Extra-corporeal Extraction + Intoxication
4/11/10
Haemodialysis Filter
= membrane contains long, tortuous interconnecting channels -> high resistance to flow
- allow the removal of H2O and solutes by diffusion across a concentration gradient.
- physical features of agent being removed: small molecule (<500 Da), water soluble, nonprotein bound, small Vd (good for correcting electrolyte abnormalities)
- recommended for the following intoxications: lithium, metformin, ethanol, methanol,
ethylene glycol, salicylates, theophylline, sodium valproate.
Haemoperfusion Filter
= provides away for exposing blood to charcoal and allowing the binding of free drug
- blood runs directly through charcoal
- uses same vascular access and dialysis pumps
- greater anticoagulation required
- saturation of charcoal limits duration
- can place in series with dialysis
- physical features of agent being removed: larger (1000-1500 kDa), non-protein bound
- recommended the following intoxications: carbamazepine, phenobarbitone, barbiturates,
phenytoin, verapamil, paraquat.
- disadvantages: expensive, won’t correct acidosis, electrolyte disturbances or fluid overload,
hypoglycaemia, hypocalcaemia, thrombocytopaenia.
Jeremy Fernando (2011)
Haemofiltration Filter
= membrane consists of relatively straight channels of every increasing diameter -> low
resistance to flow
- recommended for the following intoxications: methotrexate, procanamide
Jeremy Fernando (2011)