Chronic Cough

A cough over 2-weeks duration that has not begun to improve won’t be viral.  Over 3-weeks duration is chronic.  Our Differential is listed below.

CHRONIC COUGH

Not Pulmonary

Pulmonary

*  =  Conditions which may occur, resolve, and recur  [vs. a more continuous “cough”]

Step 1 for patient with Chronic Cough  —  Get a Chest X-Ray (CXR).  Always.

Almost always.  After taking a history & performing an initial exam, I DON’T get a CXR if the patient has:

  • Lots of Upper Respiratory Sx.  Give a therapeutic trial for Allergic Rhinitis.
  • Lots of Reflux Sx.  Give a therapeutic trial for GERD.
  • Findings strongly suggestive of Asthma.  Dx it & Tx.
  • If they’d just begun an ACE-Inhibitor.  [change it]
  • If the patient gives a convincing history of dyspnea on exertion, get a CXR no matter what.

A word about the “therapeutic trial”: we really mean a diagnostic trial of therapy.  If you want to see if treatment “x” helps, thus helping confirm diagnosis, give a good solid dose of your best med.  For GERD, try high-dose PPIs.  For allergic rhinitis, combine an H1-Blocker with a nasal steroid.  If you go for less, & it doesn’t help, you won’t know if it failed due to insufficient Tx or wrong Dx.  Should your trial work, you can always scale back therapy in a couple of weeks.

So now let’s assume we’ve eliminated the non-pulmonary possibilities, and are concerned that our patient’s chronic cough is due to lung disease.  Get a CXR — it’ll R/O TB & other pneumonias, and may find lung cancer, interstitial lung disease [ILD], and other uncommon conditions.  The only time I don’t get a CXR for chronic cough that’s not clearly upper respiratory, is when I have clinical reason to suspect Bronchospasm, primarily Asthma.

The rest of this discussion deals with patients who have a chronic cough and normal CXR.

BRONCHOSPASM

 The main reason I consider Asthma is if I auscultate wheezes, rhonchi, or merely a prolonged expiratory phase.  A history of similar episodes in past years clinches it.  I give a trial of inhaled bronchodilator; the more convinced I am, the more I’d recommend controller therapy.  But a few qualifications:

Chronic Bronchitis presents just like asthma.  Think of it in a smoker or a farmer.  Diagnosis is empiric.  Immediate treatment is the same, except that purulent sputum warrants antibiotics.  The main difference is in long-term management, employing anti-cholinergic inhalers.  When you have a smoker with ostensible asthma, seek a history compatible with “COPD”:

  • Daily cough >3 months, >2 years in a row
  • Especially if past exacerbations have involved thick green sputum

See our prior posting for Acute Cough-2.

Don’t forget “Cardiac Asthma,” i.e. Congestive Heart Failure which presents with wheezes instead of rales.  Consider it in a patient with new onset sub-acute cough and cardiac risk factors.  This presentation is pretty unusual.  See posting Acute Dyspnea – 3.

If a patient has a new cough for several weeks, I think of Pertussis.  Wheezing is uncommon, but possible.  However, by 2 weeks of illness, treatment only helps prevent transmission, not ameliorate symptoms.  And most transmission happens during the first two weeks of cough, & the prodrome before.   See Acute Cough – 1.

Finally, I’m very reluctant to use the word “Asthma” the first time a patient has a cough lasting several weeks or even months.  There’s no way to tell the difference between asthma [a chronic condition with undesirable label] and Bronchospasm Due to Post-Viral Inflammation [which may last a while, but won’t recur].  So I say that treatment is the same, time will tell, as I try to project optimism.  One patient with serologically-documented Mycoplasma pneumonia wheezed on and off for 3 years, and suddenly it all resolved, never to return.

Hypersensitivity Pneumonitis causes recurrent bouts of cough, sometimes with fever.  Lungs usually sound clear; rales are much more common than wheezes.  We’ll discuss this below.

If your patient with ostensible asthma, wheezing away, doesn’t respond to treatment, get a CXR.

NO BRONCHOSPASM

Anyone with clear lungs and cough ≥3 weeks’ duration that’s not improving needs a CXR.  More so if you hear rales.  A CXR is 100% sensitive for chronic lung infections such as TB or fungal diseases.  It’ll find bronchiectesis and a whole host of obscure entities; it may not make the final diagnosis, but will reveal some abnormality that’ll lead down the path to CT and maybe bronchoscopy.  It’s very good for a lung cancer that causes cough [screening asymptomatic smokers for lung cancer is different].

In fact, clear lungs plus a normal CXR is so reassuring that no other work-up is required except in a few cases:

  • A strong smoking history (>30 pack-years), asbestos exposure, or hemoptysis require a CT.
  • A clear history of dyspnea on exertion mandates PFTs.
  • Voice changes require an ENT referral.
  • Stroke patients, the debilitated, and others at risk for aspiration should be evaluated by speech pathologists, and may require CT ± bronchoscopy to R/O a foreign body.
  • Environmental exposures require a work-up for Hypersensitivity Pneumonitis.

One study found among 84 adults with chronic cough and normal CXRs who didn’t smoke or take ACE-Inhibitors, 99.4 % had upper airway disorders, asthma, and/or GERD.

Go for a therapeutic trial based on best-guess among the three.  For patient with nasal symptoms, treat for Allergic Rhinitis.  For asthma, you can always obtain PFTs pre- and post-bronchodilator, or request a methacholine challenge test if you want.  DO NOT diagnose “chronic sinusitis” without a CT, or you’ll find yourself throwing around a lot of unnecessary antibiotics.

A new entity has been described, Nonasthmatic Eosinophilic Bronchitis, diagnosed by biopsy.  A sputum specimen positive for eosinophils may be a useful surrogate.  The condition is very similar to “Cough Asthma” (asthma presenting with cough alone, & no other findings), the latter includes a positive methacholine challenge, without bronchial eosinophils.

Both respond to inhaled steroids.  In our clinical world, if we suspect asthma etc. as the cause of chronic cough, give an albuterol inhaler.  If it doesn’t help or suffice, give a trial of inhaled steroids.  Avoid the biopsy unless you get research dollars.

I hate Hypersensitivity Pneumonitis (HP), one of those conditions which lack easy diagnosis until irreversible damage has occurred.  It’s a environmental disease of parenchyma (not airway) that may mimic asthma in terms of intermittent exacerbations, but requires completely different management.

HP is common among farmers [“farmer’s lung”], especially in humid climates, & perhaps common among bird fanciers [“pigeon breeder’s lung” — those who host birds, not just “fancy” them].  Outbreaks have occurred among office workers [“humidifier lung”], lifeguards [“lifeguard lung”], & autoworkers.  There are long lists of culprits such as “mushroom worker’s lung,” “paprika slicer’s lung,” “sauna taker’s lung,” “mummy handler’s lung,” “bible printer’s lung,” etc…..

The key to diagnosis of HP depends on obtaining an occupational and a vocational history.  Recurrent symptoms of cough, dyspnea, malaise, fever, and/or nausea begin 4-8 hours after exposure, and resolve in 12 hours to several days after removal.  Crackles on auscultation add likelihood, wheezes are rare.  CXR is usually normal; commercial lab tests unreliable.  Subacute and chronic HP present with cough, dyspnea, and [more ominously] weight loss.

A high-resolution chest CT may point to the diagnosis, but may also be normal at a point where reversibility is possible.  If you work with farmers who don’t easily respond to bronchodilators, or if you otherwise think you have a case, send patients to pulmonology.  They may know a lab that can make a home brew of the patient’s actual exposure and run immunologic tests.

One last comment about the chronic cough — if symptoms are progressive, especially if dyspnea is involved, be more aggressive in your work-up [including CTs, PFTs, and referral].

And a final comment.  In terms of GERD, some studies suggest it’s debatable as to whether it can cause a chronic cough.  Still, clinicians all think “yes.”  It’s a diagnosis of exclusion.  Give a therapeutic trial if you want, while you work up more serious stuff [if they have symptoms of GERD, simply give therapy!].  If their cough disappears, great!!  BUT… have a little intellectual sincerity to keep placebo effect in mind.

See also our postings Acute Cough – 1 (upper respiratory conditions), and Acute Cough – 2 (lower resp.).

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