RECURRENT/PERSISTENT COUGH

Cough is a protective reflex to expel mucus or noxious substances, e.g. foreign body, dust, fumes and infectious agents from air passage by sudden and forceful expiration against partially closed glottis.

Cough reflex arc includes—(a) afferents from airways (pharynx to second-order bronchi), pleura, and ears,

(b) central cough center in medulla, and (c) efferents to laryngeal and respiratory muscles.

While acute cough is generally benign or self limiting, recurrent/persistent cough, though ill defined, needs detailed evaluation.

Etiology: Common causes of recurrent/persistent cough include—(a) infective, (b) allergic, (c) anatomical or obstructive, and (d) psychogenic or habit cough.

a. Infective cough is usually, but not always, associated with fever and indicates recurrent/persistent respiratory infections (RRTI/PRTI). RRTI generally refers to three or more documented attacks over 6 months, while PRTI denotes persistence of infection for gt; 4 weeks, despite treatment. Etiologically, RRTI/ PRTI may be due to environmental causes (re-infection from external source) due to re-activation/persistence of underlying pathology (Table 16.5).

b. Allergic cough may be due to intrinsic nasobronchial allergy, e.g. asthma, allergic rhinitis or environmental factors, e.g. air pollution, passive smoking, etc. Allergic cough is typically paroxysmal, wheezy and associated with positive family or environmental history.

c. Anatomical or obstructive cough is frequently laryngo­tracheal in origin, due to congenital or acquired airway abnormalities, e.g. foreign body, adenoids, etc. Cough is typically brassy or barking, stridor is common and

TABLE 16.5: Risk factors for RRTI/PRTI

• Environmental

- Overcrowding: Slums, orphanages

- Cross-infection in family/school

• Airway pathology

- Recurrent aspiration

Congenital anomalies: C left palate, TEF (H type) Neuromuscular: GER, C.

- Airway obstruction

Upper: Adenoids, nasal polyp

Lower: Asthma, mediastinal nodes, foreign body

- Defective mucociliary clearance

Kartagener syndrome, cystic fibrosis

Vitamin A deficiency

• Chronic lung diseases

- Tuberculosis, bronchiectesis, pertussis

- Partially-treated bacterial pneumonia

- Underlying lung cysts/hypoplasia

• Increased pulmonary vascularity

- Pulmonary hypertension, e.g. in CHDs, RHD

- Chronic renal disease (fluid overload)

• Immunodeficiency states

- Secondary: AIDS, PEM, steroid therapy

- Primary immunodeficiency disorders

• Others

- Allergic: Asthma, allergic rhinitis

- Vasomotor rhinitis or rhinitis medicamentosa

- Pollution: Environmental, passive smoking

TEF: Tracheoesophageal fistula; GER: Gastroesophageal reflux most cases present in early infancy or toddler age group.

d. Habit cough is common in older children, often as a residual lingering symptom after an attack of respiratory illness, which is typically—(a) refractory to treatment, (b) absent during sleep and when the child is unsupervised, and (c) without physical signs.

Diagnostic evaluation for recurrent/persistent cough or RRTI/PRTI includes:

• Detailed history regarding:

- Age of onset: Recurrent/persistent cough in early infancy indicates possible congenital anomaly, e.g. H-type tracheoesophageal fistula (TEF) or gastroesophageal reflux disease (GERD) while foreign body and pertussis are common in toddlers. Asthma, tuberculosis and suppurative lung diseases are common beyond older children.

- Character: Paroxysmal cough indicates asthma, pertussis and foreign body. Cough may be dry and hacking (URTI), brassy/barking (croup, habit cough), staccato (chlamydia) or hawking/throat clearing (post-nasal drip). Wet productive cough indicates parenchymal (pneumonia, bronchiectasis) or distal airway disorders (asthma, bronchitis).

- Sputum is mucoid in asthma, purulent in bron­chiectasis or lung abscess and blood-stained/rusty in pneumococcal pneumonia, foreign body, pertussis, bronchiectasis, tubercular cavity or mitral stenosis. Frank hemoptysis is uncommon, except due to cavitary tuberculosis in older children/adolescents.

- Diurnal/postural variations, e.g. morning cough (asthma, bronchiectasis), late-night cough (post­nasal drip, asthma, CCF), or cough bouts after change of posture (bronchiectasis, abscess).

- Presence of abnormal sounds, e.g. snoring (adenoids), stridor or rattling (laryngotracheal lesion), wheeze (asthma). Presence of grunt is a bad prognostic sign, indicating severe distress.

- Associated symptoms, e.g. fever (infective), exertional dyspnea (exercise-induced asthma or cardiac disease), persistent rhinorrhoea (adenoids, nasal polyp), sneezing (allergic rhinitis), etc.

- Family history of atopic disorders or contact with tuberculosis.

- Past history of sudden choking (foreign body) or similar episodes with treatment details.

- Environmental history suggestive of overcrowding, air pollution and passive smoking

- Dietary history-Top-fed infants are more susceptible for RRTI than breast-fed babies.

Clinical examination, including:

- General examination, specially for failure to thrive, clubbing (bronchiectasis, lung abscess) and central cyanosis (cardiac pathology), etc.

*To be avoided in children

- ENT examination to exclude local nasopharyneal pathology, adenoids and post-nasal drip.

- Chest examination to identify the type and location of pulmonary lesion

• Relevant investigations, including:

- Baseline investigation, e.g.

#9632; Blood counts for leukocytosis, eosinophilia

#9632; X-ray chest and sinuses

#9632; Tuberculin test

#9632; Sputum examination

#9632; Pulmonary function tests, to exclude asthma

- Selected investigations, e.g.

#9632; CT/HRCT

#9632; Milk scan to exclude GERD and H-type TEF.

#9632; Bronchoscopy with bronchoalveolar lavage

#9632; Sweat chloride test for cystic fibrosis

#9632; Microbiology/serology including HIV test

#9632; Lung biopsy in very rare cases

Management of recurrent/persistent cough depends on the identified etiology.

Non-specific cough remedies (Table 16.6) for sympto­matic relief, though frequently used in practice, are often not required. However, if necessary, single drug preparations should be preferred than irrational multidrug combinations, with following principles:

• Acute cough/coryza: Antihistaminic + Decongestant

• Persistent dry/irritating cough: Cough suppressants.

• Persistent wet cough/asthma: Mucolytics or mucokinetics.

16.4.2