Pneumomediastinum Clinical Presentation

Updated: Feb 26, 2019
  • Author: Patrick L Carolan, MD; Chief Editor: Girish D Sharma, MD, FCCP, FAAP  more...
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Presentation

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). [13]   In a narrative literature review of 216 patients, Gasser et al (2017) note that chest pain (55%), neck pain or sore throat (53%) and dyspnea (41%) were the most frequently identified symptoms. [47]  

Chest pain

In spontaneous pneumomediastinum (SPM), pain is said to be a feature in 50-90% of cases. [14, 15] 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 and pneumomediastinum in one series. However, in a pediatric series of asthma patients presenting with chest pain (Majerus 2018), the chest x-ray yielded a positive finding, including pneumomediastinum in 11% of patients. [50]

Okada et al (2014) report a series of 20 patients with SPM, all of whom had evidence of PM on chest computed tomography (CT). [16] Symptoms reported by these patients included chest pain occurring in 75%, dysphagia in 50%, and dyspnea in 40%.

Dyspnea

Dyspnea may reflect associated illnesses such as asthma, a coexistent pneumothorax, or rarely 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. [17]

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. In one series, [18] evaluating the head and neck manifestations of spontaneous pneumomediastinum, the primary initial symptoms were neck swelling, neck pain, and odynophagia.

Jaw pain

Jaw pain has occasionally been reported.

Miscellaneous

Dysphagia, neck swelling, and torticollis all have been reported in association with spontaneous pneumomediastinum.

Triggering factors

Bullaro suggests that triggering factors may be identified in 70-90% of patients with spontaneous pneumomediastinum. [19] 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 spontaneous pneumomediastinum 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. Hochlehnert et al note that starvation and malnutrition may predispose to structural changes within the lung interstitium, leading to the formation of bullae, emphysema, and bronchiectasis, which adds to the risk of spontaneous pneumomediastinum following vomiting. [20]

Hyperpnea in association with diabetic ketoacidosis may cause pneumomediastinum. [21]

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. SPM has also been reported among mothers following labor and delivery. [22]

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. In a series that included adults, Perna et al reported the most common predisposing factor was consumption of cocaine seen in 55%. [23] The pattern of cocaine use was that of occasional use (as opposed to regular or long-term abuse), typically occurring a few hours before presenting symptoms.

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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. [7] 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. Sahni et al (2013) in their meta-analysis estimate that this sign is detected in only 20% of patients with SPM. [24]

Damore reported a prevalence of 10% in his series. [13]

Associated pneumothorax

The presence of a pneumothorax should be clinically suspected in individuals with respiratory distress, asymmetry of breath sounds, and hypoxemia. Banki et al (2013) report that pneumothorax was identified in 14% of their patients with SPM. [25]

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).

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Causes

A large and diverse group of factors has been implicated in the development of spontaneous pneumomediastinum. 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. Jones et al [26] report the development of spontaneous pneumomediastinum in a military training recruit after repeatedly shouting "Hooah!" during a motivational squad competition, highlighting that unique to the military training environment, vigorous shouting as a motivational stimulus can have barotraumatic consequences.

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 musical instruments, and childbirth are also potential risk factors. Sadarangani et al provide a case report of pneumomediastinum precipitated by weight lifting. [27] Improper breathing technique during weight lifting may increase the intrathoracic pressure and the risk of pneumomediastinum. The authors note the importance of physicians and trainers who work with athletes to provide instructions regarding proper breathing techniques during weight lifting.

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. [28, 29] An association of severe spontaneous pneumomediastinum and laryngotracheitis in a young patient with asthma was reported by Lin et al, suggesting the need to consider spontaneous pneumomediastinum in the differential diagnosis of any patient presenting with cervical emphysema and signs of respiratory tract infection, especially in association with asthma. [30]

Hasegawa et al reported spontaneous pneumomediastinum complicating pneumonia in children infected with the 2009 pandemic influenza A (H1N1) virus. [31]

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. Rezende-Neto et al reported that occult pneumomediastinum occurred in approximately 6% of all trauma patients with blunt chest injuries. [32] Patients with pneumomediastinum were more severely injured than those without as indexed by higher injury severity scores (ISS). However, none of the patients with occult pneumomediastinum had aerodigestive tract injuries and follow up chest CT scans demonstrated complete resolution of the pneumomediastinum in all cases.

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.

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