Overdose

Question 1

Fast or irregular pulse from overdose DD?

Answer 1

Salbutamol, antimuscarinics, tricyclics, quinine, or phenothiazine
poisoning

Question 2

Resp. depression from overdose DD?

Answer 2

Opiate or benzodiazepine

Question 3

hypothermia from overdose DD?

Answer 3

phenothiazine or barbituates

Question 4

hyperthermia from overdose DD?

Answer 4

Amphetamines, MAOIS, cocaine, or ecstasy

Question 5

coma from overdose DD?

Answer 5

Benzodiazepines, alcohol, opiates, tricyclics, or barbiturates

Question 6

seizures from overdose DD?

Answer 6

Recreational drugs, hypoglycaemic agents, tricyclics, phenothiazines, or
theophyllines

Question 7

Constricted pupils from overdose DD?

Answer 7

Opiates or insecticides (organophosphates)

Question 8

Dilated pupils from overdose DD?

Answer 8

Amphetamines, cocaine, quinine, or tricyclics

Question 9

hyperglycaemia from overdose DD?

Answer 9

Organophosphates, theophyllines, or MAOIS

Question 10

hypoglycaemia from overdose DD?

Answer 10

Insulin, oral hypoglycaemics, alcohol, or salicylates

Question 11

Renal impairment from overdose DD?

Answer 11

Salicylate, paracetamol, or ethylene glycol

Question 12

Metabolic acidosis from overdose DD?

Answer 12

Alcohol, ethylene glycol, methanol, paracetamol, or carbon

monoxide poisoning

Question 13

increased osmolality from overdose DD?

Answer 13

Alcohols (ethyl or methyl); ethylene glycol

Question 14

Mx of suspected overdose?

Answer 14

take blood (always check paracetemol and salicylate levels)
Empty stomach if appropriate
consider specific antidote or oral activated charcoal
If not familiar with poison - Toxbase or phone the Poisons Information Service

Question 15

How to administer activated charcoal? MOA? what substances should it not be used with?

Answer 15

given as a single dose of 50g with water. given in repeated doses (50g/4h) to increase elimination of some drugs from the blood.

Reduces the absorption of many drugs from the gut

Do not use with petroleum products, corrosives,
alcohols, clofenotane, malathion, or metal salts (eg iron, lithium)

Question 16

After how long should a gastric lavage not be used? WHen should a lavage not be used?

Answer 16

Lavage after 30–60min may make matters worse

Do not empty stomach if petroleum products or corrosives such as acids, alkalis, bleach,
descalers have been ingested (exception: paraquat), or if the patient is unconscious
or unable to protect their airway (unless intubated)

Question 17

If comatose or no gag reflex - what airway protection should be used before gastric lavage?

Answer 17

Cuffed endotracheal tube

Question 18

For which poisons may haemodialysis be needed?

Answer 18

ethylene glycol, lithium,

methanol, phenobarbital, salicylates, and sodium valproate.

Question 19

Benzodiazepine overdose Mx? SEs?

Answer 19

Flumazenil (for respiratory arrest)

May provoke fi ts. Use only after expert advice

Question 20

beta blockers overdose Mx?

Answer 20

Atropine up to 3mg IV
if atropine fails: Glucagon IV bolus + 5% glucose infusion
consider including phosphodiesterase inhibitor infusions
If unresponsive, consider pacing

Question 21

Cyanide MOA? Symptoms? Mx?

Answer 21

has affi nity for Fe3+, and inhibits the cytochrome
system, reducing aerobic respiration –> acidosis with raised lactate

Mild: Dizziness, anxiety, tachycardia, nausea, drowsiness/confusion.
Moderate: Vomiting, reduced consciousness, convulsions, cyanosis
Severe: Deep coma, fi xed unreactive pupils, cardiorespiratory failure, arrhythmias,
pulmonary oedema

Mx: 100% O2, GI decontamination
Mild: supportive care
Moderate to severe: sodium nitrite/sodium thiosulfate
or dicobalt edetate then 50mL 50% glucose IV ((repeat once if no response after a minute)
or hydroxocobalamin

Question 22

Carbon monoxide poisoning symptoms? MOA? Mx?

Answer 22

Skin is pink/pale despite hypoxaemia since carboxyhaemoglobin
(COHb) displaces O2 from Hb binding sites. For the same reasons SpO2 from a pulse oximeter may be normal
therefore check ABG in co-oximeter (ensure it measures haemoglobin, SaO2, Meth-Hb and COHb) - low SaO2 and high COHb (normal <5%).

symptoms: Headache, vomiting, raised pulse, tachypnoea, and, if
COHb >50%, fits, coma, and cardiac arrest.

Mx: Give 100% O2 until COHb <10%.
If severe, anticipate cerebral oedema
and give mannitol IVI.
If COHb >20%, patient has neurological or psychological
features, or cardiovascular impairment, fails to respond to treatment, or
is pregnant, consider hyperbaric O2:

Question 23

Digoxin OD symptoms? Mx?

Answer 23

reduced Cognition, yellow-green visual halos, arrhythmias, nausea, and
anorexia

correct hypokalaemia if serious arrhythmias present. Inactivate with digoxin-specific antibody fragments

Question 24

Iron OD Mx?

Answer 24

Desferrioxamine

gastric lavage if iron ingestion in last hour; consider whole-bowel irrigation

Question 25

opiates OD Mx? SEs?

Answer 25

Naloxone0.4–2mg IV; repeat every 2min until breathing is adequate

Naloxone may precipitate features of opiate withdrawal—
diarrhoea and cramps, which will normally respond to diphenoxylate and atropine (eg co-phenotrope)

Question 26

Phenothiazine poisoning Symptoms + Mx?

Answer 26

Dystonia (torticollis, retrocollis, glossopharyngeal dystonia, opisthotonus)
- procyclidine

Treat shock by raising the legs (± plasma expander IVI, or inotropes if desperate)

Restore body 
temperature. 
Monitor ECG. 
Use lorazepam IV for prolonged fits in the usual way - 0.1mg/kg (usually 4mg) as a slow bolus into a large vein. If no response
after 10–20min give a second dose.

Neuroleptic malignant syndrome: it may be
treated with cooling. Dantrolene can help,
bromocriptine and amantadine are alternatives

Question 27

How do you administer IV lorazepam?

Answer 27

0.1mg/kg (usually 4mg) as a slow bolus into a large vein. If no response after 10–20min give a second dose.
Beware respiratory arrest during the
last part of the injection. Have full resuscitation facilities to hand for all IV benzodiazepine
use. The rectal route is an alternative for diazepam if IV access is difficult.

Question 28

Carbon tetrachloride poisoning symptoms? Mx?

Answer 28

used in many industrial processes
causes vomiting, abdominal pain, diarrhoea, seizures, coma, renal failure, and tender hepatomegaly with jaundice and liver failure
IV acetylcysteine may improve prognosis

Question 29

Organophosphate insecticides MOA? symptoms? Mx?

Answer 29

Inactivates cholinesterase causing an increase in acetylcholine –> SLUD response: salivation, lacrimation, urination, diarrhoea
also: sweating, small pupils, muscle fasciculation, coma, respiratory distress, and bradycardia

Mx: Wear gloves; remove soiled clothes. Wash
skin.
Take blood (FBC and serum cholinesterase activity).
Give atropine IV 2mg every 10min till full atropinization (skin dry, pulse >70, pupils dilated)
Also give pralidoxime
diazepam given slowly seems to help.

Question 30

Signs of full atropinization?

Answer 30

skin dry, pulse >70, pupils dilated

Question 31

Paraquat OD symptoms? where is it found? Dx? Tx?

Answer 31

D&V, painful oral ulcers, alveolitis, and renal failure.
found in weed killers
Dx: Urine test
Tx: Activated charrcoal at once (100g followed by a laxative)
avoid O2 early on as promotes lung damage.

Question 32

Ectasy OD effects?

Answer 32

mild: nausea, muscle pain, blurred vision, amnesia, fever, confusion, and ataxia
severe: tachyarrhythmias, hyperthermia,
hyper/hypotension, water intoxication, DIC, raised K+, acute kidney injury (AKI),
hepatocellular and muscle necrosis, cardiovascular collapse, and ARDS

Tx:
Administration of activated charcoal and monitoring of BP, ECG, and temperature
for at least 12h (rapid cooling may be needed)
Monitor urine output and U&E, LFT, CK, FBC, and coagulation
Metabolic acidosis - give bicarbonate
Anxiety: lorazepam IV as a slow bolus into a large vein
Narrow complex tachycardias in adults: consider metoprolol 5mg IV.
Hypertension can be treated with nifedipine or phentolamine
Treat hypotension conventionally (p790).
Hyperthermia: attempt to cool; if rectal T° >39°C consider dantrolene Hyperthermia
with ecstasy is akin to serotonin syndrome, and propranolol, muscle relaxation, and
ventilation may be needed.

Question 33

Snakes (adders) signs of envenoming? Tests? Mx?

Answer 33

low BP (vasodilation, viper
cardiotoxicity), D&V; swelling spreading proximally within 4h of bite; bleeding
gums or venepuncture sites; anaphylaxis; ptosis; trismus; rhabdomyolysis; pulmonary
oedema.

raised WCC, abnormal clotting, low platelets, U+Es, raised urine RBC, raised CK, low PaO2, ECG

Avoid active movement of affected limb and incisions and tourniquets.

Question 34

Paracetemol poisoning signs and symptoms? Mx?

Answer 34

Vomiting ± RUQ pain.
Later: jaundice and
encephalopathy from liver damage (the main danger) ± acute kidney injury (AKI)
GI decontamination if <4hr after OD - give activated charcoal
Glucose, U&E, LFT, INR, ABG, FBC, HCO3
Ω ; blood paracetamol level at 4h post-ingestion

If <10–12h since overdose, not vomiting, and plasma paracetamol is above the line on the graph , start acetylcysteine

If >8–24h and suspicion of large overdose (>7.5g) err on the side of caution and
start acetylcysteine, stopping it if level below treatment line and INR/ALT normal

Next day do INR, U+E, LFT. If INR rising - continue acetylcysteine until <1.4
consider referral to specialist liver unit guided by eg King’s College criteria

Question 35

How do you administer acetylcysteine? SEs? Alternative?

Answer 35

given by IVI: 150mg/kg in 5% glucose over 15–60min; then 50mg/
kg in 500mL of 5% glucose over 4h; then 100mg/kg/16h in 1L of 5% glucose

Rash is common - treat with chlorphenamine + observe; do not stop unless anaphylatoid
reaction with shock, vomiting, and wheeze

methionine - unreliable absorption if vomiting

Question 36

Salicylate poisoning MOA? thresholds of toxicity? signs and symptoms? Presentation?

Answer 36

Uncoupling of oxidative phosphorylation leads to anaerobic metabolism and the production of lactate and heat
150mg/kg: mild toxicity.
•250mg/kg: moderate
•>500mg/kg: severe
toxicity.
Levels over 700mg/L are potentially fatal

Many early features unlike paracetemol: Vomiting, dehydration, hyperventilation, tinnitus, vertigo, sweating
Rarely reduced GCS, seizures, reduced BP and heart block, pulmonary oedema, hyperthermia

Present initially with respiratory alkalosis due to a direct stimulation of
the central respiratory centres and then develop a metabolic acidosis. Hyper- or
hypoglycaemia may occur.

Question 37

Salicylate poisoning Mx?

Answer 37

General: Correct dehydration. Keep patient on ECG monitor.
Give activated charcoal to all presenting less than 1h

bloods: Paracetamol and salicylate level, glucose, U&E, LFT, INR, ABG, HCO3
Ω, FBC.
Salicylate level may need to be repeated after 2h, due to continuing absorption
if a potentially toxic dose has been taken. Monitor blood glucose 1–2hrly.

urine: pH - consider catheterisation to monitor output and pH

correct acidosis: If plasma salicylate level >500mg/L or severe
metabolic acidosis, consider alkalinization of the urine, eg with 1.5L 1.26% sodium
bicarbonate IV over 3h. Aim for urine pH 7.5–8. NB: monitor serum K+ as hypokalaemia may occur, and should be treated (caution if AKI)

Dialysis: May be needed if salicylate level >700mg/L and if AKI or heart
failure, pulmonary or cerebral oedema, confusion or seizures, severe acidosis
despite best medical therapy, or persistently raised plasma salicylate. Contact nephrology
early.

Question 38

When may the Plasma concentration of paracetamol vs time graph be misleading?

Answer 38

if HIV +ve (reduced hepatic glutathione)
or if long-acting paracetamol has been taken, or if pre-existing liver disease
or induction of liver enzymes has occurred