overdose and poisoning

Question 1

initial assessment

Answer 1

• AIRWAY
• BREATHING
• CIRCULATION
• DIAGNOSIS
– Cardiac monitor, oximetry, IV access depending on
the patient’s condition
– AVPU
– When GCS = 8 intubation

Question 2

common toxidromes?

Answer 2

Question 3

antidotes?

Answer 3

• COMPETITIVE eg Naloxone for opiate poisoning ,
Atropine for anticholinesterase poisoning
• CHELATING AGENTS eg Desferioximine for iron
poisoning
• SUBSTRATE COMPETITORS eg ethanol for methanol
• N-ACETYLCYSTEINE or METHIONINE for paracetamol
• ANTIBODY FRAGMENTS for digoxin

Question 4

poisons and antidotes

Answer 4

Question 5

featueres of paracetemol poisoning

Answer 5

• Extremely common: nausea and vomiting.
• Very rarely: coma and severe metabolic acidosis in patients who
have extremely high plasma paracetamol concentrations (usually
greater than 800 mg/L).
• Later features in severe cases (12-36 hours): abdominal pain.
• After 2-3 days: features of hepatic necrosis with right subcostal pain
and tenderness, recurrence of nausea, vomiting, jaundice, renal
failure and hepatic coma.
• Abnormal LFTs, acidosis, hypoglycaemia, elevated creatinine.
• Loin pain, haematuria and proteinuria after the first 24 hours
strongly suggest incipient renal failure.

Question 6

paracetmol guidelines

Answer 6

• All patients ingesting paracetamol in the context of self-harm should be
referred to hospital (irrespective of reported dose).
• All patients who are symptomatic should be referred to hospital.
• Patients ingesting 75 mg/kg or more, in a single acute overdose over less
than 1 hour, should be referred directly to hospital.
• MHRA advice is that ALL patients require medical assessment, including
blood tests, if:
• they have taken a staggered paracetamol overdose (doses taken over
more than one hour);
• they have taken chronic therapeutic excess (defined as more than a
licensed dose for that individual AND more than or equal to 75 mg/kg in
any 24-hour period);
• the time of ingestion is uncertain AND the dose is more than or equal to
75 mg/kg.

if take les than 8 hours ago:

• Paracetamol levels : Wait until 4 hours from ingestion have elapsed. Plasma paracetamol
concentration, U&Es, bicarb, LFTs,INR and FBC.
• Plasma concentrations measured less than 4 hours after ingestion cannot be interpreted.
• There is normally no indication to start acetylcysteine without a paracetamol blood
concentration provided the result can be obtained and acted upon within 8 hours of
ingestion.
• If doubts over timing careful assessment required, consider treating or seek advice!
• Assess the risk of severe liver damage from the plasma paracetamol concentration/time from
ingestion graph which follows. This has been revised following recent CHM guidance. (see
graph)
• For later presentations, staggered overdoses and chronic therapeutic excess consult
individual enteries on Toxbase

Question 7

complications of paracetamol treatment

Answer 7

• Airway compromise
• Aspiration pneumonia
• Renal failure
• Seizures
• Alcohol and drug withdrawal
• Serotinergic syndrome
• Neuroleptic malignant syndrome