Wheezing

Definition and Etiology

Definition

• High-pitched, shrill, or coarse sounds that are usually continuous 
• Can occur in either the expiratory (more commonly) or inspiratory phase
• Generally louder than normal breath sounds, but mild forms may require a stethoscope to be detected

Etiology

• In adults, 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 and chronic obstructive pulmonary disease Pulmonary disease Diseases involving the respiratory system. Blastomyces/Blastomycosis ( 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)) are the most common causes of wheezing.
  • Wheezing is 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 is associated with an exacerbation, or “ 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 attack.”
  • Wheezing in 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 associated with worse symptoms, more exacerbations, and worse lung function. 
• In children, 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, allergies Allergies A medical specialty concerned with the hypersensitivity of the individual to foreign substances and protection from the resultant infection or disorder. Selective IgA Deficiency, and respiratory tract infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease are the most common causes. 
• Other causes include anything that narrows the airways.
  • Airway Airway ABCDE Assessment obstruction, most commonly by:
    • Bronchospasm Bronchospasm Asthma Drugs or 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
    • Mucus (e.g., in cystic Cystic Fibrocystic Change fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans)
    • Foreign body Foreign Body Foreign Body Aspiration
    • Vocal cord dysfunction
  • External compression Compression Blunt Chest Trauma by a tumor Tumor Inflammation
  • Peribronchial 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 in congestive heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR)
  • 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 due to anaphylaxis Anaphylaxis An acute hypersensitivity reaction due to exposure to a previously encountered antigen. The reaction may include rapidly progressing urticaria, respiratory distress, vascular collapse, systemic shock, and death. Type I Hypersensitivity Reaction or toxic inhalation

Pathophysiology

• Caused by a narrowing of the airways resulting in the oscillation of opposing airway Airway ABCDE Assessment walls
• Wheezing is an example of Bernoulli’s principle: 
  • When airflow is forced through a narrowed tube, its velocity increases and the pressure decreases.
  • The airway Airway ABCDE Assessment just distal to the narrowing collapses and vibrates, generating a high-pitched sound.
• Depending on where the narrowing occurs within the respiratory tract, the qualities of the sound will vary.

Upper versus lower airways:

• Polyphonic wheezing: 
  • Narrowing or obstruction of the small lower airways and at multiple sites
  • Described as musical, continuous, and variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables if auscultated at different regions 
  • Examples: 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), liquid aspiration, unilateral emphysema Emphysema Enlargement of air spaces distal to the terminal bronchioles where gas-exchange normally takes place. This is usually due to destruction of the alveolar wall. Pulmonary emphysema can be classified by the location and distribution of the lesions. Chronic Obstructive Pulmonary Disease (COPD)
• Monophonic wheezing: 
  • Narrowing or obstruction of the large airways, usually in one location
  • Described as loud, low, and fixed throughout the thoracic cavity
  • Examples: foreign body Foreign Body Foreign Body Aspiration aspiration, accumulation of blood or secretions, external compression Compression Blunt Chest Trauma or by tumor Tumor Inflammation or lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy

Unilateral versus bilateral wheezing:

• Bilateral/symmetric wheezing is caused by: 
  • 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)
• Unilateral wheezing is caused by:
  • Foreign body Foreign Body Foreign Body Aspiration aspiration
  • Intrinsic or extrinsic bronchial compression Compression Blunt Chest Trauma
    • Tumor Tumor Inflammation
    • Bronchial stenosis Bronchial Stenosis Granulomatosis with Polyangiitis
    • Unilateral bronchomalacia
    • Lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy
    • Abnormal vasculature
    • Kyphoscoliosis Kyphoscoliosis Osteomalacia and Rickets

Diagnosis

The medical history and physical exam findings (both pulmonary and extrapulmonary) will suggest the most likely cause. Further laboratory studies and imaging are usually not needed if typical features of the underlying condition are present.

Laboratory studies

• Pulse oximetry to evaluate oxygenation
• Pulmonary function testing Pulmonary Function Testing Pulmonary Function Tests:
  • With testing performed pre- and post-bronchodilator (to distinguish between 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 and 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))
  • Evaluation of the flow-volume loop:
    • If the bottom of the loop (inspiratory phase) is flat, it suggests an upper airway Airway ABCDE Assessment (extrathoracic) obstruction. 
    • If the top of the loop (expiratory phase) is flat, it suggests a lower airway Airway ABCDE Assessment (intrathoracic) obstruction. 

Imaging

• Chest or neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests will confirm airway Airway ABCDE Assessment obstruction.
• Nasopharyngo-, laryngo-, or bronchoscopy Bronchoscopy Endoscopic examination, therapy or surgery of the bronchi. Laryngomalacia and Tracheomalacia to directly visualize the airways and obstruction, and extract in the case of a foreign body Foreign Body Foreign Body Aspiration aspiration

Management

Symptomatic relief can be achieved with supplemental oxygen Supplemental Oxygen Respiratory Failure, but it is important to identify and correct the underlying condition for long-term treatment.

• 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
  • Inhaled bronchodilators Bronchodilators Asthma Drugs, corticosteroids Corticosteroids Chorioretinitis, other 
  • 5-step treatment strategy from the Global Initiative for 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 (GINA)
  • 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 medication
• 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) exacerbations 
  • Bronchodilator therapy and a course of oral glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids
  • Possible oral antibiotics (antivirals if there is evidence of influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza)
  • Supplemental oxygen Supplemental Oxygen Respiratory Failure if hypoxic, and pulmonary rehabilitation program
• 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/ infectious Infectious Febrile Infant causes: requires the appropriate antibiotic for the causative pathogen
• Foreign body Foreign Body Foreign Body Aspiration aspiration: requires location and extraction of the foreign body Foreign Body Foreign Body Aspiration
• Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) 
  • Treatment depends on the type of heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) and severity.
  • Follow published guidelines for treatment.
  • Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) and angina medication Angina medication Angina is defined as chest pain or discomfort resulting from myocardial ischemia. Therapy for angina is targeted at limiting platelet aggregation and adhesion (with antiplatelet agents), reducing O2 demand (with beta-blockers), reducing preload (with nitrates), and preventing the progression of atherosclerotic disease (using statin therapy), along with the management of comorbidities. Heart Failure and Angina Medication

Differential Diagnosis

The following abnormal breath sounds should be distinguished from wheezing:

• Stridor Stridor Laryngomalacia and Tracheomalacia: an abnormal, high-pitched sound produced by turbulent airflow through a partially obstructed airway Airway ABCDE Assessment anywhere from the supraglottis Supraglottis Larynx: Anatomy to the 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: Anatomy. There are 3 types of stridor Stridor Laryngomalacia and Tracheomalacia: inspiratory (most common, due to laryngeal obstruction), expiratory (due to tracheobronchial obstruction), and biphasic (due to subglottic or glottic obstruction). Stridor Stridor Laryngomalacia and Tracheomalacia can be acute, subacute, or chronic:
  • Acute and subacute causes: laryngotracheitis, foreign body Foreign Body Foreign Body Aspiration aspiration, 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, anaphylaxis Anaphylaxis An acute hypersensitivity reaction due to exposure to a previously encountered antigen. The reaction may include rapidly progressing urticaria, respiratory distress, vascular collapse, systemic shock, and death. Type I Hypersensitivity Reaction, retropharyngeal or peritonsillar abscess Peritonsillar abscess A peritonsillar abscess (PTA), also called quinsy, is a collection of pus between the capsule of the palatine tonsil and the pharyngeal muscles. A PTA is usually a complication of acute tonsillitis, an infection caused by group A Streptococci. Patients often present with a sore throat, trismus, and a muffled voice. Peritonsillar Abscess 
  • Chronic causes: laryngomalacia Laryngomalacia A congenital or acquired condition of underdeveloped or degeneration of cartilage in the larynx. This results in a floppy laryngeal wall making patency difficult to maintain. Laryngomalacia and Tracheomalacia, tracheomalacia Tracheomalacia A congenital or acquired condition of underdeveloped or degeneration of cartilage in the trachea. This results in a floppy tracheal wall making patency difficult to maintain. It is characterized by wheezing and difficult breathing. Laryngomalacia and Tracheomalacia, vocal cord dysfunction, papillomatosis ( warts Warts Benign epidermal proliferations or tumors; some are viral in origin. Female Genitourinary Examination), tumors
• Stertor and snoring: a narrowing of the airway Airway ABCDE Assessment in the nasal, nasopharyngeal, or oropharyngeal areas that produces a low-pitched sound often referred to as snoring during sleep Sleep A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility. Physiology of Sleep and stertor if the patient is awake. Stertor and snoring are caused by hypertrophy Hypertrophy General increase in bulk of a part or organ due to cell enlargement and accumulation of fluids and secretions, not due to tumor formation, nor to an increase in the number of cells (hyperplasia). Cellular Adaptation of tonsillar tissue, micrognathia Micrognathia Abnormally small jaw. Pierre Robin Sequence, or macroglossia Macroglossia The presence of an excessively large tongue, which may be congenital or may develop as a result of a tumor or edema due to obstruction of lymphatic vessels, or it may occur in association with hyperpituitarism or acromegaly. It also may be associated with malocclusion because of pressure of the tongue on the teeth. Wilms Tumor.