Cough

Question 1

Fxn of cough

Answer 1

Cough defends the body by clearing pathogens, particulates, foreign bodies, and accumulated secretions from the lung airways, larynx and pharynx.

Question 2

Afferent pathway of cough

Answer 2

• vagus nerve helps initiate cough via 3 receptors
  
  • RAR (rapidly adapting receptors) & SAR (slowly adapting stretch receptors) ==> mechanical stimulation
  • C fibers ==> (noxious) chemical stimulation

Question 3

Phases of efferent pathway of cough

Answer 3

1. Inspiratory Phase: inhalation ends before closure of the glottis
2. Compressive Phase: thoracic and abdominal muscles contract against a fixed diaphragm (modified Valsalva maneuver); intrathoracic pressure increases (≤ 300 mm Hg)
3. Expiratory Phase: glottis opens; air is rapidly (≤ 500 miles/hr!) expelled
4. Relaxation Phase: chest wall and abdominal muscles relax

Question 4

Acute cough definition + common causes

Answer 4

• cough < 3weeks
• life-threatening causes:
  
  • PNA, sever asthma/COPD exacerbation, PE, heart failure
• non-life threatening
  
  • URI=common cold: nasal congestion, post-nasal drip, cough
  • Lower respriatory infection (acute bronchitis)
  • exacerbations of pre-existing conditions
  • environmental/occupational exposures

Question 5

Subacute cough defintion + possible causes

Answer 5

• cough lasting 3-8 weeks
• postinfectious cough = follows an obvious preceding URI/LRI
• possibly PNA or bacterial bronchitis

Question 6

Chronic cough definition + common causes

Answer 6

• cough lasting > 8wks
• most common causes (in immunocompetient adults w/normal CXR):
  
  • UACS = upper airway cough syndrome
  • asthma
  • GERD = gastroesophageal reflux disease
  • NAEB = non-asthmatic eosinophilic bronchitis
  • **may be caused by more than onde disease

Question 7

UACS: mechanism

Answer 7

• “post-nasal drip syndrome”
• secretions from nose/paranasal sinus ==> stimulation of upper airway cough receptors OR
• direct irritation/inflammation of receptors

Question 8

UACS: signs & symptoms

Answer 8

• Symptoms:
  
  • “tickle” in throat
  • throat-clearing, hoarseness
  • nasal congestion and drainage
  • cough
• Signs
  
  • oropharyngeal mucosa = cobblestone
  • mucus in nasal passages or oropharynx <== caused by nasal/sinus inflammation

Question 9

UACS: dx and tx

Answer 9

• first generation anti-histamine/decongestant combination medication for > 2 weeks
• Improvement or resolution of cough is consistent with UACS.

Question 10

Asthma: mechanism

Answer 10

• =chronic, inflammatory airway disorder w/airflow obstruction
• stimulation of cough receptors by inflammatory mediators, mucus, bronchoconstrictions

Question 11

Asthma: signs & symptoms

Answer 11

• symptoms
  
  • classic = episodes of wheezing, dyspnea, cough
  • cough-variant = cough is only symptom
• signs
  
  • bilateral, polyphonic wheezes (not always present)

Question 12

Asthma: dx tests + tx

Answer 12

• PFTs ==> >12% increase in FEV₁ after bronchodilator
  
  • methacholine challenge
• Tx = inhaled bronchodilator + inhaled corticosteroid for > 8 weeks
  
  • avoidance of triggers (e.g. allergens)
  • some cases, oral corticosteroids
  • improvement or resolution of cough confirms the diagnosis of asthma.

Question 13

GERD: mechanism

Answer 13

• backflow of stomach contents into esophagus
• stimulation of receptors via irritation @:
  
  • upper respiratory tract
  • lower respiratory tract (aspiration)
  • esophageal-bronchial cough reflex

Question 14

GERD: signs & symptoms

Answer 14

• symptoms
  
  • cough (w/ or w/out phlegm)
  • GI symptoms (heartburn, regurg) may be absent

Question 15

GERD: dx tests & tx

Answer 15

• dx: 24-hour esophageal pH monitor
• tx:
  
  • gastric acid suppression with a proton pump inhibitor (e.g. omeprazole) for ≥ 2 months
  • diet and lifestyle modification
  • improvement or resolution of cough confirms the diagnosis of GERD.

Question 16

NAEB: characteristics & mechanism

Answer 16

• eosinophilic airway inflammation, similar to that seen in asthma, but without variable airflow limitation or airway hyperresponsiveness
• stimulation of lower airway cough receptors by inflammatory mediators

Question 17

NAEB: signs & symptoms

Answer 17

• symptoms: cough w/out wheezing or dyspnea
• signs: no wheezes

Question 18

NAEB: dx test and tx

Answer 18

• PFTs = normal
• induced sputum analysis ==> increase in eosinophils
• tx: inhaled corticosteroid for >4 wks

Question 19

Antibiotics in acute cough

Answer 19

• use in case of bacterial infection e.g.:
  
  • bacterial pneumonia
  • bacterial bronchitis

Question 20

Common causes of cough in children

Answer 20

• acute = viral URI
• chronic = asthma, sinusitis, GERD
  
  • underlying lung disease
  • second-hand smoke