skip to content


Haemodialysis is effective at removing a number of low molecular weight, water-soluble poisons with a low degree of protein binding.  It is indicated when elimination by other routes is unacceptably slow, especially if renal failure is contributing to this. The following agents are usefully removed:

Inorganic acids  (Acetic, Phosphoric, Formic)

Alcohols (ethanol, methanol*)

Barbiturates

Chloral Hydrate

Ethylene glycol*

Thallium

Lithium – is the ideal poison for removal by dialysis.  Renal tubular reabsorption  leads to a renal clearance of 10-40ml/min when hydration is adequate, whereas haemodialysis can achieve clearances of up to 150ml/min.  Some suggested indications for dialysis are:

  • Lithium level of ³ 4mM
  • Lithium level of ³ 2.5 with severe symptoms or in the presence of significant renal impairment or sodium retention (eg heart failure, liver disease)
  • if the level is falling slowly

Rebound is normal, because of intracellular stores and the fact that slow-release preparations are commonly responsible for poisoning.  Try 6 hours of HD on a large kidney with maximal flow rates.  Check levels 1-2h later.

Salicylates  Although there is a high degree of protein binding at therapeutic levels, this is saturated at toxic doses, and salicylates become more widely tissue distributed, extending half life 3 to 4-fold to 15-30h.   Alkalinization of plasma and urine are beneficial.

Dialysis should be considered when

  • salicylate levels are >800mg/l
  • impaired renal function or fluid overload
  • serious toxicity (eg coma, or deterioration despite treatment)


* Ethanol should be co-administered to inhibit metabolism to toxic product.

Haemoperfusion over activated charcoal is more effective if poisons that are protein-bound in the circulation bind to it well.  This applies to (for instance), theophylline, some anticonvulsants, procainamide.  Practically this is now so rarely undertaken that obtaining the charcoal cartridge may be difficult.

Poisons Units will give detailed advice for specific drugs. TOXBASE is invaluable for all types of poisoning. Using it requires registration. Contact A&E departments or local poisons unit for help with access. For those granted access (includes users in UK hospitals), the url is http://www.spib.axl.co.uk


Acknowledgements:   Richard Phelps and Jane Goddard were the main authors for this page. The last modified date is shown in the footer.

 

Licensed under a Creative Commons LicenseCreative Commons Attribution 4.0 International License.

K  

This page last modified 13.08.2013 11:26 by Emma Farrell. edren and edrep are produced by the Renal Unit at the Royal Infirmary of Edinburgh and the University of Edinburgh. CAUTIONS and Contact us.