Poster Presentation AANZGOSA-SUGSS ASM 2024

Nitrous oxide, commonly known as laughing gas, NOS or “Nags”, is a colourless gas used in the medical field for numerous years to help with pain relief. NOS's unrestricted access to young New Zealanders has recently increased exponentially. “Nags” are sold in small 8g canisters costing around $15 (Box of 10) and inhaled for a short-lived euphoria.  NOS  is a known vasodilator that causes the relaxation of blood vessels. The long-term adverse effects of recreational inhalation of NOS have been documented with neuropathy and myelopathy. Literature of life-threatening acute adverse effects are scarce, with only a few cases reporting thromboembolic events, pneumothorax/pneumomediastinum, cardiovascular events and acute liver injury. 

We present a case of a fit and well 18-year-old male, who presented acutely with atraumatic epigastric pain, and haemodynamic instability after inhalation of recreational NOS. A bedside ultrasound demonstrated free fluid in the abdomen. A triple-phase Computed Tomography (CT) portrayed large volume haemoperitoneum, with an overall appearance suspicious of a spontaneous blood vessel rupture with a sentinel clot distending the lesser sac. The patient was appropriately stabilised and resuscitated promptly.

There are growing concerns that the prevalence of recreational NOS is increasing in New Zealand secondary to its accessibility and lack of public health interventions reporting its potential adverse effects. To our knowledge, this is the first case reported of a spontaneous haemoperitoneum after inhalation of recreational NOS in Australasia. Clinicians should be aware of this potentially life-threatening adverse effect and should remain vigilant to act promptly in such patients.