3 DISCUSSION
Bilateral pneumothorax due to COVID-19 has not been widely reported in the literature so far. The pathophysiology for the development of pneumothorax in patients with COVID-19 is unclear; however, cystic and fibrotic structural changes caused by COVID-19 may be related4. In addition to this, treatment with positive pressure by non-invasive or mechanical ventilation in patients with severe COVID-19 infection may contribute to the development of pneumothorax5. Systemic corticosteroids exhibit anti-inflammatory and anti-fibrotic effects in patients with severe COVID-19 infection. However, corticosteroid therapy may also cause a delay in the wound healing process of pneumothorax6. There is no established treatment strategy for secondary spontaneous pneumothorax due to COVID-19. Surgical intervention presents a better outcome than tube thoracostomy in simultaneous bilateral primary spontaneous pneumothorax7. However, in some patients surgical intervention for pneumothorax may pose high risk from the perspective of general and respiratory condition. In patients with poor general condition and who are not fit for surgery, refractory pneumothorax must be cured by other internal therapies. Internal treatments for pneumothorax include procedures such as chest drainage, pleurodesis, endobronchial approach8. In some cases, it is important to combine multiple methods. We decided that our patient’s general condition was not good enough to operate. Thus, the combination bronchial occlusion and pleurodesis relieved the patient’s bilateral refractory pneumothorax. Bronchial occlusion using an EWS® is one of the most effective and minimally invasive treatments for secondary refractory pneumothorax, postoperative pulmonary fistula, fistulous empyema, and bronchial fistula in patients with poor general condition. Bronchial occlusion alone or in combination with pleurodesis for secondary refractory pneumothorax, postoperative pulmonary fistula, or fistulous empyema enabled drain removal in 57.1% to 86.0% of patients9-11.
Mitsuyama et al. reported that autologous blood patch pleurodesis may be a treatment option for recurrent and refractory pneumothorax secondary to COVID-1912. In our case, pleurodesis with MINO and OK-432 was ineffective, whereas the one with autologous blood was effective. Pleurodesis with autologous blood has fewer side effects than that with other drugs such as OK-432, talc, glucose and minocycline hydrochloride13 Therefore, pleurodesis with autologous blood is a better strategy for refractory pneumothorax in patients with poor general condition after severe COVID-19 infection. In case of inoperable patients with refractory pneumothorax after severe COVID-19 infection, bronchial occlusion and pleurodesis can be key treatment strategies.