Introduction
The concept of “pneumomediastinum” alludes to the mediastinum’s presence of air or gas. It may occur spontaneously, due to trauma, or due to a pathologic process such as infection by gas-producing bacteria or esophageal rupture secondary to vomiting or endoscopic procedures. In the case of spontaneous pneumomediastinum (SPM), the etiology is frequently unclear1.
SPM refers to alveolar sac rupture due to an increase in intrathoracic pressure, followed by air dissection through the bronchovascular sheath into the mediastinum that is not preceded by any cause such as chest trauma or a medical or surgical procedure, which causes symptoms such as retrosternal pain, dyspnea, hoarseness, and odynophagia2,3.
Risk factors contributing to spontaneous pneumothorax development include tobacco smoking, age, thin stature, male sex, low body mass index, prolonged cough, strenuous exercise, and some diseases such as chronic obstructive pulmonary disease (COPD)3,4. It is usually a benign and self-limiting condition that, in most cases, necessitates a shortened hospital stay and is not associated with mortality2,5. Plain chest X-ray establishes the diagnosis in approximately 48% of patients. Computed tomography (CT) scan allows for better delimit the affected areas and detect predisposing situations. Direct visualization with esophagography, esophagoduodenoscopy, or bronchoscopy may provide further information, especially if there is a suspicion of tracheal or esophageal injuries6.
If the cardiopulmonary function is compromised, a subxiphoid drain is indicated to prevent further air space accumulation and, in that way, avoid cardiorespiratory damage6. Recurrences are infrequent7.
Even though cases of pneumomediastinum secondary to infectious processes, particularly influenza, have been described, few cases are reported in patients with severe acute respiratory syndrome virus coronavirus 2 (SARS-COV-2) infection; most of whom presented with severe disease. In severe cases of pneumonia, the alveoli are at risk of rupture due to membrane damage. The risk is higher in patients with invasive mechanical ventilation2.
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the SARS-COV-2. The disease has caused significant morbidity and mortality across the world. Common findings include fever, cough, and shortness of breath. Common radiological manifestations of COVID-19 include peripheral-based ground-glass or consolidative opacities; however, pneumothorax and pneumomediastinum are very rare manifestations8.
Case reports and epidemiological studies have shown an approximately 1% rate of pneumothorax in COVID-19. However, the pathological and prognostic significance is unclear9.
Case description
A 46-year-old female patient, previously healthy, presented to the emergency department due to increased volume in the right neck and odynophagia. His condition began on March 13, 2023, with the presence of rhinorrhea, sore throat, and fever, for which a SARS-COV-2 polymerase chain reaction was performed with a positive result. After 4 days of onset, she starts with a significant volume increase in the right neck, intense odynophagia, discomfort in the external auditory canal, and bilateral retroauricular, submandibular, and cervical lymph nodes. She reported in the direct questioning that before the increase in the volume, she performed a Valsalva maneuver. Her vital signs were normal. A physical examination detects crackles in the right neck region up to zone III. Intravenous contrast chest and skull CT scans showed pneumomediastinum and subcutaneous emphysema on the right side of the neck and face. There was no evidence of infection by gas-producing bacteria or abscesses. No areas of ground glass or consolidation were observed in the lung (Figs. 1 and 2), without a distinct source for this air leak. She was admitted for management and surveillance. She received oxygen with a nasal cannula, antibiotics, antitussives, steroids, bronchodilators, and profilactic anticoagulants. During her stay, she had reabsorption of the emphysema and she was discharged after 24 h.
Figure 1. Computed tomography scan with evidence of subcutaneous emphysema. A: air is observed in the subcutaneous tissue of the skull. B: parotid glands, and neck on the right side.
Figure 2. Computed tomography scan with evidence of pneumomediastinum and subcutaneous emphysema (arrows) can be seen; air is observed bilaterally around the trachea.
Discussion
The incidence of SPM is variable and estimated at, on average, 1/10,000 hospital admissions, representing around 1% of the total cases of pneumomediastinum. The ratio between men and women is 1-8, which makes this case even rarer7.
A retrospective comparative analysis was performed on patients with SPM over 12 years by Caceres et al. During those 12 years, they identified seventy-four patients with pneumomediastinum, of which just twenty-eight patients with SPM were recognized. In the study, the most prevalent presenting symptoms were chest pain (54%), shortness of breath (39%), and subcutaneous emphysema (32%). The most common triggers were emesis (36%) and asthma flare-ups (21%). In 21% of patients, no evident triggering event was identified. A chest radiograph was diagnostic in 69% of cases, while 31% required CT5.
Some studies have shown low mortality, but a study in Texas reported five patients with SPM and pneumothorax as late manifestations in their SARS-COV-2 infection, all of them developed the conditions while on high flow nasal cannula or while on room air, and the five patients succumbed to the illness9.
Bolaños-Morales et al. reported that in 88.9% of the cases, there is one precipitating factor, such as coughing, emesis, or vigorous exercise. In 22% of cases, one predisposing factor is smoking, asthma, respiratory infection, or interstitial lung disease2. In this case the only precipitating factor that we can identified, beside the SARS-COV-2 infection is the presence of cough.
Most cases of pneumomediastinum have a predisposing factor, such as a case reported in a hospital in Peru, where a patient with COVID infection and uncontrolled asthma, considered a precipitating factor, developed pneumomediastinum. This study by Quincho-Lopez reported that fever was the most frequent symptom in 83% of the patients, and one patient presented without symptoms10.
Presentation as chest pain, dyspnea, or a combination of both is present in up to 70% of cases; our patient did not present with any of these two signs. The Hamman’s sign, the auscultation of dry crackles in the heart foci, which translates into the existence of air in the pericardial sac, is characteristic of SPM, but it is only present in less than half of the cases. Cervical pain, cough, and dysphonia were present in 14, 11, and 5%, respectively7.
The National Institute of Respiratory Diseases, Mexico City, reported six male patients aged between 27 and 82 years who presented with SPM and subcutaneous emphysema. Four patients presented SPM and subcutaneous emphysema before arrival at the emergency department, and the other two developed the pathology 24 h after being intubated to support ventilatory mechanics. One of the patients arrived at the emergency department with subcutaneous emphysema of the head, neck, chest, and arms. On the CT scan, all patients had ground glass images and areas of consolidation in both lung fields, unlike our patient, who had her lungs clear. All these patients presented sore throat and cough. Five of them presented with severe dyspnea and low oxygen saturation. The subcutaneous emphysema and the SPM were managed conservatively with total reabsorption between 7 and 12 days2.
A case of a 38-year healthy woman who presented with SPM and SARS-COV-2 pneumonia was reported by Zhou et al. In this case, the patient did not require mechanical ventilation, and the SPM resolved with oxygen, antibiotics, antitussives, and bronchodilators without the need for invasive interventions10. This case resembles the most with our case with the exception that this patient had pneumonia.
Rodriguez et al. show that SPM is not always a pathologic feature related to invasive mechanical ventilation in SARS-COV 2 patients. Indeed, the inflammatory process induced by COVID-19 increases intrathoracic pressure. Causing the differential pressure inside the pulmonary parenchyma is the main cause of alveolar rupture that causes air leak through interstitial and bronchovascular tissues including the pneumomediastinum what causes air to dissect in between the mediastinal structures. The effect of dissection extends from the soft tissue structure in the anterior mediastinum up. In general terms, they comment that SPM is an uncommon condition resulting from an inflammation of the respiratory tract.
Carried out an unmatched case-control study in which a total of 271 patients were included. Nine hospitalized patients with COVID-19 developed SPM. In the study, age counted as a risk factor if it was < 60 years old, and body mass indexwas dichotomized into < 25 and 25 or higher. Considering gender, it was deemed that being male was a risk factor11.
Patel et al. analyzed 43 studies of SPM in patients with COVID, these studies report a total of 747 cases, of which 50.1% required intubation at the time of diagnosis, 22.5% required surgical drainage at admission, and 75.2% received conservative treatment. The mortality was 51.8%, higher than the established in other studies; however, it was difficult to determine whether the observed deaths were due to the presence of SPM. This study also found that 75.5% of the cases of SPM presented with other sites with air leaks, such as subcutaneous emphysema, like our case, pneumothorax, pneumopericardium, or embolic phenomenon6.
An extensive review of the literature was carried out; however, we did not find cases that had the same characteristics as our patient, who presented SPM with mild COVID, without evidence of pneumonia, and a satisfactory evolution with discharge in 24 h.
Conclusion
The number of cases of pneumomediastinum and subcutaneous emphysema has increased in relation to cases of SARS-COV-2 pneumonia. Within the reviewed literature, no cases of SPM were documented, nor of subcutaneous emphysema in patients with mild infection. In most reported cases, men’s incidence is much higher than women’s.
The physiopathology is not fully elucidated, but it is suspected that it is caused by the damage generated in the walls of the alveoli, causing their rupture and allowing air to leak.
Unlike what is established in SPM for other pathologies, mortality in patients with COVID can be > 50%, so patients must be closely monitored and perform an early evaluation of the procedures.
Analyzing the international literature and comparing it with our case, we conclude that it was an atypical case since it did not present with the most characteristic clinical or epidemiological characteristics of this type of event, reiterating the need to study further this pathology, which has had a dramatic increase due to the arrival of SARS-COV-2.
Acknowledgements
The authors thank all the physicians, nurses, orderlies, and residents who participated in this case.
Funding
The authors declare that they have not received funding.
Conflicts of interest
The authors declare no conflicts of interest.
Ethical considerations
Protection of human and animal subjects. The authors declare that no experiments were performed on humans or animals for this study.
Confidentiality, informed consent, and ethical approval. The authors have obtained approval from the Ethics Committee for the analysis of routinely obtained and anonymized clinical data, so informed consent was not necessary. Relevant guidelines were followed.
Declaration on the use of artificial intelligence. The authors declare that they have not used any type of generative artificial intelligence for the writing of this manuscript.
