ECMO-/ECLS

Two basic pump types are available to provide the required blood flow for
the patient: a modified roller pump and a centrifugal pump. Blood flow required
for cardiac support is based on the size and age of the patient: 100 ml/kg/min for
neonates, 80 ml/kg/min for pediatrics, and 60 ml/kg/min for adults.[ 4 ] Single
ventricle cardiac lesions and sepsis may require more with target SvO2 70% or
greater. Normal oxygen delivery rates are also weight and age based: 6
ml/kg/min for neonates , 4-5 ml/kg/min for pediatrics, and 3 ml/kg/min for
adults.[ 4 ] The blood flow must be regulated to provide adequate oxygen delivery.
Inlet pressure refers to the pressure generated in the venous drainage cannula
by the pump. With any inlet occlusion, an extreme negative pressure is created
that pulls dissolved gases out of the blood, creating a phenomenon called
cavitation.[ 4 ] To prevent cavitation, and subsequent local hemolysis, pressures
are carefully regulated by decreasing the pump’s revolutions, manually or
through a servo-regulator. Outlet pressure refers to the pressure exiting the
pump head, and extremes can lead to loss of integrity between blood tubing
connectors. Extreme positive pressure can also lead to heat generation and must
be carefully dissipated within the pump.
Roller pumps create forward displacement of blood mechanically, and
must be constantly monitored and servo-regulated to prevent excess negative
inlet pressure. Centrifugal pumps use a series of spinning concentric cones to
create centrifugal force to direct forward flow of blood, with a hole in the
pumphead to reduce stagnant flow, which acts to decrease hemolysis and heat
generation. Centrifugal pumps can be magnetically driven and suspended, and