Toxins Flashcards
benzodiazepines
flumazenil 200 mcg over 15s, then 100 mcg at 1 min intervals as needed.
usual total dose 300-600 mcg
total dose 1 mcg, 2 mcg under ITU care
s/e seizure provoking
beta-blockers
atropine 3 mg IV then... glucagon 2-10 mg IV + 5% dextrose (call MedReg/Cardio) then... glucagon infusion then... pacing (transvenous temporary)
methaemoglobinaemia, (methaemoglobin >30%)
methylthioninium chloride
what are the poisons requiring haemodialysis?
ethylene glycol, lithium, methanol, salicylates, valproate, phenobarbital
when is alkalinisation of urine useful?
salicylate poisoning
what drug(s) poisoning presents with tachycardia/tachyarrythmia?
salbutamol
antimuscarinics
tricyclics
quinine
what drug(s) poisoning presents with respiratory depression?
opiates
benzodiazepines
what drug(s) poisoning presents with hyperthermia?
cocaine, amphetamines, MDMA
MAO-I’s
SSRIs, antipsychotics (NMS, SS)
what drug(s) poisoning presents with coma?
BZD/barbituates
alcohol
opiates
tricyclics
what drug(s) poisoning presents with seizures?
recreational drugs
hypoglycaemia
tricyclics
theophylline(s)
what drug(s) poisoning presents with pin-point pupils?
opiates
organophosphates
what drug(s) poisoning presents with dilated pupils?
amphetamines, cocaine, MDMA
quinine
tricyclics
what drug(s) poisoning presents with hyperglycaemia?
organophosphate
theophylline
MAO-I’s
what drug(s) poisoning presents with hypoglycaemia?
insulin, sulphonylurea
alcohol
salicylates
what drug(s) poisoning presents with acute renal dysfunction?
salicylates
ehtylene glycol
paracetamol
what drug(s) poisoning presents with metabolic acidosis?
ethylene glycol/methanol
paracetamol/salicylates
alcohol
carbon monoxide
what blood tests should always be added (besides routine sets) in the setting of acute poisoning?
paracetamol and salicylates
blood glucose
use of activated charcoal in acute poisoning
activated charcoal given for two reasons: 1) GI decontamination; 2) increase the rate of elimination of a toxin from the blood
initially given as a 50g dose with water, then repeated 50 g/4 hrs for elimination.
use smaller doses in children.
consult with product literature or BNF with regards to the poisons that are CI’s to charcoal, such as metal salts or alcohols.
s/e: foul taste, GI disturbance, black stools
cyanide
100% oxygen and GI decontamination
sodium nitrate/sodium thiosluphate
dicobalt edetate
follow with 50 mL 50% glucose
in cyanide poisoning, what are the indications for hyperbaric oxygen?
COHb >20%
pregnant
neuro/psych disturbance
cardiovascular impairment
not responding to 100% oxygen
digoxin
anti-digoxin antibodies: DigiFab (R) 800 mg
monitor U&E for disturbance contributing to arrythmia, correct them
12-lead ECG/cardiac monitoring
iron
what are the rules for GI detox?
desferrioxamine 15 mg/kg/hr IVI
if iron ingested in the last hour, gastric lavage
if longer, consider whole bowel irrigation under expert guidance
opiates
naloxone 0.5-2 mg IV
short half-life so maybe needed repeatedly.
max dose 10 mg
give until breathing is adequate
what are the considerations with giving naloxone for opiate poisoning?
naloxone = opiate withdrawal
GI symptoms will respond to co-phenotrope/Lomotil (diphenoxylate and atropine)
anti-cholinesterase clinical features
SLUD hypersalivation lacrimation urination diarrhoea
what is an added blood test useful in organophosphate poisoning?
serum cholinesterase function
what is the treatment of organophosphate poisoning
atropine 0.5-2 mg IV, repeat until skin dry, pupil dilated, HR >70
pradiloxime
diazepam (regardless of seizure status)
treatment maybe needed over a few days
what are the signs and symptoms of paracetamol poisoning?
none initially… maybe nausea and RUQ pain
then jaundice, hepatic encephalopathy, asterixis, transaminitis, AKI
what are the lethal doses of paracetamol?
about 12 g - so 24 tablets
roughly 150 mg/kg
for patients over 110 kg, calculate exposure as 110 kg so you don’t underestimate toxicity
malnourishment - 75 mg/kg can be lethal
GI decontamination for paracetamol poisoning?
yes, if presenting under 4 hours following ingestion
what are the guiding principles of managing paracetamol poisoning?
get the graph of time since ingestion versus blood paracetamol level (mg/L)
treat if levels are above the line.
treatment is n-acetylcyctine infusion
stop infusion when levels are below the line or ALT/INR have normalised
what are the threshold levels for aspirin toxicity?
150 mg/kg - mild toxicity
500 mg/kg - severe toxicity
700 mg/L - potentially fatal
what is the pattern of metabolic disturbance in aspirin poisoning?
initial respiratory alkalosis
then metabolic acidosis …
…. as OxPhos becomes uncoupled, anaerobic takes over leading to lactic acidosis
managing salicylate poisoning
blood - glucose, acid-base, hypokalaemia (b/c therapeutic alkalinosis)
urine - catheterise and monitor pH for duration of treatment
alkalinisation - if serum levels >500 mg/L or severe acidosis
use 1.5 L 1.24% sodium bicarb IV over 3 hours. aim for urine pH 7.5-8
if resistant or serum level >700 mg/L, dialysis
