Ultrafiltration

Question 1

Conventional Ultrafiltration (CUF)

Answer 1

is a technique that removes plasma water and low molecular weight solutes by a convective process using hydrostatic pressure forces across a semipermeable membrane.

Question 2

Zero Balance Ultrafiltration (ZBUF)

Answer 2

is a technique utilizing an hemoconcentrator to maintain a controlled EQUALIZED input and output over the CPB pump run

Question 3

Slow Continuous Ultrafiltration (SCUF)

Answer 3

s a technique utilizing a slow, steady ultrafiltration during the CPB pump run

Question 4

Modified Ultrafiltration (MUF)

Answer 4

is ultrafiltration occurring after the separation from CPB.

Question 5

the Effluent path first concepts related to the use of ultrafiltration in hospital practice, date from

Answer 5

1928

Question 6

Ultrafiltration is achieved

Answer 6

(using a hemoconcentrator) in the CPB circuit and allows the filtration of body water across a semi-permeable membrane utilizing a hydrostatic pressure gradient

Question 7

Blood flow path is

Answer 7

inside the fibers. (higher pressure)

Question 8

Effluent path

Answer 8

is outside the fibers

Question 9

uses pressure gradient to

Answer 9

push crap from blood to effluent side. is outside the fibers

Question 10

Dialysis will use a dialysate solution on the

Answer 10

effluent side to control precise solute excretion

Question 11

HOW DO ULTRAFILTERS WORK?

Answer 11

Diffusion (change in concentration)

Question 12

Ultrafiltration (change in pressure)

Answer 12

 referred to as convection, is fluid flow through the membrane, forced by a difference in pressure on two sides of the membrane

Question 13

osmosis in dialysis

Answer 13

this refers not to water movement across the hemodialyzer membrane, but across cell membranes

Question 14

Achieving filtration across a membrane requires

Answer 14

blood flow and hydrostatic (pressure gradient)

 Pressure /flow and resistance is key

Question 15

The ability of a solute to be filtered through the membrane depends on

Answer 15

the molecular weight compared to the pore size of the filter (sieving coefficient)

Question 16

he rate of solute removal through the membrane depends

Answer 16

on the flow rate and transmembrane pressure (TMP)

Question 17

A dalton quanitates mass, defined as

Answer 17

/12 the mass of a carbon-12 nucleus. It’s also called the atomic mass unit, abbreviated as either “amu” or “u”. You can convert kg into u using this conversion factor:
1 u = 1.6605655(86) × 10-27 kg
BOTTOM LINE: very, very small

Question 18

Removing body water will allow

Answer 18

an elevation in the Hct without transfusion
 This is what you can do when you have extra volume in your reservoir. Can be combined with other procedures and will become CUF, SCUF, Z-BUF, MUF.

Question 19

Sieving Coefficient

Answer 19

 Ratio of blood solute concentration to plasma concentration
 Ranges from 0 to 1.0  A coefficient of 1 means the solute concentrations
equilibrate on both sides of the membrane
 A coefficient of 0 means no solute passed the membrane (large molecular weight/size)

Question 20

ca Sieving Coefficient

Answer 20

.55

Question 21

k Sieving Coefficient

Answer 21

1.0

Question 22

mg Sieving Coefficient

Answer 22

1.0

Question 23

aprotinin Sieving Coefficient

Answer 23

1.0

Question 24

digoxin Sieving Coefficient

Answer 24

.75

Question 25

fentanyl Sieving Coefficient

Answer 25

.28

Question 26

furosemide Sieving Coefficient

Answer 26

.05

Question 27

heparin Sieving Coefficient

Answer 27

.20

Question 28

midazolam Sieving Coefficient

Answer 28

.06

Question 29

pancuronium Sieving Coefficient

Answer 29

.13

Question 30

Diffusion in dialysis

Answer 30

movement of solutes from a area in which they are in high concentration to one of a lower concentration – along an electrochemical gradient. An electrolyte solution runs countercurrent to blood flowing on the other side of the membrane. Small molecules such as urea move along the into the dialysate fluid. Larger molecules are poorly removed by this process. Solute removal is directly proportional to the dialysate flow rate

Question 31

when effluent becomes pink

Answer 31

you are breaking up RBC

Question 32

Convection / ultrafiltration – solute is carried

Answer 32

(in solution) across a semipermeable membrane in response to a transmembrane pressure gradient  a process known as solvent drag

Question 33

solvent drag mimics

Answer 33

what actually happens in the normal human kidney. The rate of ultrafiltration depends upon the porosity of the membrane, and the hydrostatic pressure of the blood.

Question 34

ultrafiltration is very effective

Answer 34

in removal of fluid and middle-sized molecules, which are thought to cause uremia. Moreover, most of the cytokines involved in sepsis are “middle molecules”

Question 35

Transmembrane Pressure is the

Answer 35

the pressure across the filter capillary tubes

Question 36

pore size is the

Answer 36

molecular weight cut off the filter is designed for (in Daltons)

Question 37

Transmembrane pressure is NOT

Answer 37

pressure drop

Question 38

TMP=

Answer 38

Filter P(in) + Return P(out)/2 + [Vacuum] OR Filter P(in) + Return P(out)/2 - EFFLUENT PRESSURE

Question 39

as you increase flow of blood you increase

Answer 39

rate of removal and transmembrane pressure

Question 40

Conventional Ultrafiltration (CUF)

Answer 40

Technique that utilizes a hemoconcentrator to remove plasma water and low molecular weight solutes by a convective process using hydrostatic pressure forces across a semipermeable membrane

Question 41

cuf improves potential

Answer 41

for increasing adequate oxygen delivery to tissue (increases Hct)

Question 42

cuf draws in

Answer 42

extravascular fluid  Your level in the venous reservoir will drop

Question 43

Slow Continuous Ultrafiltration (SCUF)

Answer 43

a technique utilizing a hemoconcentrator for a slow, steady ultrafiltration during the CPB pump run  Slow rate over longer time

Question 44

 Zero Balance Ultrafiltration (ZBUF)

Answer 44

is a technique utilizing an hemoconcentrator to maintain a controlled EQUALIZED input and output over the CPB pump run IN = OUT

Question 45

 Modified Ultrafiltration (MUF)

Answer 45

is ultrafiltration occurring after the separation from CPB. This technique may utilize the existing cannulas and allows concentration of the circuit contents to be hemoconcentrated (allows post-op reduction in total body water) Considered a “standard of care” in pediatrics

Question 46

WHERE CAN ULTRAFILTERS GO IN THE CARDIOPULMONARY BYPASS CIRCUIT?

Answer 46

Oxygenator Recirculation Line  Purge Line  Sampling Manifold  Cardioplegia Circuit

Question 47

MONITORING ULTRAFILTRATION |  3 main parameters are critical:

Answer 47

 Flow  Pressure  Volume

Question 48

The blood flow through the ultrafilter should be

Answer 48

monitored, it will be easier to control when a roller pump is used exclusively for the ultrafilter.

Question 49

hen the blood to the ultrafilter is removed directly from the arterial line, flow depends on

Answer 49

the characteristics of the ultrafilter and may be reduced by partially clamping the inlet

Question 50

In general, negative pressures (vacuum)

Answer 50

of 100 to 200 mmHg may be applied

Question 51

So, greater ultrafiltration can be achieved by:

Answer 51

increasing theTMP  partially clamping the outlet line of the ultrafilter  increasing in vacuum applied to the external surface of the membranes.

Question 52

WHAT ARE THE PHYSIOLOGICAL EFFECTS OF ULTRAFILTRATION?

Answer 52

CPB causes increased capillary permeability, including the systemic inflammatory reaction triggered by CPB  Capillary permeability propitiates an increase in the total body water  This increase of the extravascular fluid affects the functions of the major organs.

Question 53

ULTRAFILTRATION AND SYSTEMIC INFLAMMATORY REACTION -ORGANS

Answer 53

 LUNGS: Pulmonary edema may reduce the efficiency of gas exchange and pulmonary complacency.  HEART: Myocardial edema may affect ventricular function making (diastolic filling difficult and reducing the efficiency of systole)  BRAIN: Cerebral edema may have serious consequences.  KIDNEY: Renal function may also be impaired and the renal immaturity may make elimination of liquids more difficult.  The most severe systemic inflammatory response may manifest as multiple system organ failure (MSOF)

Question 54

ULTRAFILTRATION AND SYSTEMIC INFLAMMATORY REACTION-

Answer 54

CPB activates the leucocytes and several proteic systems of the plasma.  Activation results in the production of a large number of cytokines, complement fractions and vasoactive substances.  The main pro-inflammatory cytokines are tumor necrosis alpha factor and the IL-1 beta, IL-6 and IL-8 interleukins. The residues of the activation of complement system is the activation of C3a and C5a

Question 55

ultrafiltration also limits

Answer 55

inflammatory mediators

Question 56

Things to be wary of.....

Answer 56

 When you filter you are losing volume- watch your level  Pink effluent is often a result of too high TMP  Vacuum will increase effluent and increase hemolysis – more is not necessarily better  Hemoconcentration is usually a shunt – it must be off if the pump is off (compensate for it)