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:
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Inorganic acids (Acetic, Phosphoric, Formic) |
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Alcohols (ethanol, methanol*) |
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Barbiturates |
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Chloral Hydrate |
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Ethylene glycol* |
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Thallium |
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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:
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. |
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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
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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
Richard Phelps and Jane Goddard were the main author sfor this page, last amended
NOTE that the accuracy of any statements in this information CANNOT be guaranteed. It is published in the belief that it is correct, and we endeavour to keep it so - but we do make mistakes. Furthermore, over some subjects there are differing opinions, or differing degrees of certainty. We have usually not attempted to discuss these here because the aim has been to provide an immediate and brief guide. In all areas, prior medical knowledge is assumed. The EdRenHANDBOOK is not suitable for use by those without such a background. Contact us by email or at the address given at the foot of the contents page with any comments or corrections.