Lethal methemoglobinemia and automobile exhaust inhalation

Comparative Evaluation of Carboxyhemoglobin Quantification in Postmortem Whole Blood by CO-Oximetry and Headspace Gas Chromatography with Flame Ionization Detection and Atom Absorption Spectrophotometry

A comparative evaluation of two methods used for carboxyhemoglobin (COHb) determination in postmortem whole blood was performed: carbon monoxide (CO)-oximetry measuring at 128 wavelengths and headspace gas chromatography with flame ionization detection (HS-GC--FID) where CO was determined after catalytic reduction of CO to CH4 and Fe was determined by atom absorption spectrophotometry (AAS, 248.3 nm). An aliquot of 100 µL whole blood was loaded into the CO-oximetry module. In the HS-GC--FID analysis, to 1.0 mL of whole blood, 3.0 mL of saponin solution was added, mixed and centrifuged. To 20 mL HS vials, 400 µL of the supernatant was added and the vials were immediately sealed. One milliliter of potassium hexacyanoferrat (III) solution was added through the HS septum and mixed. The samples were incubated at 70°C for 5 min. CO was separated using He as carrier gas and a CP-Molsieve 5 Å PLOT capillary column. Fe was determined using 400 µL of the saponin supernatant diluted to 10 mL by water. During a period of ∼3 years, 124 postmortem whole blood samples were analyzed. Bland-Altman method comparison showed satisfactory agreement and no significant bias between the methods for the whole saturation range (5 to 85% COHb). Five samples, all with %COHb >40, showed deviations of more than 10% COHb in absolute terms. One sample, in the lower COHb range <10%, was false negative on the CO-oximetry method. The between-assay accuracy, reported as bias, at 60% COHb was -0.8% and -9.0%, and precision, reported as relative standard deviation, was 1.6% and 7.7%, for the CO-oximetry and HS-GC--FID-AAS methods, respectively. Both methods obtained satisfactory results in proficiency testing rounds, with z-scores <±2 (n = 11). This study showed that the CO-oximetry method based on the 128-wavelength principle and the HS-GC--FID-AAS method are comparable and satisfactory for %COHb determination in postmortem whole blood.

Methemoglobinemia Secondary to Inhalation of Automobile Emissions with Suicide Motivations

BACKGROUND

Methemoglobinemia (MetHb) is a rare and potentially severe dyshemoglobinemia that can be induced by exposure to oxidizing agents, decreasing the functional capacity of the hemoglobin molecule to transport and release oxygen into the tissues. MetHb can originate from gases with oxidizing capacity generated by internal combustion engines, although since the universalization of catalyst converters in automobiles, a tiny proportion of MetHb poisoning is due to exposure to engine gases and fumes. Within this group, only two cases due to suicidal motivations have been reported in the last 30 years.

CASE PRESENTATION

Here, we expose the case of a patient with MetHb levels of 25.2% (normal 0-1.5%) who with suicidal motivations had attached and locked a hose to the exhaust pipe of her vehicle with electrical tape, becoming exposed to a sustained concentration of the vehicle's exhaust. Upon her arrival at the emergency department, the presence of generalized greyish cyanosis with alterations of the sensorium, dissociation between saturation measured by arterial blood gas analysis and pulse oximetry (98% vs. 85%), no response to high-flow oxygen therapy, and an excellent response to intravenous methylene blue treatment were highlighted.

CONCLUSIONS

This report illustrates an original case of acute toxic acquired MetHb due to inhalation of oxidizing substances originating from the bad ignition of an internal combustion engine. When evaluating a patient with suspected gas intoxication, we usually consider poisoning by the most common toxins, such as carbon monoxide or cyanide. In this context, we propose an algorithm to assist in the suspicion of this entity in patients with cyanosis in the emergency department. MetHb poisoning should be suspected, and urgent co-oximetry should be requested when there is no congruence between cyanosis intensity and oxygen saturation measured by pulse oximetry, if there is discordance between the results of oxygen saturation measured by arterial blood gas and pulse oximeter, and if there is no response to oxygen treatment. This algorithm could be useful to not delay diagnosis, improve prognosis, and limit potential sequelae.

Assessment of chemical asphyxia caused by toxic gases generated from rigid polyurethane foam (RPUF) fires

Rigid polyurethane foam (RPUF) is widely used for thermal and sound insulation owing to their low thermal conductivity and light weight. However, they have serious disadvantages, including flammability and toxic gas generation, which can cause chemical asphyxia during a fire. Carbon monoxide (CO) and hydrogen cyanide (HCN) are representative toxic gases formed by incomplete combustion and HCN, in particular, is closely related to polyurethane product fires. In this study, the risk of inhalation of toxic gases such as CO, HCN and NO₂ during RPUF fires was demonstrated convincingly through the analysis of carboxyhemoglobin (COHb), cyanide (CN^-) and methemoglobin (MetHb) in the postmortem blood samples of 38 victims of RPUF fires. To better understand the toxic gas poisoning and chemical asphyxia, we classified all cases into two groups based on the extent of injuries and location where the victim was found. Mean concentrations of COHb and cyanide in group 1 without injuries were approximately two times higher than in group 2 with severe injuries, while concentrations of free MetHb showing possibility of NO₂ inhalation were approximately six times lower than in group 2. Furthermore, we presumed concentrations of cyanide at the time of death and five cases showed the possibility of cyanide poisoning.

A Rare Case of Fatal Self-Poisoning With Sodium Nitrite: Autopsy and Toxicological Findings

ABSTRACT

Fatal sodium nitrite poisonings are unusual in the forensic setting. Suicide by poisoning includes drug overdose, the inhalation of toxic gasses, and poisoning from pesticides and chemical substances. Sodium nitrite is an inorganic compound usually seen as a crystalline powder that is very water soluble. Sodium nitrite is used mostly in the food industry (as a preservative) and in medical field (as an antidote to cyanide poisoning), and if ingested in large enough amounts, it can be fatal.The ingestion of sodium nitrite can cause severe methemoglobinemia, which is a metabolic disorder characterized by an inability of hemoglobin (which gets oxidized into methemoglobin) to bind (and therefore carry) oxygen. Severe cases of this condition, if not treated, can be fatal.We describe a case of fatal self-poisoning with sodium nitrite; in particular, the article focuses on the autoptic and toxicological investigations that enabled the correct diagnosis to be established.

Carbon monoxide poisoning

Carbon monoxide (CO) is the leading cause of poisoning deaths in many countries, including Japan. Annually, CO poisoning claims about 2000-5000 lives in Japan, which is over half of the total number of poisoning deaths. This paper discusses the physicochemical properties of CO and the toxicological evaluation of CO poisoning.

Is Asymmetric Dimethylarginine a Useful Biomarker in Children With Carbon Monoxide Poisoning?

OBJECTIVE

Carbon monoxide poisoning (COP) is the leading cause of mortality and morbidity due to poisoning worldwide. Because children are affected more quick and severely from COP, they may require a longer treatment period, even if carboxyhemoglobin (CO-Hb) and/or lactate levels return to normal. Therefore, a new marker that predicts the duration of treatment and the final outcomes of COP is needed.

METHODS

This case control study was conducted on 32 carbon monoxide-poisoned patients younger than 18 years who had been admitted to pediatric emergency department. The control group included age- and sex-matched 30 healthy children. Blood samples were obtained for analysis of arterial blood gases, CO-Hb percent, methemoglobine, lactate, and asymmetric dimethylarginine (ADMA).

RESULTS

Asymmetric dimethylarginine levels were significantly increased (P < 0.05) in patients with COP on admission and after the treatment when compared with controls (1.36 [0.89-6.94], 1.69 [0.76-7.81], 1.21 [0.73-3.18] nmol/L, respectively). There was no positive correlation between CO-Hb and ADMA levels on admission and at 6 hours (P = 0.903, r = 0.218, P = 0.231, r = 0.022, respectively). Positive correlation was found between lactate and CO-Hb levels on admission (P = 0.018, r = 0.423).

CONCLUSIONS

This study showed that ADMA levels were still high after 6 hours of 100% oxygen therapy in children with COP, even CO-Hb and/or lactate levels return to normal range. On the basis of these results, we consider that ADMA may be a useful biomarker in patient with COP.

Suicidal Carbon Monoxide Poisoning Using Motor Vehicle Exhaust in an Open Space

OBJECTIVES

A rare case of a suicidal use of gases from the car exhaust system of the car petrol engine in an open space is presented.

CLINICAL PRESENTATION AND INTERVENTION

To verify suicidal intent of poisoning, an experimental reconstruction of the crime scene was performed. This demonstrated that appropriately long exposure to carbon monoxide with unfavorable weather conditions can cause acute carbon monoxide poisoning in an open space.

CONCLUSIONS

This case was studied to observe the pattern of fatal carbon monoxide poisoning in an open space. This might be helpful for forensic medicine, emergency medicine, and occupational medicine.

Poppers regulation for public sale: No measure in France yet

AIM

Poppers have become legal in France since June 2013. Is their liberalisation associated with an increase of severe side effects observed?

METHODS

To identify elevated methaemoglobinaemia related to poppers abuse, we reviewed all methaemoglobin concentrations measured in Nantes university hospital, during 12 months.

RESULTS

Methaemoglobin concentrations were superior to 25% in three cases of poppers consumption that occurred after the legalisation.

CONCLUSION

Evaluating the prevalence of elevated methaemoglobinaemia could help to monitor severe complications of poppers use in France.

A Case of Methemoglobinemia Successfully Treated with Hyperbaric Oxygenation Monotherapy

BACKGROUND

Methylene blue is the first-line therapy for methemoglobinemia, but it can be intermittently unavailable due to production issues. For this clinical scenario, alternative treatment options need to be explored. Hyperbaric oxygenation (HBO) is conventionally applied as an adjunctive therapy during the systemic administration of methylene blue. Currently, little is known regarding the effects of HBO monotherapy in methemoglobinemia. We report a case of methemoglobinemia that was successfully treated with HBO monotherapy.

CASE REPORT

A 41-year-old man presented to the Emergency Department with dyspnea and dizziness subsequent to smoking in a garage filled with motor vehicle exhaust gas. There were no abnormal heart or lung sounds. While administering oxygen flowing at 15 L/min via a mask with a reservoir bag, blood tests revealed high methemoglobin (MetHb) levels at 59.6%. He was treated with HBO monotherapy, and sequential tests showed that the MetHb level decreased significantly to 34.0%, 12.8%, 6.2%, and eventually, 3.5%. He was discharged with stable vital signs the next day. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: HBO monotherapy is an effective alternative treatment for methemoglobinemia when methylene blue is not available.

Suicidal asphyxiation by carbon monoxide within a polythene bag

Suicide by inhalation of carbon monoxide is not uncommon and usually involves car exhausts or burning charcoal or defective boilers. We report a case of a 25-year-old man, who committed suicide by inhaling carbon monoxide gas inside a polythene bag in a bathroom. The open carbon monoxide cylinder found inside the polythene bag was purchased online by the deceased a few days earlier. He had stated that the gas would be used for his experiment on the environment. A suicide note recovered from his trouser pocket revealed his intention for a painless death.

Assessment of carboxyhemoglobin, hydrogen cyanide and methemoglobin in fire victims: a novel approach

To establish the cause of death, carboxyhemoglobin (COHb), total hemoglobin (tHb), methemoglobin (MetHb), and hydrogen cyanide (HCN) were quantified in the blood of fire victims. We analyzed 32 out of 33 blood samples from forensic autopsy cases in a disastrous polyurethane mattress fire, which caused the deaths of 33 inmates at a prison in Argentina in 2006. The cadaveric blood samples were collected by femoral vein puncture. These samples were analyzed using the IL80 CO-oximeter system for tHb, MetHb, and COHb levels and by microdiffusion for HCN and COHb levels. Blood alcohol (ethanol) and drugs were examined by headspace gas chromatography-flame ionization detection (HS-GC-FID) and GC-mass spectrometry (MS), respectively. Polyurethane mattress samples were analyzed according to the California 117 protocol. The saturation of COHb ranged from 10% to 43%, tHb from 2% to 19.7%, MetHb from 0.10% to 35.7%, and HCN from 0.24 to 15mg/L. These HCN values are higher than the lethal levels reported in the literature. Other toxic components routinely measured (ethanol, methanol, aldehydes, and other volatile compounds) gave negative results in the 32 cases. Neither drugs of abuse nor psychotropic drugs were detected. The results indicate that death in the 32 fire victims was probably caused in part by HCN, generated during the extensive polyurethane decomposition stimulated by a rapid increase in temperature. We also considered the influence of oxygen depletion and the formation of other volatile compounds such as NOx in this disaster, as well as pathological evidence demonstrating that heat was not the cause of death in all victims. Furthermore, statistical analysis showed that the percentage values of COHb and MetHb in the blood were not independent variables, with χ(2)=11.12 (theoretical χ(2)=4.09, degrees of freedom=12, and α=0.05). However, no correlation was found between HCN and MetHb in the blood of the victims. This is the first report to assess the relationship between COHb and MetHb in forensic blood samples. We further discuss other factors that could lead to a lethal atmosphere generated by the fire and compare the data from this disaster with that of other published fire episodes.

Suicide by carbon dioxide

Suicides by self-poisoning are common in all parts of the world. Among these intoxications, gases are rarely used, especially carbon dioxide (CO2). Very few cases of self-inflicted and deliberate carbon dioxide poisonings have been reported. This paper presents two uncommon suicides by carbon dioxide intoxication. In one case, a 53-year-old man tightly sealed a small bathroom and locked himself in it likely with dry ice. Warning notices were tagged to the door. In another case, a 48-year-old man working in a restaurant committed suicide by closing himself in a walk-in refrigerator and opening the stored carbon dioxide containers intended for the beverage dispensing equipment. The limited possibilities of proving lethal CO2 intoxications post-mortem necessitate a close cooperation of the involved parties during investigation. Only the synopsis of all findings permits a sound assessment regarding the manner and cause of death.

An accurate method for microanalysis of carbon monoxide in putrid postmortem blood by head-space gas chromatography-mass spectrometry (HS/GC/MS)

Carbon monoxide (CO) may be the cause of more than half the fatal poisonings reported in many countries, with some of these cases under-reported or misdiagnosed by medical professionals. Therefore, an accurate and reliable analytical method to measure blood carboxyhemoglobin level (COHb%), in the 1% to lethal range, is essential for correct diagnosis. Herein a method was established, i.e. head-space gas chromatography-mass spectrometry (HS/GC/MS) that has numerous advantages over other techniques, such as UV spectrometry, for determination of COHb%. There was a linear relationship (R(2)=0. 9995) between the peak area for CO and the COHb% in blood. Using a molecular sieve-packed column, CO levels in the air down to 0.01% and COHb% levels in small blood samples down to 0.2% could be quantitated rapidly and accurately. Furthermore, this method showed good reproducibility with a relative standard deviation for COHb% of <1%. Therefore, this technique provides an accurate and reliable method for determining CO and COHb% levels and may prove useful for investigation of deaths potentially related to CO exposure.

Fatal Methemoglobinemia Due to Industrial Accident

This is a case of a male who fell into a vat of industrial chemicals while at work. He became unresponsive while being transported to the hospital and was pronounced dead shortly after arrival. At autopsy there was focal cyanosis, widespread first and second degree burns, chocolate-colored blood, and a postmortem methemoglobin concentration of 61.6%. An extensive search of English-language medical literature revealed that there has not been a reported case like this, in which a patient acquired methemoglobinemia by falling into a vat of industrial chemicals, was immersed in these oxidizing agents, and subsequently died. It is important when treating a victim of an accident such as this to note the chemicals to which the patient was exposed in order to understand their possible toxic effects. It is also important at autopsy to note the coloration of the blood because in this case, this is how the pathologist first suspected the possibility of methemoglobin and then ordered the appropriate diagnostic test.

Suicide of a cyclist

The rate of suicides in road traffic fatalities is estimated at 1-8% depending on the investigated study material. Especially single-car accidents, for which no technical reason or driving error is apparent, are considered suspicious. The elucidation of suicides in road traffic is difficult if there are no relevant clues such as the announcement of suicide plans shortly before the event or a suicide note. Individuals who intentionally kill themselves in road traffic often have a history of mental illness. The authors report on a suicide using a bicycle. A 71-year-old man intentionally drove into the wall of a house situated at the end of a hill road and suffered an open craniocerebral trauma and an aortic rupture. The pattern of findings and the circumstances of the case are described.