Cerebral Air Embolism Following Pigtail Catheter Insertion for Pleural Fluid Drainage
A 67-year-old man presented with dyspnea, cough and right-side chest pain that lasted for 2 days. Five years prior, he was diagnosed with chronic obstructive pulmonary disease at our hospital and had been receiving bronchodilator therapy. He was a current smoker with a 30-pack-year smoking history and was treated for pulmonary tuberculosis 2 years ago. Auscultation of the lungs revealed an inspiratory crackle at the right lower lung field. The blood pressure was 120/70 mm Hg, the pulse rate was 84 beats per minute, the respiratory rate was 18/min and the body temperature was 36.5℃. The arterial blood gas analysis showed pH 7.45, PaCO2 27.2 mm Hg, PaO2 59.0 mm Hg, HCO3 18.5 mmol/L, SaO2 92.2% at room air. The laboratory test results were white blood cells (WBC) count 16,400/mm3, hemoglobin 13.4 g/dL, platelets 194,000/mm3, and C-reactive protein 32.5 mg/dL. The chest radiograph revealed pneumonic infiltration in the right lower lobe. The chest computed tomography (CT) found emphysematous changes in the lung parenchyma and consolidation in the right lower lobe with a right pleural effusion (). Antibiotic treatment failed to improve the right pneumonic infiltration and pleural effusion. Furthermore, a loculated fluid collection was discovered, so a pigtail catheter was inserted for pleural fluid drainage. The pigtail catheter was placed through a guide wire after thoracentesis. Pleural fluid analysis showed pH 8.0, red blood cells 460,000/mm3, WBC 1,220/mm3 (neutrophil 90%, lymphocyte 10%), protein 6.1 g/dL (plasma 7.8 g/dL), lactate dehydrogenase 176 IU/L (plasma 203 IU/L), and glucose 63 mg/dL. This finding was compatible with parapneumonic effusion, and hemothorax was suspected. As soon as the pigtail catheter was inserted, the patient complained of impaired vision. A few minutes later, he lost consciousness and had a generalized seizure. A brain CT scan was performed immediately and showed multiple low densities in the right occipital lobe, which were interpreted as gas emboli (). Cerebral air emboli were diagnosed. High concentration oxygen inhalation therapy was initiated and he was placed in the right lateral decubitus position. About 20 minutes after the pigtail catheter insertion, the seizure stopped. However, the patient's consciousness did not improve and his respiratory rate began to decline. Auscultation was no different from the first time. The arterial blood gas analysis showed pH 7.34, PaCO2 46.2 mm Hg, PaO2 114.3 mm Hg, HCO3 20.4 mmol/L, and SaO2 99.8%. Mechanical ventilation was initiated and conservative treatment was maintained in the intensive care unit. In a chest X-ray performed after the start of mechanical ventilation, the amount of right pleural effusion had decreased and there was no pneumothorax. No air leak was found through pigtail catheter. After initiation of mechanical ventilation, diffusion-weighted image and fluid attenuated inversion recovery image of brain magnetic resonance image showed no abnormal findings, such as cerebral infarction, cerebral edema or other lesions causing the seizure after pig tail catheter insertion. Electroencephalography also did not show any epileptiform discharge. Fundoscopic examination showed no abnormal findings of the retina, such as air embolism. On the next day, his consciousness was fully recovered after conservative treatment including mechanical ventilation and high-flow oxygen therapy. His pneumonia also improved with conservative treatment. He was discharged without any neurologic complications.