Friday, 17 September 2010

MRCP revision battle 14.6: TCA overdose

Lets end the day (and the working week) on an overdose.  I've always found it somewhat ironic (and at times in A&E irritating) that a medication which you give to depressed people to treat their depression is so incredibly dangerous in overdose...

TCA in overdose produce symptoms due to their:
  • anticholinergic effects (dry mouth, dilated pupils, tachycardia, constipation, urinary retention, raised intraocular pressure)
  • alpha blockade (hypotension)
  • sodium channel blockade (my personal favourite, cardiac arrhythmias)

On the ECG look out for:
  • long PR
  • wide QRS
  • long QT

In terms of managing these patients you need:
  • ECG and cardiac monitoring
  • consider charcoal if <2 hrs post ingestion
  • bloods for UEs and paracetamol and salicylate (always assume paracetamol taken until proven otherwise)
  • ABG
  • fluids if needed to support BP
  • if acidotic - bicarb
  • dialysis is NOT indicated
  • avoid class Ia/Ic/III antiarrythmics as they all prolong QT.  Also avoid flumazenil (also prolongs QT)
  • observe

Thats all for today folks, and I'm taking tomorrow off.  And possibly the day after too, depending on my mood.  But battles will definitely recommence on Monday.