The case describes a rare complication that occurred during flexible bronchoscopy - severe pneumoperitoneum (air in the abdominal cavity), mediastinal emphysema (air in the space between the lungs), and thoracoabdominal wall emphysema (air in the tissues of the chest and abdomen)[1]. The patient developed abdominal distension, abdominal distention, decreased oxygen saturation, and hemodynamic instability during the procedure performed under intravenous anesthesia with oxygen delivered through a nasopharyngeal cannula at a flow rate of 5 L/min[1]. Treatment included insertion of an endotracheal tube, administration of vasoactive drugs, and abdominal paracentesis (drainage of fluid from the abdomen)[1]. Imaging studies confirmed pneumoperitoneum, mediastinal emphysema, and emphysema of the thoracoabdominal wall, but no pneumothorax or endoscopically visible perforation of the gastrointestinal tract were detected[1]. The patient was finally discharged after improvement with conservative treatment[1]. The report emphasizes the need for vigilance against barotrauma (damage to tissues by excessive pressure) and careful management of oxygen delivery methods during bronchoscopy[1].