Metabolic encephalopathy caused by nitrous oxide ('laughing gas') induced hyperammonaemia.
Marissa Ginette Danielle Vive, Galia Valentinova Anguelova, Sjoerd Duim, Herman Marcel André Hofstee
BMJ case reports November 25, 2019 DOI: 10.1136/bcr-2019-232163 via PubMed
Summary
AI-generated from the abstractA 26-year-old man arrived at the emergency department confused and with decreased consciousness after several days of vomiting. For the preceding six months, he had used a 2-liter tank of nitrous oxide weekly. His metabolic encephalopathy was caused by hyperammonaemia, probably resulting from nitrous-oxide-induced vitamin B12 deficiency interfering with ammonia degradation. A catabolic state may have contributed. After treatment with vitamin B12 and lactulose, both his consciousness and hyperammonaemia improved. He reported no residual complaints after three months of follow-up. The authors recommend considering hyperammonaemia as a cause of metabolic encephalopathy in cases of nitrous oxide use and altered mental status.
Study at a glance
| Characteristics | Case study Case report Peer reviewed |
|---|---|
| Sample size | 1 |
| Population | A 26-year-old man |
| Interventions | vitamin B12 lactulose |
| Duration | 3-month follow-up |
| Keywords | Emergency medicine Peripheral nerve disease Sedation Vitamins and supplements |
| Key finding | Nitrous oxide use can cause hyperammonaemia leading to metabolic encephalopathy, which improves with vitamin B12 and lactulose treatment. |
Abstract
A 26-year-old man presented at the emergency department with confusion and decreased consciousness after several days of vomiting. In the preceding 6 months, he had used a 2-litre tank of nitrous oxide (N2O) weekly. His metabolic encephalopathy was caused by hyperammonaemia which probably resulted from interference of N2O-induced vitamin B12 deficiency with ammonia degradation. A catabolic state might have contributed to the hyperammonaemia in this case. After treatment with vitamin B12 and lactulose, both his consciousness and hyperammonaemia improved. He reported no residual complaints after 3 months of follow-up. Since N2O is increasingly used as a recreational drug, we recommend considering hyperammonaemia as a cause of metabolic encephalopathy in cases of N2O use and altered mental status.