Pneumomediastinum After Laparoscopy

Pneumomediastinum after laparoscopy is carbon dioxide in the mediastinum that tracks from the abdomen or retroperitoneum through diaphragmatic openings (hiatus, congenital defects) or from lung injury. It is usually benign and self-limited.

Epidemiology. It is rare (under 1%), seen after laparoscopic fundoplication, hiatal hernia repair, oesophageal surgery and long procedures. Most cases are found incidentally on imaging.

Risk factors. Hiatal and diaphragmatic surgery, operation time over 200 minutes, high insufflation pressure, positive pressure ventilation with barotrauma, extraperitoneal approach and congenital diaphragmatic defects.

Pathophysiology.

Carbon dioxide passes along fascial planes into the mediastinum through the aortic or oesophageal hiatus, or via tracheal or lung injury. Tension pneumomediastinum compresses the great veins and heart (similar to tamponade).

Often none. Possible: chest pain, dyspnoea, neck swelling or crepitus, Hamman sign (crunching sound synchronous with heartbeat), hypotension, desaturation and rising end tidal carbon dioxide. Tension pneumomediastinum causes collapse.

Red flags.

• Hypotension with rising central venous pressure.
• Dysphagia or fever (oesophageal injury).
• Severe chest pain.
• Spreading emphysema to the neck.

Chest radiograph (air lines along the mediastinum, continuous diaphragm sign) and CT (more sensitive). Exclude oesophageal perforation with water soluble contrast study or CT with oral contrast if fever, pain or sepsis. Bronchoscopy if tracheal injury is suspected.

Differential diagnosis.

• Oesophageal perforation.
• Tracheobronchial injury.
• Pneumothorax.
• Pneumopericardium.
• Pulmonary embolism.
• Myocardial infarction.

Reduce intra-abdominal pressure to the lowest effective level, desufflate if unstable, and increase ventilation to clear carbon dioxide. Give 100% oxygen to speed absorption.

Uncomplicated cases resolve in 3 to 7 days with observation, analgesia and monitoring.

• Paracetamol: 1 g orally every 6 hours; maximum 4 g daily; reduce in hepatic impairment or under 50 kg.

Treat associated pneumothorax with a chest drain and tension with mediastinal decompression (surgical, by thoracic team). Treat oesophageal or tracheal injury surgically with broad antibiotics:

• Piperacillin-tazobactam: 4.5 g IV every 6 hours for 7 to 14 days; maximum 18 g daily; monitor renal function and counts; reduce for creatinine clearance under 40 mL/min.

Monitoring. Haemodynamics, saturation, temperature and chest radiograph at 24 hours.

Referral and escalation. Thoracic surgery and critical care for tension or suspected perforation.