Article Information

Katarzyna Zimna*, Malgorzata Sobiecka, Katarzyna Lewandowska, Dorota Wyrostkiewicz, Monika Szturmowicz, Ewa Lyzwa, Katarzyna Blasinska, Lilia Jakubowska, Kazimierz Roszkowski-Sliz, Witold Tomkowski

I Department of Lung Diseases, National Tuberculosis and Lung Diseases Research Institute, Warsaw, Poland

^*Corresponding Author: Katarzyna Zimna, I Department of Lung Diseases, National Tuberculosis and Lung Diseases Research Institute, Warsaw, Poland.

Received: 09 November 2022; Accepted: 17 November 2022; Published: 01 December 2022

Citation:

Zimna K, Sobiecka M, Lewandowska K, Wyrostkiewicz D, Szturmowicz M, Lyzwa E, Błasinska K, Jakubowska L, RoszkowskiSliz K, Tomkowski W. Air Spaces in Patients Diagnosed with COVID-19 Pneumonitis- A Rare Complication. Journal of Radiology and Clinical Imaging 5 (2022): 71-77.

Abstract

Keywords

COVID-19,Thoracotomy, Pneumatocele,World Health Organisation (WHO)

Article Details

Abbreviations:

ARDS- Acute Respiratory Distress Syndrome; CM- Centimeter; COPD- Chronic Obstructive Pulmonary Disease; COVID-19- Coronavirus Disease 2019; CPAP- Continuous Positive Airway Pressure; CRP- C-Reactive Protein; CT- Computed Tomography; CTPA- Computed Tomography Pulmonary Angiography; DIC- Disseminated Intravascular Coagulation; ESBL- Extended Spectrum Beta-Lactamase; HFO₂T- High-Flow Oxygen Therapy; ICU- Intensive Care Unit; l/min- Liter Per Minute; LMWH- Low Molecular Weight Heparin; ML- Milliliter; NIC- Non-Invasive Ventilation; NT-proBNP- N-Terminal Prohormone of Brain Natriuretic Peptide; RT-PCR- Reverse Transcription Polymerase Chain Reaction; Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2); VATS- Video-Assisted Thoracic Surgery; VV-ECMO- Venous-Venous Extracorporeal Membrane Oxygenation; WHO- World Health Organisation

1. Introduction

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was initially reported to the World Health Organisation (WHO) on December 31^st, 2019. As the cases of disease increased rapidly, WHO declared COVID-19 as a global pandemic [1]. Since then more than 489 million cases and more than 6 million deaths have been reported worldwide [2]. Mild to moderate cases with the clinical symptoms such as fever, dry cough, myalgia and fatigue could be community-managed. However, severe cases of viral pneumonia, which may be accompanied by Acute Respiratory Distress Syndrome (ARDS), require hospitalization and mechanical ventilation in the Intensive Care Unit (ICU) [1,3]. The most frequent radiological manifestations described in the literature are peripheral ground-glass opacities, interlobular septal and pleural thickening, crazy paving pattern and consolidations. Rare radiological presentations include: nodules, cystic changes, bronchiectasis, lymphadenopathy and pleural effusion [4]. Long-term severe thoracic complications, such as pneumatocele, lung cysts, pneumothorax, empyema or hemothorax were mostly described in the literature as case reports and case series [5-17]. We analyzed probable pathophysiology and outcome in patients with pneumatocele and lung cysts as pulmonary complication of COVID-19 supported by recent literature review.

2. Methods

From September 2020 to December 2021, a retrospective study was performed in patients admitted with a diagnosis of air space after SARS-CoV2 infection. Clinical and demographic variables were collected, including comorbidities, smoking history, laboratory results, infection and surgical history. We described 8 consecutive cases that exemplify uncommon complication of COVID-19 pneumonitis. Typical radiological manifestations like peripheral ground-glass opacities, interlobular septal and pleural thickening as well as consolidations have been described at the onset of the pandemic [3]. However, cystic abnormalities such as pneumatocele, cystic air spaces and cavitations were rarely reported. We have searched the PubMed for studies describing air spaces in subjects with COVID-19 using the free text term: “pneumatocele + lung cyst + COVID-19”. The search found 13 citations (Table 2). Together with our 8 cases, we analyzed the probable pathophysiology of air spaces development. Data collection was performed on January 12^th, 2022. Our cases constituted 27,5% of the group. Our patients, during recovery from COVID-19 (4-6 weeks after first onset of the symptoms) presented with worsening of the clinical condition, which required further investigation. At date there is no dependable management algorithm for such pathology.

3. Results

Among these 29 patients diagnosed with COVID-19 pneumonia complicated by air spaces, 19 (65,5%) received surgical intervention. Of note, 25 (86%) were males. Of the 19 interventions, 6 (20,6%) were exclusively chest drain insertions and the rest 13 (45%) required more advanced procedures like VATS or thoracotomy. Most of the above described patients did not have any risk factor for such a complication. Among the group- 18 (62%) had no history of smoking, 16 (55%) had no history of previous diseases and only 1 (3%) had the history of COPD. More than half of the patients (18-62%) did not require mechanical ventilation during initial viral pneumonitis. Reasons for surgical intervention include continued air leak, non-resolving pneumothorax in spite of drain insertion, superinfection of pneumatocele, non-responding to antibiotic therapy, with ongoing sepsis, progressive enlargement of the cyst with normal lung compression or hemothorax. The results of pathological examinations were available in 11 of the patients, who underwent a surgical procedure (Figures 1-8).

Table 1. Summary of our cases with the dimensions of pneumatocele.

Table 2. Recent literature review.

Figure 1: A- Chest CT scan, axial view delineating extend of the lung cyst with air-fluid level B- Chest X-ray showing left side air cyst with air-fluid level.

Figure 2: A chest CT scan showing an oval air space.

Figure 3: An axial CT scan demonstrating a superinfected lung cyst in right apical segment.

Figure 4: (A,B) - A coronal chest CT scans demonstrating a complex structure of right-sided lung cyst (C) - An axial and (D) - sagittal chest CT scan showing left-sided pneumothorax (E) - An axial chest CT scan presenting air-fluid level in the lung cyst (F) - A chest X-ray showing thickening of the cyst wall and fluid level

Figure 5: An axial CT scan showing right sided pneumothorax, right sided pleural effusion and a pneumatocele.

Figure 6: An axial CT scan demonstrating a lung cyst in the left lung.

Figure 7: (A) - An axial chest CT scan presenting a pneumatocele in the right lung with a slightly thickened wall (B) - A cross-sectional chest CT scan demonstrating two pneumatocele in the right lung (C) - An axial chest CT scan presenting the second small pneumatocele in the right lung

Figure 8: A- A sagittal B- coronal and C- axial CT scan presenting a large cyst in the right lung and D- small pneumatocele in the right lung.

4. Discussion

According to the literature, including Fleishner Society Glossary [19], pneumatoceles are defined as thin-walled air-filled cysts in the lung interstitium. They often contain air-fluid level and may vary in size. Most cases of pneumatoceles are described in children or young adolescents. Pneumatocele can result from infection with Streptococcus pneumoniae, Staphylococcus aureus, Pneumocystis jiroveci, Pseudomonas aeruginosa, Klebsiella pneumoniae, adenovirus, Mycobacterium tuberculosis, Proteus mirabilis, Acinetobacter, Hemophilus influenzae B type, Bacteroid species, or noninfectious process like barotrauma from Continuous Positive Airway Pressure (CPAP) during mechanical ventilation. [20-22]. A lung cyst is described as a round parenchymal lucency with a well-defined interface with normal lung, surrounded by an epithelial or fibrous wall of variable thickness (<2mm). The both terms are used in the literature to described air spaces in COVID-19 patients. The pathophysiology of these cystic lesions in COVID-19 is not well studied, although some potential mechanisms are described. Regarding recent literature, one theory explaining the process of the development of pneumatocele, according to Manenti et al. [23] is ischemia related. Inflammatory cells infiltration and exudate lead to occlusion of alveoli and respiratory bronchioles, causing a “ball-valve mechanism”- the air is allowed to enter the cystic space but not to leave it. Presence of microthrombi in pulmonary capillaries, which are affected by endothelithis, causes ischemia, necrosis and inflammation, which lead to alveolar wall damage and accumulation of air within the lung parenchyma. Consequently, the trapped air could dissect the parenchymal tissue to the pleura or mediastinum- generating pneumothorax or pneumomediastinum or to the subpleural space, causing pneumatocele. In some of the pathological examinations of lung tissue (Table 1 and 2), diffuse necrosis, hemorrhage and thrombi are described. Nevertheless, most frequent findings are a wide range of lung interstitial inflammation with signs of organizing pneumonia, fibrosis and, in some cases, metaplasia, resulting in increased susceptibility of the lung parenchyma to damage. Supplementary factor is barotrauma, which increases intra-alveaolar pressure and leads to alveolar wall rupture [5-7,21,23]. Continuous positive airway pressure during mechanical ventilation or non-invasive ventilation may cause injury, lung tissue disruption and enlargement of air space. However, more than 50% of the patients mentioned in our review required oxygen support without the necessity of invasive ventilation. Most pneumatoceles that are not COVID-19 related resolve within a few weeks to 12 months with no additional intervention. Probably uncomplicated pneumatocele (thin-walled, with no signs of progressive enlargement) in COVID-19 patients would also resolve spontaneously. The most frequent complications of pneumatocele described in the literature are rupture resulting in pneumothorax or pneumomediastinum, superinfection or haemothorax. Among patients described in the literature, diagnosed with COVID-19 pneumonia complicated by air spaces, after unsuccessful conservative treatment, surgical intervention was necessary. Part of the patients showed clinical and radiological improvement under conservative treatment and could be discharged. Hence, CT scanning should be repeated in patients with newly discovered pneumatocele after recovering from COVID-19, which may prevent to overlook further complications. Conservative management or surgical intervention in those complications should be decided during multidisciplinary discussion (thoracic surgeon, respiratory physician, intensive care specialist) taking into consideration the patient’s clinical status, radiological manifestation and expected outcome. Particular difficulties concern the proper interpretation of CT scans in patients with pneumatocele. The CT images are deceptively similar to pleural empyema. In these cases, a precise radiological diagnosis determines the appropriate surgical therapy and outcome of treatment.

5. Conclusions

The case series and systemic review of the literature provide a few learning points.

-Not every infected pneumatocele or lung cyst requires surgical intervention

-Persistent air-leak, associated pneumothorax and haemothorax suggest more urgent surgical intervention

-Secondary infection of the pneumatocele not-responding to extended antibiotic therapy is a potential life threatening condition and should be considered for surgical resection. Prompt surgical approach may be lifesaving in patients in the critical clinical stage

-In patients with newly discovered pneumatocele after recovering from COVID-19, repeated imaging in 4-6 weeks may prevent further complications

-Second imaging in a prone position could help to distinguish a pneumothorax from a pneumatocele

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