Abstract
Sodium nitrite is a common household product with a variety of uses such as curing meat, food additive, colouring agent, anti-freezing agent and disinfectant. We report a case of sodium nitrite intoxication for deliberate self-harm and discuss the increasing number of such cases in recent times.
When a person is desperate to end his life by suicide, he chooses a potentially lethal method which gives him an instant and painless death. Poisons are used for deliberate self-harm throughout the world. Agricultural poisons like organo-phosphorous compounds, zinc phosphide and aluminium phosphide are more common in the agrarian communities of the developing world. However, in developed countries, stringent laws limit access to agricultural poisons. The data published by Poison Control in 2019 show that pharmacological products are favoured for suicide in the United States with benzodiazepine-based sedatives and opiate analgesics at the top of the list with a case reported every 15 min. 1 Sodium nitrite is a common household product with a variety of uses. We report a case of sodium nitrite intoxication for deliberate self-harm and discuss the increasing number of such cases in recent times.
Case report
A 37-year-old male was brought to the emergency department (ED) by the emergency medical service following the consumption of an unknown amount of sodium nitrite. On arrival to ED, he was in an altered mental state and was cyanosed. His oxygen saturation was 68% at room temperature, blood pressure 107/65 mmHg, pulse 105 beats per minute and respiration 15 breaths per minute. The patient was immediately intubated, and mechanical ventilation was started with FiO2 of 100% with intensive care. Examination of the respiratory and cardiovascular systems was essentially unremarkable. Neurologic examination was non-focal except for altered mental status, which was likely attributable to hypoxia.
Arterial blood gas showed oxygen saturation of 89%, oxyhaemoglobin 25.1%, carboxyhaemoglobin 10.4% and methaemoglobin >10.0%. Chest X-ray was negative for infiltrates, consolidation, pleural effusion, with a normal cardio-mediastinal silhouette. Laboratory investigations including blood counts and serum electrolytes, and renal function parameters were within normal range. Urine toxicology was negative for benzodiazepine, opiates, phencyclidine, cannabinoids and cocaine.
The diagnosis of methaemoglobinaemia was made based upon his >10% methaemoglobin level on arterial blood gas analysis. He was treated with a protocol driven methylene blue infusion. The patient made an uneventful recovery and was extubated on the third day.
The patient’s family presented the bottle of sodium nitrite that he had consumed with the intent of deliberate self-harm. The patient was later transferred to a psychiatric unit and was enrolled in cognitive behavioural and antidepressant therapy for underlying depression and suicidal behaviour.
Discussion
Sodium nitrite is an inorganic salt commonly used for wider industrial purposes such as for curing meat, food additives, colouring agents, anti-freezing agents or as disinfectants. Medically, sodium nitrite, together with sodium thiosulphate, is used in the treatment of acute cyanide poisoning and is one of the essential medicines as per World Health Organization. 2 Furthermore, the vasodilatory action of sodium nitrate has also emerged as a novel strategy to prevent delayed cerebral vasospasm after subarachnoid haemorrhage. 3
Accidental poisoning with sodium nitrite can occur when it is mistaken for common salt and is readily soluble in water. 4 The potential complication of sodium nitrite ingestion is methaemoglobinaemia, where the oxygen carrying capacity of haemoglobin is compromised which results in fatality without timely intervention. Sodium nitrite is also reported to be used as a recreational drug, consumption of which resulted in severe methaemoglobinaemia. 5 As readily available and widespread use of this compound, it is not uncommon for this substance to be kept at home.
The corona virus pandemic has brought suffering on many people through financial difficulties or loss of job or a family member. Many people were depressed and had suicidal ideation. To add fuel to fire, there are numerous webpages and shadow markets scattered all over the internet which explain the lethality of sodium nitrite for euthanasia. 6 It is unfortunate that a “suicide kit” that contains sodium nitrite can be bought easily over the internet. 7 In 2020 alone, there are five cases reported in the scientific literature where the victims committed suicide by consuming sodium nitrite after buying the compound over the internet.6–9 These cases warn us of the grim reality that there may be many more such cases which are unreported in the scientific literature.
The use of the internet is integral to everyday life. Discussions upon the use of sodium nitrite for suicide can be readily accessed from any part of the world. Online vendors who provide “suicide kits” are believed to circumvent customer service. 8 The widespread use of sodium nitrite in the household makes it an easily available substance that can be brought without restrictions, and it is not easy to see how to impose restrictions on the sale of this substance. We want to raise the clinical awareness of sodium nitrite as a potential cause of methaemoglobinaemia. Further, we would like to draw the attention of the law enforcing agencies to this, to intervene in, confront and block the surreptitious online suicide market that is functioning freely in the back alley of the web.
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.