What is the most likely diagnosis for a pediatric patient presenting with a barky cough, cyanosis, spells of breath-holding, and a monophasic wheeze without inspiratory stridor?

Most Likely Diagnosis: Tracheomalacia

The most likely diagnosis is tracheomalacia (Option B), given the presentation of barky cough, cyanosis, breath-holding spells, and a monophasic wheeze without inspiratory stridor. This clinical picture points to dynamic collapse of the trachea during expiration rather than laryngeal or bronchial pathology.

Key Diagnostic Features Supporting Tracheomalacia

The absence of inspiratory stridor is the critical distinguishing feature. 1

• Dynamic lesions of the trachea (tracheomalacia) typically cause expiratory symptoms and monophasic wheeze, whereas fixed lesions or laryngeal pathology produce biphasic stridor 1
• Laryngomalacia, the most common cause of chronic stridor in infants, characteristically presents with inspiratory stridor, not the expiratory wheeze described here 1, 2
• The monophasic wheeze indicates airway collapse during a single phase of respiration (expiration in tracheomalacia), distinguishing it from the polyphonic wheeze of asthma 1

Clinical Presentation Analysis

The constellation of symptoms fits tracheomalacia:

• Barky cough can occur with tracheomalacia, though it's also seen in croup and psychogenic cough 1
• Cyanotic episodes and breath-holding spells are consistent with central airway obstruction causing "BPD or CLDI spells" seen in tracheomalacia 1
• Chronic wheezing unresponsive to bronchodilator therapy is a hallmark of tracheomalacia, as the structural collapse cannot be reversed by bronchodilators 1

Why Other Options Are Less Likely

Bronchitis/bronchiolitis (Option A) would present with:

• Polyphonic expiratory wheeze, not monophasic 1
• Response to bronchodilators in many cases
• No breath-holding spells or severe cyanosis typically

Laryngomalacia (Option C) is excluded by:

• Absence of inspiratory stridor, which is the defining feature of laryngomalacia 1, 2, 3
• Laryngomalacia causes inspiratory collapse of supraglottic structures, not expiratory wheeze 2, 3

Bronchial asthma (Option D) is unlikely because:

• Asthma produces polyphonic wheeze (multiple airways of different caliber), not monophasic 1
• The European Respiratory Society guidelines state that localized monophonic wheeze suggests structural abnormality or foreign body, not diffuse bronchospasm 1
• Breath-holding spells and severe cyanosis are not typical asthma presentations

Critical Diagnostic Considerations

Flexible bronchoscopy is indicated to confirm tracheomalacia and evaluate for concomitant abnormalities:

• Up to 68% of children with airway obstruction have additional abnormalities below the epiglottis 1, 2
• Flexible bronchoscopy is superior to rigid bronchoscopy for assessing airway dynamics because less positive pressure is applied 1
• Indications include persistent/unexplained wheezing unresponsive to therapy, cyanotic episodes, and monophasic wheeze 1

Common Pitfalls to Avoid

• Do not diagnose asthma based on wheeze alone without considering structural causes when the wheeze is monophasic 1
• Do not assume all barky cough is croup—tracheomalacia can present similarly but lacks the acute viral prodrome and has chronic symptoms 1
• Do not miss the significance of absent inspiratory stridor—this essentially rules out laryngeal causes 1, 2