The Macklin Effect

Abstract Introduction: Pneumomediastinum is a rare clinical entity and is defined as air within the mediastinum. Symptoms of pneumomediastinum include chest pain, dyspnea, subcutaneous emphysema, dysphagia and dysphonia. It is further divided into primary spontaneous pneumomediastinum and secondary pneumomediastinum. Here we present a case of Primary Spontaneous Mediastinum in a 28-year-old asthmatic patient after ae episode of upper respiratory tract infection. Case Report: A 28-year-old patient with past medical history of well controlled mild intermittent asthma presented to the hospital with chest pain and dyspnea. On further evaluation, he reported upper respiratory tract symptoms for last 3-4 days with heavy bouts of coughing. He reported that the chest pain started after the coughing spells. He also reported to have been in close contact with his wife and kid who were recently infected with common cold. On physical exam, he had subcutaneous emphysema. His CXR showed pneumomediastinum, with a subsequent CT Chest showing extensive pneumomediastinum with air tracking around his chest and upper neck, secondary to possible alveolar rupture aka Macklin effect. CT Chest didn't show any esophageal injury or tear. Pt also reported smoking marijuana recently. Pt was treated conservatively with analgesics and oxygen, and despite his impressive CT Chest, his symptoms improved dramatically within a day, and he was discharged home with directions to follow outpatient. Pt was also advised to avoid smoking to prevent recurrence of the pneumomediastinum. Discussion: Pneumomediastinum is a rare clinical diagnosis and usually has a good clinical outcome. Spontaneous pneumomediastinum usually occurs in healthy subjects but is associated with risk factors including smoking and polysubstance abuse. Secondary pneumomediastinum is due to an identifiable risk factor including iatrogenic, surgery, trauma, COPD, bronchiectasis, and malignancy. The pathophysiology of pneumomediastinum is termed as ‘Macklin effect’, defined as 3 step process: alveolar ruptures, air dissection along bronchovascular sheaths, and spreading of this pulmonary interstitial emphysema into the mediastinum. It's important to find the inciting event causing the pneumomediastinum as that guides the management. Treatment for primary spontaneous pneumomediastinum is usually conservative with analgesic and oxygen. Focus should be on treating symptoms rather than imaging which can look dramatic in some instances. Pneumomediastinum is self-resolving, and recurrence is usually rare. References: Available on request and on QR Code