1.Introduction

Extracorporeal support is becoming an important adjunct to critically ill medical patients as well as trauma patients. There are now several means of extracorporeal support to support differently failing organ systems. These include continual renal replacement therapy and extracorporeal cardiopulmonary support. Plasmapheresis also an important procedure and temporary support for liver failure.
 

ll. Plasmapheresis

Plasmapheresis is an extracorporeal circuit that separases plasma from blood and then the blood and fresh frozen plasma (FFP) are returned to the patient. Molecules up to three million molecular weight are cleared. Exchange of one plasma volume removes 65% of substances and three and plasma volumes removes about 96%.

The indications for plasmapheresis include septic shock, toxic shock syndrome DIC, meningococcemia and possibly refractory gram negative shock.. lt is also used in autoimmune disorders such as Guillian Barre Syndrome, myasthema gravis crisis and immune alveolar hemorrhage (good pasture, Weyoner's Lupus). lt may also be used to clear toxins like dilantin or pronestyl.
 
 

lll. Continue Renal Replacement Therapy

Continuous veno-venous hemofiltration-dialysis (CAVH-D) is used to support patients through acute renal failure and possibly to help in cleaning toxins associated with septic shock. This technique is particularly useful because fluids may be removed at a deliberately controlled rate to minimize hemodynamic instability. CAVII-D requires an arterial line and uses arterial pressure to create a pressure gradient to remove plasma water and soluble by convection across a membrane and then is returned through a venous canula. CAVH-D uses two venous lines or a large double lumen line with a pump in the circuit to create a pressure head, and thus may be used in hemodynamic instability. Management must include anticoagulation.
 

The primary indication is oliguric or anuric acute renal failure. hemofiltration is used especially to remove excess ions or urea nitrogen in a controlled manner and works by convection and diff usion.
 
 

lV. Extracorporeal Cardiopulmonary Support (ECS)

The most common type of ECS is extracorporeal membrane oxygenation (ECMO). Although support Of CO₂ removal (EC-CO₂R) is occasionally needed or only ventricular assist device (RVAD or LVAD) may only be needed. ECS is very labor intensive, costly and time consuming but may be life-saving.

lndications for pulmonary support include ARDS or other forms of reversible respiratory failure or occasionally lung rest from severe barotrauma. The key is evaluating if the lung condition is reversible and there is not unsurvivable multi-organ disease. Criteria include failure of convencional mechanical ventilation or high frequency ventilation associated with refractory hypoxemia, poor compliance and high oxygen index. VV or VA ECMO may be used.
 

lndications for cardiac support include reversible cardiogenic shock, traumatic aortic rupture repair, severe hypothermia and failed CPR. This requires VA ECMO or LVAD. lt is  not uncommon that there is simultaneous failure of both cardiac and pulmonary systems and ECS is then needed until both systems are functioning. Table 1 shows some recent data on survivability according to diagnosis using ECS. The main complications inciude bleeding, coagulopathy thrombosis or mechanical failure to provide appropriate support or disruption of The circuit.

From: ELSO manual

3.         Management
a.         QB (02 delivery)
b.         Sweep Gas (C02 clearance)
c.         Ventilator management l.) "near apneic"
ventilation

w/ JPPT
4.         Complications
a.         bleeding
b.         coagulopathy
c.         thromboses
d.         mechanical