Circuit/HLM Flashcards
If money was no limitation, what would your ideal CPB circuit look like?
MECC - reduce prime volume and therefore haemodilution
Kinect thing
Oxy with integrated arterial filter
3/8” venous line to reduce priming volume
Leukocyte filter
CDI
SAFETY DEVICES:
Level detector? This isn’t needed in MECC?
Bubble detector
Arterial and venous saturation probes
Flow probes
A system that could calculate your actual delivered flow whilst taking vents into account
IFU for sorin inspire 8F oxy states the filter purge line should be kept open. Why was it partially closed?
Big shunt - 700 ml/min flow, which could go to the patient instead. If you have femoral cannulation with higher resistance and line pressures this could increase the flow down that shunt resulting in under perfusion.
The shunt could be left open and compensated for by increasing flow on the roller pump but this would increase RPMs and compression of the tubing which would risk increased red cell haemolysis, increase wearing out of the tubing, increase spallation and in long cases - risk pump boot rupture.
There may be cases where you’re not getting venous return and need to close as many shunts as possible completely in order to maintain adequate flow (dissections).
How does HLM battery testing work?
…
How does an oxygenator work?
Hollow fibre membrane?
Deoxy blood flows over the outside of the fibres
Gas flows through the inner side of the membrane
Diffusion of oxygen and co2 via concentration gradient allows for gas exchange
Co2 blown off at exhaust of oxy
Heat exchanger runs parallel to the blood to heat or cool the blood
How does a roller pump work? How is it different to centrifugal?
Positive displacement pump.
2 rollers makes if occlusive unlike centrifugal pumps (non-occlusive)
Rollers compress tubing and create a negative suction at the inlet which draws blood into the inlet of the pump boot
Compression continues towards the outlet of pump boot which drives the blood forwards via positive displacement.
How does a centrifugal pump work? How is it different to roller pumps?
Non occlusive unlike occlusive roller pump.
Works by electromagnetic force created by magnet within the centrifugal head and the drive unit (2 magnets chasing each other)
This causes centrifugal cones or impeller planes to spin very fast which creates a vortex.
This vortex’s creates a negative pressure at the inlet which sucks blood in.
The vortex is converted into kinetic energy and positive energy on the outer edge of the cones or impellers forced blood out of the outlet.
Advantages and disadvantages of roller pump
… notion notes, cardiac anaesthesia book and both bypass books
Advantages and disadvantages form of centrifugal pumps?
… notion notes, cardiac anaesthesia book and both bypass books
