Paracetomol Overdose Flashcards
(23 cards)
What is the most common agent ingested in the context of intentional self-harm in the UK?
Paracetamol
Paracetamol overdose accounts for 44% of all adult self-poisoning cases in the UK.
What percentage of adult self-poisoning cases in the UK is attributed to paracetamol overdose?
44%
Approximately 150,000 people are admitted to hospital each year due to poisoning.
What is the toxic metabolite associated with paracetamol toxicity?
NAPQI (N-acetyl-p-benzoquinone-imine)
NAPQI is normally inactivated by glutathione.
What happens to glutathione stores during a paracetamol overdose?
They are rapidly depleted
This leads to the accumulation of NAPQI.
What are the two main types of toxicity caused by paracetamol overdose?
Hepatotoxicity and nephrotoxicity
This can lead to liver and kidney failure.
Define acute overdose of paracetamol.
Excessive paracetamol taken in less than 1 hour
Usually in the context of self-harm.
Define staggered overdose of paracetamol.
Excessive paracetamol ingested over longer than 1 hour
Usually in the context of self-harm.
What is therapeutic excess in the context of paracetamol overdose?
Excessive paracetamol taken with the intent to treat pain or fever
Ingested at a dose greater than 75mg/kg/24 hours.
What symptoms may patients experience in the first 24 hours after paracetamol overdose?
Asymptomatic, nausea, and vomiting
Symptoms can vary depending on the timing of the overdose.
What symptoms may develop between 72 to 96 hours after paracetamol overdose?
Liver and renal failure, metabolic acidosis, encephalopathy, coagulopathy
Symptoms include confusion, drowsiness, reduced urine output, loin pain, jaundice, and bleeding diathesis.
When should blood tests for paracetamol levels be taken?
At least 4 hours after ingestion
This is when plasma paracetamol concentration peaks.
What important blood tests should be conducted for paracetamol overdose?
Liver Function Tests, Venous Blood Gas, Blood glucose, Salicylate levels
Salicylate levels are to check for a mixed overdose with aspirin.
What is the significance of weighing a patient in paracetamol overdose cases?
Important for determining dose of paracetamol taken per kg
Also used to calculate N-acetylcysteine dosing.
What should be considered if the paracetamol overdose was intentional?
Refer to liaison psychiatry for a mental health assessment
Assess risk to self and ongoing suicidal ideation.
What is the initial treatment for ingestion of paracetamol less than 1 hour ago with a dose >150mg/kg?
Administer activated charcoal which adsorbs onto the toxins and prevents gastric absorption
This is a critical step in acute management.
What is the treatment protocol for ingestion of paracetamol within 4-8 hours with a dose >150mg/kg?
Start N-acetylcysteine (NAC) immediately if there is a delay of ≥8 hours in obtaining the paracetamol level
Otherwise, wait for level and treat if level high.
What is the management approach for staggered overdose of paracetamol?
Start NAC immediately
This is crucial for effective treatment.
What is the role of N-acetylcysteine (NAC) in paracetamol overdose treatment?
It acts by increasing glutathione levels, thereby preventing toxicity
NAC is given as an IV medication.
What are the two regimens for administering NAC?
Standard regimen of 3 infusions over 21 hours and SNAP protocol of 2 infusions over 12 hours
The SNAP protocol is now recommended as standard.
What are common side effects of NAC?
Anaphylactoid reactions, urticaria, angioedema, nausea, vomiting, tachycardia, bronchospasm
Rarely leads to shock.
What criteria indicate the need for an urgent liver transplant after a paracetamol overdose?
INR > 3 at 48 hours, Oliguric or creatinine > 200, pH < 7.3 despite fluid resuscitation, hypotension, severe thrombocytopenia, encephalopathy
These are critical indicators for referral.
What is the King’s College Criteria used for?
To predict mortality from paracetamol overdose and identify patients who may benefit from liver transplantation
It advises consideration of liver transplantation based on specific clinical parameters.
What is the blood pH threshold that indicates potential consideration for liver transplantation?
Blood pH < 7.3
Other criteria include high serum creatinine and INR levels.
