Review Article

Pneumomediastinum
Vasileios K. Kouritas1, Konstantinos Papagiannopoulos2, George Lazaridis3, Sofia Baka4, Ioannis
Mpoukovinas5, Vasilis Karavasilis2, Sofia Lampaki6, Ioannis Kioumis6, Georgia Pitsiou6, Antonis
Papaiwannou6, Anastasia Karavergou6, Maria Kipourou6, Martha Lada6, John Organtzis6, Nikolaos
Katsikogiannis7, Kosmas Tsakiridis8, Konstantinos Zarogoulidis6, Paul Zarogoulidis6
1
Thoracic Surgery Department, Theagenio Cancer Hospital, Thessaloniki, Greece; 2Cardiothoracic Surgery Department, “Evangelismos”
Hospital, Athens, Greece; 3Department of Medical Oncology, Aristotle University School of Medicine, Thessaloniki, Greece; 4Oncology
Department, “Interbalkan” European Medical Center, Thessaloniki, Greece; 5Oncology Department, “BioMedicine” Private Clinic, Thessaloniki,
Greece; 6Pulmonary-Oncology, “G. Papanikolaou” General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece; 7Surgery
Department, University General Hospital of Alexandroupolis, Alexandroupolis, Greece; 8Thoracic Surgery Department, “Saint Luke” Private
Hospital, Thessaloniki, Greece
Correspondence to: Paul Zarogoulidis, MD, PhD. Pulmonary Department-Oncology Unit, “G. Papanikolaou” General Hospital, Aristotle University
of Thessaloniki, Thessaloniki, Greece. Email: pzarog@hotmail.com.

Abstract: Pneumomediastinum is a condition in which air is present in the mediastinum. This condition can
result from physical trauma or other situations that lead to air escaping from the lungs, airways or bowel into
the chest cavity. Pneumomediastinum is a rare situation and occurs when air leaks into the mediastinum. The
diagnosis can be confirmed via chest X-ray or CT scanning of the thorax. 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). Pnemomediastinum
may also present with symptoms mimicking cardiac tamponade as a result of the increased intrapulmonary
pressure on venous flow to the heart. The tissues in the mediastinum will slowly resorb the air in the cavity so
most pneumomediastinums are treated conservatively.

Keywords: Pneumothorax; pneumomediastinum; trauma; puncture

Submitted Dec 10, 2014. Accepted for publication Jan 07, 2015.
doi: 10.3978/j.issn.2072-1439.2015.01.11
View this article at: http://dx.doi.org/10.3978/j.issn.2072-1439.2015.01.11

Definition In cases with no mechanical ventilation applied or

where no Valsalva maneuver is performed, air in the
Pneumomediastinum is the term which defines the
mediastinum is also considered as spontaneously
presence of air in the mediastinum. It has also been described appeared (4). This entity is observed in a significant
as mediastinal emphysema (1-3). percent of patients, in whom no factor to justify the origin
of the pneumomediastinum can be identified (5).
Classification The presence of air in the mediastinum is considered
as secondary pneumomediastinum when a causative
Spontaneous pneumomediastinum (SPM) (Figure 1) factor is identified (1-3).
refers to the presence of air into the mediastinum in Respiratory diseases may lead to pneumomediastinum,
otherwise healthy subjects without an obvious causative especially at periods of exacerbation with excessive
factor such as an operation, air following a viscous coughing i.e., in asthma or respiratory infections (6-8). Usual
perforation, presence of infection or trauma (1). inducing factors include asthma, interstitial lung

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S49
Journal of Thoracic Disease, Vol 7, Suppl 1 February 2015 S45

Pneumomediastinum

Secondary Spontaneous
pneumomediastinum pneumomediastinum

Latrogenic 1. Traumatic
Endocsocpic procedures (airway, esophagus) Blunt injuries
Intubation (airway, esophagus) Penetrating chest or abdominal injuries Predisposing factors
Pleural cavity instrumentation 2. Non traumatic
asthma Tobacco use
Central vascular access procedures
COPD Recreational drug use
Chest or abdominal operations
Child birth
Bronchiectasis
Interstitial lung disease
Malignancy
Physical activity
Sports
Air trapping
Inhalation of toxic fumes

Figure 1 Classification of pneumomediastinum.

disease, COPD, bronchiectasis, lung cysts, lung malignancy, case known in current times as Hamman’s syndrome
excessive vomiting, and trauma (including iatrogenic). (11). Macklin and Macklin in 1944 provided a sound
Lately, the use of recreational drugs, such as cocaine, explanation for pneumomediastinum, based on
marijuana, methamphetamine, have been considered an experiments conducted on cats: the increase of alveolar
additional factor that can cause pneumomediastinum (9,10). pressure causes them to rupture, therefore releasing air
Other conditions leading to pneumomediastinum are the which in turn migrates through the peribronchial and
performance of vigorous Valsalva maneuver, childbirth, perivascular sheaths to the mediastinum (12).
rapid ascent of scuba-divers, presence of foreign bodies in Another possible explanation for pneumomediastinum is the
the airway with air trapping, anorexia neurosum, sporting abnormal increase of pressure in the mediastinum, which like
activities and inhalation of toxic fumes (1). the pleural cavity is subjected to low and negative pressure,
However, It must be noted, that in several reports, the causing air to dissect in between the mediastinal structures,
wider term SPM has been allowed even when a possible which support the mediastinal organs. A dramatic decrease in
causative factor is identified (1). intravascular pressure also can create a relative pressure
The lack of such clarification has sparkled discussions amongst gradient in the perivascular spaces (1). The air may then
authors, as it is obvious that SPM has a more favorable outcome dissect to the neck, upper abdomen or the skin via the loose
compared to secondary pneumomediastinum alveolar fat tissue (subcutaneous emphysema) (7). Air can also
pass the pleura resulting in pneumothorax or the peritoneum
resulting in pneumoperitoneum (13).
Pathophysiology

The entity was firstly described by Laenek in 1827 (1-3).

Incidence
Hamman in 1939 described a post-partum patient with
subcutaneous emphysema and pneumomediastinum, a The pneumomediastinum is a rare entity, diagnosed

© Journal of Thoracic Disease. All rights reserved. www.jthoracdis.com J Thorac Dis 2015;7(S1):S44-S49
S46 Kouritas et al. Pneumomediastinum

in 1/44,500 of accident and emergency attendances or patients however appearing generally well. A specific
1/100,000 of natural births, being more frequent in children sign with an infrequent appearance (6,9,10) should be
(1/800-1/15,500) (7). Others, report an incidence of sought for, known as the Hamman’s sign; it is the
1/25,000 in ages between 5-34 years (14). The majority of presence of mediastinal crunch or click present on
patients are males accounting for 76% of cases (1). auscultation over the cardiac apex and the left sternal
However, many authors believe that the occurrence of border synchronous with the heart beat (2).
pneumomediastinum is more frequent than initially Malignant pneumomediastinum is considered the
believed due to underdiagnosis (3,4), with many patients accumulation of a significant amount of air in the mediastinum,
refraining from medical help. Infrequently the pathology causing vessel or tracheal obstruction and inducing respective
may not be indentified on the chest radiograph and symptoms and signs of tamponade and decreased venous
consequently related symptoms may be attributed to return. Only few cases of this adverse appearance have been
musculoskeletal pain or other insignificant causes (15). described and on this occurrence may be considered rare.
As mentioned earlier, pneumothorax might be the
main presenting sign, with an incidence of 40% in some
Clinical presentation
studies (10). Again, only few cases of tension
It is generally agreed that pneumomediastinum usually occurs pneumothorax have been reported.
in young patients (2,5,7). One possible explanation is the fact
that in young subjects the mediastinal tissues are loose and
Diagnosis
flaccid, whereas in the elderly group the planes and sheaths are
fibrosed, making air migration more difficult to occur. The diagnosis is usually established with a plain anterior
Additionally, it is more prevalent in males (7/10 cases) (2,7) and chest film, showing lucent streaks, bubbles of air
in patients with pre existing asthma or other respiratory outlining mediastinal structures and visible mediastinal
diseases (2,4,5). In many occasions the patients present with pleura (Figures 1-3). This investigation can yield a
spontaneous pneumothorax (2,10). A tall, lean, male body diagnosis in almost 90% of reported series (6,9,10). A
habitus is generally considered as the most probable to be lateral chest film is rarely required.
presented with pneumomediastinum; however, obese patients Recent series consider a chest CT scan as a routine
are not spared from this pathology (16). diagnostic modality to assess the extent of the
The main presenting symptom is chest pain (kobashi), pneumomediastinum, (i.e., mild, moderate or severe) confirm
usually retrosternal, radiating to the neck or the back. It has the diagnosis in suspicious cases with an inconclusive chest X-
been reported to be between 60-100% (1,5,6). The onset of ray and identify causative factors or pathologies (Figure 4).
the pain is sudden and acute, or follows exacerbations of Additionally, it is needed in order to differentiate between
underlying pathology such as asthma. Some authors pneumomediastinum and pneumopericardium (air within the
suggest that when no obvious causative factor can be pericardium and not on the prepericardial fat) which may have a
identified, clinicians should retain a high suspicion of less favorable course and might require treatment. The
pneumomediastinum, especially in cases of young adults presence of a pneumothorax missed on a plain chest X-ray in
presenting with acute chest pain (5). Other frequent cases with severe subcutaneous emphysema may also be
symptoms include dyspnea (75%), coughing spells (80%), confirmed with a CT scan.
neck pain (36%), emesis or dysphagia, which however may Bronchoscopy, esophagoscopy or esophagography are
be attributed to the possible underlying disease. In cases of not routinely required, in SPM; unless an underlying
SPM no complain is usually reported (21-51%) and no pathology is suspected or confirmed by presentation and
inducing factor may be found (5,6). past medical history. A detailed information of the patient’s
Subcutaneous emphysema can be detected in 70% of previous health status and events is of paramount
patients with diagnosed pneumomediastinum (6,7,9,10). importance and cannot be emphasized enough.
Other presenting signs include rhinolalia (nasally sounding Ultrasound of the mediastinum is lately applied in the
voice, which occurs because of dissection of air into the soft accident and emergency department, in an effort to
palate), hoarseness and neck swelling, depending on identify pneumomediastinum in cases of high urgency.
underlying pathology (7). Clinical evaluation may also Many patterns of air outlining intrathoracic structures
identify tachycardia, tachypnea or anxiety with most have been described in the literature, either based on chest

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Journal of Thoracic Disease, Vol 7, Suppl 1 February 2015 S47

A
Suspicion of
pneumomediastinum

Diagnostic chest film

Yes No

No suspected or Suspected or known

causative factor.
known causative Address treatment to CT chest
factor specific underlying
oathology

Observe in hospital
Discharge if symptoms
resolve
Follow up until resolution

Figure 2 Suggested treatment algorithm of pneumomediastinum.

Figure 4 (A,B) CT scan of the same patient as in Figure 1 confirms

the presence of mediastinal air outlining mediastinal organs.

Inconclusive laboratory findings include rising white blood

cells or C-reactive protein. ECG abnormalities have also
been described without significant clinical importance (1,19).
Some authors, based on high suspicion and increased
incidence of pulmonary disease, have suggested that
pulmonary function tests should be obtained in
Figure 3 Chest film of young male patient presented with chest spontaneous cases with no obvious exacerbating factors,
pain. Plain chest film has shown mediastinal air tracking especially in children (4).
alongside the medial border of the descending aorta.

Management
X-ray or CT findings; thymic sail (elevation of thymus due to air, Pneumomediastinum is generally considered a benign
mainly seen in pediatric population), ring sign (caused by air entity of little clinical importance with good prognosis.
surrounding the pulmonary artery or either of its main After the diagnostic approach has excluded significant
branches), double bronchial wall, continuous diaphragm sign, or pathology, the pneumomediastinum treatment is directed
air adjacent to hemidiaphragm or spine (1,15,17,18). towards symptom relief (1,20).

© Journal of Thoracic Disease. All rights reserved. www.jthoracdis.com J Thorac Dis 2015;7(S1):S44-S49
S48 Kouritas et al. Pneumomediastinum

such as asthma or COPD should be adequately attended.

Most authors suggest that the control of pain and the
stability of pneumomediastinum, as well as the elimination
of complications, such as pneumothorax, should be
considered as adequate for discharging such patients.
Rare sequllae of pneumomediastinum is the accumulation of
a significant amount of air in the mediastinum in the majority of
cases due to missed esophageal/pulmonary trauma which
cause important air leak. In these cases, although rare, the
simple pneumomediastinum may progress to a malignant one,
leading to tamponade and airway compression. In such cases
VATS or even thoracotomy may be essential for decompression
(9). The development of pneumopericardium may very rarely
cause tamponade which might requiresurgical evacuation by
subxiphoid incision or VATS (5) (Figures 3-6).
Other complications of pneumomediastinum include
extensive subcutaneous emphysema or pneumothorax,
Figure 5 This young patient presented with cough and chest pain.
which usually require minor interventions, such as skin
Chest film reveals surgical emphysema. incisions and chest tube drainage. Air can also dissect in the
retropharyngeal and retroperitoneal space causing
discomfort and respiratory compromise. In rare situations air
can dissect between the mediastinum and the upper spine
causing pneumorrhachis (free air in the spinal canal) (21).

Outcome

Recurrences have been reported and therefore follow up is

advisable. Spontaneous pneumodediastinum usually
resolves by itself, but prolonged cases have also been
reported (>2 months) (6). In general, few recurrences of
pneumomediastinum have been reported enforcing its
benign entity (22). In cases of recurrence, additional
diagnostic evaluation should be conducted in an effort to
identify any missed underlying pathologies, such as
pulmonary or esophageal pathology. As stated before some
authors have suggested performing i.e., lung function tests,
Figure 6 The CT chest of this patient revealed air in the anterior
in an effort to detect missed pulmonary underlying diseases.
mediastinum.
It is suggested however, that due to the scarcity of
recurrent incidents, no long term follow up is required,
Following diagnosis patients are usually hospitalized for at unless otherwise indicated (1,20).
least 24 hours merely for observation. Physical activity should
be discouraged and bed rest must be ensured. Pain is Acknowledgements
controlled with analgesics, according to the Individual Unit’s
protocols. Anti-anxiety drugs should also be administered. Disclosure: The authors declare no conflict of interest.
Coughing should be suppressed with relative antitussives.
Administration of O2 may increase gas absorption by six References
fold and should therefore be considered (Figure 2).
1. Agut A, Talavera J, Buendia A, et al. Imaging diagnosis-
Any underlying exacerbation of a pre-existing pathology

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Journal of Thoracic Disease, Vol 7, Suppl 1 February 2015 S49

spontaneous pneumomediastinum secondary to occult complication in many respiratory diseases and other
primary pulmonary pathology in a dalmatian dog. Vet conditions: an interpretation of the clinical literature in the
Radiol Ultrasound 2014. [Epub ahead of print]. light of laboratory experiment. Medicine 1944;23:281-358.
2. Kobashi Y, Okimoto N, Matsushima T, et al. 13. Pooyan P, Puruckherr M, Summers JA, et al.
Comparative study of mediastinal emphysema as Pneumomediastinum, pneumopericardium, and
determined by etiology. Intern Med 2002;41:277-82. epidural pneumatosis in DKA. J Diabetes
3. Sahni S, Verma S, Grullon J, et al. Spontaneous Complications 2004;18:242-7.
pneumomediastinum: time for consensus. N Am J Med 14. Jougon JB, Ballester M, Delcambre F, et al. Assessment
Sci 2013;5:460-4. of spontaneous pneumomediastinum: experience with 12
4. Chiu CY, Wong KS, Yao TC, et al. Asthmatic versus patients. Ann Thorac Surg 2003;75:1711-4.
non-asthmatic spontaneous pneumomediastinum in 15. Kaneki T, Kubo K, Kawashima A, et al. Spontaneous
children. Asian Pac J Allergy Immunol 2005;23:19-22. pneumomediastinum in 33 patients: yield of chest
5. Macia I, Moya J, Ramos R, et al. Spontaneous computed tomography for the diagnosis of the mild
pneumomediastinum: 41 cases. Eur J Cardiothorac type. Respiration 2000;67:408-11.
Surg 2007;31:1110-4. 16. Mondello B, Pavia R, Ruggeri P, et al.
6. Caceres M, Ali SZ, Braud R, et al. Spontaneous Spontaneous pneumomediastinum: experience in
pneumomediastinum: a comparative study and review of 18 adult patients. Lung 2007;185:9-14.
the literature. Ann Thorac Surg 2008;86:962-6. 17. Moseley JE. Loculated pneumomediastinum in
7. Russo A, Del Vecchio C, Zaottini A, et al. Role of the newborn. A thymic "spinnaker sail" sign.
emergency thoracic ultrasonography in Radiology 1960;75:788-90.
spontaneous pneumomediastinum. Two case 18. Hammond DI. The "ring-around-the-artery" sign in
report. G Chir 2012;33:285-96. pneumomediastinum. J Can Assoc Radiol 1984;35:88-9.
8. Chu CM, Leung YY, Hui JY, et al. Spontaneous 19. Takada K, Matsumoto S, Hiramatsu T, et al. Management
pneumomediastinum in patients with severe acute of spontaneous pneumomediastinum based on clinical
respiratory syndrome. Eur Respir J 2004;23:802-4. experience of 25 cases. Respir Med 2008;102:1329-34.
9. Perna V, Vilà E, Guelbenzu JJ, et al. Pneumomediastinum: 20. Koullias GJ, Korkolis DP, Wang XJ, et al. Current
is this really a benign entity? When it can be considered as assessment and management of spontaneous
spontaneous? Our experience in 47 adult patients. Eur J pneumomediastinum: experience in 24 adult patients.
Cardiothorac Surg 2010;37:573-5. Eur J Cardiothorac Surg 2004;25:852-5.
10. Iyer VN, Joshi AY, Ryu JH. Spontaneous 21. Al-Mufarrej F, Gharagozloo F, Tempesta B, et al.
pneumomediastinum: analysis of 62 consecutive Spontaneous cervicothoracolumbar pneumorrhachis,
adult patients. Mayo Clin Proc 2009;84:417-21. pneumomediastinum and pneumoperitoneum. Clin
11. Hamman L. Spontaneous mediastinal emphysema. Respir J 2009;3:239-43.
Bull Johns Hopkins Hosp 1939;64:1-21. 22. Gerazounis M, Athanassiadi K, Kalantzi N, et al.
12. Macklin MT, Macklin CC. Malignant interstitial emphysema Spontaneous pneumomediastinum: a rare benign
of the lungs and mediastinum as an important entity. J Thorac Cardiovasc Surg 2003;126:774-6.

Cite this article as: Kouritas VK, Papagiannopoulos K, Lazaridis

G, Baka S, Mpoukovinas I, Karavasilis V, Lampaki S, Kioumis I,
Pitsiou G, Papaiwannou A, Karavergou A, Kipourou M, Lada M,
Organtzis J, Katsikogiannis N, Tsakiridis K, Zarogoulidis K,
Zarogoulidis P. Pneumomediastinum. J Thorac Dis
2015;7(S1):S44-S49. doi: 10.3978/j.issn.2072-1439.2015.01.11

© Journal of Thoracic Disease. All rights reserved. www.jthoracdis.com J Thorac Dis 2015;7(S1):S44-S49