Pediatric Respirology and Critical Care Medicine

REVIEW ARTICLE
Year
: 2021  |  Volume : 5  |  Issue : 3  |  Page : 42--47

Spontaneous pneumomediastinum in children


Yen-Jhih Liao1, Yung-Feng Huang2, Bao-Ren Nong3,  
1 Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung City, Taiwan ROC
2 Fu Jen Catholic University Hospital, Taipei, Taiwan ROC; Department of Pediatrics, National Defense Medical Center, Tri-Service General Hospital, Taipei, Taiwan ROC
3 Department of Pediatrics, National Defense Medical Center, Tri-Service General Hospital, Taipei, Taiwan ROC; Division of Pediatric Allergy, Immunology and Rheumatology/Pulmonology, Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung City, Taiwan ROC

Correspondence Address:
Bao-Ren Nong
Division of Pediatric Allergy, Immunology and Rheumatology/Pulmonology, Department of Pediatrics, Kaohsiung Veterans General Hospital, No. 386, Dajhong 1st Road, Zuoying District, Kaohsiung City 81362
Taiwan ROC

Abstract

Scarce studies about spontaneous pneumomediastinum (SPM) in pediatric patients are published because of lower incidence in a child than an adult. This article is a literature review of pediatric SPM, discussing about aspects of incidence rate, epidemiology, pathophysiology, diagnosis, management, and prognosis about pediatric SPM. In conclusion, SPM is usually a benign disease and treatable with only supportive care. However, poorer prognosis is noted; if it is complicated with other underlying diseases or complications, then aggressive treatment might be needed.



How to cite this article:
Liao YJ, Huang YF, Nong BR. Spontaneous pneumomediastinum in children.Pediatr Respirol Crit Care Med 2021;5:42-47


How to cite this URL:
Liao YJ, Huang YF, Nong BR. Spontaneous pneumomediastinum in children. Pediatr Respirol Crit Care Med [serial online] 2021 [cited 2022 Aug 14 ];5:42-47
Available from: https://www.prccm.org/text.asp?2021/5/3/42/353120


Full Text



 Key Messages:



Spontaneous pneumomediastinum (SPM) is a rare and usually self-limited disease in pediatric population. However, it might need aggressive treatment and have a poorer prognosis if complicated. Therefore, the evaluation of predisposing factor and caution on complications is important.

 Introduction



Pneumomediastinum is defined as the circumstance that air accumulated in the mediastinum. Pneumomediastinum can be categorized into two types: spontaneous and traumatic. Traumatic type is related to blunt or penetrating trauma to the chest or iatrogenic trauma such as mechanical ventilation. SPM can be further classified into primary and secondary types, based on whether there is preexisting lung disease or not.

Compared with adults, it is an uncommon disease in children under 18 years old. Therefore, there were scarce researches of primary pneumomediastinum. This article is a literature review on pneumomediastinum in pediatric patients, mainly about epidemiology, diagnosis, management, and prognosis.

 Epidemiology



It is an uncommon disease in the pediatric population. Hauri-Hohl et al. reported that it happened commonly in neonatal period, with an estimated incidence of one per 1000, and one-third of the cases received respiratory support prior to diagnosis.[1] There was a peak incidence rate between 6 months old and 3 years old, ranging from one in 800 to one in 42,000 patients presenting at hospital emergency units, which might be related to increased frequency of respiratory tract infection.[2],[3],[4],[5],[6],[7],[8] The incidence rate is higher among children with underlying asthma, which is between 0.3% and 5%.[5] In adolescence, thin, tall males were disproportionately affected and seem likely related with predisposing anatomic factors.[9]

 Pathogenesis



Most cases of SPM are due to air leakage through ruptures of pulmonary alveoli to the surrounding broncho-vascular sheath.[10] Some result from air leak secondary from the upper respiratory tract, intrathoracic airways, or gastrointestinal tract. The air then moves centripetally along the sheath and dissects to the hilum, eventually spreads into the mediastinum space, or further dissects the loose mediastinal fascia to the subcutaneous area of thorax, upper limbs, neck, peritoneum, spine, and retroperitoneum.[2],[11],[12],[13],[14],[15],[16],[17],[18],[19],[20]

In some circumstances, air spreads into the pericardial space and causes pneumopericardium. The air may accumulate in the mediastinal space and progress to tension pneumomediastinum or tension pneumopericardium because of rise in mediastinal pressure and compression of intrathoracic structure. Both tension pneumomediastinum and tension pericardium were reported to be the most common happening in patients under mechanical ventilation.[2],[21],[22],[23],[24],[25]

The predisposing factors or triggers can be found in most cases of SPM [Table 1].[2],[8],[26],[27] Acute asthma attack is the most common trigger, which accounts for 20%–30% of cases.[6],[28] Other frequent trigger includes lower respiratory tract infection, vomiting,[29] and Valsalva maneuver (e.g., coughing, sport-related).[17],[30]{Table 1}

Coronavirus illness 2019, abbreviated as COVID-19, is a novel disease, which is highly infectious and was declared a universal pandemic in March 2020. Cases of SPM in adult patients with COVID-19 were reported, incidence rate ranging from 0.64% to 13.6%.[51],[52],[53],[54],[55] The incidence of pneumomediastinum in COVID-19-related acute respiratory distress syndrome (ARDS) increases compared with ARDS from other causes; larger studies to establish the association are required.[54] In pediatric population, COVID-19 infection complicated with pneumomediastinum was also reported.[55],[56],[57],[58],[59] Pneumomediastinum might be considered as a complication of COVID-19 infection because of increased lung frailty and destruction on lung parenchyma, even in infants or children. Early detection and close monitoring are important because it might be a potential indicator of worsening disease and higher mortality rate.[60],[61],[62]

 Evaluation and Diagnosis



Most of the patients are symptomatic when SPM occurs; thus, it is suspected when typical symptoms or signs were noted. The most relevant signs of SPM are chest pain, neck pain, and sore throat.[63] Other common clinical manifestations were dyspnea, cough, odynophagia, and dysphagia.[2],[64] Pain is typically retrosternal, exacerbates during inspiration or posture change, and radiates to upper limbs, neck, or back.[2],[8],[26],[65],[66] Dyspnea may be caused by chest pain or predisposing lung disease or related to complications such as pneumothorax. Other common symptoms include neck swelling, weakness, torticollis, dysphagia, dysphonia, abdominal pain, or back pain.[2],[26],[31],[45],[47],[66],[67],[68],[69],[70],[71],[72] Some experience low-grade fever (body temperature below 38.5°C) a few hours after other symptoms occur.[20],[73],[74]

In addition to diagnosis, evaluation should also include reviewing a patient’s history to clarify predisposing or trigger factors, excluding other causes of the presenting symptoms, and evaluating complications. The history-taking focuses on predisposing and trigger factors, such as asthma, underlying lung disease, vomiting, choking, drug history, and trauma. The physical examination is normal in up to 30% of patients with pneumomediastinum without complications.[5],[75] The most common characteristic presentation is subcutaneous emphysema, ranging from 30% to 90% of patients with pneumomediastinum,[6],[63],[76] which is usually noted over neck or precordial area. Hamman sign, found in 12%–50% of patients with pneumomediastinum, is a systolic crepitation over precordium, sometimes associated with muffling of heart sounds.[75],[77]

The severity and complications must be evaluated. The accumulation of large amount of air could cause compression of airway and reduction in venous return. It is contraindicated to measure peak expiratory flow rate because it may exacerbate the pneumomediastinum.[2] We could use pulse oximetry to evaluate oxygen saturation condition in dyspneic patients. Some symptoms suggested complications other than pneumomediastinum. Marked dyspnea or respiratory distress is related with underlying lung disease, pneumothorax, pneumonia, aspiration of foreign body, or compression of airway caused by tension pneumomediastinum. Decreased breathing sound in unilateral lung area suggests association with pneumomediastinum, pneumonia, or aspiration. Distended neck veins can be seen with associated tension pneumomediastinum with compromised venous return. Esophageal perforation is a rare but relatively severe predisposing factor and should be searched for.[2]

The confirmed diagnosis is based on characteristic findings on frontal and lateral chest radiographs, including the cervical region.[78] Signs are listed in [Table 2]. Diagnosis by chest CT, neck imaging was also reported.[79] In addition to classic findings of pneumomediastinum, signs of pneumothorax, pneumopericardium, retropneumoperitoneum, and pneumoperitoneum should be looked for if patients present with related features or worsened symptoms. Subcutaneous emphysema can be evaluated with radiograph of the cervical region. Pleural effusion, usually left-sided, might be seen if associated with esophageal perforation.[80],[81] Hyperinflation may be linked with redisposing asthma attack.{Table 2}

 Differential Diagnosis



Pneumomediastinum might be combined with pneumothorax or esophageal rupture, and symptoms are easily confused with pericarditis. Pneumothorax can be distinguished by clinical manifestation and chest radiograph.

The esophageal rupture, also called Boerhaave syndrome, is rare in children and should be noted because of serious morbidity.[87] The patient usually presents with similar symptoms as pneumomediastinum. Clinical diagnosis is based on clinical presentation of vomiting, intense chest pain, and subcutaneous emphysema, also known as Mackler’s triad.[81] The severity of clinical presentation depends on the location of perforation and leakage degree. It often happens after vomiting, foreign body aspiration, or trauma.[41],[88],[89] The chest radiograph sometimes reveals accompanied presence of a pleural effusion, which might develop after injury. Confirmed diagnosis can be made with water-soluble contrast esophagram or combined with computed tomography (CT). Because of the high risk of mediastinitis and high morbidity, all suspected patients require close monitoring and further intensive care if needed.[32]

Pericarditis presents with symptoms similar to pneumomediastinum such as chest pain. Physical examination findings such as reduced heart sound, abnormal cardiac auscultation, and electrocardiogram change can differentiate pericarditis from pneumomediastinum.[33],[38]

 Management



SPM is generally a self-limited disease, which resolves without further complications within 3–18 days.[2],[26],[90] Most patients are hospitalized, and in some series, there can be up to 25.8% of patients requiring intensive care.[61] The management is based on its complication. The management of uncomplicated SPM is conservative and includes pain control, rest, avoiding pulmonary pressure increase, which included the measurement of peak expiratory flow, forced expiration, physical activity, and Valsalva maneuver.[91],[92] Therapy with high-concentration oxygen was suggested for patients with progressed or severe symptoms of dyspnea, chest pain, etc. It enhanced nitrogen washout and accelerated absorption of air accumulation.[93],[94],[95] Some suggested that further studies including repeat chest X rays, chest CT, esophagram, and diagnostic laryngoscopy did not yield additional diagnostic information in a clinically well-appearing patient after initial diagnosis.[79] Despite the lack of standardized clinical guidelines of management, stable-condition pediatric patients with SPM can be only observed for short period and discharged with resting and no further imaging follow-up according to the current evidence.[91]

The therapy of complicated SPM depends on complications. The management of SPM complicated with pneumothorax is similar to isolated pneumothorax, and needle aspiration and thoracostomy tube insertion are indicated if tension pneumothorax was diagnosed. In some case reports, severe tension pneumomediastinum mediastinal compression was treated by double mediastinotomy under local anesthesia or surgical decompression via video-assisted thoracic surgery.[11],[21],[37],[96] Some published cases reported SPM complicated with pneumopericardium that resolved spontaneously with no treatment,[7],[18],[39],[44],[65],[97],[98],[99] but we should always pay attention to the possibility of cardiac tamponade.

 Prognosis



SPM is usually a benign disease that spontaneously resolves with no complication and progression in 2–15 days.[2],[5],[26] No need of a follow-up image study was recommended because of sufficient information provided by physical examination.[6],[27] The recurrence of SPM is rare, which is less than 5% of reported cases.[2],[9],[26],[100] It is suspected that recurrence might be related with predisposing factors, so we might suggest patients to avoid certain activities or conditions that might cause increased pressure or barotrauma, such as Valsalva maneuvers, scuba diving, etc. Pneumomediastinum had worse prognosis if complicated with an underlying lung disease, pneumothorax, or measles.[65],[101]

 Conclusion



SPM is an uncommon disease in children, which is diagnosed by physical examination and radiography. It is usually benign and needs only pain control and rest if it is uncomplicated. On the other hand, SPM complicated with pneumothorax, esophageal perforation, or other underlying lung disease had poor prognosis and might need aggressive treatment. SPM is also a complication of COVID-19 and might worsen disease condition. Therefore, we should evaluate possible predisposing factors and take caution on complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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