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Cough

Editor-In-Chief: C. Michael Gibson, M.S., M.D.; Associate Editor(s)-in-Chief:Abiodun Akanmode


Overview

Cough is a physiologic reflex action, it serves to rid the respiratory tract of excessive secretions and other environmental debris such as dust, pollen, and other irritants.

Coughing also referred to as 'tussis' is associated with the rapid release of air from the lung this is associated with the loud and distinctive sound associated with coughing. Cough is the most common cause of visits to primary care doctors and pulmonologist.Cough is mostly a symptom of an underlying disease, however, establishing the exact cause of cough can be challenging. While most cough is ussaully acute due to postnasal drip,bronchial asthma and heartburn other more serious causes such as COPD,lung cancer should be considered when a chronic cough is suspected.

Classification

Cough can be classified based on duration i.e

  • Acute cough: This type of cough usually presents with a duration of fewer than 3 weeks.
  • Sub Acute cough: Last between 3-8weeks.
  • Chronic Cough: Chronic cough usually presents for a duration greater than 8weeks.

Cough can also be classified based on sputum production i.e

  • Non-productive cough.
  • Productive cough.

Pathophysiology

The act of cough is a vital one that occurs through the stimulation of the cough reflex which is a complex relex arc. The cough reflex arc is constituted by 3 main components ie

  • The Afferent pathway: This made up of sensory nerve fibers in the ciliated epithelium found in the upper airways. The afferent impulses are transmitted into the medulla.
  • The efferent pathway: cough impulse3s that is originated from the cough central travels via the vagus nerve,phrenic nerve, and spinal motor nerves to the diaphragm and abdominal wall muscles.
  • Central pathway: This is a central area located within the pons and brainstem. It coordinates the cough reflex arc.[1]

The Afferent sensory nerves:There are 3 manjor classes of afferent sensory nerves,this classification is based on there conduction velocity(A-fiber, > 3 m/s; C-fiber, < 2 m/s),origin ,myelination,neurochemistry etc.

  • Rapidly adapting receptors (RARs)
  • Slowly adapting stretch receptors (SARs)
  • C-fibres.

The series of mechanical activities that take place during coughing is divided into 3 phases.

Causes

The common causes of cough are:

Less common causes of cough are:

Causes Examples
Drug use Abacavir, Abatacept, ABVD, ACE inhibitor, Acetylmorphone, Acyclovir, Adalimumab, Adefovir, Albuterol, Alefacept, Alfuzosin, Aliskiren, Amiodarone, Amlodipine and Benazepril, Amphotericin B, Anagrelide, Anastrozole, Artemether/lumefantrine, Atazanavir, Aztreonam, Benazepril, Bepridil, Bevacizumab, Bitolterol, Bortezomib, Brimonidine, Budesonide, Busulfan, Captopril, Carvedilol, Cetuximab, Cevimeline, Chlorambucil, Ciclesonide, Cladribine, Clobutinol, Clofarabine, Clofedanol, Co-trimoxazole, Conjugated estrogens, crofelemer, Cromolyn Sodium, Cytarabine, Dacarbazine, Dactinomycin, Darbepoetin Alfa, Denileukin diftitox, Desmopressin, Diborane,
Infectious disease Adenoviridae, Aphthovirus, Ascaris infection, Aspergillosis, Blastomycosis, Bordetella pertussis, Byssinosis, Chickenpox, Chlamydophila pneumonia, Cladosporium, CMV Pneumonitis, Coccidioidomycosis, Community-acquired pneumonia, Cryptococcosis, Fasciolosis, Filariasis, Gnathostomiasis, Histoplasmosis, Human ehrlichiosis, Infectious mononucleosis, Influenza, Lady Windermere syndrome, Lassa fever, Legionellosis, Measles, Melioidosis, Miliary tuberculosis, Mucor.
Genetic diseases Cystic fibrosis, Juvenile Myelomonocytic Leukemia (JMML)
Environmental agents Chronic beryllium disease (CBD), Hay fever, Low humidity, Occupational exposure of irritants Passive smoking, Sick building syndrome, Silicosis, Smoking.
Malignancies Cervical mass, Esophageal cancer, Kaposi's sarcoma, Laryngeal cancer, Lymphangitis carcinomatous, Mediastinal tumor, Mesothelioma, Papillomatosis, Thymoma.

Cough Differential Diagnosis

  • Acute Cough Diffrential Diagnosis.
 
 
 
Acute Cough
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Viral Urti
 
Allergies
 
Pneumonia


  • Subacute cough Differential diagnosis.
 
 
 
Subacute Cough
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Asthma
 
Bacterial sinusitis
 
Postinfectious cough


  • Chronic cough Differential Diagnosis.
 
 
 
Chronic Cough
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
GERD,Tobacco use
 
Chronic diseases:CHF,Sarcoidosis,Cystic fibrosis etc
 
Asthma,Pharmacologic drug:ACEI,Beta Blockers

Overview

Associated symptoms such as fever, vomiting, night sweats, weight loss, sputum production and quantity, smoking history, drug use, etc help the clinician with making a list of plausible differential diagnoses.

Differentiating cough from other Diseases

Making a differential diagnosis when a patient presents with a cough can be challenging however the clinician should utilize other associated symptoms such as fever, vomiting, night sweats, weight loss, sputum production and quantity, smoking history, drug use and most importantly the duration of the cough to make a list of plausible differential diagnoses.

Cough epidemiology and demographics

Cough is the most common cause of visits to primary care doctors and pulmonologist, it accounts for about 40% of outpatient visits.[1][2]

Risk Factors for cough

The risk factors for cough are closely linked with its various causes, however, certain factors such as smoking, seasonal allergies, and air pollution can increase a patients cough hypersensitivity.

Natural History, Complications and Prognosis

Diagnosis

Treatment

References

  1. 1.0 1.1 Polverino M, Polverino F, Fasolino M, Andò F, Alfieri A, De Blasio F (2012). "Anatomy and neuro-pathophysiology of the cough reflex arc". Multidiscip Respir Med. 7 (1): 5. doi:10.1186/2049-6958-7-5. PMC 3415124. PMID 22958367.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  2. Irwin RS, Curley FJ, French CL (1990). "Chronic cough. The spectrum and frequency of causes, key components of the diagnostic evaluation, and outcome of specific therapy". Am Rev Respir Dis. 141 (3): 640–7. doi:10.1164/ajrccm/141.3.640. PMID 2178528.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  3. De Blasio F, Virchow JC, Polverino M, Zanasi A, Behrakis PK, Kilinç G; et al. (2011). "Cough management: a practical approach". Cough. 7 (1): 7. doi:10.1186/1745-9974-7-7. PMC 3205006. PMID 21985340.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>