136. Toxic Etoh Flashcards
What is methanol?
Clear, voltatile, colorless slightly sweet alc st room temp.
Aka wood alcohol
What things commonly have methanol?
Solvent or octane booster in gasoline
Windshield washer fluid
Antifreeze (brake line sp)
Embalming fluid
Camp stove fuel
How is methanol absorbed?
Gi
Average half life 5 mins, peak 30-60 mins
What is the toxic metabolite of methanol?
Formic acid then into formate and H ions
How is methanol metabolized?
Liver- ADH to formaldehyde
ThEN by ALDH to formic acid
Then THF to 10-formyl THF
to co2 and water
Ethanol metabolism to acetyl coa
By adh to acetylaldehyde
ALDH to
Acetate
Acetyl coa synthase to acetyl coa
Ethylene glycol 3 end products
Glycine
Oxalic acid
Alpha hydroxy beta keyoadipate
Ethylene glycol metabolism to 3 products
by adh to glycoaldehyde
ALDH to
Glycolic acid
A. Go and LDH to oxalic acid
B by pyridoxine to glycine
C by thiamine to alpha hydroxy beta ketoadipate
At toxic concentrations how long is half life of methanol?
24 h
With ADH inhibition by ethanol or fomepizole, half life of methanol extends to ?
Vs dialysis half life is ?
Upward of 50
Approx 3-4 hours
How does formic acid muck things up?
Binds iron to cause mitochondrial cyctochtome oxidase inhibition so interferes with oxidative metabolism (similar cn, co, hso4)
What concerning symptoms and diagnoses can methanol cause in the eye?
Optic disk of retina and retrolaminar optic nerve - inhibition of mitochondrial cytochrome oxidase —> myelin sheath damage and loss of vision
Basal ganglia and sub cortical white matter effected how by methanol?
inhibition of mitochondrial cytochrome oxidase —> myelin sheath damage
Major systems effected in methanol toxicity ?
Gi
Cns
Optic
Most characteristic vision change of methanol?
Spots with blurred vision/snowstorm vision
Altered visual fields
Blindness
Physical exam signs methanol toxicity
Reduced pupillary response to light
Hyperaemia optic disk
Edema retina
Loss of optic disk cupping
Central scotimata
Tachypnea
Shock
Rhabdo
Myoglobinuria
Death -cerebral edema and multi organ failure
Name 10 causes of an increased osmolar gap
Methanol
Ethylene glycol
Ethanol
Mannitol
Acetone
Fructose
Hyperlupidemia
Dka
Alcohol ketosis
Sickle cell
Multi organ failure
Septic shock
Uremia
Name 12 causes of anion gap elevation
Alcohol ketosis
Cyanide, co, colchicine
Acetaminophen
Toluene
Paraldehyde
Propylene glycol
Phenformin
Isoniazid, iron, ibuprofen
LA (sepsis, ischemia)
Ethylene glycol
Salicyclates
Methanol, metformin
Uremia
Dka
Name 7 causes of a double anion gap
Methanol
Ethylene glycol
Dka
Alc ketoacidossi
Uremia
Septic shock
Multi organ failure
Toxic etoh: vision loss?
Methanol
Toxic etoh hypocalcemia and calcium oxalare crystals
Ethylene glycol
Prognostic factors regarding methanol ingestion
Degree of acidosis (most important - high mortality at ph less than 7)
Time to presentation
Imitation of treatment
Why can methanol present with Parkinson’s like sx?
Effects on putamen and sub cortical white matter
Corrected AG equation for albumin
AG + (2.5 x (measured serum albumin)) when albumin is g/dL
Decreased albumin can falsely ? AG?
Elevate
How to calculate osmolarity
2Na + glucose + bun
Normal osmolarity gap?
Measured - calc = 10 (higher = concerning)
Management of methanol toxicity
- ABC
- Na bicarb if ph <7.3: 1-2 new/kg and infuse 150 new/L in 5% dextrose at 1.5-2x maintenance until ph I’d 7.35-7.45
- Fomepezole: load 15mg/kg iv then 10mg/kg q 12,) yo to 48 h thebc15mg/kg q12g
If Hd - same dose as above, start maintenance 6h after loading dose then every 4 hours
When to initiate fomepazole?
Plasma methanol or EG [] >/= 20
Hx of ingestion or EG and osmolar gap > 10
Or
Strong suspicion of methanol or EG and at least two:
- ph <7.3
- serum bicarb <20
- osmolar gap > 10
-urine oxalate crystal present (for EG)
Indications of HD for methanol
Ph <7.3
Renal failure
Vision abnormality with me thinks exposure
Hyperkalemia R to tx
HD instability
MEthanol or EG > 50
Dispo for methanol toxic pt
Nephro
Optho
IM
Tox
Ethylene glycol - what is this?
colourless odoeee sweet tasting liquid
Ethylene glycol often found in what products?
Antifreeze
Hydraulic brake fluids
Industrial solvents
Foam stabilizer
Paint
Cosmetic
Ethylene glycol absorption?
GI, 1-4 hours
Ethylene glycol metabolism
Liver
Ethylene glycol - where do crystals precipitate in the kidney?
Proximal tubule
Ethylene glycol - other deposits than kidney?
Brain
Intestine
Heart
Lungs
Spleeb
Ethylene glycol why get hypocalcemia?
Chelation of calcium by oxalate
Ethylene glycol - necrosis and lysis?
Myonecrosis
Rhabdo
Ethylene glycol- name 3 stages of toxicity?
- Acute neuro
- Cardiopulmonary
- Renal
Ethylene glycol- acute neuro stage finding and timing
30min-12 hours
Inebriation, euphoria, coma, seizures, nystagmus, ataxia, myoclonic jerks
Ethylene glycol- cardiopulmonary stage?
12-24 h post infection
Tachycardia
Severe metabolic acidosis from glycolic acid
ARDS
Ethylene glycol- renal stage?
24-48 hours post - ARf From calcium oxalate crystals
Flank pain
CVA tender
Hematuria
Proteinuria
Various amounts of pee
Ethylene glycol- what is frequently required in the HD stage?
Dialysis
List 4 examples of delayed neuro sequelae of Ethylene glycol
Bulbar palsy cn VII
opthalmoplegia
Auditory dysfunction
Dysphagia?
Ddx eythelne glycol - causing ARF?
abx - aminoglycosides, vanco, sulfa drugs, cipro, pneicillin
NSAID
acei
arb
hmg coa reductase inhib
antivirals
amphotericin B
chem o -mtx, cisplastin
bisphosphonates
heavy metals
PPI
DDX of hypocalcemia other than EG?
proton pump inhibitors, bisphosphonates, other phosphate-containing substances (e.g., laxatives and sodium phosphate), loop diuretics, glucocorticoids, calcitonin, cisplatin, pentamidine, interferon-alfa, fluorides (e.g., hydrofluoric acid), citrate, phenytoin, phenobarbital, carbamazepine, estrogens, and ethylenediaminetetraacetic acid
when are crystals found in urine of EG tox?
4-8 hours post exposure
What predicts mortality and cr rise in EG?
acidosis pH <7.2-7.3
what measurement/lab value to ask for in EG toxciity suspected?
ycolic acid concentrations greater than 99 mg/dL are strongly associated with severe CNS toxicity and mortal- ity. Levels greater than 76 mg/dL have nearly 100% sensitivity for pre- dicting ARF.28 Glycolic acid levels greater than 60 mg/dL could be an indication for HD, but this is not well validated
EG similar tx to methanol - what two cofactorsshould also be given to pt malnourished, with etoh hx?
thiamine 100 mg IV daily, and pyridoxine 100 mg IV daily, for 2 days.
Isopropyl alcohol - what is this?
colorless, lcear liquid, fruity odor bitter taste
Isopropyl alcohol - found in?
rubbing alcohol, antifreeze, disinfectants, cleaning solutions, skin and hair products, and hand sanitizers.
Isopropyl alcohol: GI absorption timeline?
within 30 mins
Isopropyl alcohol: acetone peak plasma concentration?
peak plasma 7-30hours post exposure
half life up to 24h
Isopropyl alcohol: sx
GI - Nausea, vomiting, and abdominal pain typ- ically ensue, but hemorrhagic gastritis, hematemesis, and significant blood loss can result with larger ingestions.
CNS - miosis amongst dizzy, ataxic, hypotnic
LOC - aspiration pneumonitis
hypothermia with large invgestion
NOT hypoglycemia
Isopropyl alcohol definitive method of dx?
IPA
Isopropyl alcohol: management.
supportive
wash skin with soap and water
PPI for hemorrhagic gastritis
GI if bleeding
hypotension - IVF
Isopropyl alcohol: Persistent hypotension despite 4L and NE?
HD
Isopropyl alcohol: fomepazole?
NO
prolong hypotensive and CNS depressent effects prolonged
What is DEG?
odorloss viscous sweet tasking liquid
in brake fluid, antifreeze, lubricants, wallpa- per strippers, and artificial fog machine solution
most in pharm preps of expensive glycols
management like EG and methanol, no crystals
PG - what is this? found in?
PG is commonly used as a solvent in various pharmaceutical prod- ucts and in antifreeze and hydraulic fluids. Common medications that use PG as a diluent include IV phenytoin, lorazepam, diazepam, eto- midate, nitroglycerin, phenobarbital, hydralazine, and trimethoprim- sulfamethoxazole
PG - tx options
Treatment typically involves stopping the offending agent, but HD and ADH blockade can be considered for severe acidosis and metabolic abnormalities
A 24-year-old man presents after intentional methanol ingestion. The patient reports that 1 or 2 hours ago he drank approximately 8 ounces of windshield washer fluid in a suicide attempt. He is not sure of the product name. His only current complaint is slight nausea. His vital signs and physical examination are within nor- mal limits. Serum chemistry reveals the following: sodium, 142 mEq/L, potassium, 4.5 mEq/L, chloride, 110 mEq/L, bicarbonate, 22 mEq/L, blood urea nitrogen (BUN), 18 mg/dL, creatinine, 1.5 mg/dL, and glucose, 111 mg/dL. Serum methanol levels are not obtainable at your hospital. The psychiatry service asks if the patient is medically cleared. Which of the following is the most appropriate response?
a. The patient is cleared; he has a normal anion gap, so no signifi- cant methanol ingestion occurred.
b. The patient is cleared; ingestion of 8 ounces is below the toxic level regardless of the concentration.
c. The patient is not cleared; he has an elevated anion gap and needs to receive treatment for methanol toxicity.
d. The patient is not cleared; he has evidence of renal failure and needs to receive treatment for methanol toxicity.
e. The patient is not cleared; not enough time has elapsed from the ingestion to determine if significant toxicity has occurred.
e
A 44-year-old woman complains of abdominal pain and headache. Her family reports that the patient drank “something” approxi- mately 8 hours ago in a suicide attempt. The patient is sleepy but arouses with manual stimulation. Her speech is confused, but she follows all simple commands. Her vital signs are blood pressure, 124/82 mm Hg, heart rate, 108 beats/min, respiratory rate, 26 breaths/min, and temperature, 37.0°C (98.6°F). Her physical exam- ination is unremarkable. Her serum chemistry reveals an anion gap of 24 mEq/L. Other laboratory work is pending. Which of the fol- lowing treatments should be administered initially?
a. Diuresis
b. Hemoperfusion
c. Intravenousflumazenil d. Intravenous fomepizole e. Oral activated charcoal
d
An otherwise healthy patient presents after suicidal ethylene gly-
col ingestion. He is drowsy. His serum pH is 7.1. You have started treatment with fomepizole and have contacted the nephrologist to arrange hemodialysis. In the meantime, what should be done about the patient’s acidosis?
a. Normal saline should be administered to facilitate clearance of the acid.
b. Nothing should be done; dialysis will correct the acidosis.
c. Nothingshouldbedone;thefomepizolewillcorrecttheacidosis.
d. Nothingshouldbedone;thepatientisnottrulyacidotic,buteth-
ylene glycol interferes with the laboratory determination of pH.
e. Sodium bicarbonate should be administered to neutralize the
exogenous acid.
e
- Which of the following is an indication for hemodialysis after meth-
anol or ethylene glycol ingestion? a. Metabolicacidosis
b. Blood level of 10 mg/dL
c. Elevated anion gap
d. Hypocalcemia
a
Whichofthefollowingcofactorshelpswiththeeliminationofmeth-
anol and should be considered in patients with methanol poisoning? a. Folinic acid (leucovorin)
b. Hydroxocobalamin (vitamin B12)
c. Niacin (vitamin B3)
d. Pyridoxine (vitamin B6)
e. Thiamine (vitamin B1)
a
Which of the following statements comparing the effects of isopro-
pyl alcohol and ethylene glycol is true?
a. Isopropyl alcohol causes less CNS depression and is less toxic
than ethylene glycol.
b. Isopropyl alcohol causes less CNS depression and is more toxic
than ethylene glycol.
c. Isopropyl alcohol causes more CNS depression and is less toxic
than ethylene glycol.
d. Isopropyl alcohol causes more CNS depression and is more toxic
than ethylene glycol.
e. Isopropyl alcohol has the same effects as ethylene glycol.
c
A patient presents with decreased mental status after drinking some homemade alcohol. Serum chemistry reveals sodium, 140 mEq/L, potassium, 4.5 mEq/L, chloride, 108 mEq/L, bicarbonate, 22 mEq/L, BUN, 28 mg/dL, creatinine, 1.0 mg/dL, glucose, 90 mg/dL, and serum osmolality, 320 mOsm/kg. Urinalysis is posi- tive for ketones. Which of the following is the most likely alcohol ingested?
a. Ethanol
b. Ethylene glycol
c. Isopropylalcohol
d. Methanol
e. On the basis of this information, the patient probably did not
ingest an alcohol.
c
