Pneumomediastinum Secondary to Barotrauma after Recreational Nitrous Oxide Inhalation

The dangers of recreational inhalation of nitrous oxide

Nitrous oxide, also known as 'laughing gas', is one of the most widely used recreational drugs among teenagers in the UK. Copious inhalation of nitrous oxide may increase intra-alveolar pressure, resulting in barotrauma secondary to alveolar rupture. Pneumomediastinum and subcutaneous emphysema are common clinical findings in nitrous oxide-associated barotrauma. Prolonged nitrous oxide misuse may inactivate vitamin B₁₂ through the alteration of its metabolism, causing demyelination of the central and peripheral nervous system. A spectrum of neurological manifestations has been reported, including peripheral neuropathy, myelopathy and subacute combined degeneration of the spinal cord. Medical therapies and psychosocial interventions aiming at nitrous oxide cessation are important treatment steps to achieve partial or complete recovery from the adverse effects associated with inhalation of nitrous oxide.

Mediastinal emphysema after long-distance flight with ketoacidosis and underlying diabetes mellitus type 1

A 21-year old female with diabetes mellitus type 1 presented to our hospital's emergency department having suffered from shortness of breath, mild chest pain, and vomiting following her arrival after a long-distance flight two days earlier. Symptoms had since subsided and physical examination was normal. Blood analysis revealed increased D-dimers and diabetic ketoacidosis. Computed tomography (CT) examination excluded pulmonary embolism but demonstrated significant mediastinal emphysema. After conservative treatment including nasal oxygen and adjustment of insulin therapy, follow-up low-dose CT after four days confirmed full regression of the emphysema. The patient was discharged feeling well, with a recommendation for improved diabetes treatment. Spontaneous pneumomediastinum is a rare condition occurring in younger patients without trauma or pulmonary disease. Over-inflation and/or pulmonary vasoconstriction have been proposed as major physiological contributors and were likely evoked in the present case by increased respiratory drive due to ketoacidosis and hypoxic vasoconstriction during long distance flight.