In contrast, both VV and DLVV support provide adequate gas exchange
without these disadvantages, though a fraction of the infused blood recirculates
back into the extracorporeal circuit. As a result, oxygenation levels are relatively
reduced and extracorporeal blood flow rates must be increased approximately
20% to account for this effect. The VV and DLVV extracorporeal circuit
configurations also do not provide cardiac support, though, patients who require
pressor support prior to initiation of bypass improve once hypoxia and acidosis
are resolved and high ventilator pressures reduced on ECLS.[ 12 ]
Since 1988, a double lumen cannula has been available for providing
DLVV bypass via a single internal jugular access site, as opposed to a two site
approach (using internal jugular vein for drainage and femoral vein for
reinfusion). The DLVV configuration of bypass has now been used in newborns
and older patients with an excellent survival rate, and minimal conversion from
DLVV to VA ECLS. In older patients, however, the side needed for adequate
drainage may preclude the use of DLVV cannulation, and two sites may be
necessary.[ 5 ] In some settings, especially sepsis or cardiac dysfunction, an
additional venous cannula may be needed for VA ECLS to provide increased
drainage. This configuration, termed VAV ELCS, may be converted to traditional
VV ECLS once cardiac support is no longer necessary.
C. Procedures on ECLS
Most operative procedures performed during ECLS are carried out in the
intensive care unit.^ Either gas anesthesia administered via the oxygenator of the