09. Approach to Cough

Resident Editor: Michael Incze, MD
Faculty Editor: Nat Gleason, MD

ACUTE COUGH

Background

  • Acute cough means a cough lasting less than 3 weeks.

Differential Diagnosis

Viral respiratory syndromes or environmental irritants cause most acute cough, although the differential is broad and overlaps with chronic cough etiologies. The focus is on ruling out serious illness, particularly pneumonia.

Life-threatening Diagnosis

 

Non-life-threatening Diagnosis

 

 

  • Pneumonia
  • Severe COPD/Asthma Exacerbation
  • Pulmonary Embolism
  • Congestive Heart Failure Exacerbation
  • Foreign body inhalation

 

  • Upper Respiratory Tract Infection
  • Mild Asthma/COPD exacerbation
  • Postnasal Drip
  • GERD
  • Environmental Irritant
  • Environmental Allergies

Evaluation

  • History – Elicit the tempo of the cough illness and associated symptoms (F/C/NS, dyspnea, pleuritic chest pain, wheezing, rhinorrhea, pharyngitis, PND, orthopnea, postnasal drip, reflux).  Assess comorbidities (age>65, asthma, COPD, CHF, immunosuppression), medications, and tobacco/drug use.
  • Physical Exam – vital signs including O2 sat, facial tenderness, sinus drainage, erythematous oropharynx, murmur, S3, JVD, LE edema, wheezing, crackles, rhonchi, fremitus, egophony
  • Labs/tests – consider CXR if abnormal vitals (T>38, HR>100, RR>24, O2 sat<94%) OR focal lung findings (consistent with consolidation or effusion).
    • Patients >65 years, immunocompromised, or with pulmonary and cardiac comorbidities may present atypically with pneumonia and evaluation should be individualized.
  • Consider other common causes: second-hand smoke, bronchial hyperreactivity, ACE inhibitors, or allergic rhinitis causing postnasal drip.

Management

  • If acute infectious cough is suspected, be judicious with antibiotic use. Most studies show no benefit, the pathogen is likely viral, and antibiotic side effects are common.
  • If influenza is clinically diagnosed within 48 hours of onset, start antiviral treatment
  • If normal VS and normal exam, consider symptomatic treatment for acute bronchitis with bronchodilator, increased fluid intake, rest, and humidified air.
    • A 2014 Cochrane systematic review of 18 RCTs comparing various OTC cough preparations with placebo found no conclusive evidence of benefit of any OTC medicine, but found preparations to be generally safe.
    • A 2017 CHEST expert panel recommends against the use of OTC cough preparations given lack of evidence
    • There remains no convincing evidence that codeine is an effective cough suppressant.
  • If both abnormal vitals and a focal pulmonary exam are present, consider empiric antibiotics for PNA even if CXR is normal.
    • Triage patients for inpatient vs outpatient management with clinical prediction tool (eg. CURB-65)
      • CURB-65 (1 pt each for): Confusion, BUN>19mg/dl, RR>30, SBP<90mmHg OR DBP<60mmHg, Age>65 (consider inpatient for score>2)
  •  Advise rest, regular fluids, and home remedies as adjunctive therapy: lemon, honey, others.
  • Therapies:

1. Over-the-counter:

  • Dextromethorphan
    • mechanism: cough suppressant
    • Some studies show mild benefit, but overall evidence too weak to recommend use
  • Guaifenesin
    • also formulated w/ dextromethorphan
    • 1 of 2 trials (the larger trial) showed benefit but avoid using as monotherapy
    • mechanism: respiratory expectorant
  • Antihistamine/decongestant
    • mechanism: vasoconstriction
    • conflicting evidence for cough suppression, but increased side effects
    • ACCP guidelines recommend as initial empiric therapy for common cold/URI

​​2. Prescription:

  • Albuterol HFA
    • mechanism: beta-agonist bronchodilator
    • decreases symptom duration in acute bronchitis
  • Ipratropium bromide
    • mechanism: muscarinic antagonist bronchodilator
    • may attenuate cough related to URI or post-infectious cough
  • Codeine
    • mechanism: opiate cough suppressant
    • two trials show no difference vs placebo for cough duration
    • usually formulated w/ guaifenesin
  • Benzonatate
    • mechanism: anesthetizes respiratory stretch receptors
    • no trial data to support its use
  • Antibiotics
    • mechanism: varies
    • avoid if no evidence of PNA
    • macrolides (i.e. azithromycin 500mg PO x1, then 250mg PO daily x 4 days) or tetracyclines (i.e. doxycycline 100mg PO BID x 7 days)
    • fluoroquinolone (Levofloxacin 750mg PO daily x 5 days; or Moxifloxacin 400mg PO daily x 7 days) in chronically ill patients or those with recent therapy (within 3 months)
  • Oseltamivir
    • mechanism: inhibits flu neuraminidase
    • most effective when started within 36 hrs of flu symptom onset, 75mg PO BID x 5 days
    • while the FDA indication is within 48 hrs, the optimal cut-off in the trial was36 hrs
  • Zanamivir
    • mechanism: inhibits flu neuraminidase
    • Most effective when started within 36 hrs* of flu symptom onset, 2 puffs BID x 5 days
    • while the FDA indication is within 48 hrs, the optimal cut-off in the trial was 36 hrs

CHRONIC COUGH

Resident Editor: Ali Khaki, MD
Faculty Editor: Nat Gleason, MD

BOTTOM LINE

✔ >90% of cases are caused by upper airway cough syndrome, asthma, or GERD

✔ All patients should get a CXR and spirometry

✔  Screen for tobacco

✔  Remember ACE inhibitors

✔  Empiric dx/tx trials need weeks to months to be effective

Background

  • Chronic cough is defined in adults as a persistent cough lasting greater than 3 weeks. Some sources define cough as sub-acute if 3 - 8 weeks, and chronic if > 8 weeks.       

Differential Diagnosis

  • In 95% of immunocompetent patients, cough is due to one or more of the following (the first three are the most prevalent):

Upper Airway Cough Syndrome

Asthma

GERD

Acute bronchitis (with cough lasting just longer than 3 weeks)

Subacute post-infectious cough

Chronic bronchitis

Bronchiectasis

ACE inhibitors

Non-asthmatic eosinophilic bronchitis

  • Less common causes include CHF, emphysema, bronchogenic carcinoma, sarcoidosis, chronic aspiration, bronchiolitis, ILD, Pertussis or Mycobacterial infection, and foreign body. Rarely is cough caused by habit or psychogenic.

“The Big Three”

A. Upper Airway Cough Syndrome (aka post-nasal drip)

  • Symptoms: frequent throat clearing, history of nasal drainage (may be silent).
  • Physical exam: cobble-stoning on oropharynx, boggy nasal mucosa.
  • Diagnostics: trial of therapy first, before additional diagnostic workup.
  • Treatment:
  • Non-allergic: first generation (sedating) H1 blocker such as brompheniramine plus ipratropium (0.06%) nasal spray TID-QID for 3 weeks.  Once cough resolves, switch to nasal steroid.  Starting with nasal steroids or newer antihistamines may be less effective. 
  • Allergic rhinitis: Start with newer H1 blocker (loratadine or cetirizine) daily for 3-4 weeks.  Switch to nasal steroid if cough improves. 
  • Vasomotor rhinitis: Start with ipratropium nasal spray (0.06%) TID-QID for 3 weeks and then as needed.
  • If no response to initial therapy, consider referral (e.g. for allergy testing in apparent refractory allergic rhinitis)

B. Asthma (especially cough-variant asthma)

  • Cough is presenting symptom up to 57% of the time.
  • Symptoms: wheezing, cough worse in cold weather, with exercise, and/or at night
  • Physical exam: pulmonary exam noting I:E ratio and forced expiration, nasal exam for polyps
  • Diagnostics: Spirometry with beta agonist (methacholine challenge if normal spirometry but high suspicion)
  • Treatment: dependent on frequency of symptoms (refer to “Asthma” chapter for more information). Some societies suggest more aggressive treatment initially (ICS and bronchodilator ) to confirm diagnosis and resolve cough, then pulling back as tolerated.

C. GERD

  • Classic symptoms may be absent in up to 75% of patients.
  • Symptoms: frequent heartburn, cough worse at night, sour taste in mouth
  • Physical exam:  evaluate for alternative causes.
  • Diagnostics: trial of therapy.  Esophageal pH probes are difficult for patients but may be useful to confirm presence of reflux if medical therapy is not improving cough.   
  • Treatment: incorporates both lifestyle modification and medications (refer to “GERD” chapter for more information).  Need at least 3 months of treatment to see significant improvement and often 6 months for complete resolution of cough.

Evaluation

  • Initial evaluation should focus on the three most common causes (UACS, asthma, GERD).
  • Character of the cough has not been shown to be diagnostically useful.
  • History – ask about tobacco history, recent respiratory infections, medication usage (ACEi), and occupational exposures
  • Physical – evaluate ears for foreign bodies (Arnold’s Syndrome), nasal passages, eyes and face for signs of allergies (nasal crease, Dennie-Morgan folds, etc), posterior pharynx, trachea, as well as pulmonary and cardiovascular systems. 
  • Labs/tests – all patients should get a PA and lateral CXR and spirometry
  • Initial empiric therapy without clear etiology per history and exam should be UACS treatment, followed by asthma work-up and treatment
  • Further work up is guided by history, exam, and initial CXR. All patients who smoke should be counseled to quit, as cough of chronic bronchitis can improve with removal of the stimulus (tobacco smoke). 
  • Those on ACE inhibitors should be changed to ARBs or other medications for at least four weeks and then re-evaluated. 

When to Refer

  • Consider referral if the above three causes have been evaluated and empiric therapy has not improved symptoms.
  • Further testing may be necessary, including sputum studies or serologies, 24-hour pH probe, TTE, barium swallow, or CT scan.   
  • The CT scan to order depends on leading suspicion as COPD, ILD, and mycobacterial infection are all best evaluated with a HRCT.  Others require contrast for optimal evaluation.  Sarcoidosis may need both a HRCT and a CT with contrast.

References

Birring SS. Controversies in the evaluation and management of chronic cough. AJRCCM 2010 Dec 183: 708-715.

Michaudet,, et al.  Chronic Cough: Evaluation and Mangement.  Am Fam Physician. 2017 Nov 1;96(9):575-580.

“Chronic Cough.” New England Journal of Medicine, vol. 376, no. 2, Dec. 2017, pp. 183–184.

Cals JW, Francis NA. Acute cough in adults. BMJ 2010; 340:c222.

Desai D, Brightling C. Cough due to asthma, cough-variant asthma and non-asthmatic eosinophilic bronchitis. Otolaryngol Clin North Am. 2010 Feb;43(1):123-30.

Gonzales R, et al. Principles of appropriate antibiotic use for treatment of uncomplicated acute bronchitis: background. Ann Intern Med 2001;134:521.

Irwin RS, et al. Diagnosis and management of cough executive summary, Chest, 2006 January, 129:1S-23S.

Smith S, Schroeder K, Fahey T. Over-the-counter medications for acute cough in children and adults in community settings.  Cochrane Database Syst Rev. 2014 Nov 24;(11):CD001831