Pneumomediastinum (from
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''pneuma'' – "air", also known as mediastinal emphysema)
is
pneumatosis
Pneumatosis is the abnormal presence of air or other gas within tissues.
In the lungs, emphysema involves enlargement of the distal airspaces, (abnormal presence of air or other gas) in the
mediastinum, the central part of the
chest cavity. First described in 1819 by
René Laennec
René-Théophile-Hyacinthe Laennec (; 17 February 1781 – 13 August 1826) was a French physician and musician. His skill at carving his own wooden flutes led him to invent the stethoscope in 1816, while working at the Hôpital Necker ...
,
the condition can result from
physical trauma or other situations that lead to air escaping from the
lungs
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side ...
, airways, or bowel into the chest cavity. In
underwater divers
This is a list of underwater divers whose exploits have made them notable.
Underwater divers are people who take part in underwater diving activities – Underwater diving is practiced as part of an occupation, or for recreation, where t ...
it is usually the result of
pulmonary barotrauma.
Signs and symptoms
The main symptom is usually severe central chest pain. Other symptoms include laboured breathing, voice distortion (as with helium) and
subcutaneous emphysema, specifically affecting the face, neck, and chest. Pneumomediastinum can also be characterized by the shortness of breath that is typical of a respiratory system problem. It is often recognized on
auscultation by a "crunching" sound timed with the cardiac cycle (
Hamman's crunch).
Pneumomediastinum may also present with symptoms mimicking cardiac tamponade as a result of the increased intrapulmonary pressure on venous flow to the heart.
Cause
It is most commonly caused by:
*
Esophageal rupture
Esophageal rupture is a rupture of the esophageal wall. Iatrogenic causes account for approximately 56% of esophageal perforations, usually due to medical instrumentation such as an endoscopy or paraesophageal surgery. In contrast, the term Boerh ...
, for example in
Boerhaave syndrome
*
Asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
,
crack cocaine use or other conditions leading to alveolar rupture
*
Bowel rupture, where air in the abdominal cavity tracts up into the chest.
It has also been associated with:
* ''
Mycoplasma pneumoniae
''Mycoplasma pneumoniae'' is a very small bacterium in the class Mollicutes. It is a human pathogen that causes the disease mycoplasma pneumonia, a form of atypical bacterial pneumonia related to cold agglutinin disease. ''M. pneumoniae'' is c ...
''
pneumonia
Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severi ...
*
obesity
Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...
It can be induced to assist thoracoscopic surgery.
[
]
It can be caused by a pulmonary
barotrauma induced by a person moving from a higher to a lower pressure environment, such as when a
scuba or surface-supplied diver,
a
free-diver
Freediving, free-diving, free diving, breath-hold diving, or skin diving is a form of underwater diving that relies on breath-holding until resurfacing rather than the use of breathing apparatus such as scuba gear.
Besides the limits of breath- ...
after , or an
airplane
An airplane or aeroplane (informally plane) is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, Propeller (aircraft), propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurat ...
passenger ascends. In the case of scuba and surface supplied divers, the diver breathes gas at ambient pressure, and if this is not able to escape freely during ascent, the pressure difference will cause it to expand, and may rupture the lung tissues (
pulmonary barotrauma), and escape to a variety of places, one of which can be the mediastinum. A diver with symptoms of mediastinal emphysema may also have any combination of
arterial gas embolism
An air embolism, also known as a gas embolism, is a blood vessel blockage caused by one or more bubbles of air or other gas in the circulatory system. Air can be introduced into the circulation during surgical procedures, lung over-expansion ...
,
pneumothorax
A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath. In a minority of cases, a one-way valve i ...
and
subcutaneous or
pulmonary interstitial emphysema. Factors which may prevent free escape of the compressed breathing gas include holding the breath or respiratory obstructions such as cysts, mucus plugs, or scar tissue.
In rare cases, pneumomediastinum may also arise as a result of blunt chest trauma (e.g. car accidents, fights, over pressure of breathing apparatus), while still evolving in the same fashion as the spontaneous form.
Pneumomediastinum is most commonly seen in otherwise healthy young male patients and may not be prefaced by a relevant medical history of similar ailments.
Diagnosis
Pneumomediastinum is uncommon and occurs when air leaks into the
mediastinum. The diagnosis can be confirmed via
chest X-ray showing a radiolucent outline around the heart and mediastinum or via
CT scanning of the
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
.
Image:PneumoMediastinum2008.jpg, Pneumomediastinum and right sided pneumothorax post first rib fracture in a mountain biking accident.
File:Pneumomediastinum-003.jpg, Pneumomediastinum with ''angel wing sign''
Treatment
The tissues in the mediastinum will slowly resorb the air in the cavity so most pneumomediastinums are treated conservatively. Breathing high flow oxygen will increase the absorption of the air.
If the air is under pressure and compressing the heart, a needle may be inserted into the cavity, releasing the air.
Surgery may be needed to repair the hole in the trachea, esophagus or bowel.
If there is lung collapse, it is imperative the affected individual lies on the side of the collapse. Although painful, this allows full inflation of the unaffected lung.
References
External links
*
{{Certain conditions originating in the perinatal period
Respiratory diseases