急性上気道閉塞のレビュー

Acute Upper Airway Obstruction

N Engl J Med 2019;381:1940-9.

DOI: 10.1056/NEJMra1811697

Review

 

非常に実臨床に即したレビュー。解剖→疾患各論→difficult airway managementの順番でまとまっている。救急・ICU医であると各病態の知識が乏しいし、非救急・ICU医の場合であるとdifficult airway managementにやや経験が乏しい可能性がある。すなわち、救急・ICU医だけでなく上気道閉塞に遭遇するすべての医師に有用な情報がカバーされている。

NEJMのレビューはよくまとまっている場合が多いが、時として病態生理に主眼が置かれるなど実臨床からやや離れているものも散見される。そもそも、今回の病態が病態生理に関して語れないという指摘はあるがそれを考慮しても明日から使える知識に満ちていて非常に勉強になりました。

 

○以下本文抜粋

 

ANATOMY

・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 subglottic subsites), and hypopharynx may lead to acute upper airway obstruction.

・Historically, the most common site for airway obstruction was the supraglottic larynx, which includes the epi- glottis, the aryepiglottic folds, the arytenoids, and the ventricular folds (or “false cords”).

PATHOPHYSIOLOGICAL FEATURES

PHYSICAL EXAMINATION

・airway managementで最も重要なadvancesの1つはdifficult airwayの予測に役立つphysical examination grading scales

・いくつかのスケールはlaryngoscopyによるもの(e.g., the Cormack–Lehane grading scale, on which grades range from 1 to 4, with higher grades indicating poorer visibility)、一方他はprelaryngoscopic factors (e.g., the Wilson score, in which a scale of 0 to 10 is used to indi- cate the likelihood of difficulty with intubation, with higher scores indicating greater difficulty)によるもの

→The factors used in assessment include increased weight, decreased cervical spine mobil- ity, decreased jaw mobility, retrognathia, and prominent incisors, all of which are associated with increased difficulty with intubation.

→Other aspects of physical examination that can be used to assess the likelihood of a difficult intubation include the hyomental–thyromental distance, with shorter distances indicating greater difficulty, and the Mallampati score, which is used to as- sess the visibility of oropharyngeal structures with the mouth opened maximally.

→結局は予測できる信頼性の高いツールはないので、常にdifficult airwayの管理に対する準備をすべき

ADVANCES IN TREATMENT ACCORDING TO CAUSE

・急性上気道閉塞の原因の分類で解剖学的なアプローチが最も実務的

○Croup

・6ヶ月から3歳の子供の3%で起きる

・a barking cough, inspiratory stridor, hoarseness, and respiratory distressがあり、典型的には夜間突然症状が生じる

・治療の根幹はoral or inhaled glucocorticoids

・Oral dexamethasone should be administered in a single dose of 0.6 mg/kg

・Nebulized dexamethasone should be administered in a dose of 160 μg, with a fill volume of 3 ml and the oxygen flow set to 5 to 6 liters per minute.

→cochrane reviewによるとglucocorticoids reduced symptoms at 2 hours and were associated with shorter hospital stays and lower rates of return to the hospital than placebo or other pharmacologic treatments(Glucocorticoids for croup in children. Cochrane Database Syst Rev 2018;8:CD001955.)

○Epiglottitis and Supraglottitis

・H. influenza type Bに対するワクチンの影響でepiglottitisの発生率と関連した死亡率は減少している。

・supraglottitis→成人ではrareであるが感染で生じることが典型的であるが、外傷や吸入による損傷や、caustic substancesの摂取による結果もある。経過はaggressiveで典型的には男性、dyspnea or stridor, epiglottis or aryepiglottic foldsの浮腫を認める。CRPと高血糖も典型的。再発のエピソードを繰り返す。よくある症状はsore throat (79%) and dysphagia (71%)。Stridor (3.6%) and dyspnea (6.7%)はless commonであるがairway interventionの必要性増加と関連している

○Ludwig’s Angina

・Patients with Ludwig’s angina have bilateral infection of the sublingual and submandibular spaces that is characterized by submental and submandibular induration, cellulitis, and a swollen and tender floor of mouth, all of which result in a posteriorly displaced tongue.

→結果的に oropharyngeal and supraglottic levelsでの閉塞をきたす

・The most common causes of Ludwig’s angina are dental infections, followed by sialadenitis, peritonsillar abscess, abscess involving the parapharyngeal space, traumatic injuries to the oral cavity, and mandibular fractures.

・Conservative management with intravenous anti- biotics is associated with a risk of airway com- promise that is nearly 10 times as high as that in patients who receive early surgical drainage (26.3% vs. 2.9%)

・死亡率は8%

○Angioedema

・最近のガイドラインの変化→遺伝性angioedemaの患者は常にon-demand treatmentを携帯し、attackを誘発するproceduresを受ける前に短期の予防を考慮することを推奨する

・The revised guidelines recommend consideration of on- demand treatment (with self-dosing of a C1 esterase inhibitor) for all attacks, treatment of attacks affecting the upper airway, early treatment, and initiation of treatment with a C1 inhibitor — either ecallantide (a kallikrein inhibitor) or icatibant (a bradykinin receptor antagonist).

・ Ecallantide should be administered subcutaneously by a health care professional in three 10-mg (1-ml) injections; if the attack persists, an additional dose of 30 mg may be administered within a 24-hour period. The recommended dose for icatibant is 30 mg injected subcutaneously in the abdominal area; additional doses may be admin- istered at intervals of at least 6 hours if the re- sponse is inadequate or if symptoms recur, but no more than 3 doses may be administered in any 24-hour period.

○Bilateral Paresisand Paralysis of the Vocal Cords

・Bilateral vocal-cord paresis and paralysis can result from tumor infiltration of the glottic larynx or both recurrent laryngeal nerves, prolonged intubation or placement of a nasogastric tube, and infectious and pathologic conditions affecting the brain stem.

・In some instances, vocal-cord paralysis can also result from complications during thoracic and anterior neck surgery.

・narrowed airwayで経過するが、ウイルス感染などの炎症をきっかけによりairwayの狭窄をきたしairway compromiseとなることも

○Subglottic and Glottic Stenosis

・Cases of subglottic and glottic stenosis are rare and challenging; they most often result from prolonged or traumatic intubation but may also be congenital or idiopathic.

・Patients with granulomatosis polyangiitis and relapsing polychondritis may also present with subglottic stenosis.

・Standard treatment involves dilation of the airway, commonly performed with the adjunctive use of lasers to radially incise the stenosis or of pressure-controlled balloons to dilate the stenosis.

○Neoplasms Intrinsic or Extrinsic to the Upper Aerodigestive Tract

・The most common intrinsic neoplasms associated with airway obstruction are glottic and supraglottic cancers, most often squamouscell carcinomas.

○Psychogenic Upper Airway Obstruction

・Psychogenic presentations of upper airway ob- struction are rare. Most patients have paradoxical vocal-fold motion disorder, a conversion disorder in which the vocal cords adduct on inspiration and abduct on expiration, leading to inspiratory stridor

・Respiratory retraining and laryngeal control therapy are the mainstays of treatment, which is performed by a speech–language pathologist. The use of counsel- ing and psychiatric assessment is in decline.

○Inhalation Injury

・熱傷患者の約15%はinhalation injuryがありそれは独立した死亡率の予測ファクター

・In those with clinical signs and symptoms of inhalation injury, such as dysphonia, dysphagia, singed nasal hairs, sooty sputum, stridor, cyanosis, or neurologic symptoms, endoscopic assessment by an otolaryngologist is warranted. Intubation is also called for if erythema, edema, or sooty exudate is detected. These patients are at a substantial risk for decline in the first 24 hours after inhalation injury.

・長期のlaryngological complicationsとなることも→Consequent to local inflammation and edema, patients may have granulation tissue, scarring, webbing, vocal-cord immobility, stenosis, and laryngeal hyperfunction.

○Traumatic Airway Injury

・Traumatic injury to the airway can be open (penetrating) or closed (blunt)→2009-2011年のU.S. Nationwide Emergency Department Sampleからのstudyでは大部分はclosed injuries(91.4%)

ALGORITHM FOR MANAGEMENT OF A DIFFICULT AIRWAY

Difficult Airway Society 2015 Guidelines for Management of Unanticipated Difficult Intubation in Adults

EMERGING TECHNOLOGIES AND SIMULATION

・video喉頭鏡について→肥満の患者で挿管率が増加したがそれ以外では変化なし。しかし、新しいテクノロジーは使用経験とともに学習カーブがあり時間とともに成功率もより増加しているであろう。Many centers have moved toward video laryngoscopy for all intubations in nonemergency settings, such as the operating room and the intensive care unit. In many countries the technology is not readily available in the emergency department.

・sugammadex→リバースには4mg/kgを使うべき。例外は術後のリバースでinitial doseは2-4mg/kgで4mg/kgを繰り返すことが推奨されている

SURGICALINTERVENTION— CRICOTHYROIDOTOMY OR TRACHEOSTOMY

・The preferred approach is a tracheostomy because of the risks of dysphonia (50%) and subglottic stenosis (2%) associated with cricothyroidotomy

CONCLUSIONS