HEMODIALYSIS AND HEMOPERFUSION IN THE TREATMENT OF DRUG OVERDOSES



The vast majority of drug overdoses can be man­aged by routine supportive measures. The excre­tion of drugs that are eliminated from the body by the kidney can be augmented by increasing the urine flow rate and expanding the extracellular fluid volume. Alteration of the pH of the urine may increase the renal excretion of some organic anions and cations . The use of extracorporeal methods to remove drugs is a val­uable and potentially life-saving procedure in some patients with drug overdoses.

Principles of Hemodialysis/Hemoperfusion. Hemodialysis is most effective for the removal of small molecular weight species that are water-sol­uble and not highly protein-bound. Hemodialysis may also be useful in the correction of severe met­abolic acidosis induced by an overdose of aspirin or by intoxication with methanol or ethylene gly­col . Hemoperfusion removes sol­utes by a process of adsorption onto an activated charcoal column or other resin adsorbents (e.g., Amberlite). Hemoperfusion is most useful for re­moving lipid-soluble or highly protein-bound species .

Complications and Indications. Use of these ancillary means of removal of drugs and toxins is not without risk, particularly in the patient who is unstable. Both hemodialysis and hemoperfusion require systemic heparinization and inser­tion of vascular catheters. Vascular instability may be a problem during hemoperfusion, as the extracorporeal volume of blood is about 500 ml. Adherence of platelets to the resin column in hemoperfusion may result in significant throm­bocytopenia.
The use of these modalities in the management of drug intoxications should be undertaken only when there are clear indications. The general in­dications are outlined below. A patient with a drug overdose and with any of the following fea­tures should be considered for treatment with he­modialysis or hemoperfusion:

1.A severe intoxication associated with hy­potension, hypoventilation, or hypothermia and poorly responsive to usual supportive measures.
2.The presence of prolonged coma, particularly in patients with underlying pulmonary disease.
3.The presence of significant hepatic or renal disease that might interfere with drug metabolism or elimination.
4.The presence of a drug or substance that is either directly toxic to tissues or is metabolized to a direct tissue toxin (e.g., methanol, ethylene glycol).
5.The presence of a potentially fatal blood level of a drug or a toxin.