Detection of ingested nitromethane and reliable creatinine assessment using multiple common analytical methods.

AIM: Nitromethane, found in fuels used for short distance racing, model cars, and model airplanes, produces a falsely elevated serum creatinine with standard creatinine analysis via the Jaffé method. Erroneous creatinine elevation often triggers extensive testing, leads to inaccurate diagnoses, and delayed or inappropriate medical interventions. Multiple reports in the literature identify "enzymatic assays" as an alternative method to detect the true value of creatinine, but this ambiguity does not help providers translate what type of enzymatic assay testing can be done in real time to determine if there is indeed false elevation. METHODS: We report seven cases of ingested nitromethane where creatinine was determined via Beckman Coulter® analyser using the Jaffé method, Vitros® analyser, or i-Stat® point-of-care testing. Nitromethane was detected and semi-quantified using a common clinical toxic alcohol analysis method, and quantified by headspace-gas chromatography-mass spectrometry. RESULTS: When creatinine was determined using i-Stat® point-of-care testing or a Vitros® analyser, levels were within the normal range. Comparatively, all initial creatinine levels obtained via the Jaffé method were elevated. Nitromethane concentrations ranged from 42 to 310 µg/mL. CONCLUSIONS: These cases demonstrate reliable assessment of creatinine through other enzymatic methods using a Vitros® analyser or i-STAT®. Additionally, nitromethane is detectable and quantifiable using routine alcohols gas chromatography analysis and by headspace-gas chromatography-mass spectrometry.

False acute kidney injury alert due to model car fuel ingestion.

We report a case of accidental ingestion of model car fuel (Optifuel) resulting in an apparent elevation of serum creatinine of 274 µmol/L (3.1 mg/dL) as measured by the Jaffe (alkaline picrate) reaction, which resulted in an acute kidney injury (AKI) stage 3 alert being reported. Optifuel contains nitromethane, which has been reported to interfere in the Jaffe reaction causing falsely high creatinine measurements. The laboratory staff were vigilant about this potential interfering substance so repeated the analysis of the creatinine using an enzymatic method that showed a markedly lower result of 47 µmol/L (0.5 mg/dL). This report highlights the ability of nitromethane to potentially mimic AKI and the importance of being aware of the limitations of biochemical tests to avoid misinterpretation of results and instigating inappropriate treatment.

An unusual suicide: asphyxia by methane gas.

Asphyxia by suffocating gases, that is, methane or carbon dioxide, is characterized by the displacement of oxygen from inspired air. Thus, the cells are unable to receive oxygen and, as a consequence, are affected by acute hypoxemic hypoxia. The brain suffers because of the hypoxemic state, the subject become unconscious, and then, respiration arrest occurs, followed by cardiac arrest. This is the physiopathologic mechanism leading to death.We report a case of a 35-year-old man found dead at home with his mouth containing a tube linked to the domestic methane gas system originating from the wall, sealed with packing tape.

Homicide by methane gas.

Methane is a suffocating gas, and "methane deaths" are largely the result of suffocation by gas-air displacement after accidental or deliberate exposure. Neither methane gas nor other suffocating gases are a common means of homicide, with the potential exception of the use of gas in chemical weapons or gas chambers. Here, we report the case of a 53-year-old woman who was killed by her husband with methane gas. The man had given his wife a dose of Lorazepam before setting up a hose that conveyed methane from the kitchen into the apartment's bedroom. The man subsequently faked his own suicide, which was later discovered.

Biogas production by anaerobic co-digestion of cattle slurry and cheese whey.

Biogas yield of mixtures of cattle slurry and cheese whey, rates of production of methane, removal efficiencies of chemical oxygen demand (COD) and biological oxygen demand (BOD) were investigated at 35 °C. Stable biogas production of 621 l/kg volatile solids at a hydraulic retention time of 42 days in a mixture containing 50% slurry and whey was obtained. The concentration of methane in the biogas was around 55%. Maximum removal efficiencies for COD and BOD5 were 82% and 90%, respectively. A maximum biogas production increase of 79% with respect to the start-up phase was achieved. The result of this study show that co-digestion of a high volume of whey (up to 65% in volume) is possible without the use of chemicals for pH correction, but also that this kind of mix has a similar energetic potential for anaerobic digestion as energy crops such as maize.

Is elevated creatinine a reliable marker for methanol toxicity in nitromethane-containing model fuel ingestions in children?

CONTEXT: In the absence of a rapid serum methanol level estimation, it is difficult to assess the risk from unintentional childhood ingestion of model fuels containing methanol and nitromethane (MFNM). Previous reports have documented false elevations of serum creatinine from the nitromethane in these fuels, suggesting its utility as a readily available marker of significant methanol ingestion. METHOD: We performed a 2-year retrospective chart review of cases of ingestion of MFNM in children, with both a methanol level and measured creatinine level. RESULTS: Seven children, ages 19 months to 3 years, ingested MFNM. All seven children were seen in a hospital and had measured methanol and creatinine levels. All blood samples for methanol and creatinine were drawn within 3 hours of ingestion with methanol estimation delayed up to 24 hours. Creatinine ranged from 0.39 (0.034 mmol/l) to 10.7 mg/dl (0.95 mmol/l). All methanol levels were <10 mg/dl (0.31 mmol/l) or reported as negative. Fomepizole was initiated empirically in two patients due to delay in obtaining methanol analysis results. DISCUSSION: Transient elevations of creatinine occurred in five of the seven children. Blood urea nitrogen was within normal limits, and there was no history of renal impairment in these children, suggesting the elevated creatinine was mostly related to nitromethane ingestion. No child had a significantly elevated methanol level. CONCLUSION: Elevated creatinine level, as measured by Jaffe colorimetric method, is not a reliable marker for elevated methanol levels after unintentional ingestion of MFNM.

Apparent elevated creatinine after ingestion of nitromethane: interference with the Jaffe reaction.

We assessed a 2-year 4-month-old boy found to have a persistently elevated serum creatinine (peak 926 µmol/L) as measured by the Jaffe reaction after ingesting an unknown quantity of fuel for a model car, which commonly contains nitromethane. The patient was otherwise clinically well and the remaining investigations were unremarkable. When creatinine concentrations were measured with specific enzymatic testing on these same blood samples, all values were within normal limits. Nitromethane has been shown to interfere with the determination of serum creatinine through the Jaffe reaction. Because many ingestions present only rarely, it is not possible for the emergency department clinician to be aware of all toxin factors affecting patient management. This case illustrates the importance of analysis of laboratory results in the context of the patient's clinical status.

Induced hypothermia in comatose survivors of asphyxia: a case series of 14 consecutive cases.

BACKGROUND: Induced hypothermia is widely used for comatose survivors of cardiac arrest. Other causes of hypoxic brain injury carry a poor prognosis when treated using traditional methods. At our hospital, hypothermia has also been used for the management of all comatose survivors of asphyxiation. The aim of the present study was to report the results of the management of these patients. METHODS: Hospital charts of all patients admitted unconscious after asphyxiation during a 7-year period were reviewed. This included patients after hanging, drowning, carbon monoxide intoxication and other gas intoxications. In all patients, hypothermia with a target temperature of 32-34 degrees C was induced with external or intravascular cooling for 24 h. The primary outcome was neurologic function at discharge. RESULTS: Fourteen male patients were treated with hypothermia, eight after hanging, three after drowning, two after carbon monoxide intoxication and one after methane intoxication. All were deeply comatose (Glasgow Coma Score 3-5) on arrival to hospital. Nine had been resuscitated from cardiac arrest. There were nine survivors (65%), all with good neurological recovery (Cerebral Performance Category 1-2). Four out of five non-survivors showed cerebral edema already on arrival computed tomographic (CT) scan while none of the nine survivors did. CONCLUSIONS: The results of this study suggest that an early abnormal CT scan of the brain in patients resuscitated after asphyxiation carries an adverse prognosis. The favorable outcome of the patients in the present study suggests that a randomized clinical trial on the use of induced hypothermia in patients exposed to severe asphyxia might be warranted.

Creatinine elevation associated with nitromethane exposure: a marker of potential methanol toxicity.

Nitromethane, methanol, and oil are the common components of radio-controlled (R/C) vehicle fuels. Nitromethane can cause a false elevation of serum creatinine concentration as measured by the widely used Jaffe colorimetric method. We gathered data from our poison control system and from previously published case reports to see if a correlation exists between serum methanol concentrations and spuriously elevated serum creatinine concentrations after human exposures to R/C fuel. The California Poison Control System (CPCS) computerized database was queried for all cases of human exposure to R/C vehicle fuel reported between December 1, 2002 and December 1, 2004. Serum creatinine and methanol concentrations were recorded when available, as was the method used to determine serum creatinine. A MEDLINE search was used to obtain previously published cases of human nitromethane exposure associated with falsely elevated creatinine concentrations. During the 2-year period, serum creatinine concentrations were recorded in 7 of 26 R/C fuel exposures (all ingestions), and 6 of these were abnormal (range of 1.9-11.5 mg/dL). In this series, the higher the serum creatinine concentration measured by Jaffe method, the higher the serum methanol concentration. The MEDLINE search yielded data from six previously published case reports on this topic. The data from these case reports seem to follow the trend seen in our case series. These data suggest that a spuriously elevated serum creatinine (by Jaffe method) may have value as an early surrogate marker of methanol poisoning in those who ingest R/C fuel. Also, the degree to which the serum creatinine is elevated may indicate the severity of methanol poisoning.

Co-ingestion of methanol and nitromethane: using falsely elevated creatinine as indicator for methanol antidote use.

OBJECTIVE: To report a case of co-ingestion of methanol and nitromethane in a child in order to heighten the awareness of false elevation of serum creatinine from nitromethane ingestion. DESIGN: Case report. SETTING: Pediatric intensive care unit. PATIENT: A 4-yr-old previously healthy girl ingested an unknown quantity of "Blue Thunder" model-engine fuel, which consisted of methanol and nitromethane. The patient was treated with fomepizole for methanol ingestion using elevated creatinine level as a reason for treatment. RESULTS: The patient was asymptomatic but her creatinine level increased ten-fold (from 0.4 mg/dL to 4 mg/dL) within 6 hrs. Blood urea nitrogen, anion gap, and osmolar gap remained within normal limits. When the serum creatinine level was measured with enzymatic method instead of Jaffe's method, a normal creatinine level was obtained. The falsely elevated creatinine level was due to nitromethane. CONCLUSION: The falsely elevated serum creatinine levels due to nitromethane ingestion can lead to unnecessary therapeutic interventions. We intend to heighten awareness of this potential misstep by reporting this case.