Re-expansion pulmonary edema post-pneumothorax

Abstract

Re-expansion pulmonary edema (REPE) is an uncommon complication that occurs in patients suffering from lung collapse, especially in cases of extensive and long-term pneu-mothorax or pleural effusion. After thoracentesis or thoracic tube drainage is carried out, the collapsed lungs can be re-expanded and acute lung edema occurs in unilateral or even bilateral lungs within a short time. Although the reported incidence of REPE is <1% [1], it can have life-threatening consequences, as reported in some studies [2]. In this article, we present the case of a young male patient who developed REPE after suffering traumatic pneumothorax. A 37-year-old man was transferred to the emergency department with severe destructive injuries, namely a com-minuted fracture of the lower right femoral shaft, ruptures of the lower right femoral artery and vein and avulsion of skin and soft tissue in the right lower limb. Eight hours earlier, the patient was hit by a twisted cable rope. The patient was admitted to the burn and trauma intensive care unit. On admission, his vital signs were as follows: heart rate, 88/min; blood pressure, 85/52 mmHg; respiratory rate, 18/min; pulse oximetric saturation (SpO 2), 99%; and arterial blood partial pressure of oxygen (PaO 2), 176 mmHg. The chest X-ray was normal (Figure 1a). The laboratory tests showed a hemoglobin level of 72 g/L (normal range: 120-160 g/L) and a hematocrit of 19.5% (normal range: 42-49%). Resuscitative measures were carried out immediately. Despite emergency femoral artery and vein repair surgery being carried out immediately, the patient's distal lower extremity showed ischemic manifestations 1 day post-surgery. After comprehensive evaluation, including vascular ultrasound and computed tomography angiography, amputation of the right leg above the knee was performed under general anesthesia with endotracheal intubation. On the second day after surgery, the SpO 2 of the patient was decreased gradually from 100% to 88%. The situation did not improve with increasing oxygen concentration. Blood gas analysis indicated that the PaO 2 had dropped to 81 mmHg. Physical examination showed right thorax fullness and silent right breath sounds. Rapid chest X-ray showed severe right pneumothorax (Figure 1b). A chest drain was inserted into the right pleural cavity under ultrasound guidance at the intersection of the fourth intercostal line and the right anterior axillary line for continuous closed thoracic drainage (−0.3 kPa), although the cause of pneumothorax was not very clear. On the following day, the patient suffered worsening respiratory distress and his SpO 2 declined. Chest X-ray examination showed successful pulmonary re-expansion and right lung edema (Figure 1c). Based on the clinical and radiological findings, a diagnosis of REPE was made. The patient subsequently received comprehensive treatment measures, including limited fluid input, diuretics, sedation, analgesia and mechanical ventilation with high positive end expiratory pressure (PEEP). His pulmonary function completely recovered 3 days later, and a further chest X-ray showed clear bilateral lung fields (Figure 1d). REPE is considered an iatrogenic complication occurring in patients who undergo rapid re-expansion of collapsed lungs following pleural effusion and pneumothorax. REPE was first reported after thoracentesis in 1853, and after pneu-mothorax treatment in 1958 [3]. Since then, there have been several reports of REPE following pleural fluid aspiration and pneumothorax. Although the pathophysiological mechanism of REPE has not yet been clarified, it is generally believed that increased vascular endothelial permeability and destruction of microvessels are the most important potential mechanisms [4]. Lung collapse induced by pleural effusion and pneumoth-orax can lead to histological abnormalities, such as thickening of the pulmonary microvasculature. When the lung is re-expanded, especially when undergoing a large amount of