Subcutaneous Emphysema After Laparoscopy

Subcutaneous emphysema after laparoscopy is tracking of insufflated carbon dioxide into subcutaneous tissue. It is usually benign and self-limited, but can signal more serious problems (pneumothorax, pneumomediastinum, pneumopericardium).

Epidemiology. It occurs in about 0.4% to 2.3% of laparoscopic procedures (higher with extraperitoneal surgery, hernia repair and prolonged operations), and 2% to 3% of laparoscopic cholecystectomies.

Risk factors. Operative time over 200 minutes, multiple trocar insertions, trocars loosely seated, high insufflation pressure (over 15 mmHg), extraperitoneal insufflation, high end tidal carbon dioxide, old age, extraperitoneal surgery (hernia, prostatectomy), and trocar placement at the edge of the field.

Pathophysiology.

Gas dissects along fascial planes from the peritoneum or preperitoneal space or through defects of the diaphragm. Carbon dioxide absorbed through tissue raises arterial carbon dioxide and causes respiratory acidosis.

Crepitus on the abdominal wall, chest, neck or face, swelling, rising end tidal carbon dioxide (over 50 mmHg), high airway pressures, and in extreme cases airway compromise and facial swelling. Patients are often asymptomatic.

Red flags.

• Rapid spread to the neck and face with airway swelling.
• End tidal carbon dioxide rising over 60 mmHg.
• Hypotension, desaturation or arrhythmia (pneumothorax, tamponade).
• Chest pain.

Clinical. Chest radiograph for pneumothorax or pneumomediastinum, blood gas for hypercapnia, ultrasound of lungs and pericardium, and CT for suspected organ injury (tracheal, oesophageal, bowel).

Differential diagnosis.

• Pneumothorax.
• Pneumomediastinum.
• Airway or oesophageal injury.
• Bowel perforation.
• Gas gangrene (fever, severe pain, toxicity).
• Anaphylaxis (swelling).

Reduce pressure to 8 to 10 mmHg or desufflate, increase minute ventilation to clear carbon dioxide (target end tidal 35 to 45 mmHg), and suspend surgery if instability occurs. Check airway swelling before extubation, and delay extubation if the neck or face is swollen. Gas is usually reabsorbed in 24 to 72 hours.

Treat pneumothorax with a chest drain and tension pneumothorax with immediate needle decompression. Antibiotics are not needed, unless infection (gas gangrene is suspected from fever, pain and rapid spread, and needs surgery and broad antibiotics).

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

Prevention. Use the lowest effective insufflation pressure, minimise trocar changes, secure trocars, limit operating time and monitor end tidal carbon dioxide.

Monitoring. Extent of emphysema, end tidal carbon dioxide, blood gas, saturation, and neck swelling until resolved.

Referral and escalation. Senior help, thoracic or ENT review for pneumothorax, airway compromise or suspected injury.