eMedicine Specialties > Pediatrics: General Medicine > Pulmonology

Pneumomediastinum

Patrick L Carolan, MD, Adjunct Associate Professor, Departments of Pediatrics, Family Practice, and Community Health, University of Minnesota Medical School; Medical Director of Minnesota Sudden Infant Death Center; Attending Staff, Department of Emergency Services, Children's Hospitals and Clinics of Minnesota

Updated: Nov 20, 2009

Introduction

Background

Pneumomediastinum (PM) was first described by Laennec in 1819 as a consequence of traumatic injury. Spontaneous pneumomediastinum (SPM) was reported in 1939 by Hamman, for whom the Hamman sign (see Physical) is named. Pneumomediastinum is an uncommon entity in pediatric practice. It is defined as free air or gas contained within the mediastinum, which almost invariably originates from the alveolar space or the conducting airways. The etiology of pneumomediastinum is multifactorial. Many authors distinguish SPM as a form of pneumomediastinum that is not associated with blunt force or penetrating chest trauma, endobronchial or esophageal procedures, neonatal lung disease, mechanical ventilation, or chest surgery or other invasive procedures. Because of the infrequent occurrence of pneumomediastinum, the pediatric literature relating to pneumomediastinum involves individual case reports or small case series and is retrospective in nature.

This chest radiograph (posteroanterior and lateral view) is from a 3-year-old girl with a history of prematurity, chronic lung disease, and asthma who presented with a viral pneumonitis and persistent cough. A chest radiograph on admission did not reveal any air leak. On the posteroanterior view, a pneumomediastinum (arrow) is noted. Also, extensive subcutaneous air is observed.

On the lateral radiograph from the patient in Media file 2, anterior mediastinal air is observed. Left lower lobe atelectasis is also present. The child was asymptomatic and was discharged 2 days later.

This chest radiograph (posteroanterior and lateral view) is from a 3-year-old girl with a history of prematurity, chronic lung disease, and asthma who presented with a viral pneumonitis and persistent cough. A chest radiograph on admission did not reveal any air leak. On the posteroanterior view, a pneumomediastinum (arrow) is noted. Also, extensive subcutaneous air is observed. On the lateral film, anterior mediastinal air is seen. Left lower lobe atelectasis is also present. The child was asymptomatic and was discharged 2 days later.

Chest radiographs in anteroposterior (AP) and lateral projections obtained in a 9-year-old girl with wheezing and pneumonitis. The arrows highlight the "spinnaker sail sign" in which free mediastinal air lifts the thymus off of the heart and major vessels.

Pathophysiology

Pneumomediastinum rarely leads to clinically significant complications. More commonly, the associated or precipitating condition underlying pneumomediastinum may be the cause of significant illness. Rarely, tension pneumomediastinum has been reported in which elevated mediastinal pressure leads to diminished cardiac output because of direct cardiac compression or reduced venous return. When extensive subcutaneous and mediastinal gas is present, airway compression may also occur.

The generally accepted explanation for the development of pneumomediastinum is that free air tracks from ruptured alveoli along peribronchial vascular sheaths toward the hilum of the lung. From there, it extends proximally within the mediastinum.

The Macklin effect, first described in 1939, highlights the sequence of events in the development of pneumomediastinum as follows: (1) alveolar rupture, (2) air dissection along the bronchovascular sheath, and (3) free air reaching the mediastinum.

The dissection of free air may not be confined solely to the mediastinum. Zylak et al note that the mediastinum communicates with the submandibular space, the retropharyngeal space, and vascular sheaths within the neck.¹ In addition, 2 routes of communication with the retroperitoneum have been noted: via a tissue plane extending through the sternocostal attachment to the diaphragm, as well as periaortic and periesophageal fascial planes. As a result, air present within the mediastinum may dissect through these tissue planes, causing pneumopericardium, pneumothorax, subcutaneous emphysema, pneumoperitoneum, or pneumoretroperitoneum.

Frequency

United States

The epidemiology of pneumomediastinum reflects that of the associated disease states, when present.

SPM is a rare condition. A review by Chalumeau et al summarized the available literature.² Based on previous studies, they determined a prevalence of SPM ranging from 1 per 800 to 1 per 42,000 pediatric patients presenting to a hospital emergency department. Stack et al reported a 0.3% incidence of pneumomediastinum in association with asthma presenting to their institution over a 10-year period.³ The mean age of affected patients was 11 years. No sex differences were observed in this cohort.

A study from Nashville, Tennessee, reported the frequency of extra-abdominal gas in a series of patients undergoing laparoscopic esophageal surgery. Forty-seven percent of patients (N = 45) had evidence of extra-abdominal air on chest radiography. Of these, 86% had a pneumomediastinum. Pneumomediastinum persisted at least 1 postoperative day in two thirds of these cases. However, no mortality or morbidity was attributable to the presence of pneumomediastinum.

In a series of patients with sepsis-induced acute respiratory distress syndrome (ARDS), air leaks of any type, excluding pneumothorax, occurred in 3.7% of patients.⁴ Ventilator pressures and volumes delivered were not correlated with the development of air leak.

In a series of adult patients presenting with blunt chest trauma, as many as 10% had evidence of pneumomediastinum.

International

A study by Briassoulis et al from Athens, Greece, evaluating the frequency of air leaks in children receiving mechanical ventilation reported a prevalence of 27%.⁵ However, they did not report the prevalence of specific types of air leak.

Esayag et al reported an Israeli series of 13 patients with SPM.⁶ This group represented 1 in 41,600 referrals to the emergency room and 1 in 15,500 hospitalizations. The median age of the patients was 19 years (range 2–72 y). Males comprised 77% of this group.

Mortality/Morbidity

The mortality and morbidity associated with pneumomediastinum are generally attributable to underlying disease states. SPM is usually a self-limited condition that rarely produces significant or life-threatening symptoms.

The mortality rate associated with pneumomediastinum may be as high as 50-70% as seen in Boerhaave syndrome (esophageal rupture following vomiting). The development of air leak, according to Weg et al, is not associated with an increased mortality rate in patients with sepsis-induced ARDS.⁴ Other predisposing conditions associated with high mortality rates include trauma (blunt and penetrating, especially high velocity injury), asthma, and tracheobronchial perforation.

The most common morbidities attributable to pneumomediastinum are symptoms such as chest pain, voice change, and cough. Rarely, tension pneumomediastinum may result in decreased cardiac output. Laryngeal compression leading to stridor has been reported. Gas embolism has rarely been reported.

Sex

In a series of pneumomediastinum occurring in persons with asthma, there was a very slight male predominance in the prevalence of SPM. Other series confirm this excess of male cases. Damore reported 29 cases of pneumomediastinum over a 10-year period unrelated to trauma, intubation, or surgical procedures; 69% of patients were male.⁷ Some have suggested that a body habitus favoring a tall thin build is an additional risk factor for the development of SPM. The mechanisms underlying this association are unclear. Traumatic pneumomediastinum is more common in males, reflecting the male predominance among those who experience trauma and accidents.

Age

The peak prevalence of SPM is seen in the second to fourth decades of life. This presumably reflects involvement in activities that increase the risk for developing pneumomediastinum, such as diving or marked physical exertion (eg, athletic activities, weight lifting). Moreover, the force of an individual's cough, vomit, and Valsalva maneuvers (all of which may lead to pneumomediastinum) attenuates with age, accounting for the decline in the prevalence of pneumomediastinum with age.

The age distribution for pneumomediastinum occurring in conjunction with specific disease processes reflects the age profile of the particular disease.

Clinical

History

In Damore's series, the most common symptoms seen with pneumomediastinum (PM) were subcutaneous emphysema (76% of patients) and neck or chest pain (38% of patients).⁷

• Chest pain
  • In spontaneous pneumomediastinum (SPM), pain is said to be a feature in 50-90% of cases. Typically, it is retrosternal in location and worsened by inspiratory maneuvers. The pain may radiate to the shoulders or back suggesting the possibility of myocardial infarction or pericarditis, under the appropriate clinical circumstances.
  • Chest pain was a presenting feature in 27% of persons with asthma with pneumomediastinum in one series.
• Dyspnea: Dyspnea may reflect associated illnesses such as asthma, a coexistent pneumothorax, or a tension pneumomediastinum.
• Fever: Low-grade fever may be present. Fever may occur following cytokine release that is associated with air leak. However, mediastinitis or infectious/inflammatory disorders should be included in the differential diagnosis when fever is present.
• Dysphonia: Walsh-Kelly and Kelly reported a 14-year-old girl with pneumomediastinum whose only presenting symptom was dysphonia.⁸
• Throat pain: Patients may present with symptoms of throat pain. In some cases, pneumomediastinum may follow relatively innocuous oropharyngeal trauma that presents as mouth or throat pain.
• Jaw pain: Jaw pain has occasionally been reported.
• Miscellaneous: Dysphagia, neck swelling, and torticollis all have been reported in association with SPM.
• Triggering factors
  • Bullaro suggests that triggering factors may be identified in 70-90% of patients with SPM.⁹ Attempt to identify precipitating factors, such as the Valsalva maneuver, illicit drug ingestion, vigorous vomiting or cough, or activities that may lead to barotrauma (eg, scuba diving, flying). The forceful cough of asthma is one of the most common triggers of SPM in children and, for some, may be an initial presenting symptom or sign.
  • One report suggested an association between belching in a heavy drinker and the development of Boerhaave syndrome (esophageal rupture following vomiting). Patients with cyclical vomiting may also be at increased risk of developing pneumomediastinum.
  • Pneumomediastinum may be observed in pediatric patients (usually female) with anorexia nervosa.
  • Hyperpnea in association with diabetic ketoacidosis may cause pneumomediastinum.¹⁰
  • Catamenial pneumomediastinum has been reported. A woman with endometriosis developed retrosternal chest pain at the time of menstruation and was found to have subcutaneous emphysema. A pneumomediastinum was noted on chest radiography.
• Drug history: In school-aged or adolescent patients, a comprehensive drug history should be taken, including a history of smoking and drinking (to elicit pneumomediastinum associated with vomiting). Ask the patient specifically about inhalation of illicit drugs, chemical compounds, or commercial aerosols.
  • A report from the Partnership For a Drug Free America notes that the practice of sniffing or "huffing" vapors from ordinary products like glue, spray paint, nail polish remover, and gasoline in order to get high is once again gaining popularity. The report notes that approximately 20% of US teenagers admit to getting high by inhaling common household products, with few teens understanding the dangers of this practice.
  • Huffing has been reported among elementary school–aged children. Parents may recognize signs of inhalant abuse, such as chemical odors on children's hands or clothes, spray cans or soaked rags in their rooms, and physical and behavioral signs, such as a dazed appearance, red or irritated eyes or nose, irritability, or problems at school.
  • A parents' guide is published on the Partnership for a Drug Free America's Web site.
  • The pulmonary toxicities of inhalant abuse are generally due to asphyxia or direct chemical pneumonitis. However, air leak is possible.

Physical

• Subcutaneous air
  • Although not pathognomic of pneumomediastinum, the presence of subcutaneous crepitations suggests free air is present within the thoracic cavity.
  • Stack reported finding subcutaneous emphysema in 73% of patients presenting with asthma subsequently found to have pneumomediastinum.³ The positive predictive value of this sign for pneumomediastinum in their series was 100%.
• The Hamman sign
  • This sign, which some authors have suggested is pathognomic of pneumomediastinum, consists of precordial systolic crepitations and diminution of heart sounds.
  • Damore reported a prevalence of 10% in his series.⁷
• Associated pneumothorax: The presence of a pneumothorax should be clinically suspected in individuals with respiratory distress, asymmetry of breath sounds, and hypoxemia.
• Other diseases: Associated conditions that may predispose to pneumomediastinum, particularly asthma, should be sought.
• Oxygen saturation
  • Pulse oximetry is mandatory in all children with suspected pneumomediastinum.
  • In a series of children with asthma presenting to an emergency department, those with pneumomediastinum had a significant difference in oxyhemoglobin saturation (90% vs 94% of those without pneumomediastinum, p = 0.03).

Causes

A large and diverse group of factors has been implicated in the development of SPM. Various respiratory maneuvers that have in common the development of high intrathoracic pressures may lead to pneumomediastinum. These include Valsalva maneuvers, coughing, vigorous crying, and forceful retching or vomiting.

• Elevated pulmonary (alveolar) pressures
  • Numerous maneuvers that lead to elevated alveolar pressures may result in pneumomediastinum (see discussion of the Macklin effect in Pathophysiology).
  • Forceful coughing, crying, or shouting may elevate pressures.
  • Vomiting, defecation, and Valsalva maneuver may elevate pulmonary alveolar pressures, as may illicit drug use, especially if associated with coughing.
  • Strenuous athletic activity, diving, flying, playing woodwind instruments, and childbirth are also potential risk factors.
  • Spirometry has been associated with the development of pneumomediastinum in 3 individual case reports.
• Respiratory illness
  • Obstructive lung disease (eg, asthma, bronchiolitis, foreign body aspiration, bronchopulmonary dysplasia), especially in intubated and mechanically ventilated patients, is a risk factor.
  • Respiratory tract infections, especially if associated with asthma, may predispose a patient to the development of a pneumomediastinum. Fearon et al and Vazquez et al report cases in which pneumomediastinum is associated with mycoplasma lower respiratory tract infection.^11,12
  • Foreign body aspiration has been reported in association with pneumomediastinum.
• Organ injury
  • Penetrating or blunt injury to the thorax may cause air leak syndromes including pneumomediastinum. The etiology is thought to be related to the Macklin effect.
  • Tracheobronchial rupture, esophageal injury, or perforation of a hollow abdominal viscus may lead to free mediastinal air.
• Miscellaneous medical conditions: Pneumomediastinum has been reported in association with convulsions, tooth extraction, and dermatomyositis.

Differential Diagnoses

Workup

Laboratory Studies

The following studies are indicated in suspected cases of pneumomediastinum (PM):

• ABG
  • ABG should be checked in individuals presenting with respiratory distress.
  • Depending on the severity of the underlying respiratory compromise, the blood gas may be normal or may reveal hypoxia, hypocarbia, or hypercarbia.
• Cardiac enzymes: Evidence of myocardial infarction should be sought in individuals with chest pain of unclear etiology. Myocardial infarction is very rare in children. However, it has been seen in patients with the coronary vasculitis of Kawasaki syndrome and with congenital coronary artery anomalies.
• Toxicology: Blood or urine should be tested for the presence of illicit drugs when indicated by history or physical examination.

Imaging Studies

• Chest radiography
  • Chest radiography usually (although not invariably) reveals a pneumomediastinum. Chest radiography reveals air within the mediastinal space. Coexisting disease (eg, pneumothorax, pneumoperitoneum, pneumoretroperitoneum of pneumopericardium) may also be evident.
  • Radiolucent streaks representing free air may be observed tracking along the margins of the heart, within the retrosternal space, or surrounding the trachea. Typical features of pneumomediastinum seen on chest radiography are caused by air outlining normal anatomic structures as it tracks from the mediastinum producing the thymic sail sign, "ring around the artery" sign, tubular artery sign, double bronchial wall sign, continuous diaphragm sign, and the extrapleural sign (see Media file 1, which is a chest radiograph demonstrating pneumomediastinum as well as subcutaneous emphysema in a female with asthma intubated for respiratory failure).
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    The chest radiograph is taken from an adolescent girl with status asthmaticus who was intubated for respiratory failure. A rim of air consistent with a pneumomediastinum may be observed along the upper left border of the heart. Subcutaneous air is observed in the soft tissues of the neck. She required very high peak inspiratory pressures (50 cm H2), which in conjunction with marked air trapping due to her asthma, caused alveolar rupture, allowing air to track to the mediastinum. A central venous line was placed.

    
    
    • Ring around the artery (tubular artery): A radiolucent area is observed surrounding the right pulmonary artery when viewed on a lateral chest radiograph.
    • Thymic sail sign: In infants with pneumomediastinum, the thymic lobes are shifted upwards resembling a full sail.
    • Continuous diaphragm sign: Free air is present between the pericardium and diaphragm, causing the central parts of the diaphragm to become apparent. 
• Chest CT scanning: Chest CT scanning has 2 major roles in the diagnosis of pneumomediastinum.
  • Chest CT scanning may be used to diagnose pneumomediastinum not visualized on chest radiography. A study from Japan describes the use of chest CT scanning in diagnosing small pneumomediastinum not visible on chest radiography. In a series of 33 patients diagnosed with spontaneous pneumomediastinum (SPM) on the basis of clinical presentation and/or chest radiography findings, chest CT scanning revealed pneumomediastinum in 3 patients in whom the chest radiography findings were unremarkable. The authors concluded that chest radiography alone may result in a missed diagnosis in 10% of patients presenting with pneumomediastinum. Fujiwara reported that pneumomediastinum was found in 15% of patients with idiopathic pulmonary fibrosis.¹³
  • CT scanning may provide additional diagnostic information regarding the presence of coexisting illness, such as perforated esophagus. Dissanaike et al noted that major injuries to the aerodigestive tract were readily identified on chest CT scans performed in adult patients with blunt trauma and pneumomediastinum.¹⁴
• Contrast radiography: In cases of suspected esophageal perforation, contrast studies are mandatory. Some authors recommend the use of a water-soluble contrast agent followed by a barium meal if the findings are normal, in order to increase the sensitivity of the test.
• MRI: The routine use of MRI in the diagnostic evaluation of pneumomediastinum has not been reported. However, Castellote et al reports the sensitivity of MRI in detection of free air as well as other forms of intrathoracic pathology.¹⁵
• Ultrasonography: Megremis et al details the use of ultrasonography in the detection of pneumomediastinum.¹⁶

Other Tests

• Spirometry: Spirometry or measurements of peak expiratory flow should not be undertaken in patients with pneumomediastinum because the increased alveolar pressures may further exacerbate the air leak.
• Electrocardiography: An ECG may be performed to evaluate for myocardial infarction, pericarditis, and myocarditis. Decreased voltage, ST segment depression, and nonspecific T-wave changes may be noted as indications of these potential disease processes.

Procedures

• Diagnostic or therapeutic procedures are generally not necessary. Placement of a chest tube should not be attempted unless an accompanying symptomatic pneumothorax is present.
• Bronchoscopy is indicated if a tracheobronchial perforation is suspected, which may occasionally be observed following blunt chest trauma. Neal et al observed that pneumomediastinum after blunt trauma in clinically stable children is rarely associated with significant underlying injury to the tracheobronchial tree.¹⁷ In addition to trauma indications, bronchoscopy may assist with localization and removal of foreign bodies as well as the evaluation of endobronchial lesions that may occur in association with pneumomediastinum.¹⁸
• Esophagoscopy is indicated if an esophageal perforation is suspected.

Treatment

Medical Care

Medical therapy depends on the clinical status of the patient. In general, most children with pneumomediastinum (PM) are asymptomatic, and the natural course is for the pneumomediastinum to spontaneously resolve.

• Mechanical ventilation
  • Although mechanical ventilation (MV) may cause air leaks, including pneumomediastinum, continuing the MV and even escalating respiratory support may be necessary depending on the severity of the underlying respiratory distress and the degree of compromise caused by the air leak. Principle objectives include the use of the lowest pressures or tidal volumes necessary to achieve satisfactory carbon dioxide removal and oxygenation. Permissive hypercapnia, a ventilatory strategy that is based on maintaining adequate oxygenation and blood pH while allowing high partial pressure of carbon dioxide, allows for ventilatory support while minimizing barotrauma.
  • Case reports have described the successful use of high-frequency oscillatory ventilation (HFOV) in a child with acute respiratory distress syndrome (ARDS) and pneumomediastinum.
  • Asynchronous independent lung ventilation has been reported as a therapy for pneumomediastinum.
  • Nitrogen washout with inhalation of 100% oxygen has been suggested as a possible therapy for pneumomediastinum. The actual indications for this procedure are unclear.
  • Adequate analgesia is necessary in children with pain.

Surgical Care

Surgical intervention has rarely been described in pneumomediastinum. Its use is reserved for pneumomediastinum leading to marked cardiorespiratory compromise.

• The use of mediastinoscopy in alleviating life-threatening pneumomediastinum has been reported in a small number of cases.
• Percutaneous placement of mediastinal drainage tubes has been reported. Chau et al describe percutaneous decompression of tension pneumomediastinum under fluoroscopic guidance using a drainage catheter and Heimlich valve in a 2-year-old girl with dermatomyositis and lung involvement.¹⁹ CT-guided placement may also be considered.

Diet

• No special diet is indicated.

Activity

• Patients should avoid strenuous physical activity until resolution of the pneumomediastinum has occurred.

Medication

No medical therapy is indicated. Associated conditions (eg, asthma, gastroesophageal reflux disease [GERD]) should be aggressively treated.

Follow-up

Further Inpatient Care

• Patients should be closely monitored (clinically and with pulse oximetry or cardiorespiratory monitors) to anticipate development of more serious complications associated with pneumomediastinum (PM), such as tension pneumomediastinum, pneumothorax, or pneumopericardium. The patient should avoid strenuous physical activity; forced expiratory maneuvers such as spirometry or pulmonary function testing should also be avoided. If esophageal perforation has occurred, the risk of developing mediastinitis is very high. These patients should be observed very closely for evolving fever and signs of worsening respiratory distress or systemic sepsis.
• Esophageal perforation, with the attendant risk of developing mediastinitis, may require treatment with broad-spectrum antibiotics.

Further Outpatient Care

• The patient should avoid risk factors associated with the development of pneumomediastinum. However, published evidence to support the following guidelines is sparse, and the following recommendations are in large part drawn from those relating to pneumothorax.
  • Physical activities associated with the development of pneumomediastinum (eg, weight lifting, scuba diving, playing wind instruments) should be minimized. Indeed, extrapolating from the data relating to air leaks and scuba diving, a history of pneumomediastinum should be considered an absolute contraindication to diving. The authors suggest abstaining from other activities listed above for a minimum period of 6 months. If pneumomediastinum recurs, avoidance of these activities permanently would be advisable.
  • Medical conditions associated with the development of pneumomediastinum should be treated aggressively. These include asthma and recurrent vomiting (eg, from gastroesophageal reflux disease [GERD], chemotherapy, cyclic vomiting, bulimia).²⁰
  • Pneumomediastinum has been reported in association with childbirth (vaginal delivery).
  • Children at risk for pneumomediastinum or with a history of developing pneumomediastinum should be fully vaccinated, including vaccinations for pertussis and influenza.

Inpatient & Outpatient Medications

• No specific medical therapy is indicated for the prevention or treatment of pneumomediastinum. As noted above, associated conditions should be treated aggressively.
• Those with a history of pneumomediastinum may benefit from antitussives during coughing spells.

Transfer

• Intensive care: Patients with severe respiratory distress, increasing oxygen requirements, other air leak syndromes, or signs of cardiovascular compromise may require transfer to a pediatric intensive care unit for further monitoring and management.
• Pediatric tertiary care: If the patient has cardiorespiratory compromise or a serious condition associated with a pneumomediastinum (eg, esophageal perforation), transfer to a pediatric tertiary care facility may be necessary.

Deterrence/Prevention

• Avoidance of high-risk behavior
  • High-risk behavior includes strenuous athletic activities, scuba diving, weight lifting, and playing wood instruments.
  • Paroxysmal coughing, screaming, and crying may all result in pneumomediastinum.
  • Inhalation of both legal drugs (cigarettes) and illicit drugs (eg, cocaine, marijuana) should be avoided.

Complications

• Associated air leaks
  • Other air leak syndromes (in particular, pneumothorax) may be observed in conjunction with pneumomediastinum.
  • Subcutaneous emphysema is commonly noted, although it is not usually associated with serious complications.
• Tension pneumomediastinum: Although rare, tension pneumomediastinum may occur, leading to compression of the great veins, compromising venous return, which may result in hypotension and hypoxemia secondary to ventilation/perfusion mismatch.
• Mediastinitis: Pneumomediastinum following massive vomiting may be associated with Boerhaave syndrome; developing mediastinitis is a risk.
• Associated conditions: Complications may arise from associated conditions such as asthma, a foreign body, or drug ingestion.

Prognosis

• Although recurrent pneumomediastinum is a risk, the pneumomediastinum is almost invariably benign, with morbidity or mortality principally attributable to the associated or precipitating condition.

Patient Education

• Advise the patient to avoid high-risk activities. Instructions include the following:
  • Avoid strenuous athletic activities, particularly those involving Valsalva maneuvers such as weight lifting.
  • Avoid playing woodwind instruments.
  • Avoid barotrauma from activities such as flying, parachuting, or scuba diving.
  • Maintain good asthma control. Ensure that influenza and pertussis vaccinations are current.
  • Avoid smoking and inhalation of illicit drugs.
• For excellent patient education resources, visit eMedicine's Lung and Airway Center. Also, see eMedicine's patient education articles Emphysema and Chest Pain.

Miscellaneous

Medicolegal Pitfalls

• Failure to diagnose: A missed diagnosis of a clinically significant pneumomediastinum (PM) is unusual. Chest radiography in children with significant pain, subcutaneous emphysema, Hamman sign, or respiratory distress will help to identify patients with pneumomediastinum.
• Failure to diagnose related conditions
  • The clinician should always consider differential diagnoses that may be associated with the development of pneumomediastinum. These include asthma, an inhaled foreign body, vomiting, and especially Boerhaave syndrome, which, if unsuspected, may lead to mediastinitis.
  • Other etiologies to be considered include esophageal and tracheobronchial perforation, which may be observed in cases of chest trauma.
• Inappropriate treatment
  • Although the vast majority of cases of pneumomediastinum resolve without intervention, occasional patients with a tension pneumomediastinum may benefit from decompression. Failure to consider this therapeutic option may be considered negligent.
  • Conversely, surgical intervention, particularly if complications arise, may result in medicolegal consequences.
• Failure to offer behavior modification advice
  • All patients with pneumomediastinum should be advised of risk factors. These include certain athletic activities, playing wood instruments, and scuba diving.
  • Patients should be advised of the risks of smoking and inhalation of illicit drugs.

Special Concerns

• Although pneumomediastinum occurring during pregnancy (predominantly during labor but also associated with hyperemesis gravidarum) has been reported, no data reporting recurrence risk during pregnancy are available.

Multimedia

Media file 1: The chest radiograph is taken from an adolescent girl with status asthmaticus who was intubated for respiratory failure. A rim of air consistent with a pneumomediastinum may be observed along the upper left border of the heart. Subcutaneous air is observed in the soft tissues of the neck. She required very high peak inspiratory pressures (50 cm H2), which in conjunction with marked air trapping due to her asthma, caused alveolar rupture, allowing air to track to the mediastinum. A central venous line was placed.

Media file 2: This chest radiograph (posteroanterior and lateral view) is from a 3-year-old girl with a history of prematurity, chronic lung disease, and asthma who presented with a viral pneumonitis and persistent cough. A chest radiograph on admission did not reveal any air leak. On the posteroanterior view, a pneumomediastinum (arrow) is noted. Also, extensive subcutaneous air is observed.

Media file 3: On the lateral radiograph from the patient in Media file 2, anterior mediastinal air is observed. Left lower lobe atelectasis is also present. The child was asymptomatic and was discharged 2 days later.

Media file 4: This chest radiograph (posteroanterior and lateral view) is from a 3-year-old girl with a history of prematurity, chronic lung disease, and asthma who presented with a viral pneumonitis and persistent cough. A chest radiograph on admission did not reveal any air leak. On the posteroanterior view, a pneumomediastinum (arrow) is noted. Also, extensive subcutaneous air is observed. On the lateral film, anterior mediastinal air is seen. Left lower lobe atelectasis is also present. The child was asymptomatic and was discharged 2 days later.

Media file 5: Chest radiographs in anteroposterior (AP) and lateral projections obtained in a 9-year-old girl with wheezing and pneumonitis. The arrows highlight the "spinnaker sail sign" in which free mediastinal air lifts the thymus off of the heart and major vessels.

References

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Keywords

pneumomediastinum, PM, spontaneous pneumomediastinum, SPM, mediastinal emphysema, mediastinal air, mediastinum, mediastinal gas, chest trauma, pneumopericardium, pneumothorax, subcutaneous emphysema, pneumoperitoneum, pneumoretroperitoneum, treatment, diagnosis, symptoms

Contributor Information and Disclosures

Author

Patrick L Carolan, MD, Adjunct Associate Professor, Departments of Pediatrics, Family Practice, and Community Health, University of Minnesota Medical School; Medical Director of Minnesota Sudden Infant Death Center; Attending Staff, Department of Emergency Services, Children's Hospitals and Clinics of Minnesota
Patrick L Carolan, MD is a member of the following medical societies: American Academy of Pediatrics and International Society of SIDS Researchers
Disclosure: Nothing to disclose.

Medical Editor

Susanna A McColley, MD, Director of Cystic Fibrosis Center; Head, Division of Pulmonary Medicine; Associate Professor, Department of Pediatrics, Children's Memorial Medical Center of Chicago, Northwestern University
Susanna A McColley, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Chest Physicians, American Sleep Disorders Association, and American Thoracic Society
Disclosure: Genentech Honoraria Speaking and teaching; Genentech Honoraria Consulting; Novartis Honoraria Consulting; Altus  Consulting fee Consulting; Axcan Scandi Consulting fee Consulting; Boston Scientific Consulting fee Consulting; Gilead  Speaking and teaching

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Heidi Connolly, MD, Associate Professor of Pediatrics and Psychiatry, University of Rochester; Director, Pediatric Sleep Medicine Services, Strong Sleep Disorders Center
Heidi Connolly, MD is a member of the following medical societies: American Academy of Pediatrics, American Thoracic Society, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

CME Editor

Mary E Cataletto, MD, Associate Director, Division of Pediatric Pulmonology, Winthrop University Hospital; Professor of Clinical Pediatrics, State University of New York at Stony Brook; Director of Children's Sleep Services, Winthrop University Hospital
Mary E Cataletto, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Chest Physicians
Disclosure: Shering Plough Pharmaceuticals Honoraria Consulting

Chief Editor

Michael R Bye, MD, Professor of Clinical Pediatrics, Division of Pulmonary Medicine, Columbia University College of Physicians and Surgeons; Attending Physician, Pediatric Pulmonary Medicine, Morgan Stanley Children's Hospital of New York Presbyterian, Columbia University Medical Center
Michael R Bye, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Chest Physicians, and American Thoracic Society
Disclosure: Merck Honoraria Speaking and teaching

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author David J Vaughan, MBBCh, to the original writing and development of this article.

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