Blood pumps

2. • Purpose of Blood Pumps
• Ideal Blood Pump
• Types of Blood Pumps
• Most Commonly Used Pumps
• Types of Blood Flow
• Other Blood Pumps Used

3. • To replace the beating heart during heart surgery
• They propel blood and other physiologic fluids
throughout the extracorporeal circuit; which
includes the patient’s natural circulation as well as
the artificial one

4. The Ideal Blood Pump
 Move volumes of blood up to 5.0 L/Min
 Must be able to pump blood at low velocities of flow
 All parts in contact with blood should have smooth
surface
 Must be possible to dismantle, clean and sterilize the
pump with ease, and the blood handling components
must be disposable

5. The Ideal Blood Pump
(continued)
 Calibration should be easy, reliable, and reproducible
 Pump should be automatically controlled; however,
option for manual operation in case of power failure
 Must have adjustable stroke volume and pulse rate

6.  The average human heart can pump up to 30 liters of
blood per minute under extreme conditions.
 In the operating room setting this is not necessary due
to may reasons:
 patient is asleep
 patient is given muscle relaxants
 patient metabolic rate is greatly reduced
 patient is cooled during CPB

7. Types of Blood Pumps
 Kinetic Pumps
 Centrifugal pumps
 Positive Displacement Pumps:
 Rotary Pumps
 Reciprocating Pumps

8. Centrifugal Pumps
 The pumping action is performed by the addition of
kinetic energy to the fluid through the forced rotation
of an impellerDesigned with impellers arranged with
vanes or cones
 Centrifugal pumps are magnetically driven and
produce a pressure differential as they rotate
 It is the pressure differential between the inlet and
outlet that causes blood to be propelled

9. Positive Displacement Pumps
This type of pump moves blood forward by displacing
the liquid progressively, from the suction, to the
discharge opening of the unit
 Rotary Pumps
 Roller Pumps
 Screw Pumps
 Reciprocating Pumps
 Pistons
 Bar Compression
 Diaphragm

10. Rotary Pumps
 Rotary Pumps
 use rollers along flexible tubing to provide the pumping
stroke and give direction to the flow
 Archimedean Screw Pumps
 a solid helical rotor revolving within a stator with
different pitches so the blood is drawn along the
threadsMultiple Fingers
 the direction of flow is produced by a series of keys that
press in sequence against the tubing

11. Reciprocating Pumps
 Pistons
 this pump uses motor driven syringes that are equipped
with suitable valves, delivering pulsatile flow
 limited to low output capacity
 Bar Compression
 blood moves from the alternate compression and
expansion of the tube or bulb between a moving bar
and a solid back-plate

12. Reciprocating Pumps (continued)
 Diaphragm Pumps
 with a flat diaphragm or finger shaped membrane made
of rubber, plastic, or metal, blood is propelled forward
 Ventricle Pumps
 a compressible chamber mounted in a casing and are
activated by displacement of liquid or gas in the casing

13. Two Most Common Pumps Today
 Roller Pump
 Advantages
 Occlusive, therefore if power goes out the arterial line
won’t act as a venous line
 Out put is accurate because it is not dependent of the
circuits resistance (including the patients
resistance)
 Disadvantages
 Can cause large amounts of damage to blood (hemolysis)
if over-occluded

14. Two Most Common Pumps Today
(continued)
 Centrifugal Pump
Advantages
 Reduced hemolysis
 No cavitation
 No dangerous inflow/outflow pressures
 Air gets trapped in pump
 No need to calibrate
Diadvantages
 Extra priming volume requires
 Can not be able work at high speed
 Can not deal with high viscous fluid

15. Roller pump centrifugal
pump

16. Two Types of Perfusion
 Pulsatile Flow (simulates the human heart)
 Decreases peripheral resistance
 Increases urinary flow
 Better lymph formation
 Increases myocardial blood flow
 Need 2.3 times more energy to deliver blood in a pulsatile
manner than with non-pulsatile flow
 Non-Pulsatile Flow
 Simply means continuous flow

17. Various Opinions on Pulsatile
Flow
 Advocates
 It simulates the beating heart, aiding in preserving
capillary perfusion and cell function
 With the extra energy produced with pulsatile flow, we
can avoid the closing down of the capillary beds.

18. Various Opinions on Pulsatile Flow
(continued)
 Opponents
 Pulsatile flow is a more complex procedure for minimal
benefits
 Capillary Critical Closing Pressure: (although never
seen under microscope) The belief that when the
pressure in the capillary system goes below a certain
point the capillaries will close…reducing the gas
exchange between the blood and the tissues