Major Air Leak Syndrome in Child Secondary to Sporadic H1N1 Influenza: An Unusual Occurrence

Abstract

The symptoms of H1N1 influenza infection may be similar to those of seasonal influenza, and hospitalization is not required in most of the cases. However, the virus can infect the lower respiratory tract and cause rapidly progressive pneumonia, especially in susceptible children. Air leak in children with influenza has been mainly described with the pandemic variant of H1N1; however, sporadic strains of H1N1 also have the potential to cause massive air leak. secondary causes should be judiciously excluded before the management of such cases.

Keywords

H1N1 influenza - air leak - pneumomediastinum

Introduction

Swine origin influenza (H1N1) virus infection is mostly described in the settings of pandemic. Most patients have mild disease course, however spread of infection to lower respiratory tract can lead to pneumonia especially amongst children. Thoracic air leak syndrome with pneumomediastinum, pneumopericardium, pneumorrhachis, pulmonary interstitial emphysema with extensive subcutaneous emphysema is unusual occurrence with few case reported.

Here we present a case of 7-year-old male child who developed major thoracic air leak secondary to sporadic H1N1 influenza virus.

Case Presentation

A 7-year-old male child appeared in the pediatric emergency department with complaints of continuous high-grade fever associated with chills, rigors, and dry cough for 8 days, along with swelling over the neck that was gradually progressing and had increased over the last 24 hours. On clinical examination, the patient was unconscious, tachypneic, tachycardiac, and hypotensive. On palpation, there was smooth bulging of skin with crackling sensation present over the face, neck, chest, back, and abdomen. On auscultation, bilateral air entry was reduced with the presence of crepitations. A provisional clinical diagnosis of acute respiratory distress syndrome with septic shock and extensive subcutaneous emphysema was made.

Routine blood investigations showed leukocytosis, and raised C-reactive protein. Portable chest radiography showed areas of consolidation and ground-glass opacities (GGO) in the bilateral lung fields, a rim of air outlining the heart border, and areas of lucency in the subcutaneous plane of the chest and the visualized neck and abdomen ([Fig. 1]).

Fig. 1 Portable chest radiograph anteroposterior view shows patches of consolidation and GGO in bilateral lung fields (black arrow), rim of air outlining the cardiac border suggestive of pneumopericardium (white arrow) and areas of lucencies in subcutaneous plane of neck and chest (blue arrow). GGO, ground-glass opacity.

Real-time qualitative PCR for the influenza panel was done which came out to be positive for H1N1 (Influenza A virus).

Imaging Findings

Cross-sectional imaging was advised for further evaluation .Non-contrast computed tomography (NCCT) of chest was done, which showed areas of consolidation and GGO in the bilateral lung fields, massive pneumomediastinum, pneumopericardium, air-filled areas in the pulmonary interstitium and along the bronchovascular bundles, and a thin rim of bilateral pneumothorax ([Fig. 2A–C]). Air was also seen extending into spinal canal along the dorsal and lumbar nerve roots, suggestive of pneumorrhachis ([Fig. 3A] and [B]). Extensive subcutaneous emphysema was noted, extending superiorly into all neck spaces up to the base of skull, with inferior extension including chest, bilateral arms, and abdomen ([Fig. 3C]). No obvious laryngeal, tracheal, and esophageal injury was noted. These findings were consistent with the diagnosis of thoracic air leak syndrome secondary to acute pneumonitis.

Fig. 2 Nonenhanced chest thin section computed tomography image obtained with lung window settings- Label (A) shows patches of consolidation (blue arrow), pneumomediastinum (red arrow) and thin rim of pneumothorax (green arrow); Label (B) shows air along the bronchovascular bundle (yellow air) and pneumopericardium (white arrow); Label (C) shows pulmonary interstitial emphysema (black arrow).

Fig. 3 Nonenhanced chest thin-section computed tomography image obtained with mediastinal window settings. Labels (A and B) show sagittal and axial reformatted images, respectively showing air lucencies within spinal canal (red arrow in A) and along dorsal nerve roots (yellow arrow in B) that is consistent with pneumorrhachis. Label (C) shows subcutaneous emphysema with air reaching up to the base of skull (blue arrow).

Discussion

Swine origin influenza (S-OIV), also known as H1N1 influenza, contains genes from swine, avian, and human influenza viruses and is highly contagious acute respiratory illness.[1] The majority of cases are mild presenting with fever, dry cough, sore throat, chills, and joint pain and are self-limited; however, severe respiratory distress with rapid progression to pneumonia can develop in children.[2] The most common radiologic abnormalities are bilateral asymmetric GGO in a random distribution, with or without associated consolidatons.[2] The majority of air leak syndromes in children were reported with the pandemic strain of H1N1 influenza virus; however, this case shows that sporadic variant also have the potential to cause massive air leak . Air leak associated with H1N1 has been postulated to occur from airway necrosis, vigorous coughing, or both.[3] However, in our case, no obvious signs of tracheobronchial injury were seen. Bronchial asthma, even of mild degree, has been a risk factor for disease severity in H1N1 influenza, as alveolar rupture is more prone to occur in hyperinflated lungs.[3] In thoracic air leak syndrome, there is a spontaneous leakage of air from pulmonary air spaces weakened by infection or inflammation, and the underlying mechanism has been attributed to the Macklin effect. Increased alveolar pressure leads to alveolar rupture, with air dissecting along the bronchovascular sheaths, which in turn causes pulmonary interstitial emphysema and pneumomediastinum. Leaked air also tracks into the neck along the deep fascial planes and then into the subcutaneous planes, leading to subcutaneous emphysema of the neck and chest.[4] In severe pneumomediastinum, trapped air may cause airway obstruction or impingement on venous return due to tamponade effect.[5] Management of thoracic air leak syndrome depends on the severity of the air leak, with no clear consensus regarding its treatment. Mild cases of pneumomediastinum are treated with bed rest and high-flow oxygen therapy.[6] Severe cases may require mechanical ventilation. Cervical mediastinotomy with or without tracheostomy is reserved for pneumomediastinum causing marked cardiorespiratory compromise.[7] In our case, there was a major air leak, so the child was placed on pressure-controlled mechanical ventilation and was treated with intravenous antibiotics and the antiviral drug oseltamivir.

Conclusion

Pneumomediastinum should be considered in a child presenting with dyspnea, chest pain, and fever accompanied by palpable crepitations, particularly if is a history of bronchial asthma even if mild.

Secondary causes of pneumomediastinum, such as foreign body ingestion and esophageal perforation, should be judiciously excluded, as in the majority of children, isolated cases of primary spontaneous pneumomediastinum can be managed conservatively with careful observation. Prognosis is generally good, and spontaneous pneumomediastinum usually resolves within a few days if the patient receives good supportive care and treatment of the underlying medical conditions.

Conflict of Interest

None declared.

Patient Consent

Prior consent obtained from the patient.

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Publication History

Article published online:
19 February 2026