Cough

Question 1

Describe the cough reflex

Answer 1

Stimuli- mechanical (FB, dust), chemical (smoke, acetic acid), or inflammatory mediators (histamine, bradykinin, prostaglandin) - interact with cough receptors in the upper and lower airways to cause production of mediators (tachykinins, neurokinin A)
Stimulation of the cough receptors is transmitted via the vagus nerve to the “cough center” of the brainstem (the pons)
The efferent limb includes the spinal cord from C3-S2, the spinal nerves, and the recurrent laryngeal nerve (for glottic closure)
Activation of the efferent pathway causes constriction of the expiratory muscles - producing increased airway pressure against the closed glottis - airway narrows slightly and when the glottis opens suddenly - air is expelled with high velocity clearing the airway of secretions and foreign material

Question 2

How can we suppress cough?

Answer 2

Largely involuntary

Morphine - impact cough center
Inhalation of lido neb - suppresses the cough receptors

Question 3

DDx of persistent cough by age

Answer 3

Infancy

• Infection: viral, bscterial, chlamydial, pertussis
• Anatomic abnormalities: tracheomalacia, vascular rings
• Cystic Fibrosis
• Bronchopulmonary dysplasia (premature infants)

Preschool (1-5 years)

• Asthma
• Infection: viral, bacterial, chlamydial, pertussis
• FB aspiration
• Cystic Fibrosis

School Age (>5-18 years)

• Asthma
• Infection: viral, bacterial, chlamydial, pertussis
• Smoking
• Psychogenic causes (habit cough)

NOT:
- GERD

Question 4

What is a staccato cough classic for?

Answer 4

Chlamydia trachomatis

A dry, rapid fire, repetitive cough with inspiration in between every cough

Presents as an insidious, afebrile, pneumonitis in infants 3 weeks to 3 months
CXR - bilateral infiltrates
Conjunctivitis in half of kids with it
Peripheral eosinophilia
Tx- PO Erythromycin
Tx associated with pyloric stenosis in infants younger than 4-6 weeks

Question 5

What is a paroxysmal cough classic for?

Answer 5

Pertussis

Whooping cough - paroxysms of coughing followed by an inspiratory whoop

4 classic stages
1 - Incubation stage
- ASmxtc, 7-10 days
2 - Catarrhal stage
- Viral URI, 1-2 weeks
3 - Paroxysmal stage
- Coughing paroxysms, whoop, 1-6 weeks 
4- Convalescent stage
- gradual recovery with possible recurrent exacerbations, 2-12 weeks

Contagious from the onset of the catarrhal stage to 3 weeks into the paroxysmal stage
Infants may present with only poor feeding, apnea and bradycardia

Early treatment before the catarrhal stage with macrolide antibiotics may decrease symptoms
Treatment at any time within 21 days of the onset of cough will decrease transmission

Question 6

What do you worry about in a toddler with a persistent cough after a choking episode?

Answer 6

FB aspiration

Question 7

Describe what a habitual cough is

Answer 7

Habit, psychogenic or tic cough
A type of conversion reaction
Often huge discrepancy between child’s reaction and caretaker - caretaker is “at end of rope”
Honking cough, harsh, loud, impossible to ignore

Question 8

What is the weirdest cause of a persistent cough?

Answer 8

Eyelash in the ear canal

Stimulates the auditory branch of the vagus nerve but does not cause pain or obstruct hearing