Toxicology

Question 1

Toxin exposure from burning plastics & causes a severe lactic acidosis?

Answer 1

Cyanide

Question 2

Mx for cyanide poisoning

Answer 2

Mild: Sodium thiosulphate
Severe: hydroxocobalmin (cyanokit)

Question 3

Iron poisoning antidote

Answer 3

Desferrioxamine 15mg/kg/hr, max 80mg/kg/24hrs, reduce dose after 4hrs, can do higher doses on liason w/ toxbase

Question 4

ethyline glycol/methanol antidote

Answer 4

fomepazole 15mg/kg over 30 mins

Question 5

serotonin syndrome antidote

Answer 5

Cyproheptadine is a histamine and serotonin antagonist with anticholinergic properties. Give 8mg PO/NG

Question 6

sulfonyurea poisoning (glibenclamide, gliclazide, glimepiride and gliplizide)

Answer 6

IV glucose
Octreotide

Question 7

Mx for LA toxicity

Answer 7

20% 1.5ml/kg intralipid over 1 min, up to 3 boluses 5 mins apart. then infusion of 15ml/kg/hr, doubled to 30ml/kg/hr id req

Question 8

What has organophosphates in?

Answer 8

Pesticides

Question 9

What is the mechanism of action of organophosphates

Answer 9

acetylcholinesterase inhibitors

Question 10

Aim of atropinisation in organophosphate poisoning?

Answer 10

HR>80, BP adequate & lungs clear. Pupils may remain constricted for many days.

Question 11

Maintenance of atropinisation in organophosphate poisoning

Answer 11

20% initial dose per hr

Question 12

calculate an anion gap

Answer 12

Na - (bibarb + chloride)
Normal is approx 4-12
High anion gap can be caused by lactate, uraemia, ketones & exogenous toxins

Question 13

% threshold over which CO poisoning is likely to be severe

Answer 13

30%

Question 14

CO poisoning assoc. symptoms

Answer 14

Headache 90%
N&V 50%

Question 15

Normal COHb

Answer 15

Non smoker 1-2%
Smoker 5-10%
Haemolytic anaemia <5%

Question 16

CO elimination half life

Answer 16

Fetal can up to 4x maternal.

Question 17

hydrofluoric acid burns

Answer 17

Irragate & repeated calcium glucinate gel

Question 18

When may methylene blue not be effective when Mx methhaemaglobinaemia

Answer 18

G6PD, hereditary methaemoglobinaemia, dapsone poisoning & chlorate poisoning

Question 19

Threshold for bloods in paracetamol OD taken over <1hr

Answer 19

> 6yo >75mg/kg
<6yo >150mg/kg

Question 20

When to give activated charcoal for paracetamol OD

Answer 20

If >150mg/kg + <1hr ago. Give 50g for adult or 1g/kg for children

Question 21

Paracetamol in pregnancy

Answer 21

Calculate toxic dose from pre-pregnancy dose.
Calculate NAC from current actual weight.

Question 22

Paracetamol OD in the obese adults/kids

Answer 22

if pt weighs >110kg: Calculate toxic dose & NAC dose as if pt was 110kg

Question 23

Single paracetamol OD with 8hrs, Mx?

Answer 23

Levels at 4hrs post ingestion.
NAC if over line (100 at 4hrs)
If >700 consider haemofiltration
Consider D/C if below Tx line, INR & ALT are normal.

Question 24

When can paracetamol OD take paracetamol again

Answer 24

-below treatment line, normal LFTs=12hrs
-Abnormal LFTs=2/52
-Tx w/ NAC, after NAC

Question 25

When to continue NAC after SNAP?

Answer 25

ALT has doubled ALT > upper limite of normal Paracetamol level >10 If INR raised, recheck in 4-6hrs

Question 26

Single paracetamol OD 8-24hrs

Answer 26

-Take bloods (if done after commencing NAC, likely will be underestimated) -If >150mg/kg or unknown: start NAC immediately -If <150mg/kg start NAC if level above normogram line OR raised ALT NB some labs threshold of detection is above the Tx line, at circa 12+ hrs, if this is the case treat as if above line.

Question 27

Mx NAC anaphylactoid reaction

Answer 27

Pause NAC antihistamine Consider slowing rate by half

Question 28

Single paracetamol OD >24hrs

Answer 28

-As for 8-24hrs, but start NAC if <150 if pt symptomatic -Start NAC if: >ALT (if chronically raised ask NPIS) INR>1.3 (new) paracetamol level detectable

Question 29

Staggered paracetamol OD

Answer 29

If likely >75mg/kg give NAC

Question 30

Therapeutic excess

Answer 30

NAC if >75mg/kg/24hrs

Question 31

Cyanide poisoning on bloods

Answer 31

High lactate (>7) High anion gap metabolic acidosis Higher than expected venous oxygen

Question 32

Cyanide poisoning sources

Answer 32

-Inhaled from burning some plastics/wool/silk -vehicle exhausts -cigarette smoke -bacteria/fingi algae -nitroprusside -Industry: metal extraction -apricot stones, bitter almonds

Question 33

Cyanide poisoning symptoms

Answer 33

Onset within minutes. Cherry red skin & bitter almond breath can occur. -MILD: headache, vomiting, anxiety, followed by tachycardia/confusion, drowsiness. -MOD: breif LOC, seizure, vomiting, hypotension -SEVERE: coma, fixed unreactive pupils, MI, pulmomary oedema, cardiovascular collapse, profound bradycardia, AV disosciation, cyanosis, death.

Question 34

Cyanide poisoning-what is it?

Answer 34

Carbon tripple bonded to nitrate. Blocks intracellular metabolism, cells unable to make ATP & use oxygen.

Question 35

Cyanide poisoning Mx

Answer 35

If asymptomatic-observe 6 hrs ECG Cyanide assay-will take ages. 1-2-mild, 2-3 mod, >3 severe9 Lactate <10-mild lactate 10-15-mod Lactate >15 severe Gastric lavage in <1hr if ingested (prob intubated), if not possible then activated charcoal. Mild: adult-12.5g of sodium thiosulphate, paeds-400mg/kg (reacts with cyanide to make thiocyaniate) Mod: Hydoroxycobalamin (cyanokit) Adults: 5g/200ml of 25mg/ml over 15mins Paeds: 70mg/kg Severe: as for moderate. Can give a second dose cyanokit. If cannot get cyanokit, use sodium thiosulphate.

Question 36

Anti-Cholinergic Toxicity sources

Answer 36

Tricyclics, old antihistamines, polypharmacy, nightshade

Question 37

Cholinergic Toxicty sources

Answer 37

Organophosphate (anticholinergic esterase inhibitor), Nerve agents (novochoc), drugs: neostigmine (myasthenia gravis), rivastigmine, donepezil (alzhimer's), blue-green algae.

Question 38

Malignant hyperthermia

Answer 38

Hyperventilate aiming for normocapnia Tx hyperkalaemia Dantroline 2.5mg/kg initially, then 10mg/kg Active cooling-water & ice