Extracorporeal techniques may be used to treat some poisoned patients. The toxin must be amenable to removal by the technique if the treatment is to be effective.
Extracorporeal techniques that may be employed:
(1) hemodialysis
(2) hemoperfusion using activated charcoal or resin
(3) hemofiltration
General features favoring success in an extracorporeal technique:
(1) small volume of distribution ( < 1 L/kg)
(2) single compartment kinetics
(3) low endogenous clearance (< 4 mL per minute per kg)
Protein binding:
(1) hemodialysis and hemoperfusion: good for toxins poorly bound to plasma proteins
(2) hemofiltration: can be used for toxins show poor or high protein binding
|
Technique |
Physical Factors |
|
hemodialysis |
relative molecular mass < 500 water soluble |
|
hemodialysis, continuous |
relative molecular mass < 500, and large volume of distribution |
|
hemoperfusion, activated charcoal |
adsorbed by activated charcoal may or may not be water soluble |
|
hemoperfusion, resin |
adsorbed by resin may or may not be water soluble |
|
hemofiltration |
relative molecular mass less than cutoff of the filter fibers (usually < 40,000) |
|
hemofiltration, continuous |
relative molecular mass less than cutoff of the filter fibers (usually < 40,000), and a large volume of distribution |
|
Technique |
Examples of Use in Poisonings |
|
hemodialysis |
ethylene glycol, lithium, aspirin, methanol, ethanol, many other drugs and chemicals |
|
hemoperfusion |
cyclic antidepressants, barbiturates |
|
hemofiltration |
good for toxins with larger molecular weights; aminoglycosides, iron deferoxamine |
Limitations:
• Controlled studies have been difficult to perform, and benefits have often been anecdotal.
Specialty: Toxicology, Emergency Medicine, Critical Care
ICD-10: ,
