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33 Cards in this Set
- Front
- Back
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List some common household products that contain methanol.
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Antifreeze, winshield washer fluid, glass cleaners, shellacs, lacquers, adhesives
Moonshine |
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What are the relevant pharmacodynamics of methanol?
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M - metabolism is delayed by coingestion of ethanol. Metabolized by ADH to formaldehyde then to formic acid.
E - eliminated with first-order kinetics at low concentrations, but zero-order kinetics at high concentrations. |
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How does methanol cause optic toxicity?
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Retinal Muller cells metabolize methanol to formate which injures the optic nerve and retina.
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Besides the eyes, where does methanol classically cause CNS toxicity?
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The basal ganglia.
Bilateral, symmetrical putaminal hypodensities, hemmorhages and cystic lesions are characteristic. Parkinsonian motor dysfunction (hypokinesis and rigidity) results. |
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How does methanol cause an AGMA?
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-Metabolism from an osmol to an anion (formic acid)
-inhibition of cytochrome oxidase resulting in lactic acidosis |
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What is the triad of methanol toxicity?
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Visual complaints, metabolic acidosis and altered mental status
Can also see weakness, dizziness, nausea, ataxia, abdominal pain |
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What are the classic visual symptoms of methanol toxicity?
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-Central scotoma
-"stepping out into a snowstorm |
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How is serum osmolarity calculated?
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2Na + glucose + urea + 1.25EtoH
"two salts and a sticky bun" Normal gap ~10 |
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What substances can cause an elevated osmolar gap?
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Methanol, Ethylene glycol, Mannitol, Propylene glycol, Acetone
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List some common household products that contain ethylene glycol.
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Antifreeze, coolant, brake fluid, lacquers, cosmetics
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What are the relevant pharmacodynamics of ethylene glycol?
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M - metabolism is delayed by coingestion of ethanol. Metabolized by ADH and other hepatic enzymes to glyoxylic acid then oxalic acid which combines with Ca++ and precipitates. Pyridoxine & Thiamine can be added to metabolize glyoxylic acid to non-toxic compounds.
E - some is excreted unchanged by the kidneys, |
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How does ethylene glycol cause damage?
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When metabolized to oxalic acid and combined with Ca++ it precipitates in the kidneys, retina, brain and perivascular spaces.
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How does ethylene glycol cause an AGMA?
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This is due to its metabolism to Glycolic acid.
Lactic acid also contributes in a minor way secondary to inhibition of oxidative phosphorylation by ethylene glycol metabolites |
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What are the stages of ethylene glycol poisoning?
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1 - Acute neurologic stage
2 - Cardiopulmonary stage 3 - Renal stage 4 - Delayed neurologic sequelae stage |
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Describe the acute neurologic stage of ethylene glycol toxicity.
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Stage 1, 30m-12h post ingestion
Patient is basically drunk +/- hallucinations/coma |
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Describe the cardiopulmonary stage of ethylene glycol toxicity.
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Stage 2, 12-24h post ingestion
Acidosis causes tachycardia Calcium deposition causes hypocalcemia and organ damage - pulmonary infiltrates/ARDS, myositis, circulatory collapse |
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Describe the renal stage of ethylene glycol toxicity.
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Stage 3, 24-72h post ingestion
Flank pain, costophrenic angle tenderness U/A shows hematuria, proteinuria, calcium oxalate, oliguria Acidosis worsens |
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Describe the delayed neurologic sequelae stage of ethylene glycol toxicity.
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Stage 4, 6-12 days post ingestion
Cranial neuropathy (facial diplegia, deafness, dysarthria, visual deterioration), ataxia, chorea, coma, personality changes, polyradiculopathy, paralysis. |
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What is the coolest test for antifreeze ingestion?
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Shine a Wood's lamp on pee. Flourescein is added to aid in its detection and it may light up.
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Is there efficacy for gastric emptying for toxic alcohol exposure?
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No. Maybe within 30-60 minutes but there is no evidence for it.
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Is there efficacy for activated charcoal for toxic alcohol exposure?
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No. It doesn't absorb it.
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What are the treatment goals for toxic alcohol ingestion?
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1 - correct metabolic acidosis (HCO3)
2 - ADH blockade (ethanol/fomepizole) 3 - removal of the parent alcohol and its metabolites (dialysis) |
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What level of EtOH is protective for metabolism of toxic alcohols?
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>20mmol/L
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What is fomepizole?
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Fomepizole is a drug that blocks ADH metabolism of toxic alcohols.
NOTE that this does not supplant the need for hemodialysis |
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What are the benefits/disadvantages of fomepizole and ethanol?
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Ethanol is cheaper
Fomepizole is easier to use, has predictable kinetics, is safer, is less complicated, does not require direct observation or monitoring, lasts longer and doesn't depress the CNS. |
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When is hemodialysis indicated for methanol and ethylene glycol?
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Metabolic acidosis, renal compromise, visual symptoms (methanol), deterioration, uncorrectable electrolyte imbalance, absolute values are debatable.
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What is the endpoint of dialysis in toxic alcohol ingestion?
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Undetectable level
Corrected acid-base abnormalities |
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What co-factors can be used in methanol toxicity?
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Folinic acid IV q4h
Thiamine 100mg IV q6h & Magnesium (prn) Pyridoxine 50mg q6h |
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List some common household products that contain isopropyl alcohol.
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Rubbing alcohol, nail polish remover, disinfectants, cleaners and antifreeze.
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What are the relevant pharmacodynamics of isopropyl alcohol?
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D - peak levels in 30m-3h; 2x the CNS depressive effects
M - by alcohol dehydrogenase to acetone |
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How do patients present after ingesting isopropyl alcohol?
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Altered mental status, acetone breath, drunk.
Hypotension signifies severe poisoning with high mortality. Generally does NOT cause acidosis. |
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What are the laboratory findings in isopropyl alcohol ingestion?
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-Osmolar gap, ketosis, normal glucose, no acidosis
-Can give a "pseudo-renal failure" - false elevation of creatinine with a normal urea because of acetones affect on creatinine. |
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Are ADH blockade or dialysis indicated for isopropyl alcohol ingestion?
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No. ADH blockade will not help.
Dialysis may be indicated for crazy high levels but is generally not necessary. Intubate and provide supportive care. |
