A 20-year-old man diagnosed with oto-brachial renal syndrome and resultant end-stage renal disease presented to The Ohio State University Hospitals for kidney transplant. After general anesthesia and intraoperative placement of a left internal jugular central venous catheter, the renal transplant proce-dure occurred without complication. In preparation for discharge on postoperative day 11, the internal jugular central venous catheter was removed, and the patient subsequently developed chest crepitus with complaints of shortness of breath over the ensuing 24 hours.
Prepared by Indu Tara Agarwal, MD and Daniel E. Long, MD of
the Department of Radiology, The Ohio State University,
A 20-year-old man diagnosed with oto-brachial renal syndrome and
resultant end-stage renal disease presented to The Ohio State
University Hospitals for kidney transplant. After general
anesthesia and intraoperative placement of a left internal jugular
central venous catheter, the renal transplant proce-dure occurred
without complication. In prepar-ation for discharge on
postoperative day 11, the internal jugular central venous catheter
was removed, and the patient subsequently developed chest crepitus
with complaints of shortness of breath over the ensuing 24
The diagnosis was pneumomediastinum secondary to removal of the
internal jugular central venous catheter. Subcutaneous emphysema in
the neck upon removal of the central venous catheter dissected to
the mediastinum, which resulted clinically in crepitus and
difficulty breathing. Over the ensuing days, the pneumomediastinum
decompressed itself via subsequent dissection of air along fascial
planes to the retroperitoneum, peritoneum, and into loops of
Prior to discharge on postoperative day 11, the left internal
jugular central venous catheter was removed at the patient's
bedside, which proceeded without incident. Six hours after the
procedure, a nurse noted anterior chest crepitus near the patient's
clavicle on physical examination. At this time, the patient felt
well and was without complaint. An emergent chest x-ray revealed
bilateral subcutan-eous emphysema in the soft tissues of the neck
and a small amount of mediastinal emphysema in the upper part of
There was no pneumothorax. Two liters of oxygen by nasal cannula
was ordered, and an occlusive dressing was applied to the spot
where the internal jugular catheter had exited the skin. Despite
oxygen saturation of 99%, the patient experienced difficulty
breathing on postoperative day 12, so the oxygen level was
increased to 4 L by nasal cannula. The patient continued to
complain of increased swelling around his neck, a choking feeling,
and difficulty breathing throughout the early afternoon despite
consistent oxygen saturation of 100%. On physical examination,
crepitus around the clavicle and down the center of the back were
noted. The patient was immediately transported for neck and chest
CT. The neck CT scan revealed pneumomediastinum and extensive
subcutaneous emphysema throughout the soft tissues of the neck
(figure 1A). The chest CT scan demonstrated pneumomediastinum and a
small left-sided pneumothorax (figure 1B), as well as
pneumoretroperitoneum (figure IC) and air in the anterior chest
wall (figure 1B).
Esophagram was negative for leak. Finally, abdominal radiographs
showed pneumatosis intestinalis at the hepatic flexure of the colon
Over the ensuing days, the patient improved clinically with
improvement of the pneumothorax and subcutaneous emphysema. The
patient was discharged on postoperative day 15. On postoperative
day 17, outpatient abdominal films were obtained due to complaints
of back pain. The films revealed more extensive pneumatosis
intestinalis along several bowel loops, indicating dissection of
the pneumomediastinum into the abdomen.
Pneumomediastinum, defined as free air in the mediastinum, can
be caused by trauma,
iatrogenic trauma to the thoracic
or abdominal structures,
and acts associated with the Valsalva maneuver (such as childbirth,
emesis, and cough),
or via spontaneous alveolar rupture.
The pathogenesis of pneumomediastinum involves the introduction and
subsequent dissection of air along the perivascular,
or retroperitoneal fascial planes,
which are continuous with the visceral space in the thorax. Since
these facial sheaths are continuous, air in the mediastinum can
then dissect to the cervical, retroperitoneal, or abdominal area
resulting in subcutaneous emphysema in the neck
or pneumatosis intestinalis
Mauder et al
state that deep cervical fascia divides the neck into middle, and
posterior compartments. The anterior compartment, the previsceral
space, and the posterior compartment, the prevertebral space,
surround the middle compartment, the visceral space. The visceral
space invests the trachea and esophagus in the neck, and extends
posterolaterally to surround the carotid sheaths. It descends
inferiorly and extends past the pulmonary hilar vessels and airways
to the distal bronchovascular sheaths. Continuing inferiorly, the
visceral space also invests the retroperitoneal soft tissues, and
extends to the extraperitoneal fat which lies deep to the
transversalis fascia. Thus, the visceral space extends superiorly
from the neck to the mediastinum, and finally to the
retroperitoneum and abdomen.
If air is introduced into any of these areas, it can track along
the fascial planes,
eventually collecting in an area that may be as much as a meter
from the original site of air leak. Finally, unlike the visceral
space, the previsceral and the prevertebral spaces terminate
inferiorly at the upper thoracic spine, so they do not communicate
with the mediastinum.
Pneumomediastinum is considered a benign process, with
spontaneous resolution in the majority of cases, yet progressive
pneumo-mediastinum can be fatal if left untreated.
As air pressure in the mediastinum increases, the trapped air
simply flows out of the mediastinum along continuous fascial planes
that line the visceral space.
This escape mechanism allows air to track superiorly to the neck or
inferiorly to the abdomen.
In the neck, the air collects and presents as subcutaneous
emphysema. In the abdomen, the air can aggregate retroperitoneally,
resulting in pneumoretroperitoneum, or it can collect in the walls
of the hollow viscera resulting in pneumatosis intestinalis.
Incomplete decompression of the air superiorly or inferiorly may
result in rupture of the mediastinal pleura, leading to
Additionally, if the escape mechanism does not open at all, then
pressure in the mediastinum can be high enough to cause tension
pneumomediastinum, which occurs when accumulated mediastinal air
compresses the heart and causes cardiac tamponade
and impaired normal circulation from accumulated air impinging upon
The signs and symptoms of pneumo-mediastinum and subcutaneous
emphysema include pain radiating to the neck,
or without cyanosis;
and neck crepitus.
Additionally, air is seen in the mediastinum on chest x-ray.
The first-line treatment for pneumo-mediastinum is to relieve
the inciting factor.
Otherwise, no specific therapy is recommended for uncomplicated
cases, except palliative measures such as bed rest, reassurance,
and analgesics since symptoms usually subside spontaneously.
suggests that the most effective treatment is 95% oxygen by mask.
After just a few hours of breathing 95% oxygen, the partial
pressure of nitrogen in the blood decreases markedly due to gas
exchange, yet the air bubbles in the tissues retain their nitrogen
partial pressure. As the partial pressure of nitrogen in the blood
is reduced, the partial pressure gradient between the blood and the
bubbles widens. This allows more rapid absorption of the air into
the blood, thereby reducing the emphysema.
Additionally, treatment of contributing causes allows an increase
in relative oxygen intake, further widening the partial pressure
gradient. Such adjuvant treatments include antibiotics for
infection, bronchodilators for bronchial spasm, steroids to reduce
airway inflammation, and humidified air to loosen secretions.
Rarely, surgical opening of the fascial planes might be considered
if the situation is serious enough to warrant this
In this case, removal of the left internal jugular central
venous catheter presumably introduced air into the carotid sheath,
resulting in perivascular air dissection to the media-stinum.
Within hours, the mediastinal air was decompressed by dissection
along fascial planes to the neck and abdomen, presenting with
subcutaneous emphysema and pneumatosis intestinalis. Additionally,
the mediastinal air decompressed itself by forming a small,
left-sided pneumothorax. Further air was prevented from entering
the carotid sheath by an occlusive dressing placed over the
catheter site. The patient was placed on oxygen by nasal cannula
once he became symptomatic, which likely aided resorption of the
subcutaneous emphysema and pneumothorax, leading to clinical