Paracetamol Overdose

Question 1

What are some early symptoms of paracetamol overdose?

Answer 1

FIRST 24 HOURS

Symptoms of the actual overdose take quite a long time to occur - usually when people are unwell when they come in is because they’ve ingested the pills with a lot of alcohol

• NAUSEA AND VOMITING

Question 2

What are some of the mid-symptoms of PCM OD and when do they occur?

Answer 2

24-72h

• RUQ pain (this occurs due to inflammation in the liver that stretched the liver capsule)
• Further N&V

Question 3

What are some of the LATE symptoms of PCM OD and when do they occur?

Answer 3

After 72h

JAUNDICE
Coagulopathy (bleeding and bruising)
Encephalopathy (nitrogenous waste goes to the brain) this leads to confusion, agitation, drowsiness, irritable and seizures
Low glucose - this can be another cause of the seizures

Question 4

If someone comes in with PCM OD what is important to find out in the history?

Answer 4

How many tablets did they take?
Did they take anything else?
When did they take them?
Did they take them all at once or did they take breaks?

Question 5

What makes treating PCM OD more difficult to treat?

What is deemed a large overdose?

Answer 5

If the person took a STAGGERED OVERDOSE
- this is if they took the tablets over a time period of 4 hours or longer
Large overdose >10g

Question 6

How does PCM have a negative effect on the body in OD (pathophysiology)?

Answer 6

Metabolised by liver. 5% will become toxic metabolite NAPQI - this happens normally but body binds it to glutathione and excretes it
TOO MUCH PCM = NOT ENOUGH GLUTATHIONE. NAPQI builds up - toxic to hepatocytes leading to hepatitis and liver failure

Takes a while to metabolise and build up NAPQI and then exhaust glutathione reserves hence why symptoms take a while to start

Question 7

What groups of people have low levels of glutathione?

Answer 7

Alcoholics and malnourished (very low BMI)

Question 8

What medications might decrease someones tolerance to paracetamol?

Answer 8

Rifampicin (TB), some anti-convulstants and St Jonh’s Wort

Question 9

What investigations are needed in someone who has taken a PCM OD

Answer 9

PARACETAMOL LEVELS - no point taking until at least 4 hours after
THEN PLOT THIS ON PCM CHART - helps to decide management and whether to initiate management
- If someone is presenting later than 15hrs after the PCM OD then there is no point taking their levels before treatment because most of the PCM will have been metabolised - just start them on treatment immediately
LFTS usually normal until at least 18h post OD
INR is often good to get - suggestive of liver damage if high
ABG (lactic acidosis can occur)

Question 10

What is the treatment for PCM OD and how do you decide how much to give an at what rate?

Answer 10

N-ACETYL CYSTEINE (NAC)

The DOSE and infusion rate depends on the weight of the patient so refer to the table
- there is also different doses depending on whether it is the first, second or third infusion

GIVEN WITH 5% DEXTROSE OR 0.9% NaCl

(activated charcoal if less than 4hr)

Question 11

Once the treatment is done what should we measure?

Answer 11

Creatinine, ALT and INR - if any of them are raised then continue with NAC treatment.
If they are all fine then discharge to psychiatric services

Question 12

What are the complications of PCM OD?

Answer 12

Acute liver failure
Cerebral oedema
Renal failure
Pancreatitis