POISONING (PARACETAMOL)

Recognition

Definition

• Paracetamol is a common drug to take in an overdose. If it is treated early, recovery is usually excellent, however in delayed presentation it can lead to Liver failure and death

History

• Time of overdose
• Dosage
• Single ingestion or staggered overdose
• Was it a mixed overdose
• Any other regular medications or alcohol
• Intent (accidental vs self-harm)

General symptoms

• Initially mild and non-specific
• Delayed signs:> 24 hrs
  • Abdominal pain particularly right upper quadrant pain
  • Nausea and vomiting
  • Jaundice
  • Reduced GCS
  • Deranged LFTs
  • Coagulopathic
  • Renal failure
  • Hypoglycaemia
  • Lactic acidosis

Initial Assessment and Investigations

• ABCDE assessment
• Sit patient up if able to tolerate
• Assess patient’s airway– call an anaesthetist if airway compromised
• Monitor oxygen saturations and respiratory rate
  • If patient is hypoxic give Oxygen (O₂) to achieve target saturations. Initially give 15 L/min via a reservoir mask if the patient is acutely unwell
• Target saturations:
  • 94 - 98% for patients not at risk of hypercapnic respiratory failure
  • 88 - 92% for patients at risk of hypercapnic respiratory failure due to conditions such as Chronic Obstructive Pulmonary Disease (COPD)
• Examine patient’s chest. If the patient is vomiting there is a risk of aspiration
• Chest X-ray if concerned about the patient’s ventilation or risk of aspiration. If the patient is unwell request a portable X-ray
• Obtain intravenous access by placing 2 large bore cannulae in the antecubital fossa. Take blood to check Full Blood Count (FBC), Urea and Electrolytes (U&Es), Liver Function Tests (LFTS), International Normalized Ratio (INR), Amylase, Glucose and Venous Blood Gas (VBG)
• Check Capillary Refill Time (CRT) - hold for five seconds and refilling should occur in 3 seconds
• Assess pulse rate, rhythm and character
  • Abnormal rhythms should be managed immediately as in “Arrhythmias - Bradycardia” and “Arrhythmias - Tachycardia” Chapters in the “Medical Emergencies” section
• Monitor heart rate and blood pressure
• Listen to patient’s heart sounds
• Check urine output and consider catheterisation
• Intravenous (IV) fluids as required by clinical picture and balanced with patients’ risk of fluid overload. See more details in the “Circulation” Chapter in the “Response” Section under “Fluid Challenge”
• Check pupils are equal and reactive
• Assess Glasgow Coma Scale or ACVPU using the NEWS2 chart
• Check patient’s temperature and blood sugar
• Examine patient’s abdomen and legs
  • Check sclera for jaundice and for liver flap (encephalopathy)
• Consider venous thromboembolism prophylaxis
• Call for senior help if not done already

Response

Management

New treatment nomogram for paracetamol overdose (Reproduced with permission of MHRA under the terms of OGL v3.0).

• If < 1 hour of ingestion
  • Give activated charcoal
• If < 4 hours of ingestion:
  • Check bloods at 4 hours, including paracetamol levels
  • Use paracetamol overdose treatment nomogram with paracetamol blood levels to decide if treatment needed with antidote (Intravenous N-Acetylcysteine)
• 4-8 hours
  • Check paracetamol levels
  • Use paracetamol overdose treatment nomogram with paracetamol blood levels to decide if treatment needed with antidote (Intravenous N-Acetylcysteine)
• If 8-16 hours
  • Start treatment with antidote (Intravenous N-Acetylcysteine) and check bloods including paracetamol levels
  • Use paracetamol overdose treatment nomogram with paracetamol blood levels to decide if treatment should be continued
  •  If level below the treatment line stop treatment
• If > 16 hours, a staggered overdose or signs of hepatotoxicity – Give full treatment – paracetamol levels not accurate

Intravenous N-Acetylcysteine

• 3 infusions over a total of 24 hours based on weight
• After treatment:
  • Repeat bloods
    • If bloods are normal N-Acetylcysteine can be stopped
    • If bloods abnormal continue N-Acetylcysteine and discuss with the gastroenterology team

If deranged bloods or patient unwell:

• IV fluids
• Monitor for encephalopathy
• Referral
  • Discuss with senior member of the team
  • Contact critical care outreach team
  • Consider referral to Gastroenterology team and Intensive Care Unit (ICU) if:
    • Coagulopathic
    • Renal failure
    • Reduced GCS

Future management

• Patient may require referral to a transplant centre and should be discussed early in severe overdoses
• Once the patient is medically fit they need to be assessed by the psychiatric team to ensure they are safe to be discharged and have appropriate support