CPB(CARDIO PULMONARY BYPASS) DR NIKUNJ R SHEKHADA (MBBS ,MS GRN SURG , DNB CTS SR

1. CARDIOPULMONARY BYPASS
BY DR NIKUNJ
(CTS RESIDENT STAR HOSPITAL)
(Coordinator:DR P.SATYENDRANATH PATHURI)
(25/9/18)

2. • Cardiopulmonary bypass (CPB) is one of the most important biomedical
inventions in the history of health care

3. HISTORY
• 1812: Le Gallois showed that extracorporeal circulation is Possible, part of the
body might be preserved by some sort of external perfusion device. Tissues and
organs of apparently dead animals could be brought back temporarily to an
apparent living state by restoring the flow of blood to them.
• 1858: Brown-Sequard arterialized desaturated blood. He used syringes for
perfusion and put oxygen into the dark venous blood by beating the blood
vigorously. An interesting observation he made was the temporary disappearance
of the rigor mortis of muscles of guillotined animals when they were perfused with
their own blood, it was evident that supplying an adequate amount of oxygen to
the blood is essential for successful perfusion.
• 1882: first “bubble”-oxygenator by von Schroeder
Bubbling method was based on the supposition that bubbles of a gas, such as air
or oxygen passing through blood, would become surrounded by a thin layer of the
blood that in turn would absorb oxygen, give off carbon dioxide, and then burst
and leave the blood free of gas.
Drawback: foaming of the blood and gas embolism

4. HISTORY
• 1885: first “film”-type oxygenator
Filming Method
It is best technique for oxygenating the blood, the one that would form the basis
of techniques currently in use. Von Frey and Gruber achieved this objective by
dispersing the blood as a thin film inside a rotating slanted cylinder filled with
oxygen.
• 1890: Jacob j described an device with a bubble oxygenator & bladder pump in
order to provide pulsatile flow (oxygenating the blood with a mechanical device
altogether by accomplishing this objective through the use of the animal's own
lungs)
• 1916: discovery of heparin by McLean
significant step in evolution of heart-lung-machine
• 1928: Dale & Schuster described the prototype pumping mechanism (valved
pump)
• 1934: Debakey modified the twin roller pump

5. • 1929: BRUKHONENKO
• He perfused Guillotined head of a dog.
• This preparation relied on gas exchange
from a second donor dog's lungs.
• Diaphragm-like pumps pumped blood
into the recipient dog's carotid arteries.
• Dog heads perfused in this manner
remained functional for a few hours.

6. BIRTH OF AN IDEA AND THE DEVELOPMENT OF
CARDIOPULMONARY BYPASS
• a patient in distress
• It was mid afternoon on October 3, 1930 and a patient at the Massachusetts
General Hospital in Boston.
• For 2 weeks her convalescence from an uncomplicated cholecystectomy had been
uneventful.
• she suddenly developed discomfort in her right chest, and immediately the
discomfort gave way to sharp pain.
• Dr. Edward Churchill, who saw her at once in consultation, found her frightened,
pale, cyanotic, cold, and moist.
• John H. Gibbon, Jr. was assigned the task of watching the patient and monitoring
her vital signs
• He believed that the diagnosis of massive pulmonary embolism.
• she was moved to the operating room where pulmonary embolectomy done.
• “Idea naturally occurred to him that if it we continuously remove some of the blue
blood from the patient's swollen veins, put oxygen into that blood and allow
carbon dioxide to escape from it, and then inject continuously red blood back into
the patient's arteries, we might have saved her life. We would have bypassed the
obstructing embolus and performed part of the work of the patient's heart and
lungs outside the body”

7. • Gibbon planned to build an apparatus with the
oxygenating capacity, which permit safe total CPB in
humans.
• Gibbon later estimated that if this objective were
achieved using the rotating drum technique.
• Dr.Gibbons, inventor of the cardio-pulmonary bypass
machine.
•
• 1935 –He maintained a cat’s circulation on CPB
while closing the pulmonary artery

8. • University of Minnesota
• Hospital operating room on
September 2, 1952 near the
end of the first successful
open heart operation in
medical history.
• Dr. F. John Lewis closed an
atrial septal defect under
direct visualization using
inflow stasis and moderate
total body hypothermia
(26°C).
• In a 5-year-old girl who
remains alive and well today.
• Postoperative heart
catheterization confirmed a
complete closure.

9. • 1953:JohnGibbon
• Cecelia Bavolek First patient to undergo open heart surgery using CPB to
repair an atrial septal defect.
• Just as Gibbon was ready to close the defect, the oxygen saturation of the
blood began to rapidly fall, and clots began to form on the oxygenator
screens because of inadequate heparinization.

10. AZYGOUS FLOW PRINCIPLE
• Morley cohen during some canine experiments in which the cavae were
temporarily occluded to test tolerance limits of the brain and heart to
ischemia.
• It was discovered that if the azygos vein was not clamped the resulting
very small cardiac output (8 to 14 mL/kg body weight/min) was sufficient
to sustain the vital organs safely in animals for a minimum of 30 minutes
at normothermia.

11. Cardiopulmonary Bypass
• Controlled Cross-circulation
• 1954. LILLEHEI
1st surgical closure of VSD under
controlled cross- circulation.
• Based on placental function &
azygous flow principle.
• Used in 45 patients between
1954 to 1955.
• VSD ,TOF .

12. • March 26, 1954:
• University of Minnesota
• Medical Center, during the
• first controlled cross- circulation operation.
• VSD was successfully visualized by ventricular cardiotomy and closed in a 12-
month-old infant. The lightly anesthetized donor
• ( patient's father) with the groin cannulations serving as the extracorporeal
oxygenator. The VSD was closed by direct suture during a bypass time of 19
minutes.

13. • 1955: Mayo Clinic-Gibbon heart lung machine (screen oxygenator + rollar pump) .
This model was used in first series of open heart operations performed by Dr. John
Kirklin and associates
• at the Mayo Clinic

14. More than 30 years of Innovation, Research, and
Hard Work

15. • 1951. Dodrill. Mitral valve surgery under left heart bypass
• 1952. Dodrill. Relief of PS under right heart bypass
• 1952. Lewis. ASD closure under surface cooling
• 1953. Gibbon. ASD closure by heart-lung machine
• 1954. Lillihei. VSD closure under controlled cross- circulation
• 1954. Kirklin. Establishment of CPB with oxygenator in cardiac surgery

16. FUNCTIONS OF CPB
• Diversion of blood from heart
• Oxygenation, elimination of CO2
• Systemic cooling and rewarming
• Circulation of blood.
• Non physiological hypothermic hemodiluted non pulsatile circulation.

17. PRINCIPLES OF CPB
• HYPOTHERMIA
• HEMODILUTION
• ULTRAFILTRATION
• ANTICOAGULATION & NEUTRALIZATION

18. HYPOTHERMIA
• Feasibility and applicability of hypothermia for heart surgery was first
suggested by Bigelow and colleagues in (1950)
• Rationale – provide organ protection and safety margin during CPB
• ↓ metabolic rate and o2 consumption.
• Preserve high energy po2 store and ↓ excitatory NT release.
• Lower pump flows suffice- ↓return, improve visibility, less blood trauma.
• Better myocardial protection.
• Safety margin in equipment failure.

19. EFFECT OF HYPOTHERMIA ON MYOCARDIUM
• Basal myocardial O2 requirement is 10 ml/100g/min
• In the asystolic state this goes down to 0.1 ml/100g/min
• For every 10 degree drop in temperature there is an additional 50%
decrease in O2 requirements.
• However there is a potential for myocardial damage below 10 degrees due
to damage to the membrane enzymes responsible for cellular integrity.
• Therefore target myocardial temperatures are usually 10-15 degrees

20. EFFECT OF HYPOTHERMIA
Heart
• ↓HR
• ↑Contractility ↑dysarythmia Coronary b f preserved
Lungs
• progressive↓ in ventilation
• Gas exchange unchanged • Kidney
• ↓renal b f ↓concentrating ability Glycosuria.
Liver
• ↓ metabolic & excretory function
• Marked hyperglycemia
blood vessels: vasoconstriction-skeletal muscles and extremities
Blood :↑ blood viscosity
• RBC- aggregation
Portal platelet sequestration
Complement activation, catecholamine release Bradykinnin release.

21. Brain-
• With a linear decrease in CBF, CMRO2 decreases exponentially.
• At normothermia CBF/CMRO2 of 20:1 changes to 75:1 at deep
hypothermia.

23. ACID BASE MANAGEMENT IN HYPOTHERMIA
• ALPHA STAT
• Alpha = unprotonated histidine imidazole group/[H+]
• total CO2 content kept constant
• PH & PCO2 is allowed to vary with temperature
• PH STAT
• pH kept constant at all temperatures

24. ALPHA STAT Vs PH STAT
• ALPHA STAT
• Less but adequate cerebral flow
• Better cerebral recovery
• Cerebral autoregulation
• preserved
• Less arrhythmias
• Better in adults
PH STAT
• Increased CBF
• Global cerebral cooling
• Better flow to deep brain
structures
• ↑ risk microemboli, cerebral
edema, ↑icp, redistribution
away from marginally perfused
area
• Better in children

25. HEMODILUTION
• CPB
• ↓ flow rate & hypothermia → ↑viscosity
• ↑ vascular resistance
• Hemodilution
• ↓ Hct → shear rate increasebridges disintegrate ↓viscosity 
improve microperfusion.

26. HEMODILUTION
Advantages
↓ CPB complications
• Good tissue perfusion
• Good oxygen delivery
Disadvantages
• ↓plasma colloid oncotic pressure ↓plasma protein conc( PK & PD of
drugs) ↓coagulation factor/ platelet conc ↓immunoglobulin conc.
• Extreme hemodilution cause inadequate O2 delivery.
• At 25%- myocardial O2 extraction is complete.
• < 15%- maldistribution of coronary flow from sub endocardium.
• Target HCT- 20-25%
• Prime – crystalloid + colloid

27. FLOW RATES, PERFUSION PRESSUR AND AUTOREGULATION
• Flow is generally kept in the range of 2.2 to 2.5 liter/min/ m2 to provide a
margin of safety during CPB, because systemic blood flow distribution and
O2 consumption remain normal at this level.
• At normothermia, a target mean blood pressure of 50 to 70 mm Hg is
used. (As a rule of thumb in adults, the mean pressure chosen should be
equal to the patient’s age.)
• Autoregulation of CBF is also related to changes in perfusion pressure. At
normothermia, a mean pressure of 50 mm Hg is the threshold at which
the brain autoregulates flow, but with hypothermia (26°C), the threshold
drops to 30 mm Hg . At deep hypothermia (<20°C), there is a loss of
pressure- flow autoregulation, as severe temperature reductions impair
cerebral vascular relaxation and changes in cerebral perfusion pressure
alone result in corresponding proportional changes in CBF.

28. • Flow Rates In Hypothermia:
• 32 c: 2.1 to 2.2 lit / min /m2.
• 30 c: 1.8 to 1.9 lit / min /m2.
• 25 c: 1.6 lit / min /m2.
• 20 c: 1.4 to 1.5 lit / min /m2.
• 15 c: 1 to 1.1 lit / min /m2.

29. • The two commonly used types of pumps for CPB
involve either roller or centrifugal fluid propulsion.
•
• Roller
• noninterrupted contact of the rollers with the
tubing in the track results in the nonpulsatile
nature of the flow .
• Flow is calculated from the RPM of the roller pump
knowing the diameter of the tubing and thus
precisely the volume displaced.
• A low compression will result in inadequate flow,
whereas excessive compression may aggravate
hemolysis and tubing wear. Other complications
associated with the use of the roller pump include
(1) cavitation caused by excess pressure and (2)
spallation (the release of particles from the inner
surface).

30. • centrifugal
• A rotating impeller spins at 2000 to 5000 revolutions per minute on a
small bearing, or the blades are magnetically suspended. This creates a
vortex that draws blood into the pumphead and thrusts it to the
oxygenator.
• The advantages of this device include its relatively small priming volume
• with a roller pump, venous drainage to the reservoir from the patient is
dependent on gravity drainage, centrifugal pumps are not constrained by
this action.
• these devices are susceptible to air locks, thus requiring vigilance by the
perfusionist
• power outage with a centrifugal pump can be a disaster

31. ULTRAFILTRATION
• Reverses the `hemodilution` during CPB initiation and Optimises perfusate
Hct
• Raises colloid osmotic pressure
• Decreases post CPB edema and weight gain
• Improved tissue perfusion and oxygenation
• Removes the vasoactive substances eg. C3a, C5a, TNF-α, IL-1b, IL-6, IL-8
• Improves hemostasis - increasing relative conc. of clotting factors

32. PRINCIPLES OF ULTRAFILTRATION
• Filtration rate –
• Directly proportional to transmembrane pressure gradient & inversely
proportional to Hct.
• Concentration of all molecules smaller than smallest pores equal on both
sides of the membrane.
• Conc. of molecules larger than the smallest pores, but smaller than the
largest pores is dependent on the sieving coefficient of that molecule.
• No fluid is given to replace that removed- creates negative balance

33. MONITORING PERFUSION ADEQUECY
• Systemic measurements that indicates adequecy of perfusion are
• 1) Svo2
2) Ph
3) lactate concentration
• Venous Saturation
• High Svo2 does not mean adequate perfusion
• Low Svo2 indicates inadequate tissue perfusion.
• Relation b/w perfusion and O2 consumption
• Oxygen consumption plateauing
• Vo2 optimization.
• Disadvantage:
• Vo2 is calculated for awake or anesthetized prebypass volume.
• During CPB with hypothermia baseline Vo2 would yield excess
perfusion during CPB.

34. THANK YOU