From the Guidelines
Pneumomediastinum is most commonly caused by airway trauma, such as difficult intubation, which can lead to air leaking into the mediastinum. This condition can be characterized by symptoms such as severe sore throat, deep cervical pain, chest pain, dysphagia, and painful swallowing, as well as fever and crepitus 1. The causes of pneumomediastinum can be categorized into several groups, including:
- Trauma to the chest or neck
- Medical procedures, such as mechanical ventilation, bronchoscopy, or esophagoscopy
- Underlying lung diseases, such as emphysema, interstitial lung disease, or pneumonia
- Recreational drug use, particularly cocaine, marijuana, or inhalants
- Rare causes, such as Boerhaave syndrome (esophageal rupture) and alveolar rupture from pressure changes during scuba diving or rapid ascent to altitude
According to the Difficult Airway Society guidelines, airway trauma most commonly involves the larynx, pharynx, and oesophagus, and can be difficult to diagnose, with pneumothorax, pneumomediastinum, or surgical emphysema present in only 50% of cases 1. It is essential to closely monitor patients for warning signs, such as stridor, obstructed pattern of breathing, agitation, and resulting from surgery, and to inform them about the symptoms of mediastinitis, and advise them to seek medical advice should they occur. The "Macklin effect" is a mechanism by which air escapes from ruptured alveoli and travels along bronchovascular sheaths into the mediastinum, leading to pneumomediastinum 1.
From the Research
Causes of Pneumomediastinum
- Pneumomediastinum can result from physical trauma or other situations that lead to air escaping from the lungs, airways, or bowel into the chest cavity 2
- It can also be caused by spontaneous pneumomediastinum, esophageal injuries, pneumothorax, and airway injuries 3
- The condition may be associated with mediastinal organ injury, including airway injuries and esophageal injuries 3
- Predictors of esophageal injury include instrumentation, pleural effusion, and vomiting, while previous instrumentation is a significant predictor of airway injury 3
- Pneumomediastinum can occur in up to 10% of patients with blunt thoracic and cervical trauma 4
- Incidental pneumomediastinum is a common radiologic finding following blunt thoracic injury, but the clinical significance of pneumomediastinum on screening imaging is poorly defined 5
Types of Injuries Associated with Pneumomediastinum
- Aerodigestive injuries, including tracheobronchial injuries and esophageal injuries 4, 5
- Laryngeal injuries, tracheal disruptions, and esophageal perforations 4
- Airway injuries and esophageal injuries in patients with spontaneous pneumomediastinum 3
Diagnosis and Treatment
- Pneumomediastinum can be diagnosed via chest X-ray or CT scanning of the thorax 2
- CT scan is the preferred screening tool for airway injury in patients with pneumomediastinum 4
- Highly selective workup is warranted in patients with isolated findings of pneumomediastinum on screening chest X-ray or CT following blunt trauma 5
- Most pneumomediastinums are treated conservatively, as the tissues in the mediastinum will slowly resorb the air in the cavity 2