Overview

Definition

Airway obstruction is a blockage of the airways, which impedes air flow and effective respiration.

Anatomic classification

• Upper airway obstruction (UAO):
  • Nasopharynx, larynx Larynx The larynx, also commonly called the voice box, is a cylindrical space located in the neck at the level of the C3-C6 vertebrae. The major structures forming the framework of the larynx are the thyroid cartilage, cricoid cartilage, and epiglottis. The larynx serves to produce sound (phonation), conducts air to the trachea, and prevents large molecules from reaching the lungs. Larynx, and trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea
• Central airway obstruction (CAO):
  • Trachea and mainstem bronchi
• Lower airway obstruction (LAO): 
  • Distal to mainstem bronchi
  • Involves small airways
  • Usually a manifestation of chronic disease

Epidemiology

• Exact incidence is unknown.
• Occurs in 20%–30% of patients with lung cancer Lung cancer Lung cancer is the malignant transformation of lung tissue and the leading cause of cancer-related deaths. The majority of cases are associated with long-term smoking. The disease is generally classified histologically as either small cell lung cancer or non-small cell lung cancer. Symptoms include cough, dyspnea, weight loss, and chest discomfort. Lung Cancer

Etiology

Upper airway obstruction and CAO (large airway obstruction):

• Masses:
  • Lung cancer most common
  • Benign masses (papillomas)
• Aspiration of foreign body
• Mucous plug
• Tracheomalacia Tracheomalacia Laryngomalacia and tracheomalacia are the most common upper airway conditions that produce stridor in newborns. Laryngomalacia and tracheomalacia tend to present in the 1st 2 weeks of life, with symptoms ranging from stridor to respiratory distress. The symptoms are caused by narrowing of the airway, which may be due to weakened cartilage, redundant tissue, external compression, or hypotonia of the affected area. Laryngomalacia and Tracheomalacia
• Angioedema Angioedema Angioedema is a localized, self-limited (but potentially life-threatening), nonpitting, asymmetrical edema occurring in the deep layers of the skin and mucosal tissue. The common underlying pathophysiology involves inflammatory mediators triggering significant vasodilation and increased capillary permeability. Angioedema ( tongue Tongue The tongue, on the other hand, is a complex muscular structure that permits tasting and facilitates the process of mastication and communication. The blood supply of the tongue originates from the external carotid artery, and the innervation is through cranial nerves. Oral Cavity: Lips and Tongue swelling)
• Anaphylaxis
• Obstructive sleep apnea Obstructive sleep apnea Obstructive sleep apnea (OSA) is a disorder characterized by recurrent obstruction of the upper airway during sleep, causing hypoxia and fragmented sleep. Obstructive sleep apnea is due to a partial or complete collapse of the upper airway and is associated with snoring, restlessness, sleep interruption, and daytime somnolence. Obstructive Sleep Apnea ( OSA OSA Obstructive sleep apnea (OSA) is a disorder characterized by recurrent obstruction of the upper airway during sleep, causing hypoxia and fragmented sleep. Obstructive sleep apnea is due to a partial or complete collapse of the upper airway and is associated with snoring, restlessness, sleep interruption, and daytime somnolence. Obstructive Sleep Apnea)
• Laryngoceles
• Tracheal strictures/stenosis
• Airway hematomas (trauma)
• Extrinsic compressions (e.g., vascular rings Vascular rings Vascular rings are a group of rare malformations featuring congenital abnormalities of the aortic arch. The aberrant arteries often form a ring around the esophagus and trachea, putting pressure on these structures. Vascular Rings, thyroid tumors)
• Infections

Lower airway obstruction (small airway obstruction):

• Asthma
• Chronic obstructive pulmonary disease ( COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD))
• Post-infective bronchial hyperreactivity
• Bronchiectasis Bronchiectasis Bronchiectasis is a chronic disease of the airways that results from permanent bronchial distortion. This results from a continuous cycle of inflammation, bronchial damage and dilation, impaired clearance of secretions, and recurrent infections. Bronchiectasis and cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis
• Infections:
  • Allergic bronchopulmonary aspergillosis Aspergillosis Aspergillosis is an opportunistic fungal infection caused by Aspergillus species, which are common spore-forming molds found in our environment. As Aspergillus species are opportunistic, they cause disease primarily in patients who are immunocompromised. The organs that are most commonly involved are the lungs and sinuses. Aspergillus/Aspergillosis
  • Endobronchial tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis

Pathophysiology

Mechanisms

• Extrinsic or intrinsic compression due to tumors
• Endobronchial granulation tissue or calcifications
• Thinning or collapse of the airway wall due to tracheomalacia
• Airway edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema due to infection, inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation, or bleeding

Chronic and subacute

• Minor obstruction is often asymptomatic initially.
• Can be caused by a mass, a stricture, or external compression
• Can be exacerbated by exertion, increased ventilatory demands (e.g., pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia), or progressive obstruction; and then become acute

Acute

• Precipitating events:
  • Foreign body aspiration Foreign body aspiration Foreign body aspiration can lead to choking and death by obstructing airflow at the larynx or trachea. Foreign bodies may also become lodged deeper in the bronchi; this may not affect breathing but can cause infection or erosion of bronchial walls. Foreign Body Aspiration
  • Mucous plug
  • Laryngotracheal trauma
  • Smoke inhalation
  • Pediatric infections:
    • Epiglottitis Epiglottitis Epiglottitis (or "supraglottitis") is an inflammation of the epiglottis and adjacent supraglottic structures. The majority of cases are caused by bacterial infection. Symptoms are rapid in onset and severe. Epiglottitis
    • Croup Croup Croup, also known as laryngotracheobronchitis, is a disease most commonly caused by a viral infection that leads to severe inflammation of the upper airway. It usually presents in children < 5 years of age. Patients develop a hoarse, "seal-like" barking cough and inspiratory stridor. Croup
    • Tonsillar or retropharyngeal abscess Retropharyngeal abscess Retropharyngeal abscesses occur in the retropharyngeal space, which extends from the base of the skull to the posterior mediastinum. The abscesses occur due to extension of local infections, including upper respiratory infections or localized infections from trauma such as dental procedures. Retropharyngeal Abscess
    • Diphtheria Diphtheria Diphtheria is an infectious disease caused by Corynebacterium diphtheriae that most often results in respiratory disease with membranous inflammation of the pharynx, sore throat, fever, swollen glands, and weakness. The hallmark sign is a sheet of thick, gray material covering the back of the throat. Diphtheria
• Acute exacerbation of mild chronic obstruction in the setting of swelling, bleeding, or increased secretions

Clinical Presentation

Chronic and subacute

• Symptoms are non-specific:
  • Dyspnea
  • Wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing
  • Cough
  • Hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis
  • Hoarseness
  • Chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain
• Frequently misdiagnosed as asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma/ COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD)
• Diagnostic clues:
  • Positional symptoms rather than diurnal (day vs. evening)
  • Inspiratory wheeze (stridor)
  • History of intubation or tracheal disease (tracheal stenosis)

Acute

• Acute onset tachypnea
• Tachycardia
• Inspiratory stridor
• Wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing
• Increased respiratory effort: suprasternal retractions, nasal flaring, grunting
• Gagging, gasping
• Cyanosis
• Obtunded mental status

Diagnosis

History

History can be obtained from a responsive patient not in extremis.

• Does the patient have a history of:
  • Respiratory disease
  • Lung or head/neck cancer
  • Foreign body aspiration Foreign body aspiration Foreign body aspiration can lead to choking and death by obstructing airflow at the larynx or trachea. Foreign bodies may also become lodged deeper in the bronchi; this may not affect breathing but can cause infection or erosion of bronchial walls. Foreign Body Aspiration
  • Previous intubation/tracheostomy
  • Neck surgery

Physical exam

• General: 
  • Cyanosis
  • Pulse oximetry < 90%
  • Facial/neck swelling
  • Signs of respiratory distress (tachypnea, nasal flaring, gasping, use of accessory muscles)
• Direct inspection of the airways:
  • Visual inspection (angioedema, foreign body)
  • Laryngoscopy
  • Bronchoscopy

Imaging

• Should only be performed after airway stabilization
• Chest X-ray:
  • Mass
  • Tracheal deviation
  • Mediastinal shift
  • Endobronchial luminal defect
• Neck X-ray:
  • Thumbprint sign for epiglottitis
• Chest computed tomography (CT):
  • More detailed imaging than X-ray
• Magnetic resonance imaging (MRI):
  • For vascular pathology
  • Soft tissue tumors (e.g., sarcomas)

Pulmonary function test (PFT)

For chronic/subacute symptoms in the setting of suspected obstruction:

• Minimal variability in peak flow/spirometry
• Characteristic “squared-off” flow-volume loop 
• Fall in peak expiratory flow rate (PEFR) relatively greater than fall in forced expiratory volume in 1 second (FEV1)

Management

Life-threatening obstruction

• If a foreign body is suspected, abdominal thrusts (Heimlich maneuver) or back slaps (for infants) should be performed for responsive patients.
• Cardiopulmonary resuscitation is initiated for unresponsive patients.
• The goal of initial management:
  • Provide adequate oxygenation
  • Secure airway
• The initial step is bag-mask ventilation.
• Maneuvers to help open the airway:
  • Head tilt-chin lift (if no cervical spine trauma is suspected)
  • Jaw Jaw The jaw is made up of the mandible, which comprises the lower jaw, and the maxilla, which comprises the upper jaw. The mandible articulates with the temporal bone via the temporomandibular joint (TMJ). The 4 muscles of mastication produce the movements of the TMJ to ensure the efficient chewing of food. Jaw and Temporomandibular Joint-thrust (allows airway opening without disturbing the cervical spine)
• Endotracheal intubation is the definitive airway management.
• If intubation cannot be accomplished:
  • A laryngeal mask can be inserted if obstruction is from a swollen tongue Tongue The tongue, on the other hand, is a complex muscular structure that permits tasting and facilitates the process of mastication and communication. The blood supply of the tongue originates from the external carotid artery, and the innervation is through cranial nerves. Oral Cavity: Lips and Tongue.
  • Emergent cricothyroidotomy or tracheostomy
  • Rigid bronchoscopy and retrograde intubation may be needed in case of bronchial obstruction.

Not immediately life-threatening obstruction

• History, laboratory, and imaging evaluations can be obtained.
• Initial management:
  • Sit the patient up.
  • High-flow oxygen or heliox (a mixture of oxygen and helium) via a mask
  • Intravenous high-dose corticosteroids (reduce edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema around the obstruction)
  • Nebulized salbutamol and adrenaline
  • Intravenous fluid replacement
• Definitive management depends on the underlying cause.

Differential Diagnosis

• Chronic obstructive pulmonary disease: chronic obstructive inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the small airways and changes in the lung parenchyma and pulmonary vasculature. Patients usually present with dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea and chronic cough. COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD) is a progressive condition with acute flares. Management includes smoking cessation, pulmonary rehabilitation, and pharmacotherapy.
• Asthma: chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. Patients typically present with wheezing, cough, and dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea. Diagnosis is confirmed with a PFT showing a reversible obstructive pattern. Treatment, based on symptom severity, includes bronchodilators and inhaled corticosteroids for control of inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation.