List the extracoporeal therapies used in the critically ill and outline the indications for their use.

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College Answer

1) Dialytic techniques. 
Traditional indications used for acute renal failure, are concerns about fluid overload (actual or to facilitate nutritional support), hyperkalaemia or other uncontrolled electrolyte disorders, metabolic acidosis, hyponatraemia, uraemic symptoms or elevated urea (e.g. 30 mmoJIL).

2) Dialysis or haemoftltration (e.g. with charcoal filter) can be used to increase the clearance of toxic products from the circulation (e.g. lithium, theophylline, myoglobin). 

3) Newer related extracorporeal techniques have also been developed to support liver dysfunction. 

4) ECMO - Severe respiratory failure 

5) ECC02-Severe respiratory failure 

6) Extracorporeal ventricular assist device - Severe myocardial dysfunction 

7) Plasmapheresis/filtration-meningococal infection, Guilian Barre, ITP

Discussion

This question would benefit from a tabulated answer.

Extracorporal Therapies in the ICU and their Indications
Therapy Indications
Dialysis
  • Oliguria with volume overload
  • Oliguria is relative; urine output may be high and still inadequate in clearing the fluid.
  • Uremia with symptoms
  • Hyperkalemia ( K+ over 6.0)
  • Metabolic acidosis due to renal failure (pH < 7.2)
  • Removal of dialysable drugs/toxins
  • Control of electrolytes
  • Control of body temperature
Hemoperfusion
  •  There is severe life-threatening intoxication with substances which are not going to be well removed by the liver or kidneys.
  • There is an impairment of liver and kidneys, preventing clearance.
  • If a toxin is equally well cleared by hemodialysis and hemoperfusion, then hemodialysis is preferred, because it will also correct any underlying acid-base disturbance
ECMO
  • Cardiac arrest (in certain settings)
  • Failure to wean from cardiopulmonary bypass
  • Cardiogenic shock
  • Hypoxic respiratory failure
  • Hypercapneic respiratory failure
ECCO2R
  • Hypercapnic respiratory failure with adequate oxygenation
MARS
  • Fulminant hepatic failure with encephalopathy, awaiting transplant
Plasma exchange
  • HELLP syndrome
  • Multiple sclerosis
  • HIV-related neuropathy
  • Pemphigus
  • Coagulation inhibitors
  • DIC
  • Overwhelming sepsis syndromes eg meningococcaemia
  • Reye’s syndrome
  • Paraquat poisoning
  • A more complete summary of indications is available elsewhere
LVAD/RVAD
  • Cardiogenic shock
  • Cardiac arrest
  • Fulminant myocarditis
  • Failure to wean off bypass

References