief history of tracheostomy and tra- rotid chemoreceptors, and NTS neurotrans- Croup: diagnosis and management. Am cheal intubation, from the Bronze Age to mission. Physiol Rep 2018;6(3):1141-5. Fam Physician 2018;97:575-80. the Space Age. Intensive Care Med 2008; 8. Mattila T, Vasankari T, Rissanen H, 16. Gates A, Gates M, Vandermeer B, et al. 34:222-8. Knekt P, Puukka P, Heliövaara M. Airway Glucocorticoids for croup in children. Co- 3. Hermansen MN, Schmidt JH, Krug obstruction and the risk of myocardial chrane Database Syst Rev 2018;8:CD001955. AH, Larsen K, Kristensen S. Low incidence infarction and death from coronary heart 17. Shapira Galitz Y, Shoffel-Havakuk H, of children with acute epiglottis after in- disease: a national health examination Cohen O, Halperin D, Lahav Y. Adult troduction of vaccination. Dan Med J 2014; survey with a 33-year follow-up period. acute supraglottitis: analysis of 358 pa- 61:1-5. Eur J Epidemiol 2018;33:89-98. tients for predictors of airway interven- 4. Butler DF, Myers AL. Changing epide- 9. Lévy P, Kohler M, McNicholas WT, tion. Laryngoscope 2017;127: 2106-12. miology of haemophilus influenzae in chil- et al. Obstructive sleep apnoea syndrome. 18. Edetanlen BE, Saheeb BD. Compari- dren. Infect Dis Clin North Am 2018;32: Nat Rev Dis Primers 2015;1:1-20. son of outcomes in conservative versus 119-28. 10. Cormack RS, Lehane J. Difficult tra- surgical treatments for Ludwig’s angina. 5. Takeuchi M, Yasunaga H, Horiguchi H, cheal intubation in obstetrics. Anaesthesia Med Princ Pract 2018;27:362-6. Fushimi K. The burden of epiglottitis 1984;39: 1105-11. 19. Sittitrai P, Srivanitchapoom C, Reun- among Japanese children before the Hae- 11. Yentis SM, Lee DJ. Evaluation of an makkaew D. Deep neck infection in pa- mophilus influenzae type b vaccination improved scoring system for the grading tients with and without human immuno- era: an analysis using a nationwide admin- of direct laryngoscopy. Anaesthesia 1998; deficiency virus: a comparison of clinical istrative database. J Infect Chemother 2013; 53:1041-4. features, complications, and outcomes. 19:876-9. 12. Wilson ME, Spiegelhalter D, Robert- Br J Oral Maxillofac Surg 2018;56:962-7. 6. Dion GR, Achlatis E, Teng S, et al. son JA, Lesser P. Predicting difficult intu- 20. An J, Singhal M. Ludwig angina. In: Changes in peak airflow measurement bation. Br J Anaesth 1988;61:211-6. StatPearls. Treasure Island, FL: StatPearls during maximal cough after vocal fold 13. Detsky ME, Jivraj N, Adhikari NK, et al. Publishing, 2019. augmentation in patients with glottic in- Will this patient be difficult to intubate? 21. Banerji A, Sheffer AL. The spectrum

1948 n engl j med 381;20 nejm.org November 14, 2019 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved. Acute Upper Airway Obstruction

of chronic angioedema. Allergy Asthma 36. Semdaie D, Haroun F, Casiraghi O, impedance in healthy volunteers. Respir Proc 2009;30:11-6. et al. Laser debulking or tracheotomy in Care 2015;60:1397-403. 22. Maurer M, Magerl M, Ansotegui I, et al. airway management prior to total laryn- 51. Spoletini G, Alotaibi M, Blasi F, Hill NS. The international WAO/EAACI guideline gectomy for T4a laryngeal cancer. Eur Arch Heated humidified high-flow nasal oxygen for the management of hereditary angio- Otorhinolaryngol 2018;275: 1869-75. in adults: mechanisms of action and clin- edema — the 2017 revision and update. 37. Du E, Smith RV, Ow TJ, Tassler AB, ical implications. Chest 2015;148:253-61. Allergy 2018;73: 1575-96. Schiff BA. Tumor debulking in the man- 52. Park L, Zeng I, Brainard A. Systematic 23. Bork K, Davis-Lorton M. Overview of agement of laryngeal cancer airway ob- review and meta-analysis of first-pass suc- hereditary angioedema caused by C1-inhib- struction. Otolaryngol Head Neck Surg cess rates in emergency department intu- itor deficiency: assessment and clinical 2016;155: 805-7. bation: creating a benchmark for emer- management. Eur Ann Allergy Clin Immu- 38. Matrka L. Paradoxic vocal fold move- gency airway care. Emerg Med Australas nol 2013;45: 7-16. ment disorder. Otolaryngol Clin North Am 2017;29:40-7. 24. Lunn ML, Santos CB, Craig TJ. Is there 2014;47: 135-46. 53. Lee JK, Kang H, Choi HJ. Changes in a need for clinical guidelines in the United 39. Chiang T, Marcinow AM, deSilva BW, the first-pass success rate with the Glide- States for the diagnosis of hereditary Ence BN, Lindsey SE, Forrest LA. Exercise- Scope video laryngoscope and direct laryn- angioedema and the screening of family induced paradoxical vocal fold motion dis- goscope: a ten-year observational study in members of affected patients? Ann Allergy order: diagnosis and management. Laryn- two academic emergency departments. Asthma Immunol 2010;104:211-4. goscope 2013;123: 727-31. Clin Exp Emerg Med 2016;3:213-8. 25. Hirose T, Kimbara F, Shinozaki M, 40. Hogg G, Goswamy J, Khwaja S, Khwaja 54. Yousef GT, Abdalgalil DA, Ibrahim TH. et al. Screening for hereditary angioedema N. Laryngeal trauma following an inha- Orotracheal intubation of morbidly obese (HAE) at 13 emergency centers in Osaka, lation injury: a review and case report. patients, comparison of GlideScope video Japan: a prospective observational study. J Voice 2017;31(3):388.e27-388.e31. laryngoscope and the LMA CTrach with Medicine (Baltimore) 2017;96(6): e6109. 41. Osler T, Glance LG, Hosmer DW. Sim- direct laryngoscopy. Anesth Essays Res 26. McCormick M, Folbe AJ, Lin HS, Hoo- plified estimates of the probability of 2012;6:174-9. ten J, Yoo GH, Krouse JH. Site involvement death after burn injuries: extending and 55. Belze O, Lepage E, Bazin Y, et al. Glide- as a predictor of airway intervention in an- updating the Baux score. J Trauma 2010; scope versus Airtraq DL for double-lumen gioedema. Laryngoscope 2011;121: 262-6. 68:690-7. tracheal tube insertion in patients with a 27. Kieu MC, Bangiyev JN, Thottam PJ, Levy 42. Kot Baixauli P, Morales Sarabia JE, predicted or known difficult airway: a ran- PD. Predictors of airway intervention in Rovira Soriano L, De Andrés Ibáñez J. domised study. Eur J Anaesthesiol 2017; angiotensin-converting enzyme inhibitor- Proposal for an algorithm for the man- 34:456-63. induced angioedema. Otolaryngol Head agement of the patient’s airway after 56. Sakles JC, Mosier J, Patanwala AE, Neck Surg 2015;153:544-50. smoke inhalation. Rev Esp Anestesiol Dicken J. Improvement in GlideScope Video 28. Driver BE, McGill JW. Emergency de- Reanim 2018;65:170-2. Laryngoscopy performance over a seven- partment airway management of severe 43. Wan J, Zhang G, Qiu Y, Wen C, Fu T. year period in an academic emergency de- angioedema: a video review of 45 intuba- Heat dissipation by blood circulation and partment. Intern Emerg Med 2014;9:789-94. tions. Ann Emerg Med 2017;69:635-9. airway tissue heat absorption in a canine 57. Cook TM, Boniface NJ, Seller C, et al. 29. LoVerde D, Files DC, Krishnaswamy G. model of inhalation thermal injury. Burns Universal videolaryngoscopy: a structured Angioedema. Crit Care Med 2017;45:725- 2016;42: 548-55. approach to conversion to videolaryngos- 35. 44. Casper JK, Clark WR, Kelley RT, copy for all intubations in an anaesthetic 30. Ugan Y, Doğru A, Aynalı G, Şahin M, Colton RH. Laryngeal and phonatory sta- and intensive care department. Br J Anaesth Tunç SE. A clinical threat in patients with tus after burn/inhalation injury: a long 2018;120:173-80. granulomatosis polyangiitis in remission: term follow-up study. J Burn Care Rehabil 58. Cook TM, Kelly FE. A national survey subglottic stenosis. Eur J Rheumatol 2018; 2002;23:235-43. of videolaryngoscopy in the United King- 5:69-71. 45. Reid A, Ha JF. inhalation injury and dom. Br J Anaesth 2017;118:593-600. 31. Childs LF, Rickert S, Wengerman OC, the larynx: a review. Burns 2019 45:1266- 59. Wu TS, Tseng WC, Lai HC, Huang YH, Lebovics R, Blitzer A. Laryngeal manifes- 74. Wu ZF. Sugammadex and laryngospasm. tations of relapsing polychondritis and a 46. Sethi RKV, Khatib D, Kligerman M, J Clin Anesth 2019;56:52. novel treatment option. J Voice 2012;26: Kozin ED, Gray ST, Naunheim MR. Laryn- 60. Greenaway S, Shah S, Dancey M. Su- 587-9. geal fracture presentation and manage- gammadex and laryngospasm. Anaesthe- 32. Feinstein AJ, Goel A, Raghavan G, et al. ment in United States emergency rooms. sia 2017;72:412-3. Endoscopic management of subglottic Laryngoscope 2019;129:2341-6. 61. McGuire B, Dalton AJ. Did sugamma- stenosis. JAMA Otolaryngol Head Neck 47. Randall DR, Rudmik L, Ball CG, dex cause, or reveal, laryngospasm? A reply. Surg 2017;143:500-5. Bosch JD. Airway management changes Anaesthesia 2016;71:1112-3. 33. Hoffman MR, Coughlin AR, Dailey associated with rising radiologic incidence 62. Cole RR, Aguilar EA III. Cricothyroid- SH. Serial office-based steroid injections of external laryngotracheal injury. Can J otomy versus tracheotomy: an otolaryngol- for treatment of idiopathic subglottic ste- Surg 2018;61: 121-7. ogist’s perspective. Laryngoscope 1988;98: nosis. Laryngoscope 2017;127:2475-81. 48. Jain U, McCunn M, Smith CE, Pittet JF. 131-5. 34. Franco RA Jr, Husain I, Reder L, Pad- Management of the traumatized airway. 63. Terlinden N, Van Boven M, Hamoir M, dle P. Awake serial intralesional steroid Anesthesiology 2016;124:199-206. Schmitz S. An innovative approach to tra- injections without surgery as a novel tar- 49. Frerk C, Mitchell VS, McNarry AF, cheotomy in patients with major obstruc- geted treatment for idiopathic subglottic et al. Difficult Airway Society 2015 guide- tion of the upper airway. Am J Otolaryn- stenosis. Laryngoscope 2018;128:610-7. lines for management of unanticipated gol 2014;35: 445-8. 35. Gelbard A, Shyr Y, Berry L, et al. difficult intubation in adults. Br J Anaesth 64. Soleimanpour H, Shams Vahdati S, Treatment options in idiopathic subglot- 2015;115: 827-48. Mahmoodpoor A, et al. Modified crico- tic stenosis: protocol for a prospective in- 50. Parke RL, Bloch A, McGuinness SP. thyroidotomy in skill laboratory. J Cardio- ternational multicentre pragmatic trial. Effect of very-high-flow nasal therapy on vasc Thorac Res 2012;4:73-6. BMJ Open 2018;8(4): e022243. airway pressure and end-expiratory lung Copyright © 2019 Massachusetts Medical Society.

n engl j med 381;20 nejm.org November 14, 2019 1949 The New England Journal of Medicine Downloaded from nejm.org at SAN FRANCISCO (UCSF) on November 13, 2019. For personal use only. No other uses without permission. Copyright © 2019 Massachusetts Medical Society. All rights reserved.