Pneumomediastinum while using mechanical insufflation-exsufflation after recovery from riluzole-induced interstitial lung disease

We, herein, report a 61-year-old male patient with amyotrophic lateral sclerosis (ALS) complicated pneumomediastinum while using mechanical insufflation-exsufflation (MI-E) after recovery from riluzole (RZ)-induced interstitial lung disease (RZ-ILD). After the treatment of RZ-ILD, he required non-invasive mechanical ventilation (NIV) at minimal pressure settings and MI-E to manage ALS-related breathing and airway-clearance issues, respectively. After a while, he developed progressive worsening dyspnoea, and chest computed tomography revealed extensive pneumomediastinum that had spread to the area surrounding the oesophagus, the retrosternal space, and the pericardial space. He was treated with immediate discontinuation of MI-E; however, he had to keep using NIV to support his severe respiratory muscle involvement. Pneumomediastinum gradually reduced in size and no recurrence of pneumomediastinum occurred. The clinical course of our patient suggests that excessive coughing associated with MI-E combined with his previous RZ-ILD, which potentially renders his lungs vulnerable to airway pressure, may have been the aetiological factors for secondary pneumomediastinum, i.e. barotrauma. Clinicians should be aware of the risk of pneumomediastinum while using MI-E in patients with ALS, who have other pre-existing risk factors for pneumomediastinum, such as drug-induced ILD in our case.