Paracetamol Overdose Flashcards
What is the most common Overdose seen in the UK?
Paracetamol overdose
What does Risk Assessment of a Paracetamol Overdose pt involve? (7 things)
- Date of ingestion (was there a delay in CF?)
- Timing of ingestion (single overdose / staggered)
- Time of last ingestion
- Weight
- Pregnancy
- Total amount ingested
- Current suicidal risk
If a pt is above 110kg, what should you do for weight calculations of meds?
Use 110kg as maximum weight
How does Pregnancy affect weight calculations of meds? (2 things)
- Use Pre-preg weight to determine toxicity
- Current weight for Tx
What should you consider if a pt has a high current suicidal risk?
Have a MH nurse stay with them
What ACUTE dose of Paracetamol will cause Toxicity?
Over 75mg / kg
What STAGGERED dose of Paracetamol will cause Toxicity?
Over 150mg / kg over 24 hours
What ACUTE dose of Paracetamol will kill you (or haver serious fx)? (2 things)
- 150mg / kg
- 12g +
If timing of ingestion is unknown, how should you treat the pt?
As staggered overdose
What are the RF for developing toxicity with Paracetamol overdose? (2 things)
- Liver enzyme-inducing drugs
- Malnourished
What are some liver enzyme-inducing drugs that increase the risk of developing Toxicity with Paracetamol Overdose? (5 things)
- Rifampicin
- Phenytoin
- Carbamazepine
- Chronic alcohol excess (not ACUTE tho)
- St John’s Wort
How long does it take Paracetamol to reach peak Conc once ingested?
4 hours
What is the half life of Paracetamol?
2 hours
How early after Paracetamol ingestion can levels be measured?
4 hours after last ingestion
(can’t interpret levels before 4 hours)
How long after ingestion can Paracetamol levels be detected for?
24 hours
(but any detectable level after 16 hours is concerning)
What Toxic metabolite is Paracetamol converted to?
NAPQI
What are the bad things NAPQI can lead to? (3 things)
- Oxidative damage
- Mitochondrial dysf
- Hepatocellular injury
What are the CF in the early stages of Paracetamol overdose?
Asymptomatic for a bit
How long does it take for FIRST CF of Paractamol overdose to appear?
12-36 hours
What are the FIRST CF of Paracetamol overdose to appear?
Abd pain
How long does it take for the SECOND batch of CF of Paractamol overdose to appear?
48-72 hours
How long does it take for the SECOND batch of CF of Paractamol overdose to appear?
48-72 hours
What are the SECOND batch of Paracetamol overdose CF? (10 things)
- Confusion / Coma
- Nausea
- Jaundice
- Vomiting
- Tachycardia / hypotension
- Asterixis (flapping hands)
- RUQ pain
- Hepatic encephalopathy
- AKI (oliguria / anuria)
- Coagulopathy (INR 1.5+)
What does Hepatic encephalopathy w Coagulopathy indicate?
Acute liver failure (ALF)
What do Paracetamol overdose pt with ALF require?
Urgent transfer to transplant unit
What is Dx of Paracetamol overdose based on?
Hx
What bloods should you do for Paracetamol overdose? (8 things)
- FBC
- UnE
- LFT
- Bone profile
- ABG
- BG
- Paracetamol levels
- Salicylate levels
What investigation is used to determine if NAC should be used for Paracetamol overdose Tx?
Nomogram
How do you use a Nomogram for Paracetamol overdose? (2 steps)
- Plot paracetamol conc vs time of ingestion
- If conc lies in Tx line –> administer NAC
What Tx should you give if ingestion is 150+ mg/kg + presented within 1 hour?
Activated charcoal 50g
What is the GOLD standard Tx for Paracetamol overdose?
NAC
(N-acetylcysteine)
What is the NAC regimen called?
Standard 21 hour regimen
What is the Standard 21 hour regimen of NAC? (3 steps)
- 1st infusion (@ 1 hour): 150mg/kg NAC + 200ml 5% dextrose / 0.9% NaCl
- 2nd infusion (@ 4 hours): 50mg/kg NAC + 500ml 5% dextrose / 0.9% NaCl
- 3rd infusion (@ 16 hours): 100mg/kg NAC + 1L 5% dextrose / 0.9% NaCl
What should you do for after the 21 hour regimen of NAC?
Check bloods for signs of Hepatic impairment (aka coagulopathy / abn LFT / renal function)
What should you do if there are signs of Hepatic impairment even after 21 hour regimen of NAC? (2 things)
- Discuss with liver transplant centre
- Give 3rd infusion of NAC continuously until further advice
What are the Side fx of NAC 21 hour regimen?
Anaphylactoid reaction (30% of pt)
What is an Anaphylactoid reaction?
Same CF of Anaphylaxis but not IgE mediated
What are the CF of Anaphylactoid reaction to 21 hour regimen of NAC? (6 things)
- Nausea
- Vomiting
- Angioedema (eyes + lips swelling)
- Tachycardia
- Bronchospasm
- Urticarial rash
(shock is uncommon)
What should you do if pt has Anaphylactoid reaction to 21 hour regimen of NAC? (4 steps)
- Temporarily stop infusion
- Give chlorphenamine (anti-histamine)
- Give nebulized salbutamol
- Restart infusion (once reaction settles)
When can you End Tx of Paracetamol overdose? (2 things)
- INR less than 1.3 + ALT normal // OR //
- INR less than 1.3 + ALT raised but less than 2x upper limit + not over double admission ALT
What criteria is used to refer Paracetamol overdose pt for liver transplant?
Kings college criteria
What are the Kings college criteria? (5 things)
- Arterial pH: less than 7.3 aftr resus + over 24 hours since ingestion
- Lactate: 3+ // OR //
- Hepatic encephalopathy grade 3+
- Creatinine: 300+
- INR: 6.5+
What should you do with a Paracetamol overdose pt once medically cleared?
Transfer to inpatient MH bed