Pneumothorax has been reported in a few patients with coronavirus disease 2019 (COVID-19), although the exact incidence and risk factors are still unknown. Retrospective studies of patients with COVID-19 have suggested that pneumothorax might occur in 1% of those requiring hospital admission, 2% of patients requiring intensive care unit (ICU) admission and 1% of patients dying from the infection.1 The clinical presentation of SARS-CoV-2 infection is variable. Most of the patients develop fever and cough. The diagnosis is confirmed by reverse transcription–PCR (RT-PCR). Several literatures described the radiologic hallmarks of COVID-19 on chest CT scan such as groundglass opacity patterns (peripheral, nodular, or mass-like). The other reported features include bronchiectasis, lymphadenopathy, and pleural and pericardial effusion, but pneumothorax is either uncommon or underreported in patients with COVID-19. In addition, Chen et al. first reported pneumothorax as a rare radiologic feature in 1% of 99 patients, early in the pandemic. Thus, the prompt identification and management of pneumothorax is essential.3
Pneumothorax is defined as the presence of air in the pleural cavity. Pneumothorax can be categorized by etiology which are spontaneous and traumatic, and spontaneous pneumothorax can be further characterized into primary or secondary. Primary spontaneous pneumothorax occurs in patients with no background of respiratory disease, and the pathophysiology is thought to be from asymptomatic blebs and bullae which disrupt due to shear force. Secondary pneumothorax occurs in patients with underlying lung abnormality and lung diseases. Pulmonary barotrauma is another cause of iatrogenic pneumothorax occurring in patients being mechanically ventilated due to high inspiratory inflation pressures.2 Tension pneumothorax which is a medical emergency develops when damaged tissue forms a one-way valve leading into the accumulation of air in the pleural space with inhalation. This results in rising volume of air and pressure in the affected hemithorax, leading to collapse of the affected lung and displacement of the mediastinum towards the contralateral side. As the mediastinal shift exerts pressure on the contralateral lung and the vena cava, resulting in respiratory insufficiency, cardiovascular compromise, and death if untreated.2
Patients with COVID-19 infection can develop severe pneumonia leading to acute respiratory distress syndrome (ARDS). Their disease is characterized radiographically by ground glass opacities, evolving into consolidative changes and in late stages of the disease, fibrotic changes. Similar changes including severe lung injury and diffuse alveolar damage were thought to contribute to the mechanism of spontaneous pneumothorax complicating severe acute respiratory syndrome (SARS). These changes, in addition to possible overdistention of the alveoli by using mechanical ventilation may put patients at risk for developing pneumothorax. In addition, it is possible that the triggering factor is prolonged coughing, which is a predominant symptom of COVID-19 disease.4 In a journal by Zantah et al., an underlying pulmonary disease is the primary risk factor for the development of secondary spontaneous pneumothorax. These include chronic obstructive pulmonary disease with emphysema, cystic fibrosis, tuberculosis, lung cancer, HIV associated Pneumocystis jiroveci pneumonia, and other pulmonary cystic lung diseases.4
In a case series by Martenelli (2020), the study includes ventilated and non-ventilated patients, pneumothorax with COVID-19 found out that it occurs even in patients with no pre-existing lung disease and does not require positive-pressure ventilation. Demographically they stated that, cases are atypical for either primary spontaneous pneumothorax, being of average height with 48% aged between 60 and 80 years, or secondary pneumothorax, with few having significant pre-existing respiratory disease or significant smoking history. The case series suggests the complication of pneumothorax is more prevalent in males (3.3:1); large series of patients with COVID-19 suggest that males are more commonly affected by severe forms the disease, which may account for this observation.1 In another case series by Al-Shokri et al, the occurrence of pneumothoraces were reported on day 2, 7 and 15. The probability that pneumothorax occurs in the setting of COVID-19 pneumonia may result from advanced alveolar damage, bronchiolar distortion and narrowing caused by SARS-CoV-2 leading to pulmonary bullae formation. Moreover, the severe cough associated with viral infections increases the intrapulmonary pressure. This may precipitate bullae rupture and pneumothorax formation. 3
In addition to Chest radiograph, chest CT has a high sensitivity in suggesting pulmonary involvement from SARS-CoV-2 infection. The most common and early radiological findings of COVID-19 pneumonia are ground-glass opacities with a multi-lobular, bilateral and peripheral distribution. CT also highlights consolidations, air bronchogram and crazy paving pattern. Both pleural effusion and pneumothorax are rare findings. Spontaneous pneumothorax is reported in only 1% of cases with a higher prevalence (88%) in men.6
In summary, the main cause of pneumothorax in patients with COVID-19 are cystic lesions, which could occur as a result of barotrauma due to mechanical ventilation, and alveolar damage due to coughing, which causes an increase in chest pressure and ultimately an alveolar breach. Moreover, COVID-19 pneumonia results in alveolar swelling, inflammation of alveolar septa, fibrosis, giant bullae and subpleural infiltrates. All of these conditions contribute to parenchymal damage with possible alveolar rupture and pneumothorax. A review of the literature shows that pneumothorax is an uncommon complication that occurs predominantly during active SARS-CoV-2 infection and it is scarcely reported after the recovery from the disease. This means that even after the infection is overcome, severe complications are still possible.6
Pneumothorax can be an emergency. It can easily be diagnosed by physical examination and chest radiograph. In conclusion, the reported cases of COVID-19 pneumonia can be complicated by pneumothorax and also can occur after recovery from the disease. The timely diagnosis and management will reduce COVID-19–associated morbidity and mortality.3 It is therefore necessary to maintain a high level of attention in monitoring patients who have overcome active infection, and to exclude pneumothorax in case of sudden respiratory symptoms appearance.6
