Overdose and Poisoning Flashcards
You are on duty in ED and a nurse asked you to assess a 48-year-old patient, Ms Kirsty Sommers. After SBAR handover, you found out that Ms Sommers has been brought to hospital by ambulance. She told the paramedics that she has taken an overdose of some tablets but she is not sure what the drug was. She has a history of depression.
You carry out an ABCDE assessment and note the following:
A - Clear
B - RR 9 min-1
C - P 110 min-1, BP 90/40 mmHg
D - Confused with slurred speech, GCS 13/15 (E3, V4, M6), dilated pupils
E - Unremarkable.
Based on the ECG findings, consider what type of drug that Mrs Sommers is llikely to have taken.
tricyclic antidepressant
The ECG shows a tachycardia with broad QRS complexes as occurs with tricyclic antidepressant toxicity.
The initial management of all poisonings, including in Mrs Sommers’ case, is supportive using the ABCDE approach. Some types of poisonings require specific treatments. Patients at risk of deterioration should be transferred to a critical care area.
How would you approach the A-E assessment/management of a patient with overdose/poisoning?
- A - ensure that the airway is assessed and supported correctly, consider intubation if reduced consciousness
- B - correct hypoxia, request ABG, consider mechanical ventilation if there is persistent hypoxia or hypercarbia
- C - obtain IV access, give the patient fluids, use inotropes if needed, monitor the ECG
- Consider specific treatments to decrease absorption or enhance elimination e.g. activated charcoal, haemodialysis
- If you are unsure of the drug that a patient has taken, or you need further advice, contact TOXBASE®. Print out the guidelines and attach this to the patients notes
- Consider antidotes
When is activated charcoal prescribed for overdose?
Prescribe activated charcoal if the overdose is within 1 h. You should give activated charcoal only to patients with an intact or protected airway.
You may consider prescribing 50 mmol L-1 of _________? in moderate to severe overdoses of tricylic antidepressants.
You may consider prescribing 50 mmol L-1 of sodium bicarbonate in moderate to severe overdoses of tricycylic antidepressants.
Which poisons should haemodialysis be considered for?
methanol, ethylene glycol, salicylates, and lithium
What treatment can be used for cardiac arrest caused by local anaesthetic toxicity?
IV 20% lipid emulsion (Intralipid)
What is TOXBASE? When should it be used?
TOXBASE® is an online poisons information database. You will need a log-on name and password to access the database - www.toxbase.org.
If you are unsure of the drug that a patient has taken, or you need further advice, contact TOXBASE®. Print out the national guidelines and attach to patients notes.
What are the signs of opioid poisoning?
Respiratory depression – can last 4-5 hours after opioid overdose
Pinpoint pupils
Constipation
Hypotension
Reduced GCS
Coma –> Respiratory arrest
How should opioid poisoning be managed? What is the antidote?
Supportive care should be given. Opioid antagonist naloxone rapidly reverses these effects.
What are the signs of benzodiazepine overdose?
loss of consciousness, respiratory depression and hypotension
What is the antidote for benzodiazepine overdose? When should it be given?
Flumazenil, a competitive antagonist of benzodiazepines, should be used only for reversal of sedation caused by a single ingestion of any of the benzodiazepines and when there is no history or risk of seizures.
Are all cases of benzodiazepine toxicity treated with flumezanil?
No. The mainstay of management is ABCDE supportive care. Flumezanil is associated with complications e.g. seizures and is reserved for certain cases.
What are the signs of a paracetamol overdose?
- Usually asymptomatic
Late signs:
- N&V
- RUQ pain
- AKI
- Signs of liver failure - confusion (encephalopathy), hypoglycaemia
- Multiorgan failure
- Death
When is n-acetylcysteine given?
Staggered overdose
Staggered overdose or time/ of paracetamol ingestion unknown but dose ingested is 75mg/kg or more in 24hr period
More than 4 hours since presentation and paracetamol level is on or above treatment line
Symptomatic
How does N-acetylcysteine work?
- In an overdose, paracetamol is metabolised by the CYP450 enzymes when conjugating with glucoronide or sulphate becomes saturated.
- This leads to accumulation of the metabolite NAPQI
- NAPQI is a strong oxidising agent. Therefore, it requires conjugation by glutathione (anti-oxidant) to prevent damage to hepatocytes.
- Glutathione is depleted in a paracetamol overdose
- Acetylcysteine works by replenishing the glutathione
