Approach to Cough

Definitions: Subacute cough: 3–8 wk; Chronic cough: >8 wk
Epidemiology: Cough is common symptom-based visit complaint (NHAMCS 2010, cdc.gov)
Pathophysiology: Cough receptors found in airways, lung parenchyma, tympanic membranes, esophagus, & pericardium; cough is reflex w/ cortical control (may be initiated or suppressed voluntarily); cough mechanism involves diaphragm, glottis, & muscles of expiration
Etiology: Varies by duration, can include airway (upper airway cough syndrome [UACS]), HEENT, GI, and CV causes

Evaluation

General approach: Hx/exam to screen potential etiologies; if none discovered → trial of empiric tx for either UACS (upper airway cough syndrome), asthma, or GERD
History: Often nonspecific; ask about onset (post-URI), duration, triggers (after meals—GERD, allergens—asthma); Red flags: Wt loss, hemoptysis, systemic sx
- Assoc sx: Postnasal drip, sinusitis, hoarseness, reflux sx, edema
- PMHx: Atopy, GERD, CHF, immunocompromise, CA, TB exposure/RF
- Meds/toxins: ACEI, βB, smoking status/exposure, occupational/environmental exposures
Physical exam: VS: Incl SaO2, HEENT: Auditory canal foreign body, nasal polyps (asthma), cobblestoning (UACS); Pulm: wheezes, crackles; Cardiac: volume overload, valvular disease; Extremities: clubbing
Diagnostics: If dx not suggested by above (e.g., ACEI) → CXR; given that most chronic cough 2/2 GERD, UACS, or asthma, may be deferred in nonsmokers until failure of 1st-line empiric tx; further studies (PFTs, CBC, sinus films) as per Ddx (below)

Subacute cough: Postinfectious cough (48%), infectious sinusitis (33%), asthma (16%) (Chest 2006;129:1142; NEJM 2006;355:2125)
- Postinfectious cough: Respiratory tract infection → postnasal drip, tracheobronchitis; resolves w/o tx; average duration of bronchitis-associated cough is 24 d
- Sinusitis: See “Sinusitis”
Chronic cough: Often multifactorial; may require tx of multiple causes

Etiology	Management/Notes
Smoking	Tx: Smoking cessation; see “Tobacco Use”
ACEI	Sx can occur 1 wk–6 mo after starting Rx; cough resolves w/in 2–4 wk of discontinuation of Rx
UACS (34%)	Allergic or nonallergic rhinitis, sinusitis Tx: See “Allergic Rhinitis”
Cough-variant asthma (28%)	Dx: PFTs (for cough, may start w/ trial of empiric SABA tx) Tx: See “Asthma”
GERD	Dx/Tx: Empiric trial of PPI; see “Gastroesophageal Reflux Disease”