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Flashcards in Toxicology Deck (60)
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1

When to NOT use charcoal

Later than 2-4 hours
Risk of aspiration
Alcohols
Hydrocarbons
Metals
Corrosives

2

Indications for whole bowel irrigation

Iron > 60mg/kg
Slow release potassium > 2.5mmol/kg
Lead
Arsenic
Life threatening slow release verapamil/diltiazem
Body packers

3

Indications for multi dose activated charcoal

Massive modified release paracetamol
Carbamazapine
Phenobarbitone
Theophylline
Quinine
Dapsone

4

Indications for dialysis (apart from AEIOU)

Toxic alcohols
Salicylate
Theophylline
Lithium
Metformin
Potassium
Valproate
Carbamazapine
Phenobarbitone

5

1 pill can kill in toddler

Amphetamines
Diltiazem/verapamil
Chloroquine
Oxycodone, morphine, methadone
Propanolol
Sulfonylureas
Theophylline
TCAs

6

1 sip can kill in toddler

Organophosphates
Paraquat
Hydrocarbons
Toxic alcohols
Eucalyptus oil, camphor
Naphtholene
Caustic agents - ammonia, boric acid, hydrofluoric acid

7

Toxic causes of delirium

Alcohol intoxication/withdrawal
Serotonin syndrome
Neuroleptic malignant syndrome
Anticholinergic syndrome
Sympathomimetic syndrome
Benzodiazapines
Cannabis
Hallucinogenic agents
Salicylate OD
Theophylline OD
Atypical antipsychotics

8

Methanol - features and investigations

Home brew, paints, varnishes, dyes, carburettor fluid
Metabolised to formic acid
Ingestion > 0.5ml/kg fatal
Effects at 12-24 hours
- Headache, dizzy, blindness, cerebral oedema, permanent extrapyramidal disorders
High osmolar gap and HAGMA

9

Ethylene glycol - features and investigations

Antifreeze, radiator coolant, brake fluid, solvents
Metabolised to glycolic and oxalic acid
Ingestion > 1ml/kg fatal
Effects 4-12 hours
- SOB, tachycardia, HTN, seizures, coma, cranial nerve palsies, oxalate deposits in kidneys (RTA)
High osmolar gap and HAGMA
AKI and hypocalcaemia

10

Treatment methanol/ethylene glycol

Prevent metabolism
- 1.8ml/kg 43% vodka PO or 8ml/kg 10% ETOH IV
- infusion to maintain ETOH level 100
Manage acidosis
- 50mmol bicarb IV
- hyperventilate if ETT
Elimination
- Dialysis
Fomepizole is antidote, not available here

11

Isopropanolol

Surgical spirits - disinfectant, solvents, window cleaners
4ml/kg can cause coma
Supportive as per ETOH intoxication

12

Beta blocker OD features

Bradycardia and hypotension
Bronchospasm and pulmonary oedema - increased risk if elderly or asthmatic
Hypoglycaemia, hyperkalaemia
Altered mental state

ECG - bradycardia, conduction defects, AV block

13

Beta blocker OD treatment

- Charcoal
- Expect bradycardia and hypotension - IVF, atropine 0.6mg, isoprenaline 1-10mcg/min, adrenaline 1-10mcg/min (pacing rarely useful)
- High dose insulin glucose 1unit/kg/hr up 10 10 with 10% dextrose 100ml/hr - titrate BSL 4-8, check every 30-60 mins, anticipate K replacement
- glucagon rarely used
- ECMO

14

Propanolol OD

Treat as TCA OD
Toxicity can start at 1g
CNS effects - seizures, coma
QRS widening - treat with bicarbonate 50-100meq (1-2meq/kg) repeated until normal QRS

15

Sotalol OD

Can cause prolonged QTc -> torsades
Isoprenaline +/- adrenaline
10mmol magnesium sulphate IV

16

Calcium channel blocker OD features

Most concerning are diltiazem and verapamil
2-3x normal dose (10 tabs, > 15ml/kg) toxic
Can be immediate release - first 2-4 hours or delayed 4-16 up to 24 hours
Bradycardia, 1-3 HB, hypotension, ACS, CVA, ischaemic gut, hyperglycaemia, lactic acidosis, shock, seizures

17

Calcium channel OD treatment

- Charcoal (up to 4 hours slow release)
- Expect bradycardia and hypotension - IVF, pacing (rather than drugs), adrenaline, ECMO/bypass
- High dose insulin glucose therapy
Calcium glutinate 10-20mls 10% IV repeated with monitoring of Ca levels

18

Acute digoxin OD features

Drugs, toad toxin, oleanders
10 x daily dose toxic, lethal > 10mg (4mg children)
GI early - n+v, abdo pain
CVS later 8-12 hours - bradycardia, slow AF, HB, increased automaticity, bigeminy, SVT, VT, hypotension
CNS - leathery, confusion, seizure

Dig levels at 4 hours
< 1 therapeutic
2-3.2 potentially toxic
> 3.2 toxic

Often hyperkalaemia - poor sign if > 5.5 early

ECG - reverse tick ST depression lateral leads, shortened QTc

19

Acute digoxin OD treatment

- Cardiac arrest - 20 amps digibind
- Life threatening arrhythmia, refractory hypotension, refractory hyperK, significantly symptomatic then give digibind
- dose digibind vials = ingested dose in mgx0.8x2
- if unknown start 2-5

- atropine 0.6mg, pacing
- arrhythmia - magnesium, lignocaine
- hyperK - insulin/dextrose, bicarb NOT calcium

20

Chronic digoxin toxicity

Usually intercurrent illness (sepsis, NSAIDs etc) so renal impairment and delayed elimination
GI upset, bradycardia, syncope
Lower levels than acute cause problems
- bradycardia alone with level 2.5 50% toxic
- GI alone with level 2.5 60% toxic
- bradycardia and GI level 2.5 90%
- automaticity + others level 2.5 100%

- cardiac arrest 5 amps
- digibind 1-2 amps

21

Salicylate features and investigations

GI - n+v, mucosal erosion, GI bleed
Resp - tachypnoea, pulmonary oedema 10%
CNS - tinnitus 90%, tetany, confusion, seizures, coma
Other - sweating, hyperthermia, nephrotoxicity

< 150mg/kg OK
300mg/kg mild/mod
< 500mg/kg serious
> 500mg/kg potentially fatal

Salicylate levels to guide treatment, peak 12 hours
Hypokalaemia
Mild transaminitis
Resp alkalosis then metabolic acidosis
20% have hyperchloraemic NAGMA
Resp acidosis is sign of severity

22

Salicylate treatment

Activated charcoal
Maintain adequate hydration and high urine flow
Correct electrolytes
Alkalinisation urine if pH < 7.1
Haemodialysis if level > 9.4
ETT is high risk - pretreat with bicarb and hyperventilate pre/during/post

23

Opiods

Triad - miosis, resp depression, CNS depression
Aspiration, hypothermia, hypoxic brain injury, rhabdo

Pethidine - serotonin syndrome
Dextropropoxyphene - seizures

Naloxone 100-400mcg bolus
2 x boluses needed then start infusion at 2/3 initial dose required/hr and titrate

24

Iron

20-60mg/kg moderate, 60-90mg/kg requires decontamination, > 130 potentially fatal

Vomiting within 80 mins in 90%, direct GI irritation
Hypotension, acidosis, myocardial damage, inhibition coagulation, confusion, coma
0-3 hrs GI symptoms
12-48 hrs systemic symptoms
2 weeks strictures

Iron level at 4 hours
Hyperglycaemia, acute tubular necrosis, hepatoxicity, prolonged INR/APTT, elevated WCC, metabolic acidosis
CXR/AXR for FB

Resonium, gastric lavage, whole bowel irrigation, scope
Desferioxamine if coma, acidosis, peak level > 90. Can promote infection - stop if fever, give abs

25

Lithium

Narrow therapeutic index 0.8-1.2
Toxicity with intercurrent illness
Acute > 40mg/kg, symptoms over 3-5 days

< 1.5 Lethargy, fine tremor, memory deficits
< 2.5 confusion, visual disturbances, ataxia, coarse tremor, hyperactive reflexes
< 3.5 myoclonic twitches, nystagmus, stupor
> 3.5 seizure, flaccid paralysis, coma

T wave flattening or inversion, prolonged PR/QRS/QT
Hypokalaemia, abnormal TFTs

Gastric lavage
Diuresis with IVF
Dialysis
Supportive

26

Arsenic

Acute - n+v, diarrhoea, hyper salivation, garlic odour, haematemesis, hyperthermia.
Subsequent hepatic/renal damage and encephalopathy
Bone marrow suppression 2-4 weeks
Painful peripheral neuropathy 1-3 weeks

Chronic - hair and nails, mees lines, desquamating rash, headache, confusion, seizures

24 hour urine arsenic level, X-ray, hair/nail clippings, prolonged QT

Whole bowel irrigation
Chelation - BAL, DMSA, Penicillamine

27

Lead

Fumes, FB retention, contaminated drinks, improper storage foods in pewter, leaded glass, paint, batteries

Myalgia, hypo chromic microcytic anaemia, painless wrist drop, encephalopathy, HTN, gout, nephritis, abdo pain, infertility

Lead levels represent last 3-5 weeks
Children > 0.5 act on, symptomatic > 2.9

Chelation BAL or CaEDTA

28

Mercury

Inorganic - batteries, vinyl, acetaldehyde, embalming, cosmetics
Ashen grey MM, metallic taste, stomatitis, abdo pain, poor muscle tone, red/oedmatous soles and palms, tachycardia, high/low BP

Organic - contaminated foods, paper/wood preservatives
Over days/weeks
Scotoma, ataxia, parasthesia, hearing loss, dysarthria, tremor, cognitive defects, paralysis

Mercury blood or urine levels
Xray

Decontamination
Can dialyse
Chelation - BAL, penicillamine

29

Chelating agents

CaEDTA - lead, zinc

Penicillamine - copper, second line lead, iron, zinc, mercury, arsenic.
CI in pregnancy, renal disease, penicillin allergy

BAL - acute inorganic mercury, lead
CI in peanut allergy

DMSA - mercury, lead

30

Paracetamol toxicity

Large ingestions mean P450 pathway needed to metabolise which produced NAPQI - hepatic, renal, cardiac, neuro toxic

Increased risk hepatoxicity:
- depletion glutathione - malnutrition, HIV, chronic hepatic
- induction P450 - ETOH, anticonvulsants etc

Toxic doses:
> 10g or > 200mg/kg
Very large > 50g or > 1000mg/kg or > 3 x above nomogram

Repeated:
> 12g or > 300mg/kg (>150mg/kg children) over single 48 hour period OR
> 4g or > 60mg/kg per 24 hour period for 48 hours with associated abdo pain/nausea/vomiting