Flashcards in Ultrafiltration- Final Exam Deck (94)
What is hemoconcentration?
Increase in the number of red blood cells resulting from a decrease in plasma volume
What does hemoconcentration increase?
Why is it important to know if it's whole blood or PRBCs?
Whole blood has normal HCT.
Conventional Ultrafiltration (CUF)
removes plasma water and low molecular weight solutes by a convective process using hydrostatic pressure forces across a semipermeable membrane
Zero Balance Ultrafiltration (ZBUF)
technique utilizing a hemoconcentrator to maintain a controlled equalized input and output over the CPB pump run
Slow Continuous Ultrafiltration (SCUF)
technique utilizing a slow, steady ultrafiltration during the CPB pump run; slow rate over time
Modified Ultrafiltration (MUF)
ultrafiltration occuring after the separation from CPB
When were the first concepts related to the use of ultrafiltration in hospital practice?
Where do modern hospitals incorporate ultrafiltration?
In many areas of surgical and medical therapy
What are two areas constantly requiring ultrafiltration as a significant part of their respective protocols of patient's management?
Medicine and surgery
What does ultrafiltration allow?
filtration of body water across a semi-permeable membrane utilizing a hydrostatic pressure gradient
What are 4 hemoconcentrator companies?
Where is the blood flow path in a hemoconcentrator?
Inside the hollow fibers
Where is the effluent path in a hemoconcentator?
Outside the hollow fibers
How does water get to the effluent side in a hemoconcentrator?
Letting the pressure gradient "pushes" body water to the effluent side (can be used with or without vacuum)
What does dialysis use?
Dialysate solution on the effluent side to control precise solute excretion
exchange of things dissolved in fluid (solutes) across a membrane due to differences in amount of the solutes on the two sides (concentration gradient)
What will happen if a higher concentration of a given solute is on one side?
Diffusion will try to make the concentrations the same on both sides
What else is ultrafiltration referred to as?
What is ultrafiltration?
Fluid flow through the membrane, forced by a difference in pressure on two sides of the membrane
net movement of water across a selectively permeable membrane
What drives osmosis?
Difference in the amounts of solute on the two sides of the membrane
What does osmosis refer to in dialysis?
Water movement across cell membranes (not across hemodialyzer membrane)
Achieving filtration across a membrane requires __________ and ____________.
Blood flow; hydrostatic pressure gradient
The ability of a solute to be filtered through the membrane depends on what?
The molecular weight compared to the pore size of the filter (sieving coefficient)
The rate of solute removal through the membrane depends on ________ and ___________.
Flow rate; transmembrane pressure (TMP)
What is pore size measured in?
Where are pore size and transmembrane pressure (TMP) limites noted?
What does a dalton quantitate?
Definition of a dalton.
1/12th the mass of carbon-12 nucleus
What is a dalton also called?
atomic mass unit (amu or u)
How can you convert kg to amus?
1 amu (u) = 1.6605655(86) x 10^-27
What does removing body water in ultrafiltration allow?
An elevation in the Hct without transfusion
What can you do if you have extra volume in your reservoir?
When ultrafiltration is combined with other procedures it can become....
CUF, SCUF, Z-BUF, MUF
What is the sieving coefficient?
Ratio of blood solute concentration to plasma concentration
What is the range of sieving coefficient?
0 to 1.0
1.0= solute concentrations equilibrate on both sides of the membrane
0= no solute passed the membrane (large molecular weight/ size)
What ions/drugs have a sieving coefficient of 1.0?
What is the sieving coefficient of Ca++?
What is the sieving coefficient of heparin?
What is the sieving coefficient of furosemide?
If you see pink urine on bypass, what is the first thing you should be thinking about?
Occlusions; or a lot of air/blood interface
What should you do if you see pink urine on bypass?
Slow down flow through hemoconcentrator; turn down vacuum
What makes the filter selectively permeable?
Diffusion in dialysis
movement of solutes from an area in which they are in high concentration to one of a lower concentration
What kind of gradient is diffusion in dialysis?
Can an ultrafilter be dialysis?
Yes, but not necessarily
Describe the dialysis setup.
Electrolyte solution runs countercurrent to blood flowing on the other side of the membrane. Small molecules such as urea move along into the dialysate fluid. Larger molecules are poorly removed by this process. Solute removal is directly proportional to the dialysate flow rate.
What's more expensive? Dialysis or ultrafiltration.
What is solvent drag?
Solute is carried (in solution) across a semipermeable membrane in response to a transmembrane pressure gradient; as in convection/ultrafiltration
What does the rate of ultrafiltration dpeend on?
Porosity of the membrane and the hydrostatic pressure of the blood
Ultrafiltration is very effective at removing what size molecules? What do these cause?
Middle-sized molecules, which are thought to cause uremia (cytokines in sepsis are also middle-sized)
the pressure across the filter capillary tubes
the molecule weight cut off the filter is designed for (in Daltons)
Transmembrane pressure is a pressure drop (T/F).
False! Transmembrane pressure is not a pressure drop.
What two equations are "pressure principles"
TMP=[Filter P(in) + Return P(out)]/2 + [Vacuum] asbolute value of vacuum
TMP Membrane Capacity
Membrane material and type of Minntech Hemocor Hemoconcentrator
Type: Microporous Hollow Fibers
Memrane Area of Minntech Hemocor
Pressure drop of Minntech Hemocor
Max Transmembrane pressure of Minntech HEmocor
Priming volume of Minntech Hemocor
Molecule Weight Cut off Minntech Hemocor
Conventional Ultrafiltration (CUF) improves potential for what?
Increasing adequate oxygen delivery to tissue (increases Hct); draws in extravascular fluid
Your level in the venous reservoir will drop in CUF. (T/F)
MUF may utilize the existing _________ and allows concentration of the circuit contents to be hemoconcentrated.
MUF allows post-op reduction in __________.
Total body water
What is considered the standard of care in pediatrics?
What 4 places can ultrafilters go?
Oxygenator Recirculation Line
Sampling Manifold: ANy _______ will work
What's the downside of placing ultrafiltration in sampling manifold?
Small tubing, may want to increase the diameter of that tubing. Not enough flow to do a lot with and flow is key
What 3 parameters do we monitor in ultrafiltration?
Flow, pressure volume
The _________ through the ultrafilter should be monitored, it will be easier to control when a ___________ is used exclusively for the ultrafilter.
Blood flow; roller pump
When the blood to the ultrafilter is removed directly from the _________, flow depends on the characteristics of the ultrafilter and may be reduced by ______________.
Arterial line; partially clamping the inlet
The mean pressure on the inside of the fibers depends on what?
Pressure drop through the ultrafilter
How can we vary the TMP?
Varying the negative pressure applied
What negative pressures of vacuum may be applied to an ultrafilter?
How can effluent flow be augmented?
Regulating the vacuum source; more vacuum equals more H20 removal
Greater ultrafiltration can be achieved by (3)?
1. increasing TMP
2. Partially clamping the outlet line of the ultrafilter
3. increasing in vacuum applied to the external surface of the membranes
CPB causes increased ___________.
Capillary permeability; including the systemic inflammatory response triggered by CPB
Capillary permeability propitiates and increase in what?
Increase in the total body water; affects functions of major organs.
What 4 organs are affected by ultrafiltration?
LUngs, heart, kidneys, brain
What does pulmonary edema do?
Reduce the efficiency of gas exchange
What does myocardial edema affect?
Ventricular function making (diastolic filling difficult and reducing the efficiency of systole)
The most severe systemic inflammatory response may manifest as ______________.
Multiple system organ failure (MSOF)
CPB activates the ________ and several _________of the plasma.
Leucocytes; proteic systems
Activation of leukocytes and proteic systems in plasma results in production of large number of what 3 substances?
Cytokines, complement fractions, vasoactive substances
WHt are the main pro-inflammatory cytokines?
Tumor necrosis alpha factor
The resides of the activation of complement system is hte activation of ______ and ______.
C3a and C5a
C3a and C5a with the vascular endothelium and neutrophils produce a set of alterations that result in what?
Systemic inflammatory reaction of the organism
What should you always be doing when you're filtering?
Watch your reservoir! You are losing volume.
Pink effluent is a result of ________.
too high TMP
_______ will increase effluent and increase hemolysis.