Survival after severe methemoglobinemia secondary to sodium nitrate ingestion

Optimizing the lyophilization of Lumbricus terrestris erythrocruorin

Haemorrhagic shock is a leading cause of death worldwide. Blood transfusions can be used to treat patients suffering severe blood loss but donated red blood cells (RBCs) have several limitations that limit their availability and use. To solve the problems associated with donated RBCs, several acellular haemoglobin-based oxygen carriers (HBOCs) have been developed to restore the most important function of blood: oxygen transport. One promising HBOC is the naturally extracellular haemoglobin (i.e. erythrocruorin) of Lumbricus terrestris (LtEc). The goal of this study was to maximise the portability of LtEc by lyophilising it and then testing its stability at elevated temperatures. To prevent oxidation, several cryoprotectants were screened to determine the optimum formulation for lyophilisation that could minimise oxidation of the haem iron and maximise recovery. Furthermore, samples were also deoxygenated prior to storage to decrease auto-oxidation, while resuspension in a solution containing ascorbic acid was shown to partially reduce LtEc that had oxidised during storage (e.g. from 42% Fe3+ to 11% Fe3+). Analysis of the oxygen equilibria and size of the resuspended LtEc showed that the lyophilisation, storage, and resuspension processes did not affect the oxygen transport properties or the structure of the LtEc, even after 6 months of storage at 40 °C. Altogether, these efforts have yielded a shelf-stable LtEc powder that can be stored for long periods at high temperatures, but future animal studies will be necessary to prove that the resuspended product is a safe and effective oxygen transporter in vivo.

Massive Sodium Nitrite Overdose: A Case for Prehospital Methylene Blue

Sodium nitrite overdose leads to profound methemoglobinemia and may quickly progress to death. It is an increasingly common method of suicide and is often fatal. Methylene blue is an effective but time-sensitive antidote that has the potential to save lives when administered early. In this case report, we describe a fatal sodium nitrite overdose and the subsequent creation of a prehospital protocol for our large urban Emergency Medical Services system.

Special Report from the CDC: Suicide rates, sodium nitrite-related suicides, and online content, United States

BACKGROUND

In 2022, suicide ranked as the 11th leading cause of death in the United States with 49,513 deaths. Provisional mortality data from 2022 indicate a 2.8% increase in the number of suicides compared to 2021. This paper examines overall suicide trends, sodium nitrite ingestion as an emerging suicide method, and the role that online forums play in sharing information about suicide methods (including sodium nitrite ingestion).

METHODS

Suicides were identified from CDC's National Vital Statistics System (2018-July 2023 provisional) multiple cause-of-death mortality files using International Classification of Diseases (ICD), Tenth Revision underlying cause-of-death codes U03, X60-X84, and Y87.0 and T code T50.6 (antidotes and chelating agents). Google search popularity metrics were captured from January 2019 to January 2023. Case reports of sodium nitrite related suicide and suicide attempts (through February 2024) were identified in the medical and forensic literature.

RESULTS

At least 768 suicides involving antidotes and chelating agents (including sodium nitrite) occurred between 2018 and July 2023, set in the context of 268,972 total suicides during that period. Overall, suicides involving antidotes and chelating agents (including sodium nitrite) represent <1% of all suicides, however, numbers are rising.

CONCLUSIONS

Suicide methods are known to change over time. These changes can be influenced by, among other factors, online forums and means accessibility, such as internet purchase availability. CDC remains committed to prevention through comprehensive public health strategies that protect individuals, families, and communities.

PRACTICAL APPLICATIONS

States and community partners might consider leveraging physicians, emergency responders, and other appropriate crisis response groups to disseminate information on sodium nitrite self-poisoning and its antidote, methylene blue. Efforts should be part of a comprehensive public health approach to suicide prevention.

Systematic Review of Fatal Sodium Nitrite Ingestion Cases: Toxicological and Forensic Implications

Documented cases of sodium nitrite toxicity are almost exclusively caused by accidental ingestion; however, self-poisoning with sodium nitrite represents an increasing trend in nitrate-related deaths. This systematic review summarizes the most crucial evidence regarding the fatal toxicity of sodium nitrite. It identifies gaps and differences in the diagnostic forensic approaches and the detection methods of sodium nitrite intoxication. A total of eleven research articles were selected for qualitative and quantitative data. Most of the studies (6/11) were case reports. Fifty-three cases of fatal intoxication with sodium nitrite were chosen for the review. More research is required to develop cost-effective techniques and uniform cutoffs for blood nitrite and nitrate levels in the event of deadly sodium nitrite poisoning. There is still a lack of critical information on other matrices and the impact of time since death on toxicological results in such situations. The available evidence provides useful recommendations for forensic pathologists and health practitioners engaged in instances of sodium nitrite poisoning or death. The data should also set off alarm bells in the public health system, in prosecutor's offices, and for policymakers so that they may undertake preventative measures to stop and restrict the unregulated market for these substances.

Sodium nitrite suicide and social media influence

ABSTRACT

This article addresses the increase in suicide rates in the US, emphasizing the emergence of sodium nitrite ingestion as a method of self-harm, particularly among adolescents and young adults influenced by social media. Given the rising incidence of sodium nitrite-related suicide attempts, healthcare providers must remain vigilant and prepared to respond effectively.

Impact of methemoglobin on carboxyhemoglobin saturation measurement in fatal sodium nitrate and sodium nitrite cases

An increase in suicide cases by sodium nitrate and sodium nitrite ingestion has been noted in the scientific literature. We report on the possible impact of nitrate/nitrite-caused methemoglobinemia on carboxyhemoglobin measurement by spectrophotometric methods. Elevated methemoglobin saturation may result in insufficient reducing agents to convert methemoglobin into deoxygenated hemoglobin, affecting the measured total hemoglobin and carboxyhemoglobin saturation. We highlight four cases where the cause of death was attributed to sodium nitrate or sodium nitrite ingestion. The possible impact of the nitrate/nitrite-caused methemoglobinemia on the carboxyhemoglobin saturation as measured by spectrophotometry is discussed. Further studies are needed to identify a causal relationship between nitrate/nitrite-caused methemoglobinemia and carboxyhemoglobin saturation as measured by spectrophotometric methods.

Mechanisms and physiological function of daily haemoglobin oxidation rhythms in red blood cells

Cellular circadian rhythms confer temporal organisation upon physiology that is fundamental to human health. Rhythms are present in red blood cells (RBCs), the most abundant cell type in the body, but their physiological function is poorly understood. Here, we present a novel biochemical assay for haemoglobin (Hb) oxidation status which relies on a redox-sensitive covalent haem-Hb linkage that forms during SDS-mediated cell lysis. Formation of this linkage is lowest when ferrous Hb is oxidised, in the form of ferric metHb. Daily haemoglobin oxidation rhythms are observed in mouse and human RBCs cultured in vitro, or taken from humans in vivo, and are unaffected by mutations that affect circadian rhythms in nucleated cells. These rhythms correlate with daily rhythms in core body temperature, with temperature lowest when metHb levels are highest. Raising metHb levels with dietary sodium nitrite can further decrease daytime core body temperature in mice via nitric oxide (NO) signalling. These results extend our molecular understanding of RBC circadian rhythms and suggest they contribute to the regulation of body temperature.

Nitrites: An Old Poison or a Current Hazard? Epidemiology of Intoxications Covering the Last 100 Years and Evaluation of Analytical Methods

In recent times, there has been a concerning and noteworthy rise in the global use of sodium nitrite for suicidal purposes. This is facilitated either through the employment of specialized "suicide kits" or by acquiring sodium nitrite through alternative means. Additionally, another occurrence contributing to nitrite poisoning is the recreational utilization of nitrites in the form of volatile aliphatic esters of nitrous acid, commonly referred to as "poppers". Based on current available papers and reports on the subject of nitrates, nitrites, and poppers intoxications, an epidemiological analysis and evaluation of analytical methods were performed. A total of 128 papers, documenting a collective count of 492 intoxication cases, were identified. Additionally, in order to complete the epidemiological profile of nitrite poisoning, the authors briefly examined six cases of nitrite intoxication that were under investigation in our laboratory. Furthermore, a review of nitrite poisoning cases over the past 100 years shows that the old poison is still in use and poses a substantial risk to society.

Sodium nitrite poisoning: A series of 20 fatalities in which post-mortem blood nitrite and nitrate concentrations are reported

Sodium nitrite has several industrial applications however its accidental or intentional ingestion has been associated with severe toxicity and death. We present a series of 20 cases over 2 years in which evidence of sodium nitrite ingestion was found at the scene and supported by biochemical analysis of post-mortem blood nitrite and nitrate levels. Routine toxicological screening was performed on post-mortem blood samples received at University Hospitals of Leicester (UHL) NHS Trust, including ethanol analysis by headspace gas chromatography-flame ionisation detection (HS GC-FID), drug screening by high resolution accurate mass-mass spectrometry (HRAM-MS) and confirmatory drug quantitation by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cases in which the history indicated the possibility of nitrite salts present at the scene, purchase of a suicide kit or a dusky-ash appearance of skin on post-mortem were referred to a specialist laboratory for nitrite and nitrate analysis. Analysis was based upon the gas-phase chemiluminescent reaction between nitric oxide (NO) and ozone; NO levels were determined using an NOA 280A, Sievers NO analyser. Twenty post-mortem cases in which sodium nitrite ingestion was the most probable cause of death were reported between January 2020 and February 2022; mean age was 31 years (range 14-49) with 9/20 (45%) female. 16/20 (80%) of cases had a history of depression and / or mental health issues. In half of the cases, anti-depressant / anti-psychotic drugs were prescribed; these drugs were detected in 8/20 (40%) cases. Ethanol was detected in 4/20 (20%) cases and anti-emetic drugs in 7/20 (35%) cases; anti-emetic drugs may be used to aid retention of sodium nitrite. Illicit drugs (amphetamine, cannabis and cocaine) were present in 3/20 cases (15%). Nitrite was found to be elevated in all but one case (95%), and nitrate was elevated in 17/20 (85%) cases. This paper highlights a surge in numbers of deaths across England and Wales due to sodium nitrite toxicity. Although, nitrite poisoning remains a rare cause of death, it is worthwhile considering its use in individuals with suicidal ideation given its unregulated availability online. The detection and quantitation of nitrite and nitrate requires specialised, highly reliable methodology currently only available in research laboratories. Implication of sodium nitrite ingestion also relies heavily upon circumstantial evidence combined with quantification. The provision of a quantitative nitrite / nitrate analytical service greatly assists in determining the cause of death in these cases.

Sodium Nitrite Intoxication and Death: Summarizing Evidence to Facilitate Diagnosis

BACKGROUND

Over the years, forensic pathology has registered the spread of new methods of suicide, such as the ingestion of sodium nitrite. Sodium nitrite causes increased methemoglobin, resulting in systemic hypoxia, metabolic acidosis, and cyanosis. Since sodium nitrite is a preservative, the ingestion of foods containing an excessive amount of this substance can also cause acute intoxication up to death. The present review is aimed at guiding health professionals in the identification and management of sodium-nitrite-related intoxications and deaths.

METHODS

A systematic literature search was carried out on PubMed by following the PRISMA statement's criteria. A total of 35 studies with 132 cases were enrolled, and the data were cataloged in Microsoft Excel. To establish the causal correlation between sodium nitrite ingestion and death, the Naranjo Adverse Drug Reaction Probability Scale was used.

RESULTS

In addition to the small number of cases that have currently been published, the study demonstrated that there was a general methodological discrepancy in the diagnostic process. However, some interesting results have emerged, especially in post-mortem diagnostics.

CONCLUSION

Sodium-nitrite-related deaths represent a challenge for forensic pathologists; therefore, it is important to promptly recognize the essential features and perform the necessary and unrepeatable examinations for the correct diagnosis of the cause of death.

Two cases of fatal methemoglobinemia caused by self-poisoning with sodium nitrite: A case report

RATIONALE

Sodium nitrite intoxication reportedly causes severe methemoglobinemia. Recent studies reported that most clinically significant cases resulted from intentional exposure in suicidal attempts. We describe 2 cases of severe methemoglobinemia secondary to intentional sodium nitrite intoxication in suicidal attempts.

PATIENTS CONCERNS

A 26-year-old man and 20-year-old woman attempted suicide by taking sodium nitrite, and were brought to the emergency department.

DIAGNOSIS

The male patient collapsed at the scene. He ingested approximately 18 g of sodium nitrate, and his methemoglobin level was 90.3%. The female patient was conscious, but was cyanotic. She ingested approximately 12.5 g of sodium nitrite, and her methemoglobin level was 54.6%.

INTERVENTIONS

The male patient received advanced cardiac life support in the emergency department. Methylene blue was immediately administered for the female patient.

OUTCOMES

The male patient died despite aggressive resuscitation. The female patient's cyanosis resolved, and her methemoglobin level decreased to 1.2% 3 hours later.

LESSONS

The immediate administration of methylene blue in severe methemoglobinemia patients prevented fatal consequences. The public should be informed about the accessibility and toxicity of sodium nitrite.

Fatal methemoglobinemia: A case series highlighting a new trend in intentional sodium nitrite or sodium nitrate ingestion as a method of suicide

Unintentional exposure to nitrite- or nitrate-containing toxic salts is a recognized cause of acquired methemoglobinemia (MetHb). This systemic alteration of the blood can be fatal if not recognized and treated promptly. The intentional ingestion of sodium nitrite (NaNO₂) or sodium nitrate (NaNO₃), causing MetHb, is an uncommon and recently identified method of suicide, with the first reported case in the literature occurring in New Zealand in 2010. In this case series we present 28 cases of sudden death of individuals with evidence of MetHb and/or toxic salt ingestion, occurring in the Province of Ontario, Canada, between the years 1980 and 2020, inclusive. Of the 28 deaths in our case series, 25 showed evidence of intentional ingestion of sodium nitrite or sodium nitrate salts. Our year-over-year data demonstrated this is an increasingly used method of suicide in our provincial population, with the majority of cases occurring in the final two years of our study. Postmortem detection of MetHb is typically established via screening techniques such as scene evidence suggesting fatal consumption of a toxic salt in addition to the characteristic grey-purple lividity observed upon the body. The diagnosis can be established via postmortem blood testing demonstrating elevated methemoglobin saturation. Additionally, we have confirmed that postmortem MRI in cases of MetHb demonstrates a T1-bright (hyperintense) signal of the blood; both within intracardiac blood on chest MRIs and postmortem blood samples in tubes.

Code Blue: Life-threatening Methemoglobinemia

Most cases of acquired methemoglobinemia result from exposure to certain drugs or toxins. One of the more common and well-described causes in the literature is exposure to topical benzocaine during medical procedures. We present a case series of acute acquired methemoglobinemia from a food source that has not been previously described in the literature: a dessert. Three patients, ages 5, 33, and 86 years, were brought to our emergency department by ambulance after becoming extremely ill from ingesting a dessert containing nitre powder at a family gathering. They all presented with hypotension, cyanosis, and hypoxia that was not responsive to oxygen administration. The adult patients had major improvement of symptoms after a single dose of methylene blue. In contrast, the 5-year-old child who had the worst symptoms minimally improved with administration of two doses of methylene blue requiring intensive care admission and transfer to a tertiary care center.