Multi-loculated pneumothorax post COVID-19 pneumonia.

Discussion

Spontaneous pneumothorax has been reported as a complication of COVID-19, in about 1.7% of the patients, however multi-loculated pneumothorax is an uncommon finding. The proposed mechanisms of spontaneous pneumothorax in COVID-19 disease are the structural changes in the lung parenchyma, extensive pulmonary injury, pulmonary infarction leading to cavitation, and progression of areas of consolidation to bulla. , Loculated pneumothorax is a diagnostic dilemma as it can mimic tension pneumothorax, bullous disease, giant pneumatocoele or tension gastrothorax clinically or radiologically.

A 56-year-old male patient, diabetic, hypertensive, and case of coronary artery disease, with prior coronary artery bypass surgery, presented to the emergency department with sudden onset shortness of breath associated with left-sided chest pain. On examination, the patient was tachypneic with a respiratory rate of 30 per minute, room air oxygen saturation of 78%, and heart rate of 124 beats per minute. The patient was propped up and started on supplemental oxygen via non rebreather face mask which improved his SpO2 to 98%. On further examination, there was diminished breath sounds on the left side of the chest. One and a half months prior to presentation, the patient was diagnosed to have severe COVID-19 pneumonia with a CT severity index of 20/25 (more than 50 to 75% involvement in bilateral mid and lower lung zones) and CORAD-6 indicating high level of imaging suspicion for COVID-19 infection with positive RT-PCR for COVID-19. During admission for COVID-19 illness, he was managed with escalating and de-escalating oxygen therapy including non-invasive ventilation, antiviral (Injection Remdesvir), intravenous antibiotics, anti-coagulation, steroids, and other supportive measures. The patient had improved, was weaned off oxygen therapy and was discharged on room air saturation of 96%. During this visit, patient's ECG was suggestive of sinus tachycardia, cardiac biomarkers were within normal limits, and arterial blood gas analysis was suggestive of type 1 respiratory failure. His-Chest X-ray (description in Fig. 1 ) and computed tomography of thorax (described in Fig. 2, Fig. 3 ) revealed CT-severity index of 22/25 (owing to lung fibrosis from previous COVID infection) and multi-loculated hydro pneumothorax. The patient was managed with image-guided chest tube insertion and improved subsequently.

Fig. 1

Chest X-ray.

Fig. 2

NCCT Thorax (Axial view).

Fig. 3

NCCT Thorax (Coronal view).

An acute deterioration with rapid desaturation in a patient of COVID-19 or post-COVID patient could indicate a pneumothorax. An important differential to consider in sudden onset shortness of breath associated with pleuritic chest pain in post- COVID patients is pulmonary embolism. The overall incidence of pulmonary embolism in COVID-19 patients was 13% and as high as 19% among ICU patients.

Imaging is crucial to differentiate the above; especially a loculated pneumothorax from giant bullae. Radiologically, bullae appear as avascular radiolucent areas with thin curvilinear walls of less than 1 mm thickness, masquerading pneumothorax. CT is regarded as the ‘gold standard in the detection of small pneumothoraces and in size estimation. CT scans are more sensitive than chest x-rays in diagnosing bullae. The double-wall sign distinguishes pneumothorax from a giant bulla. This sign occurs when air outlines both sides of the bulla wall parallel to the chest wall and may not be seen on all CT slices. USG may show absent lung sliding in cases of sub-pleural bullae, hence not a specific modality to differentiate between the two.

Our patient was managed with supportive care and ultrasound-guided intercostal drainage with 16 French thoracostomy tube. Image-guided chest tube insertion is the management of loculated pneumothorax causing respiratory distress . USG, CT Chest, and fluoroscopy may be the imaging techniques used to guide pneumothorax drainage. While failure of clinical improvement in loculated pneumothorax may require VATS (Video Assisted Thoracoscopic Surgery) guided intervention, inadvertent thoracostomy tube placement in a large cavity or bullae may cause broncho-pleural fistula (BPF) resulting in prolonged hospital stay and secondary complications in the patient.

Visual discussion

Chest X-ray reveals multiple large thick-walled cavities throughout the left hemi thorax with complete obscuration of the broncho-vascular markings of the left lung (denoted by red pointers) with the displacement of the mediastinum towards the right side. The left diaphragmatic silhouette is not well defined. Another large radiolucency is seen in the abdominal cavity likely dilated stomach (denoted by R2). Multiple patchy opacities are seen in the periphery of the right lung.

Figure 2: NCCT Thorax (Axial view) & Figure 3: NCCT Thorax (Coronal view)

Non-enhanced computed tomography thorax shows right-side heterogeneous areas of ground-glass opacities with associated fibrosis (blue pointer) in the lower lobe. The left side shows multiple hypo dense lesions in the pleural cavity, not-communicating with bronchus, with the intact diaphragm, and an air-fluid level (axial section) suggestive of hydro pneumothorax (denoted by red pointer).

Questions and answers with a brief rationale

Question 1

Which of the following radiological signs may suggest diagnosis of pneumothorax in a patient?

1: Continuous diaphragm sign

2: Double wall sign

3: Deep sulcus sign

4: Lung point sign

Answer Options:

1 & 2

1, 2 & 3

1, 3 & 4

2, 3 & 4

3 & 4

Correct Answer = d

Explanation: Double wall sign in the chest occurs when air outlines both sides of bulla wall parallel to the chest wall and may not be seen in all CT slices. This sign helps in differentiating giant bulla from pneumothorax. Deep sulcus sign is seen in supine chest radiograph. The cost phrenic angle is abnormally deepened when the pleural air collects anteriorly & in basal region when patient in supine position, producing the deep sulcus sign (1). The ‘lung-point sign’ is a point of care Ultrasound sign, which occurs at the border of a pneumothorax, due to sliding lung intermittently coming into contact with the chest wall during inspiration. It is 100% specific for pneumothorax and defines its border (2). However continuous diaphragm sign is a radiographic sign of pneumomediastinum (if lucency is above the diaphragm) or pneumoperitoneum (if lucency below the diaphragm).

Question 2

Which of the following is a highly sensitive & Gold standard test for diagnosing small pneumothorax?

Answer Options:

Ultrasonography (USG)

Computed tomography (CT Scan)

Chest radiograph – upright position

Chest radiograph – Supine position

Fluoroscopy

Correct Answer = b

Explanation: CT scan is the most sensitive test to detect small pneumothorax; which if missed has the potential to expand and cause hemodynamic compromise especially with positive pressure ventilation. Bedside USG is found to be very sensitive to detect pneumothoraxes, however needs to be performed by trained clinician for early detection (18–20 ml of intra-pleural air). The sensitivity of bedside lung USG increases with the volume of air in pleural cavity (above 50 ml) even with novice users. Chest-X-ray is the least sensitive modality for early detection of pneumothorax (requiring at least 400 ml of intra-pleural air) even when interpreted by trained clinicians or radiologists (3).

Reference:

H, M., Bell, D. Deep sulcus sign (chest). https://doi.org/10.53347/rID-13294

Husain LF, Hagopian L, Wayman D, Baker WE, Carmody KA. Sonographic diagnosis of pneumothorax. J Emerg Trauma Shock. 2012;5(1):76–81. doi:10.4103/0974–2700.93116

Oveland NP, Søreide E, Lossius HM, Johannessen F, Wemmelund KB, Aagaard R, et al. The intrapleural volume threshold for ultrasound detection of pneumothoraces: An experimental study on porcine models. Scand J Trauma Resusc Emerg Med Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3602194/

Declaration of Competing Interest

The authors have no conflict of interests.