Methanol and ethylene glycol acute poisonings – predictors of mortality

Abstract

Context. Methanol and ethylene glycol cause significant mortality post-ingestion. Predicting prognosis based on the biomarkers osmolal gap, anion gap and pH is beneficial. Objective. To evaluate the relationship between biomarkers, measured post-methanol and ethylene glycol exposure, and clinical outcomes. Methods. A review of the literature identified cases where methanol or ethylene glycol had been ingested and clinical outcomes were recorded. Biomarkers were extracted including osmolal gap, anion gap and pH, with clinical outcomes categorised as recovered, recovered with adverse sequelae and death. Biomarkers were analysed using the Mann–Whitney test for two samples; sensitivity and specificity were evaluated using receiver operating characteristic (ROC) curves. Results. In total, 119 cases of methanol and 88 of ethylene glycol poisoning were identified; 21 methanol and 19 ethylene glycol patients died. For methanol ingestion the mean values, for survival compared to death, were 48 (range: 6–138) and 90 (range: 49–159) mOsm/kg water for osmolal gap (p=0.0052), 31 (range: 11–50) and 41 (range: 30–53) mmol/L for anion gap (p=0.0065) and 7.21 (range: 6.60–7.50) and 6.70 (range: 6.34–7.22) for arterial pH (p<0.0001). The area under the ROC curve was highest for arterial pH, 0.94 (95% CI: 0.89–0.99). For ethylene glycol, these were 49 (range: 0–189) and 79 (range: 25–184) mOsm/kg water for osmolal gap (p=0.050), 28 (range: 6–48) and 38 (range: 20–66) mmol/L for anion gap (p=0.0037) and 7.08 (range: 6.46–7.39) and 6.98 (range: 6.50–7.16) for pH (p=0.072), for survival compared to death. The area under the ROC curve was highest for anion gap, 0.73 (95% CI: 0.60–0.87). Conclusion. Post-methanol ingestion a large osmolal gap, anion gap and low pH (<7.22) were associated with increased mortality; and pH has the highest predictive value. Post-ethylene glycol ingestion, both osmolal gap and anion gap were associated with increased mortality.

Keywords:

• Metabolic
• CNS/Psychological
• Kidney

Declarations of interest

The authors report no conflicts of interest.

Appendix 1: Bibliography of papers publishing methanol and ethlylene glycol cases.

Methanol

1. Brahmi N, Blel Y, Abidi N, Kouraichi N, Thabet H, Hedhili A, Amamou M. Methanol poisoning in Tunisia: report of 16 cases. Clinical Toxicol 2007;45:717 – 720.

2. Hantson P, Haufroid V, Wallemacq P. Formate kinetics in methanol poisoning. Hum Exp Toxicol 2005;24:55 – 59.

3. Haviv Y, Rubinger D, Zamir E, Safadi R. Pseudo-normal osmolal and anion gaps following simulataneous ethanol and methanol ingestion. Am J Nephrol 1998;18(5):436 – 438.

4. Hovda KE, Hunderi OH, Rudberg N, Foyshov S, Jacobsen D. Anion gap and osmolal gaps in the diagnosis of methanol poisoning: clinical study in 28 patients. Intensive Care Med 2004;30:1842 – 1846.

5. Hovda KE, Hunderi OH, Tafjord A-B, Dunlop O, Rudberg N, Jacobsen D. Methanol outbreak in Norway 2002 – 2004: epidemiology, clinical features and prognostic signs. J Intern Med 2005;258:181 – 190.

6. Meyer RJ, Beard MEJ, Ardagh MW, Henderson S. Methanol poisoning. N Z Med J 2000;113(1102)11 – 13.

Ethylene glycol

1. Amathieu R, Merouani M, Borron SW, Lapostolle F, Smail N, Adnet F. Prehospital diagnosis of massive ethylene glycol poisoning and use of an early antidote. Resuscitation 2006;70:285 – 286.

2. Cox RD, Phillips WJ. Ethylene glycol toxicity. Mil Med 2004;169(8):660 – 664.

3. Darchy B, Abruzzese L, Pitiot O, Figueredo B, Domart Y. Delayed admission of ethylene glycol poisoning: lack of elevated serum osmol gap. Intensive Care Med 1999;25:859 – 861.

4. Freilich B, Altun Z, Ramesar C. Neuropsychological sequelae of ethylene glycol intoxication: a case study. Applied Neuropsychology 2007;14(1):56 – 61.

5. Lovric M, Granic P, Cubrilo-Turek M, Lalic Z, Sertic J. Ethylene glycol poisoning. Forensic Sci Int 2007;170:213 – 215.

6. Mycyk MB, Aks SE. A Visual Schematic for clarifying the temporal relationship between the anion and osmol gaps in toxic alcohol poisoning. Am J Emerg Med 2003;21(4):333 – 335.

7. Wisse B, Thakur S, Baran D. Recovery from prolonged metabolic acidosis due to accidental ethylene glycol poisoning. Am J Kidney Dis 1999;33(2)E4,1 – 5.