1. Basics of cardiopulmonary bypass
Dr. S. Parthasarathy
MD., DA., DNB, MD (Acu),
Dip. Diab.DCA, Dip. Software statistics,
Phd (physio)
Mahatma Gandhi Medical college and research institute , puducherry , India

2. Why do we need ?? Unlike nasal polyp ,gut Cardiac surgery needs a
motionless, bloodless
surgical field

3. Definition
Cardiopulmonary bypass(CPB) is a form of extracorporeal circulation
It temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the body
Don’t think it stops with two functions ??

4. four major functions 1) oxygenation and carbon dioxide elimination,
(2) circulation of blood,
(3) systemic cooling and rewarming,
(4) diversion of blood from the heart to provide a bloodless surgical field.

5. When to use ?? Cardiac Noncardiac Thoracic aortic surgeries ,
mediastinal masses,
we cant intubate in a respiratory obstruction , lung transplantation,
liver transplantation
DHCA in neurosurgical procedures

6. The process Typically, blood is gravity drained from
the heart and lungs to a reservoir via venous
cannulation and tubing,
returned oxygenated to the cannulated arterial system by utilizing a pump and artificial lung (oxygenator or gas-exchanger).

8. Venous arterial + venous

10. Gravity based venous flow
Height
Tubings
CVP
Determine venous flow
arterial
Aorta is preferred – large , less pressure more flow , dissection chance is less

11. Oxygen flow meter and blender

12. Oxygenator and heat exchanger
Water

13. oxygenators
provided gas exchange by contact of a blood film to an oxygen rich atmosphere (e.g. disc oxygenators)
by bubbling oxygen through blood (e.g. bubble oxygenators). Pump ??
Modern day oxygenators provide gas exchange to blood through a membrane
(e.g. sheet and hollow-fibre oxygenators).

14. Bubble oxygenator

15. Need to have a defoaming matrix

16. artificial lung
The artificial lung material is more gas permeable to CO2 than O2;
silicone membranes have a CO2:O2 transmission ratio of about 5 : 1.
0.05 to 0.3 µm
( PP, area but thickness) law ??
CO2 transfer – difficult to predict
Sweep gas !!

18. Artificial lungs
Diffusional distances are greater (approximately 200 mm in comparison with 10 mm in the human alveolus)
surface area for gas exchange is 1.7–3.5 m2 compared with 70–100 m2 in the human lung.

19. Arterial line

20. Hemotherm CPB is performed under systemic hypothermia
(typically a nasopharyngeal temperature of 25–32C)
Single tank and double tank are available

21. Arterial and venous cannula

22. The tubing and cannulae are manufactured of clear polyvinyl chloride,
while the oxygenator casing and connectors consist of polycarbonate.

23. Why should we so many ??

26. Cardioplegia Solution of potassium – aortic root – diastolic arrest
concentration of approximately 20 mmol litre
Anterograde or retrograde
Warm or cold
blood or crystalloid
1:2 or 1:1 0r 1:4 mixing
Glutamate, aspartate, mannitol
Nicorandil or esmolol cardioplegia

29. cardioplegia ??
Non-cardioplegic techniques include the use of moderate systemic hypothermia (i.e. core temperature of 30–32C) with short periods of aortic cross-clamping and ventricular fibrillation (VF).
Also beating heart surgeries !!

30. Cardiotomy and vent
The suckers attached to the CPB circuit allow blood to be salvaged from the operative field to be returned to the circuit via the reservoir.

31. Vent suckers
specifically used to drain blood that has not been directly removed from the heart by the venous pipes. The most common sites for placing dedicated vents are:
• the aortic root;
• the left ventricle;
• the right superior pulmonary vein;
• the left ventricular apex;
• the left atrium or pulmonary artery.

32. Why we need venting to prevent distension of the heart;
• to reduce myocardial re-warming;
• to evacuate air from the cardiac chambers during the de-airing phase of the procedure;
• to improve surgical exposure;
• to create a dry surgical field, especially during the distal coronary anastamosis phase of CABG surgery

34. Roller pumps -- Produces flow Nearly occlusive
Nonpulsatile or pulsatile
Low flow and low cost
afterload – ok
Low priming volume

35. Problems
Tubing rupture
Hemolysis
Air embolism

36. Centrifugal pumps Produces pressure
Superior for right or left heart bypass
Preferred for long-term bypass
nonocclusive
After load sensitive
But large priming vol and cost ??

37. Centrifugal pumps
CPs consist nest of smooth plastic cones within a plastic casing.
These impellers or cones are magnetically coupled (at the base) with an electric motor
when rotated rapidly, generate a centrifugal force to the blood, which is received by the pump body
CF == Mass of blood * radius of pump head*
speed of revolutions (RPM)

38. Filters
Haemofilters (haemoconcentrators or ultrafilters) are utilized in CPB circuitry to remove excess fluid and electrolytes, attenuate inflammatory mediators and raise haematocrit.
These devices mainly consist of a hollow-fibre semipermeable membrane to allow the passage of water and electrolytes from the blood to a
filtrate compartment.

41. Inline monitoring systems

42. Aortic cross clamp
cross-clamp is placed across the ascending aorta above the coronary ostia and proximal to the aortic cannula,
isolating the coronary circulation
preventing blood entering the chambers of the heart.
ACC time ??

43. Priming solution
The cardiopulmonary bypass (CPB) circuit must be primed with a fluid solution, (1500 ml to 2 litres) so that adequate flow rates can be rapidly achieved on initiation of CPB without risk of air embolism.
Crystalloid, colloids and blood
Mannitol, sodabicarb, heparin, steroids – additives
17 % hematocrit tolerated

44. Back to square one !!

45. Partial bypass ??
T.A
Operation
No oxygenator

46. CPB starts an extremely complex and multifactorial response involving activation of complement, platelets, neutrophils, monocytes and macrophages, thus initiating the coagulation, fibrinolytic and kallikrein cascades.

47. Neurologic dysfunction,
pulmonary dysfunction,
renal dysfunction,
hematologic abnormalities.
SIRS

48. The fundamentals Check and prime
Monitoring lines, temperature, blood gases, urine _ GA- narcotics
Incision, sternotomy
Heparinization
Cannulation – pump on
ACC and cardioplegia, surgery – oxygen ! Agent?
ACC off , ( O2 + agent) warm, investigations, TEE, hemodynamics, pump off , protamine, cannulae off – suturing

49. Thank you