Tox - OSCE - Poisoning Flashcards
What is the anion gap and what is a normal anion gap
Na + K - (Cl + HCO)
Varies with texts but between 8-6 without potassium and 10-20 with
How does albumin alter the anion gap
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
Causes of a high anion gap metabolic acidosis
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
What is the Calculated Osmolality?
What is the Osmolar gap?
2x (Na) + glucose + urea
OG = Measured = calculated
> 10 abnormal
Causes of a normal anion gap met acidosis
Loss of HCO
CAGE Chloride excess Acetazolamide /Addisons GI - , DV, ileus, fistula Extra - rental tubule acidosis
ABCD Addisons Bicarbonate loss Chloride excess Dieuretics - acetazolamide
Features of ethylene glycol poisoning
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
Why do you get a high lactate in ethylene glycol poisoning
Common lab error.
Common analysers measure glycolate as L-lactate, leading to misdiagnosis of lactic acidosis
BUT - may be hypoperfusion
Investigations for EG poisoning
Ethylene glycol level (delays result)
Ethanol/methanol/paracetamol
Lactate gap
Osmolar gap
Met acidosis
Urine microscopy - oxalate crystals
Treatment of EG poisoning
Tube, MV and inotropic suppler
Conisder bicarbonate
Consider RRT
Antidote - ethanol/fomepizole
How does fomepazole work
Competitive antagonists of Alcohol Dehydrogenase
RRT then aids elimination
Sources of ethylene glycol
De-icer Anti freeze Radiator coolant Brake fluid Cleaning polishes
Metabolism of Ethyline Glycol
EG metabolised by alcohol dehydrogenase to
Glycoaldehyde then by Aldehyde dehrdorgenase to
Glycolic Acid and Oxalic Acid
