What is the appropriate evaluation and management of a 9‑month‑old male infant presenting with subcutaneous emphysema of the neck and upper chest?

Evaluation and Management of Subcutaneous Emphysema in a 9-Month-Old Infant

Immediately assess airway patency and breathing, deliver high-flow oxygen to both the face and any potential airway opening, and urgently investigate for pneumomediastinum, pneumothorax, or iatrogenic airway injury as the underlying cause, because subcutaneous emphysema in an infant signals air dissecting from a breach in the respiratory tract that can rapidly compromise ventilation.

Initial Assessment and Stabilization

Airway and Breathing Evaluation

• Position the infant in a neutral head-and-shoulder alignment with a small pillow or rolled towel under the shoulders to optimize upper airway patency 1
• Look, listen, and feel for airflow at the mouth and nose, assessing for signs of respiratory distress including stridor, accessory muscle use, tracheal tug, and intercostal recession 2
• Apply high-flow oxygen immediately to the infant's face using appropriate delivery devices 1
• Monitor oxygen saturation continuously, with immediate escalation if SpO2 falls below 94% 3

Clinical Signs Requiring Immediate Intervention

• Agitation, restlessness, or changes in level of consciousness indicate hypoxia and demand urgent airway intervention 3
• Increasing work of breathing, tachypnea, or bradypnea signal impending respiratory failure 3
• Rapidly expanding subcutaneous emphysema suggests ongoing air leak that may progress to tension pneumothorax 4

Diagnostic Evaluation

Imaging Studies

• Obtain chest radiography (anteroposterior view) immediately to identify pneumomediastinum, pneumothorax, or pneumopericardium 2, 5
• Chest CT with contrast should be performed if initial radiography is equivocal or if surgical intervention is being considered, as it defines the extent of air dissection and identifies underlying structural injuries 2
• Ultrasound can rapidly detect pneumothorax at the bedside in unstable patients 2

Identify the Underlying Cause

At 9 months of age, subcutaneous emphysema most commonly results from:

• Iatrogenic airway injury (recent intubation, central line placement, or airway procedures) 4
• Blunt neck or chest trauma, even seemingly minor 6, 7
• Esophageal perforation from foreign body or instrumentation 6
• Rib fracture with parenchymal lung injury (consider non-accidental trauma) 6
• Rarely, spontaneous alveolar rupture in the setting of severe coughing or respiratory illness 5, 8

Management Strategy

Conservative Management (Stable Patient)

Most cases of subcutaneous emphysema in children resolve spontaneously with conservative treatment 5, 8:

• Admit for close observation with continuous cardiorespiratory monitoring 5
• Administer supplemental oxygen to accelerate nitrogen washout and air resorption 5
• Provide adequate analgesia with acetaminophen 15 mg/kg every 4-6 hours (maximum 650 mg) or ibuprofen 10 mg/kg every 6-8 hours (maximum 400 mg) 3
• Monitor for progression of emphysema every 3 hours during the first 4 days, as new or worsening emphysema signals ongoing air leak 1
• Obtain serial chest radiographs to document resolution, typically within 2 weeks 5

Surgical Intervention (Unstable Patient or Identified Structural Injury)

• If pneumothorax is present and causing respiratory compromise, insert a chest drain under ultrasound guidance 2
• Esophageal perforation requires urgent surgical consultation for repair and drainage 7
• Tracheal or laryngeal injury necessitates immediate otolaryngology and anesthesiology involvement for definitive airway management 7

Critical Pitfalls to Avoid

• Never attempt positive pressure ventilation (bag-mask or mechanical) through a potentially compromised airway without first confirming patency, as this can massively worsen subcutaneous emphysema and cause cardiovascular collapse 2, 1
• Do not dismiss minor trauma history in infants; seemingly trivial neck or chest impacts can cause significant aerodigestive injury 7
• Avoid delaying imaging in a stable patient—early identification of pneumomediastinum or pneumothorax guides appropriate monitoring intensity 5
• Do not discharge the patient until emphysema is clearly resolving and underlying cause is identified or confidently excluded 5

Red Flags Requiring Immediate Escalation

• Respiratory distress with oxygen saturation <94% despite supplemental oxygen 3
• Hemodynamic instability or signs of tension pneumothorax (hypotension, distended neck veins, tracheal deviation) 4
• Rapidly progressive emphysema extending beyond the initial distribution 1
• Fever or signs of infection suggesting mediastinitis or empyema 9
• Any bleeding from the mouth, nose, or neck suggesting vascular injury 1

Follow-Up and Safety Netting

• Repeat chest radiography in 1-2 weeks to confirm complete resolution of air collections 5
• Educate caregivers on signs of deterioration: increased work of breathing, color change, lethargy, or refusal to feed 5
• If spontaneous pneumomediastinum is diagnosed, investigate for predisposing factors including undiagnosed airway disease or anatomic abnormalities 8