Toxicology Flashcards by Emma Feechan

gliclazide overdose

high insulin

high C-peptide (T1DM have low)

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how to calculate the anion gap in metabolic acidosis?

(Na + K) - (Cl + HCO3)

normal is 8-16

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what does a negative base excess indicate?

metabolic acidosis

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what does a positive base excess indicate?

metabolic alkalosis

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three methods for increasing elimination of toxins?

urinary alkalisation
haemodialysis
haemofiltration

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what are the five toxidromes?

anticholinergic
cholinergic
opioid
sympathomimetic
sedative- hypnotic

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anticholinergic toxidrome

hot as a hare
dry as a bone
red as a beet
mad as a hatter
blind as a bat

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causes of anticholinergic toxidrome

antihistamines
antidepressants
antipsychotics
antiparkinson

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management of anticholinergic toxidrome

charcoal if within 1 hour

if seizure use BZDs

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cause of cholinergic toxidrome

organophosphate pesticides

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presentation of cholinergic toxidrome

SLUDGE - salivation, lacrimation, urination, diarrhoea, GI upset and emesis
can lead to bradycardia
miosis

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management of cholinergic toxidrome

PPE (absorbed through skin)
atropine
pralidoxie mesylate
BZDs

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presentation of opioid toxidrome

sedation
reduced RR
bradycardia
hypotension
pinpoint pupils

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management of opioid toxidrome

naloxone IM or IV if problem in A or B (dilute to avoid precipitating an acute episode)
need 6 hours observation post dose

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what causes the sympathomimetic toxidrome?

recreational drugs such as ecstasy, amphetamine, cocaine, cathinones and novel psychoactive substances

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presentation of sympathomimetic toxidrome

excited state with dilated pupils, tachycardia, hypertension, hyperpyrexia

can progress to seizures and reduced consciousness

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what causes the sedative-hypnotic toxidrome?

BZDs or zopiclone causing similar opioid symptoms with miosis

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management BZDs toxicity with

flumazenil (BZD antagonist) - may precipitate withdrawal and lower seizure thresholds

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what is the problem with charcoal?

patietns have to be willing to drink it as aspiration causes pneumonitis

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substances not absorbed by activated charcoal

iron
lithium
K+ 
ethanol
methanol
ethylene
isoprophyl alcohol
hydrocarbons
solvents
cyanide
CO

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what makes paracetamol toxic?

CP450 metabolise toxic metabolic N-acetyl-p-benzoquinone imine (NAPQI) which causes liver damage

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when to check the patients blood level in paracetamol overdose?

4 hours after last dose ingestion and plot on nomogram (only if taken all at once - cannot do for staggered)

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what additional investigations are needed in paracetamol overdose?

LFTs
U&Es
INR
assessing heptorenal toxicity

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management of paracetamol overdose

N-acetylcysteine IV 12 hours or methionine PO within 8 hours

activated charcoal if within 1 hour

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what happens once aspirin is ingested?

metabolised to salicylic acid causing respiratory alkalosis (resp centres activated) > metabolic acidosis (raised anion gap due to lactic acidosis)

presentation of salicylates overdose

tinnitus N&V epigastric pain, haematemesis sweating, pyrexia, tachycardia, tachypnoea

management of salicylates overdose

give charcoal if within 1 hour Level <450mg/L give oral hydration level >450mg/L give IV fluids, urinary alkalisation, check pH hourly and WATCH K+

what is the action of cocaine?

alkaloid which blocks reuptake of serotonin, dopamine and NA

what does repeated use of cocaine risk?

thrombogenesis | coronary vasospasms

management of cocaine overdose

BZDs check CK for agitation ECGs for vasospasms (give BZDs)

management of sympathmimometic toxidrome (amphetamines, ecstasy)

hydration BZDs ecstasy can cause SIADH effect (hyponatraemia) due to thirst

management of hallucinogens (LSD, magic mushrooms, ketamine)

supportive | BZDs for acute psychosis

what is methanol present in?

de-icer | moonshine

presentation of methanol

ethanol toxicity | driving in a snowstorm (damage to the optic nerve risks permanence)

management of methanol poisoning

raised anion gap metabolic acidosis - sodium bicarbonate ethanol dialysis

what is ethylene glycol

also present in antifreeze. give sodium bicarbonate and ethanol and fomepizole

TCA toxicity triad

1. anticholinergic effect 2. sodium channel blockade of myocardium 3. alpha adrenoceptor blockade

what is the toxidrome in tricyclics?

anticholinergic

management of tricyclic overdose

ECG (narrow complexes > broad > VT/VF) charcoal within 1 hour NaHCO3 8.4% sodium bicarbonate BZDs for seizures

which SSRI is dangerous?

paroxetine

which drugs increase the risk of serotonin syndrome?

``` SSRIs TCAs MAOIs MDMA, amphetamines, cocaine, cathinones tramadol ```

presentation of serotonin syndrome

``` agitation tremor hypertonia diaphoresis tachycardia hyperpyrexia ```

beta blocker overdose presentation

bronchospasm, glucose tolerance bradycardia hypotenison cardiogenic shock

management of serotonin syndrome

chlorpromazine | cyproheptadine

maangement of beta blocker overdise

IV glucagon 5-10mg atropine 3mg IV fluids

what does CCB overdose cause?

``` myocardial depression bradycardia peripheral vasodilation metabolic acidosis hyperglycaemia hyperkalaemia ```

management of CCB overdose

``` atropine 3mg IV fluids IV calcium chloride 10% 0.2ml/kg up to 10ml over 5 minutes insulin and dextrose glucagon if severe hypotension arrhythmias= intralipid ```

how does CO poisoning impair oxygen availability?

1. oxygen carrying capacity of blood is reduced 2. oxygen curve shifts to the left so less is delivered to tissues 3. mitochondrial function is impaired

presentation of CO poisoning

``` headache malaise lethargy nausea cherry red discolouration is a late sign ```

what is the COHb level in smokers?

<10%

why is pulse oximetry of no use in CO poisoning?

cannot differentiate between CO and oxyHb

management of CO poisoning

oxygen | neurological sequelae can happen

substances that cause metHB

- Local anaesthetics= prilocaine, lidocaine, benzocaine - Antibiotics= dapsone, sulphonamides, trimethoprim - Nitrites and nitrates - Others= metoclopramide, aniline dyes

presentation of metHB

slate grey | ABG will be chocolate brown

management of metHB

methylthioninium chloride or methylene blue IV | if fails consider G6PD deficiency

management of acute dystonias?

procyclidine 5-10mg IV/IM (risks euphoria and abuse) or benztropine 1-2mg IV/IM

management of neuroleptic malignant syndrome

dantrolene 1mg/kg IV

what does myoglobin cause?

renal injury due to free radicals, renal tubules damage and vasoconstriction

what is elevated in rhabdomyolysis

creatinine potassium CK phosphate dark urine is positive for Hb

management of myoglobin

urine output 200-300ml/hr urinary alkalisation with 1L sodium bicarbonate treat hyperkalaemia