Thursday, March 12, 2015

Treatment in Paraquat Poisoning

Initial Hospital Management
1. Ensure Airway, Breathing and Circulation are intact
2. Control vomiting with
  • 5HT3 antagonists e.g. Ondansetron 8mg (5mg/m2 in children) by slow i.v. injection or i.v. infusion over 15 minutes
  • Phenothiazine anti-emetics e.g. prochlorperazine Dopamine antagonists such as metoclopramide should be avoided as they may impair therapy for renal support with dopamine
3. Decontamination:
  • Activated charcoal - 100g for adults or 2 g/kg body weight in children [50g Stat and 25g 4 hourly] OR
  • Fuller’s Earth - 15% solution; 1 litre for adults or 15ml/kg body weight in children [300ml Stat than 20ml every hour till diarrhoea] 
  • NOTE: The use of gastric lavage without administration of an adsorbent has not shown any clinical benefit.
  • *[] recommendation from Sarawak Handbook of medical emergencies
  • A purgative should also be used, e.g. mannitol or magnesium sulphate
  • Rehydrate the patient to optimise renal clearance of paraquat, paying attention to the possibility of fluid overload and electrolyte imbalance. 
  • NOTE: Forced diuresis is not recommended
4. Do not give supplemental oxygen unless serious hypoxia is present

Subsequent Management
  • i.v. fluids – the kidney is the major route of excretion of paraquat and renal function must therefore be closely monitored and optimum function maintained.
  • analgesics – aggressive analgesia (e.g. opiates) may be required since patients can have severe pain from oral, oesophageal or abdominal corrosive injury.
  • mouth care for ulceration and inflammation. - patients should be kept nil by mouth if there is a suspicion of oropharyngeal or oesophageal injury
Immunosuppresion
  • widely practised as a treatment of paraquat self-poisoning
  • The theory is that as paraquat leads to an acute inflammatory response, interference with this may inhibit the processes that follow that then lead to lung fibrosis and death
  • might have a role in moderate to severe poisoning
  • methyprednisolone 15mg/kg +/- Cyclophosphamide 15mg/kg followed by a high dose Dexamethasone [Sarawak Handbook 3rd edition]
  • other treatment used are 1 g of cyclophosphamide daily for 2 days and 1 g of methylprednisolone daily for 3 days
  • current practice 15mg/kg in 250 NS for 2 days
References:
  1. Medical Management of Paraquat Ingestion http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3243009/#b84
  2. Paraquat Poisoning. http://www.syngenta.com/global/corporate/en/pqmedguide/documents/paraquat-booklet.pdf
  3. Sarawak Handbook of Medical Emergencies 3rd Edition

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