Methanol is a highly toxic alcohol

Abstract

Methanol is a highly toxic alcohol commonly available as an industrial solvent, antifreeze or fuel for small stoves. Methanol toxicity correlates poorly with blood levels. Toxicity is assumed to be the results of its metabolites, primarily formic acid. The lethal dose of pure methanol is estimated to be 1–2 ml/kg; however, permanent blindness and death have been reported with as little as 0.1 ml/kg [[1]Methanol toxicity. Agency for toxic substances and disease registry. Am Fam Physician 1993;47:162–71.Google Scholar]. We report a case of fatal methanol poisoning in a person who was successfully resuscitated from cardiac arrest. This has not been described previously in the literature. A 75-year-old man, with a medical history of renal insufficiency and coronary artery disease, was found unresponsive at home by his family who admitted that the patient might have swallowed an unknown amount of methanol in a suicidal attempt because an empty bottle of methanol was found at the scene. Emergency medical technicians arrived 5 min later and started cardiopulmonary resuscitation (CPR) after documenting cardiac asystole on the automated external defibrillator (AED). CPR was continued en route to the nearest emergency department (ED). On arrival at the ED, the patient was intubated and mechanically ventilated with 100% oxygen. Vasoactive agents including adrenaline (epinephrine) were given in accordance with the ALS guidelines. Return of spontaneous circulation was achieved after 25 min of external chest compressions. He was then transferred to an intensive care unit (ICU) for further treatment. On admission to the ICU, his vital signs were as follows: Glasgow coma scale, E1M1VIntubated; blood pressure, 147/80 mmHg; pulse, 104 beats per minute and temperature, 36.7 °C. Initial laboratory data showed abnormal blood urea nitrogen (39 mg/dl), creatinine (2.2 mg/dl), and white blood cell count (18 200 μl−1). The measured osmolality was 512 mOsmol/kg H2O and the calculated osmolality was 301 mOsmol/kg H2O, yielding an osmolal gap of 211 mOsmol/kg H2O. Arterial blood gas analysis revealed: pH, 7.28; PCO2 43 mmHg; PO2, 96 mmHg and HCO3, 20 mEq/l. The patient was treated with vasopressors to maintain blood pressure, intravenous sodium bicarbonate to correct acidosis, and 15% ethanol via nasogastric tube to delay the metabolism of methanol to its toxic products. Emergency haemodialysis was started immediately after consultation with a nephrologist. The methanol level was later reported as 826 mg/dl. Serum levels of methanol and ethanol were measured every 12–24 h to guide treatment (Fig. 1). Fifty six hours after admission, the patient awakened and was able to follow simple commands. By day 4, he regained full consciousness with normal ophthalmic assessment. However, his renal function deteriorated progressively and long-term haemodialysis was inevitable. Classically, the combination of high anion-gap metabolic acidosis, high osmolal gap and a history of ingestion, should always suggest methanol poisoning [[2]McCoy H.G. Cipolle R.J. Ehlens S.M. Severe methanol poisoning.Am J Med. 1979; 67: 804-807Abstract Full Text PDF PubMed Scopus (94) Google Scholar]. However, there may be an initial lack of clinical data for patients who are unable, or unwilling, to supply a history of ingestion. In such situations, obtaining a patient history from family or friends can be valuable. In any patient with methanol poisoning, aggressive treatment with sodium bicarbonate to correct the acidosis rapidly, ethanol to inhibit the metabolism of methanol to its toxic metabolites, and haemodialysis to enhance elimination may prevent ocular damage and greatly increase the chances of survival [[3]Suit P.E. Eotes M.L. Methanol intoxication: clinical features and differential diagnosis.Cleve Clin J Med. 1990; 57: 464-471Crossref PubMed Scopus (27) Google Scholar]. This case demonstrates that methanol poisoning presenting with an out-of-hospital cardiac arrest can be resuscitated successfully. The prognosis should not be made on the basis of the serum methanol level or initial vital signs alone. In conclusion, this patient illustrates the need to emphasise that early CPR, early ALS, and aggressive treatment with bicarbonate, ethanol and haemodialysis are vital in the resuscitation of cardiac arrest from methanol poisoning.Confict of interest None declared.