Question 28

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

Hughes, T., et al. "Novel uses of arteriovenous extracorporeal membrane carbon dioxide removal (AV-ECCO2R)–two case studies." (2013): 169-73.

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