Non‐surgical pneumoperitoneum associated with mechanical ventilation

Non-surgical pneumoperitoneum from an intrathoracic route is the most frequently reported cause in non-surgical peritoneal air collection.1, 2 The true incidence of pneumoperitoneum associated with mechanical ventilation is unknown, but current estimates range from rare to 7% of intubated patients in the intensive care unit. This complication may lead to unnecessary laparotomy, however, if correctly diagnosed, it can be observed successfully without surgical intervention. We experienced a patient with subcutaneous emphysema, mediastinal emphysema, and pneumoperitoneum in whom coughing may have had a causative role, which was recognized and was managed without laparotomy. A 40-year-old female was transferred to our hospital due to loss of consciousness following a suicide attempt (hanging) and an overdose of anti-anxiety medicine. Although her vital signs were stable at admission, the patient was intubated, sedated, and ventilated in the intensive care unit, as her Glasgow Coma Scale score was 3 (E1, V1, and M1). Assisted ventilation was used with a fractional inspired oxygen concentration (FiO2) of 0.4 and a positive airway pressure of 5 cm H2O or less. On the second day of admission, she was alert with strong spontaneous breathing on the ventilator. Routine chest and abdominal X-ray revealed pneumothorax and pneumoperitoneum. Computed tomography scan of the chest and abdomen confirmed the presence of free intraperitoneal air without free fluid (Fig. 1). The patient was not symptomatic and had no fever or dyspnea. The abdomen was soft and flat without guarding or distension. Leukocytosis was present, with a white cell count of 16.1 × 103 /mm3. Serum electrolytes, urea, creatinine, and amylase levels were normal. Based on the diagnosis of pneumoperitoneum and pneumothorax due to barotrauma during mechanical ventilation, the tracheal tube was removed and a chest tube was placed on suction. The management included broad-spectrum antibiotics and careful observation. The patient made an uneventful recovery and was discharged home 13 days after admission. Images of computed tomography scans on day (d) 1 (on admission), 2, and 5 of a 40-year-old female who was intubated, sedated, and ventilated in the intensive care unit following a suicide attempt (hanging) and an overdose of anti-anxiety medicine. Although free air was not seen on day 1, computed tomography scan of the chest and abdomen confirmed the presence of free intraperitoneal air without free fluid under the diaphragm (arrows). Left chest tube was inserted on day 2. Pneumoperitoneum was almost cleared with conservative management. We retrospectively reviewed cases of non-surgical pneumoperitoneum during mechanical ventilation between January 1990 and December 2013.3, 4 A review of published reports found using a MEDLINE computer search revealed 115 adult cases. All published cases of pneumoperitoneum related to mechanical ventilation were associated with either pneumothorax or pneumomediastinum or both, and usually these complications preceded the development of pneumoperitoneum. It is noteworthy that simple pneumothorax is not always associated with pneumoperitoneum as intra-abdominal pressure normally exceeds intrathoracic pressure during both inspiration and expiration and prevents the spread of air. Surprisingly, 57 of the 115 reported cases underwent surgical treatment without evidence of perforated viscus. In the present case, free or interstitial air from above the diaphragm may dissect along mediastinal planes to the retroperitoneum and rupture into the peritoneal cavity, possibly producing pneumoperitoneum.5 However, the reports of pneumoperitoneum are still rare, even following tension pneumothorax. In conclusion, non-surgical pneumoperitoneum may be an uncommon complication of mechanical ventilation. To avoid unnecessary surgical procedures, both intensive care physicians and surgeons need to recognize non-surgical causes of pneumoperitoneum associated with mechanical ventilation. Needless to say, conservative management is warranted in the absence of symptoms and signs of peritonitis. None.