Bronchial Stenting and High-Frequency Percussive Ventilation Treatment of Descending Aortic Aneurysm-Induced Atelectasis of the Left Lung

A 34-yr-old man was admitted to the intensive care unit after a reoperative aortic valve replacement and mitral valve reconstruction. The patient also had an aneurysmatic aortic dissection of the descending aorta extending from the left subclavian artery into the iliac vessels. No physical signs of Marfan’s syndrome were present. The postoperative chest radiograph showed a broadening of the cardiac silhouette to the left (Fig. 1A); however, oxygenation was normal, and the patient was quickly weaned from mechanical ventilation. A few hours after tracheal extubation, the patient developed acute respiratory failure (Spo2 84% with O2 12 L/min by face mask) and was reintubated and mechanically ventilated. A subsequent chest radiograph revealed a pneumothorax, a pleural effusion, and atelectasis of the left lung (Fig. 1B). However, despite immediate drainage by a chest tube, atelectasis persisted, and arterial oxygenation was seriously compromised (Fig. 2; t1). Bronchoscopic examination showed a stenosis of the left main bronchus and purulent mucus in the distal airways of the left lung; the chest radiograph showed persistent atelectasis (Fig. 1C). Piperacillin-sulbactam was started to prevent imminent pneumonia. Cultures of bronchial aspirates were later found to be sterile. In the following 3 days, the patient was mechanically ventilated with an assisted mode. He received intensive percussive physical therapy and large doses of mucolytics (ambroxol 1 g/d and acetylcysteine 1800 mg/d) and was repeatedly suctioned bronchoscopically. However, the atelectasis persisted, and oxygenation remained compromised (Fig. 2; t2). Additionally, he developed fever and leucocytosis. A thoracic computed tomography scan showed pulmonary infiltrates in the atelectatic left lung compatible with bronchopneumonia and the descending aorta compressing the left main bronchus. Additionally, increasing infiltrates were also observed in the right lung. Because the risk of an emergency replacement of the descending thoracic and abdominal aorta was deemed to be unacceptably high, a self-expandable uncovered endobronchial nitinol stent (Ultraflex; length, 4 cm; diameter, 12 mm; Boston Scientific Corp., Natick, MA) was implanted according to the recommendations of the manufacturer into the left main bronchus by specialists of the respiratory care unit. The procedure was performed with rigid bronchoscopy under fluoroscopic control during general anesthesia. After the procedure, gas exchange was still moderately compromised during airway pressure release ventilation (Fig. 2; t3), a chest radiograph showed persisting atelectasis (Fig. 1D), and high-frequency percussive ventilation (HFPV) was started 4 h after stent implantation. The device used (VDR-4-G Servolator; Percussionaire Corp., Vienna, Austria) combines pressure-controlled ventilation with superimposed high-frequency oscillations induced by a flow interrupter, leading to a percussion effect and an increase in mean airway pressure without increasing peak airway pressure. The respiratory rate (15 to 20 breaths/min) and the percussive frequency (550 to 650/ min) were adjusted to achieve normocapnia (Fig. 2; t4). Sedation was performed with a continuous infusion of propofol, and analgesia was achieved with piritramide administered intermittently. After 36 h, the chest radiograph revealed that the left lung was fully ventilated (Fig. 1E), and airway pressure release ventilation was reinstituted (Fig. 2; t5). The patient was weaned from mechanical ventilation 48 h later and was successfully discharged on Day 12 after surgery.