OSCE - Poisoning Flashcards

1
Q

What is the anion gap and what is a normal anion gap

A

Na + K - (Cl + HCO)

Varies with texts but between 8-6 without potassium and 10-20 with

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2
Q

How does albumin alter the anion gap

A

Albumin is a major unmeasured anion

1g/l decrease in albumin decreases the anion gap by 0.25

Therefore - a high anion gap may appear like a normal AG if albumin is low

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3
Q

Causes of a high anion gap metabolic acidosis

A

Reason - accumulation of organic acids OR loss of H excretion

LTKR
Lactate, toxin, ketones, renal

CATMUDPILES

CO or cyanide
Alcoholic ketoacid (and starvation)
Toluene
Metformin / methanol
Ureamia
DKA
Pyglutamic, propoylene glycol, para-aldehyde
Iron
Lactic Acidosis
Ethylene Glycol
Salicylate
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4
Q

Calculated Osmolality

Osmolar gap

A

2x (Na) + glucose + urea

OG = Measured = calculated

> 10 abnormal

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5
Q

Causes of a normal anion gap met acidosis

A

Loss of HCO

CAGE 
Chloride excess
Acetazolamide /Addisons
GI - , DV, ileus, fistula 
Extra - rental tubule acidosis
ABCD
Addisons
Bicarbonate loss
Chloride excess
Dieuretics - acetazolamide
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6
Q

Features of ethylene glycol poisoning

A

Neuro - similar to alcohol.
Inebriation, slurred speech, euphoria, drowsiness —> oedema, conclusions, coma

Cardio - myocardial depression, hypotension, failure, severe acidosis

Renal - ATN —glycolate is directly toxic and Calcium oxalate crystals

Alternative way:
30 min to 12 hours - confusion,ataxia, lethargy, coma, N/V, seizures, cranaial nerve defect

12-24: cardio failure

24-72 - renal failure from ATN

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7
Q

Why do you get a high lactate in ethylene glycol poisoning

A

Common lab error.

Common analysers measure glycolate as L-lactate, leading to misdiagnosis of lactic acidosis

BUT - may be hypoperfusion

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8
Q

Investigations for EG poisoning

A

Ethylene glycol level (delays result)
Ethanol/methanol/paracetamol

Lactate gap
Osmolar gap
Met acidosis

Urine microscopy - oxalate crystals

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9
Q

Treatment of EG poisoning

A

Tube, MV and inotropic suppler

Conisder bicarbonate
Consider RRT

Antidote - ethanol/fomepizole

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10
Q

How does fomepazole work

A

Competitive antagonists of Alcohol Dehydrogenase

RRT then aids elimination

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11
Q

Sources of ethylene glycol

A
De-icer
Anti freeze
Radiator coolant
Brake fluid
Cleaning polishes
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12
Q

Metabolism of EG

A

EG metabolised by alcohol dehydrogenase to

Glycoaldehyde then by Aldehyde dehrdorgenase to

Glycolic Acid and Oxalic Acid

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