Pneumomediastinum also known as mediastinal emphysema is a rare entity, characterised by presence of air in the mediastinal tissues. Although this condition is rare, in literature it has been described patients with severe asthma exacerbation can produce enough increase in intrathoracic pressure to produce this rare complication. Like pneumothorax, pneumomediastinum can be classified as spontaneous or secondary. In this case report we describe a young male patient with spontaneous pneumomediastinum (SPM) who presented to our emergency department in acute asthmatic attack with severe shortness of breath, chest tightness and pain, productive cough, wheezing and pain & swelling of base and right side of neck. Chest X-Ray and non-contrast CT confirmed diagnosis of SPM with subcutaneous emphysema (SE) of neck. The patient was managed conservatively without any surgical intervention and discharged on day 4 after complete resolution of SPM and SE of neck.
Abstract
Introduction
Spontaneous pneumomediastinum (SPM) refers to presence of extra luminal air in the mediastinum in patients without obvious causative factors like previous surgery, thoracic trauma or any medical procedure causing viscous perforation. Patients with acute asthma exacerbation with severe bouts of coughing can sometimes produce abnormal increase in alveolar pressure leads to rupture of alveoli and leakage of air into the mediastinum. The air can tracks along the subcutaneous tissues to anterior chest wall and neck producing subcutaneous emphysema (SE). SPM is an uncommon condition. Clinical experts report SPM occurs predominantly in young male patients aged between 15-34 years. In our case study the patient was a 27 years old male known case of intermittent asthma not on any maintenance therapy presented with acute infective exacerbation of asthma found to have SPM with SE on clinical examination and chest imaging.
Case
Report
A 27 years old male patient known case of intermittent asthma, not on any regular maintenance therapy presented to our Emergency Department (ED) with two days history of worsening cough with sputum, increasing shortness of breath, chest pain and tightness, diffuse wheezing with sharp right lower neck pain, swelling and decrease range of motion. He was not a smoker with no other medical or surgical past history and denied taking any illicit drug. He had never been hospitalised before for his asthma exacerbation, but last year he visited ED twice for his increase asthma symptoms and discharged from there after receiving bronchodilator nebulisation and oral corticosteroid. This time he was in acute respiratory distress with vital signs of oxygen saturation 93% on room air, heart rate 110 beats per min, respiratory rate 30 beats per min, blood pressure 122/58 mm Hg and temperature 370C. On physical exam, there was a palpable crepitus present in his right lower neck with bilateral diffuse ronchi all over chest as well as a positive Hamman's sign on cardiac auscultation. The patient was immediately connected to oxygen and blood samples were taken for routine tests including blood gas analysis. A Chest X- Ray was performed that showed sharp lines of increased lucency along left heart border suggestive of pneumomediatinum in his left heart border as well as SE in his right lower neck (Figure1). The patient was managed in ED with bronchodilator nebulisation, intravenous corticosteroid and oxygen inhalation. After stabilising the patient a non-contrast CT Chest and Neck was performed to confirm pneumomediastinum and SE and to rule out underlying lung pathology (Figure 2, 3). The patient was admitted in intensive care unit for further care and management. He was put on bronchodilator nebulization, systemic corticosteroid as per latest clinical guidelines. Initially he received high flow oxygen which was titrated according to saturation and eventually completely weaned off. His cough, chest pain, shortness of breath, and neck pain significantly improved. We discharged the patient on day four with maintenance inhaled corticosteroid therapy along with a course of oral corticosteroid. He was given an outpatient chest medicine follow- up after five days.
Figure 1: Plain
chest radiograph demonstrating pneumomediastinum (sharp line of increased
lucency outlining left heart border - lower arrow) and subcutaneous emphysema
(increased lucency visualized in right lower neck - upper arrow).
Figure 2 & 3: Non- contrast CT of the chest and
neck demonstrating pneumomediasinum,
presence of sharp lines of increased lucency within the
mediastinum(marked with green arrow) and subcutaneous emphysema (hypodense gas
denoted by green arrow).
Figure 4 & 5: Post resolution Thoracic CT scan images.
Discussion
The
present case highlights an uncommon complication of an acute asthma
exacerbation. In severe asthma, pneumomediastinum and SE develop because of
over dilatation of the distal airways due to the obstruction in the small
airways causing abnormal rise in intra-alveolar pressure with severe coughing
and deep forced full inspiration leading to alveolar rupture. Because of the
intrathoracic pressure difference, the free air tracks from ruptured alveoli
along peribronchial vascular sheaths toward the hilum of the lung. From there
it extends proximally to enter mediastinal, subcutaneous, retropharyngeal,
retroperitoneal, and even epidural areas. In our patient, air tracked from
ruptured alveoli into mediastinal and subcutaneous structures in the neck.
Other conditions like tracheal, bronchial or esophageal rupture in association
with chest trauma, iatrogenic injury, esophageal perforation (Boerhaave
syndrome), the Valsalva maneuver (during child birth), positive pressure
ventilation, barotrauma (diving, intubation), recreational drugs like cocaine
inhalation, COPD, and interstitial lung disease have been described to cause
pneumomediastinum [1-3]. Overall, SPM is a rare condition. Experts reported an
incidence of 1 in 25000 with a male preponderance of 76% [4]. In pneumomediastinum
the most common presenting symptom is central chest pain (60-100%) [4] Which is
sudden and acute, usually retrosternal radiating to the neck or to the back
[5,6]. Other frequent symptoms include severe dyspnea, cough, neck pain,
hoarseness, emesis or dysphagia (if esophageal pathology). On physical
examination, subcutaneous emphysema is frequently palpable in the neck. Pulsus
paradoxus has been described in the absence of asthma. The normal area of
cardiac dullness to percussion may be diminished [7,8]. Hamman’s sign,
mediastinal crunch or click heard on auscultation over the cardiac apex and the
left sternal border synchronous with the heart beat is present on around 50%
[9]. On rare occasions sufficient air under tension surrounds the heart to
cause cardiac tamponade with signs and symptoms of increased breathlessness,
cyanosis and hypotension. Presence of fever, sepsis, pleural effusion or
empyema warrants secondary pneumomediastinum due to esophageal rupture, which
can be detected by methylene dye test. Sometimes air from the rupture alveoli
track to the visceral pleural leading to formation of sub pleural bullae, which
can rupture and lead to secondary pneumothorax. The diagnosis of SPM is usually
established with a plain chest radiograph showing lucent streaks, bubbles of
air outlining mediastinal structures. In reported series Chest X-Ray can yield
a diagnosis in almost 90% of cases [10]. Non-contrast CT scan chest confirm the
diagnosis of SPM and SE in suspicious cases with an inconclusive chest X-ray.
It also identify causative factors or secondary pathologies and helps in
identifying missed pneumothorax in plain chest radiograph. In SPM;
bronchoscopy, esophagoscopy or esophagography are not routinely required,
unless an underlying pathology is suspected. SPM is generally a benign and
self-limiting condition with good prognosis that responds to conservative
therapy. High concentration of oxygen helps to absorb air quickly. Resolution
of pneumomediastinum is usually achieved within two to five days in most asthma
patients if treated with bronchodilators, systemic steroid oxygen therapy and
other supportive care. Our patient responded well to the conservative treatment
given. He was discharged on day four and asked to follow up in OPD after 5
days.
Conclusion
· This
report demonstrate a case of SPM and SE as a complication of an asthma
exacerbation, although rare yet important complication to keep in mind in these
patients.
· Although
these complications usually resolve with good asthma control and other
supportive management, there is recurrence rate of 5%-10%.
· There
is also the risk of spontaneous primary pneumothorax in SPM, so a high index of
suspicion is warranted in asthmatic patients who present with chest, neck, and
throat pain, along with severe dyspnea not responding to medical therapy.
Additional
Information
Author
contributions: AKA, PT and RD have contributed equally
in writing and reviewing of the manuscript. AKA is the article guarantor.
Funding: Not applicable
Disclosure:
The authors declare no conflict of interest.
Patient
consent for publication: Not required.