Airway management: induced tension pneumoperitoneum

Pneumoperitoneum is not always associated with hollow viscus perforation. Such condition is called non-surgical or spontaneous pneumoperitoneum. Intrathoracic causes remain the most frequently reported mechanism inducing this potentially life threatening complication. This clinical condition is associated with therapeutic dilemma. We report a case of a massive isolated pneumoperitoneum causing acute abdominal hypertension syndrome, in a 75 year female, which occurred after difficult airway management and mechanical ventilation. Emergent laparotomy yielded to full recovery. The recognition of such cases for whom surgical management can be avoided is primordial to avoid unnecessary laparotomy and its associated morbidity particularly in the critically ill.


Introduction
Pneumoperitoneum (PP) commonly indicates a perforated hollow viscus that requires prompt surgical exploration and intervention [1]. However, cases of nonsurgical PP have also been reported.
Ventilator induced barotrauma appears to be the most common underlying condition resulting in this kind of PP also termed spontaneous [1]. In these cases, the PP is often well tolerated and accompanied by pneumothorax and/or pneumomediastinum and/or subcutaneous emphysema. We report a case of isolated, compressive and poorly tolerated PP due to mechanical ventilation.
This condition has opposed a double challenge, not only mechanism understanding but also management.

Patient and observation
A 75-year-old female was admitted in the medical ICU for a sudden onset severe coma related to acute ischemic stroke complicating persistent atrial fibrillation after a short course in the cardiology department. She was obese (BMI, 36kg/m 2 ). She had no surgical past history and she experienced no other recent complaints especially gastrointestinal. On first examination by the resuscitation team, the patient was in a comatose state with GCS at 3/15. She was afebrile. She had blood pressure at 90/40mmHg and heart rate at 140bpm. She had no dyspnea. White blood cells count was 7500/mm 3 and CRP, 8mg/L. Airway management has been performed by a young trainee after a rapid sequence induction using hypnomidate (20mg) and suxamethonium (100mg).
Mallampati classification [2] was graded III and Cormack-Lehane classification [3] graded III. At the first attempt the tube was misplaced in the esophagus, and then relayed as soon by endotracheal intubation. Mechanical ventilation under sedation was undertaken with assist-control ventilation (ACV) mode with a tidal volume set at 8ml/kg ideal body weight, respiratory rate at 16/min,

Discussion
Non-surgical pneumoperitoneum (NSP) is a commonly described entity but not always recognized by physicians. Its prevalence is estimated at 5 to 15% [4]. Most cases of NSP occur as a procedural complication such as endoscopic procedures, peritoneal dialysis catheter placement or as a complication of medical intervention such as thoracic causes including ventilatory support and cardiopulmonary resuscitation [4]. Apart from the existence of diaphragmatic defects, the most likely mechanism of air entry into the peritoneum results from ruptured alveoli adjacent to the mediastinum. With the increasing pressure, the air dissects along anatomical fascial planes in the mediastinal structures into the retroperitoneum. The pressurized air then enters the peritoneal cavity through the mesentery [5]. This mechanism is called the "Macklin" effect [6]. In these cases, PP is usually well tolerated and associated with pneumothorax or pneumomediastinum [7]. In The diagnostic approach of NSP is usually facilitated by the chronological relationship between the procedure likely to cause and its occurrence. Indeed, in the present case, the PP onset in the hour following the airway management and mechanical ventilation startup was very suggestive [5]. However, the fact that it was the only manifestation of barotrauma is rare, which represents one of the originalities of the reported case. The fact that, in the present case, there was neither per-procedural cough effort nor high airway pressure, prompted us to think that the origin of the air leak would

Competing interests
The authors declare no competing interests.