A case series of pneumothorax, pneumomediastinum and surgical emphysema in coronavirus disease 2019 (COVID-19)

Introduction

Coronavirus disease 2019 (COVID-19) is a multi-system disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the World Health Organization declared a pandemic in early 2020, there have been cases nearly 126 million cases globally and 3 million deaths at the time of writing (1). Typical radiological findings include bilateral, multi-lobar, posterior, peripheral, and basal ground-glass opacity (GGO) with or without consolidation (2). Atypical features are often pleuro-parenchymal or mediastinal associated with air leaks (pneumothorax and/or pneumomediastinum and/or surgical emphysema) (2). The largest case series by Martinelli et al. showed the development of pneumothorax in approximately 1% of COVID-19 inpatients. Mechanical ventilation and previous lung disease were not risk factors and the authors cautioned against nihilism (3). Mortality is not seemingly ascribed to air leaks (3). Observational case series through rigorous searches of health data sets can capture the true incidence of, and inform local as well as global practice. We thus sought to add to the existing literature by performing a local case review. We present the following article in accordance with the STROBE reporting checklist (available at https://asj.amegroups.com/article/view/10.21037/asj-21-14/rc).

Methods

Materials and methods

All COVID-19 inpatients in Northumbria Healthcare NHS Foundation Trust in the North East of England from 1st March 2020 until 31st of January 2021 were identified. All chest X-rays (CXR) and chest computed tomography (CT) reports were searched for “surgical emphysema” and “pneumothorax” and “pneumomediastinum”. Positive reports were identified and independently verified. Demographics and outcomes were collected. Informed consent was not required due to the nature of this anonymized retrospective analysis and nationwide provisions for the use of confidential patient information without consent for COVID-19 purposes. Caldicott approval was granted from Northumbria HealthCare NHS Foundation Trust (RPI-1279). The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013).

Statistical analysis

Basic statistical methodology was applied. Continuous variables are presented as mean (± range) and categorical variables as percentages where appropriate.

Results

During the defined period which spanned first and second waves, out of 2,827 inpatients with COVID-19, 32 (1.1%) patients with air leaks were identified. Mean age was 63 years (range, 29–91 years); 27 (84%) were male; all were white Caucasian except one (East Asian). Seventeen were ex-smokers, 12 never smokers and 2 were current smokers. There was no documented marijuana smoking. Comorbidities were treated chronic obstructive pulmonary disease (COPD) (4), asthma (5) and hypertension (5). Most patients did not have pre-existing documented lung disease, although 13 (41%) were smokers. None of those patients had enough accumulated pack years to develop COPD. One patient had a previous pneumothorax. Median clinical frailty score (CFS) was 2 (range, 1–6), mean body mass index (BMI) was 27.6 kg/m² (range, 18.5–46.7 kg/m²), mean height 1.7 m (range, 1.55–1.9 m). Mean number of days to development of air leak was 13 (range, 1–120). Fifteen patients have died. The inspired fraction of oxygen (FiO₂) at the time of air leak development was 0.21 (air) in 7 patients, 0.24 in 1, 0.35 in 2, 0.4 in 1 and 0.9 (15 liters via non-rebreathe bag) in 3. Seventeen (53%) patients were on continuous positive airways pressure (CPAP) or mechanical ventilation. Ten patients were on CPAP with positive end expiratory pressures (PEEP) between 10 and 12 centimeters (cm) of water. Seven patients were on mechanical ventilation (one via a tracheostomy) on PEEPs between 12 and 16 cm and FiO₂ ranging from 0.75 to 1. The annexed supplementary material summarizes the air leaks and respective outcomes (Table S1). Table 1 below summarizes the outcomes according to the type of air leaks

Two deaths were directly attributable to a pneumothorax. This is explained in greater detail below. All the pneumothoraces that were large (n=3), according to British Thoracic Society criteria (4), had intercostal drainage. All other pneumothoraces were small.

Discussion

COVID-19 causes diffuse alveolar damage (6). Rupture of any alveolar sacs combined with pleural porosity will lead to pneumothorax. Subsequent air leaks can penetrate into the mediastinum and skin via the Macklin effect, causing pneumomediastinum and surgical emphysema. The Macklin effect, described in 1939, is the movement of air along the sheaths of the pulmonary vasculature from the alveoli into the mediastinum (7). “Lung frailty” and “architectural disruption” seems to be the etiological factor rather than ventilation associated lung injury (5,6,8). The majority of patients were male, had a higher-than-normal BMI and were White Caucasian, reflecting local demographics in the North East of England.

Two deaths were directly attributable to a pneumothorax. One patient was elderly, frail with a CFS of 6, early dementia, an acute cerebrovascular incident. He acquired COVID-19 as an inpatient and developed subsequent respiratory failure. He then developed a large pneumothorax with significant distress and agitation and was thus palliated. Another patient had a CFS of 6 and end-stage COPD who presented with COVID-19 and a small pneumothorax. He was in significant respiratory failure and was palliated appropriately. Another patient developed a pneumothorax whilst receiving CPAP (ceiling of treatment established on admission) and was successfully treated with a small-bore chest drain, but developed progressive respiratory failure and was palliated. Martinelli et al. caution against nihilism in the treatment of pneumothorax (3), and our findings would replicate that. A timely, holistic and overall assessment of the patient is advised.

All patients who developed an isolated pneumomediastinum (n=7) were managed conservatively and are still alive. All were discovered as an incidental finding on CT scans or CXRs. As such, it seems that an isolated pneumomediastinum is not an adverse prognostic development.

Of the 6 patients who developed a combination of pneumomediastinum, surgical emphysema and pneumothorax (unilateral or bilateral), only 1 survived. All had a number of small (12 Fg) and large bore (24 Fg) drains placed either intrapleurally or subcutaneously, and 3 patients with massive surgical emphysema also had subcutaneous incisions made and vacuum dressings placed over. The surviving patient was a 46-year-old who presented with bilateral pneumothorax, surgical emphysema and pneumomediastinum. He was maintained on FiO₂ of 0.4 until acute worsening prompted mechanical ventilation. A 24-Fg drain was inserted which improved the surgical emphysema but respiratory failure worsened significantly in the next 24 hours. He was referred and accepted for extracorporeal membrane oxygenation (ECMO) at a national tertiary center, and survived to discharge after a prolonged inpatient stay. The foregoing perhaps signals that the development of pneumothorax, surgical emphysema and pneumomediastinum is an adverse prognostic sign, unless “lung rest” via ECMO is possible. It should be noted that all other patients were referred for ECMO, but declined.

The only survivor out of the two patients who developed pneumothorax and pneumomediastinum was a 79-year-old patient whose PCR test was positive was 21 days prior to an acute presentation with chest pain. A CT thorax showed a pulmonary embolus, a small pneumothorax and pneumomediastinum. He was anticoagulated and oxygen saturations remained above 94% on air. He was discharged with no intervention required for his air leak. The other patient who died was on mechanical ventilation.

This is a single centre retrospective study with no control group, and thus significant limitations exist. For example, 4 patients with COPD, 7 with asthma and 17 ex-smokers having air leaks might sound significant in a cohort of 32, but we cannot infer substantial associations from this.

Conclusions

Air leaks in the context of COVID-19 are rare. Isolated pneumothorax and pneumomediastinum are not adverse prognostic signs, but the development of pneumothorax, surgical emphysema and pneumomediastinum on mechanical or non-invasive ventilation might be. Large data sets must be analyzed to confirm these findings.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://asj.amegroups.com/article/view/10.21037/asj-21-14/rc

Data Sharing Statement: Available at https://asj.amegroups.com/article/view/10.21037/asj-21-14/dss

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://asj.amegroups.com/article/view/10.21037/asj-21-14/coif). The authors have no conflicts of interest to declare.

Ethical Statement:The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). Informed consent was not required due to the nature of this retrospective analysis and nationwide provisions for the use of confidential patient information without consent for COVID-19 purposes. Caldicott approval was granted from Northumbria HealthCare NHS Foundation Tru (RPI-1279).

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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