Discussion
Tension pneumomediastinum (TPM) is caused by direct injury or barotrauma
to the tracheobronchial tree, alveoli, or esophagus, leading to air
leakage into the mediastinum and causing tension in the closed cavity.
This may cause compression of large vessels, heart, and lungs leading to
cardiovascular and respiratory compromise, which can be a threat to the
patient’s life.2, 4 COVID-19 infection attacks
initially the respiratory system causing pneumonia. Complications
include acute respiratory distress syndrome requiring invasive
ventilation with higher or maximum ventilator settings. This carries an
increased risk of barotrauma to the lungs and tracheobronchial tree.
There is not much literature about COVID-19 pneumonia and complicating
into TPM or pneumomediastinum, there are only one case report of TPM,
and a series of 8 cases of pneumomediastinum are described till date.2, 3, 5-7 COVID-19 infection is known to cause airway
inflammation and edema, which puts these patients at a higher risk of
airway tract injuries following instrumentation.3Placement of a large size endotracheal tube (ETT) also carries a risk of
development of TPM in COVID-19 patients.3 Although in
our case series, only one patient had a tracheal injury but three
patients required reintubation due to secondary bacterial and fungal
pneumonia with increased risk for TPM.
All our patients were given intermittent prone positioning after the
intubation as a therapeutic approach for COVID19 respiratory failure.
Prone positioning in acute respiratory distress patients is known to be
a risk factor for the development of pneumomediastinum and
TPM.8 Wali et al. described in their case series that
one of their COVID-19 patients developed pneumomediastinum immediately
after prone positioning.3 All our patients had
pneumo-mediastinum at day 10 post-intubation or later. They had
secondary bacterial and or fungal pulmonary infections. The majority of
our patients also had complex previous medical histories, which may be
contributing to their frail condition.
For the diagnosis of TPM apart from hemodynamic instability, imaging
studies are confirmatory. Initial CXR will show the presence of air in
mediastinum, around or earth heart sign due to collapsed and restricted
filling of the heart chambers. 9 Sometimes, it’s
difficult to see the heart shadow in the x-ray of TPM patients; hence it
is called ”vanished heart sign”. 10 A computerized
tomography of the chest will show more detailed extension of air in the
mediastinum, including the retromediastinum.3
TPM is treated with insertion of suprasternal drains or through
xiphisternum to decompress the mediastinum. The conservative management
includes reducing airway pressures, allowing permissive hypercapnia and
denitrogenation of the mediastinum air by increasing the percentage of
oxygen supplementation.2, 3 Two of our patients were
managed by insertion of the intercostal drain and three patients were
managed conservatively. One patient required extracorporeal membrane
oxygenation (ECMO) therapy. One of conservatively managed and one
patient managed with drainage of TPM died later due to other
complications.