Bilateral spontaneous pneumothorax in a non-intubated COVID-19 patient

Spontaneous bilateral pneumothorax is a rare condition occurring only in 1,3% of cases of spontaneous pneumothorax. Although spontaneous pneumothorax is recognized complication of COVID it is usually associated with severe cases of COVID pneumonia with massive lung involvement and a high level of inflammatory cytokines – so called "inflammatory storm". Large percentage of this patients requires life support with mechanical ventilation and pneumothorax is usually accompanied with pneumomediastinum. Nevertheless occurrence of spontaneous pneumothorax in non-intubated patients is very low. Therefore the presented case is exceptional in two ways – spontaneous pneumothorax occurred in non-intubated patient and is presented bilaterally. Early diagnosis of spontaneous bilateral pneumothorax can pose a diagnostic dilemma as it mimics progression of lung involvement in the course of COVID, pulmonary embolism or myocardial infarction. In our case apart from COVID pneumonia, patient had typical clinical presentation of myocardial infarction and known coronary artery disease, which initially mislead clinicians toward diagnosis of myocardial infarction (MI). However after exclusion of MI, chest radiograph was requested which revealed bilateral pneumothorax. The exact mechanism of pneumothorax development in non-intubated patients is not clear. Lung inflammation in COVID causes formation of pneumatocele, which can predispose to spontaneous pneumothorax. It is important to note that our patient developed pneumothorax without evident pneumatocele, underlying lung condition or history of trauma. This case shows that bilateral pneumothorax in COVID-19 can develop also in patients with only mild clinical course of COVID pneumonia. Early diagnosis and proper management is essential and can prevent life-threatening complications.

Spontaneous bilateral pneumothorax is a rare condition occurring only in 1,3% of cases of spontaneous pneumothorax. Although spontaneous pneumothorax is recognized complication of COVID it is usually associated with severe cases of COVID pneumonia with massive lung involvement and a high level of inflammatory cytokines -so called "inflammatory storm". Large percentage of this patients requires life support with mechanical ventilation and pneumothorax is usually accompanied with pneumomediastinum. Nevertheless occurrence of spontaneous pneumothorax in non-intubated patients is very low. Therefore the presented case is exceptional in two ways -spontaneous pneumothorax occurred in non-intubated patient and is presented bilaterally. Early diagnosis of spontaneous bilateral pneumothorax can pose a diagnostic dilemma as it mimics progression of lung involvement in the course of COVID, pulmonary embolism or myocardial infarction. In our case apart from COVID pneumonia, patient had typical clinical presentation of myocardial infarction and known coronary artery disease, which initially mislead clinicians toward diagnosis of myocardial infarction (MI). However after exclusion of MI, chest radiograph was requested which revealed bilateral pneumothorax. The exact mechanism of pneumothorax development in non-intubated patients is not clear. Lung inflammation in COVID causes formation of pneumatocele, which can predispose to spontaneous pneumothorax. It is important to note that our patient developed pneumothorax without evident pneumatocele, underlying lung condition or history of trauma. This case shows that bilateral pneumothorax in COVID-19 can develop also in patients with only mild clinical course of COVID pneumonia. Early diagnosis and proper management is essential and can prevent life-threatening complications.

Case
78-year old female patient diagnosed with SARS-CoV-2 for 7 days was admitted to the hospital with sudden shortness of breath and tightness of chest. At presentation saturation was 85%. After application of oxygen mask with reservoir with flow rate 5 l/min saturation increased to 98%. Clinical examination showed no abnormalities. Medical history of coronary artery disease and hypertension treated with Ramipril 10 mg since 2010. Laboratory results reveled normal troponin and CK-MB levels. NT-pro BPN was level was 1580 pg/mL (borderline for 78 year old patient). D-dimers level was 1370 ng/ml. Based on clinical and laboratory findings myocardial infarction was excluded and further diagnosis in CXR was requested.

Discussion
The described case is exceptional in two ways -spontaneous pneumothorax occurred in the disease with only mild lung involvement and is presented bilaterally.
Although spontaneous pneumothorax is recognized complication of COVID it is usually associated with severe cases of COVID pneumonia with massive lung involvement and high level of inflammatory cytokines -so called "inflammatory storm". Large percentage of this patients requires life support with mechanical ventilation and pneumothorax is usually accompanied with pneumomediastinum.
The exact mechanism of pneumothorax development in non-intubated patients is not clear. Lung inflammation in COVID causes formation of pneumatocele, which can predispose to spontaneous pneumothorax. There are documented cases of pneumatocele formation as well as its progression and spontaneous rupture in COVID (3). Although formation of pneumatocele is largely facilitated by mechanical ventilation, there are documented cases of spontaneous pneumothorax in patients without mechanical ventilation (4).
In SARS-CoV-1 patients spontaneous pneumothorax was more often reported in patients with neutrophilia, severe lung involvement and grave clinical course (5). However in study on SARS-CoV-2 only high leucocyte count was associated with pneumothorax. Other inflammatory cytokines such as C reactive protein, procalcitonin and D-Dimers did not significantly differ in patients with and without pneumothorax (6). Other study performed on SARS-CoV-2 patients without mechanical ventilation linked pneumothorax only to male gender (4).
It is important to note that our patient developed pneumothorax without evident pneumatocele or underlying lung condition.
Pneumothorax in COVID studies often proves to have grave prognosis (7), especially in older studies of SARS-CoV-1 patients (5,8). Nevertheless all this studies were conducted on patients on mechanical ventilation, which significantly worsens treatment of pneumothorax. Although there is a very limited data on the prognosis of COVID patients with pneumothorax without mechanical ventilation, available date suggests much better prognosis, with survival rate of 63% (4). Due to extremely rare occurrence of bilateral pneumothorax in COVID patients without mechanical ventilation, there are no clinical studies to compare our case with.
Bilateral spontaneous pneumothorax can also be the result of unilateral pneumothorax with congenital connection between pleural cavities causing the air to pass to the contralateral side. This abnormality is often referred to as "buffalo pneumothorax" and has usually worse prognosis than unilateral pneumothorax of the same size.
This case shows that bilateral pneumothorax in COVID-19 can develop also in patients with only mild clinical course of COVID pneumonia. Early diagnosis and proper management is essential and can prevent life-threatening complications.