Extracorporeal removal of drugs and toxins

Indications for extracorporeal removal of drugs and toxins are mostly clinical and include hemodynamic instability; clinical deterioration despite supportive treatment; mental status alteration; and midbrain/brainstem dysfunction resulting in respiratory depression, hypothermia, hypotension, or bradycardia. Further indications are evidence of failure of organ systems; impaired endogenous drug clearance due to cardiac, renal, or hepatic failure; and when a drug or poison can be removed more rapidly compared with endogenous elimination. Hemodialysis and hemofiltration techniques are most effective for the elimination of small molecular size, high water soluble compounds with a low degree of protein-binding, a small volume of distribution, and rapid equilibration of drug between plasma and tissues. Peritoneal dialysis can also be employed as an acute treatment modality for intoxication with water-soluble, small-molecular-weight solutes but should probably be limited to infants, children, and hemodynamically unstable adults intolerant of a blood circuit or anticoagulation. Therapeutic plasma exchange is of clinical utility when blood purification is required for substances with very high molecular weight and/or high degree of protein binding. Hemoperfusion is an absorptive modality which effectively can clear substances that are lipid-soluble or as much as 95% protein-bound. It provides superior drug clearance and is the preferred modality for extraction of theophylline, barbiturates, organophosphates, and many hypnotics/sedatives/tranquilizers.