CARDIOPULMONARY BYPASS

CARDIOPULMONARY BYPASS
;;FOR PERFUSION STUDENTS.

1. MANU JACOB PERFUSIONIST KMCT MCH

2. CPB Cardiopulmonary bypass is the diversion of the flow of blood to the aorta, via a pump& oxygenator; avoiding both the heart & lungs

3. GOALS OF CPB Oxygenation and carbon dioxide elimination Circulation of blood Systemic cooling and re-warming Diversion of blood from the heart to provide a bloodless surgical field

4. COMPONENTS OF CPB

5. Operational Parts of CPB Pump Takes over the function of heart Oxygenator Gas exchange function of lung Circuits Direct venous blood to oxygenator and return to systemic circulation. Prime Fluid used to prime oxygenator and circuits prior to CPB

6. Scheme of CPB Circuit Pump Oxygenator Heat exchanger Reservoir Filter Sucker & vent Cardioplegic solution delivery system

7. Venous blood is intercepted as it returns to the RA and diverted through the venous line of the CPB circuit to a venous reservoir. Cardiopulmonary Bypass

8. Cardiopulmonary Bypass The arterial pump functions as an artificial heart by withdrawing blood from the reservoir and propelling it through a heat exchanger , an artificial lung (the oxygenator), and an arterial line filter before returning it through the arterial line to the patient's arterial system.

9. Additional pumps and components are used to assist in the operation to manage shed blood (the pump sucker), decompress the heart (vent), and deliver cardioplegia solution Cardiopulmonary Bypass

10. The CPB circuit performs the function of heart and lungs The blood is drained from the right side of the heart and returned to the systemic circulation through the aorta Cardiopulmonary Bypass

11. Blood Tubing The tubing used to connect the various components and divert blood into and out of the patient's vascular system Newer generation of PVC tubing has surface coating with heparin

12. TUBINGS The tubings which are used for CPB are made of PVC’s. There are 4 standard tubing sizes which are commonly used on CPB circuit. a)3/16 ” b) ¼” c) 3/8” d) ½”

13. TUBINGS According to the height and weight of the patient the size of the tube varies. The length of the tubing should be as minimum as possible, which reduces the priming volume and haemolysis .

14. Venous Reservoirs Positioned between the venous line and the arterial pump Blood reservoirs may be clear plastic hard-shelled containers. Accomodates large volume of blood out of the circulation

15. Arterial Pumps The pumping device used to replace the function of the heart Two primary technologies: a roller pump or a centrifugal pump

16. Arterial Pumps Both pump technologies are traumatic to the blood cells; however centrifugal pumps are thought to be less traumatic than roller pumps

17. Roller pumps Roller pumps are positive-displacement pumps that function by occluding a point in a piece of tubing and then rolling the occlusive point of contact along a length of the tubing. This forces the fluid in the tubing to move forward in front of the occlusive point while simultaneously drawing in fluid behind the occlusive point.

18. Centrifugal pumps Centrifugal pumps, in contrast, are nonocclusive kinetic pumps that generate flow by magnetically coupling the high-speed revolution of a reusable motor to the plastic plates, fins, or channels inside a disposable cone.

19. Centrifugal pumps Centrifugal pumps, in contrast, are nonocclusive kinetic pumps that generate flow by magnetically coupling the high-speed revolution of a reusable motor to the plastic plates, fins, or channels inside a disposable cone.

20. Heat Exchanger Facilitate management of the patient's blood temperature The heat exchangers may be used to reduce the temperature of the blood on initiation of CPB and then to warm the blood before the termination of CPB. Reduces the temperature of the cardioplegia blood to the required level

21. Oxygenator The oxygenator substitutes for the patient's native lungs and performs the essential function of gas exchange.

22. Oxygenator Oxygen and CO2 diffuses across a membrane in the oxygenator. The membrane is usually made from microporous polypropylene. The oxygenator has separate gas inlet and outlet ports

23. Arterial Line Filter These filters are placed in the arterial line as the last component through which blood passes before it returns to the patient.

24. Arterial Line Filter With pore sizes of 20 to 40 µm, arterial line filters increases patient safety by removing particulate and gaseous microemboli .

25. Management before Cardiopulmonary Bypass Anticoagulation Cannulation of the heart Careful monitoring Protection of the heart Preparation for cardiopulmonary bypass

26. Physiologic parameters of CPB Perfusion pressure Pump flow Temperature management Central nervous system monitoring Pulsatility

27. Sequence of Events Circuit selection and priming Anticoagulation Cannulation Initiation and maintenance of CPB Myocardial protection Weaning and termination from CPB.

28. Fluid Management Crystalloid solutions lead to decreased colloid osmotic pressure with a resultant increase in extracellular water retention, irrespective of the osmolarity of the pump prime. Albumin, can decrease the interaction of blood components with the bypass circuit by coating the fluid pathway surfaces

29. Priming “prime volume” is the volume of balanced electrolyte solution necessary to completely de-air the circuit Main cause of the hemodilution associated with CPB This increased volume of distribution dilutes all of the proteins, coagulation factors and formed elements of the blood Dilutes plasma levels of drugs

30. Anticoagulation Heparin is a heterogeneous, heavily sulfated polysaccharide compound derived from pig intestinal mucosa or bovine lung. It binds antithrombin III, profoundly facilitating its native ability to inhibit plasma coagulation, most prominently through inhibition of factors IIa (thrombin) and Xa

31. Anticoagulation Anticoagulation with heparin for CPB can be monitored by measuring clotting times or whole blood heparin concentrations Most commonly test used for CPB are the ACT Heparin resistance: AT III concentrate or FFP

32. Protamine , a polycationic protein derived from salmon sperm contains two active sites It neutralizes heparin It exerts a mild anticoagulant effect independently of heparin Anticoagulation

33. CANNULAS The cannulas are the catheters which are used to connect the patients circulation to the extracorporeal circuit. There are three types of cannulations involved in CPB. Arterial, Venous Cardioplegia cannulation .

34. Cannulation The target for venous cannulation is generally the RA. Target for the arterial cannula is ascending aorta Aortic Cannulas

35. Cannulation The target for venous cannulation is generally the RA. Target for the arterial cannula is ascending aorta Aortic Cannulas

36. Arterial Cannulation Oxygenated blood is returned to the patient via the arterial cannulae . Before arterial cannulation heparin is given IV. 1 st dose: 3mg/ kg to achieve an ACT above 480 seconds. Anticoagulation is monitored by ACT at regular intervals and supplementary doses given according to the requirements.

37. Venous Cannulation Systemic venous blood is diverted to the oxygenator through two flexible plastic cannulae which are inserted into the superior and inferior venacavae . Otherwise a single cannulae inserted into RA through RA appendage.

38. Venous Cannulation There are two types of venous cannulation . Single stage venous cannulation : Cannula is inserted directly into the IVC and SVC Double stage venous cannulation : inserted into the RA

39. Venous Cannulation Blood flows freely into the oxygenator under the influence of Gravity Siphon.

40. CARDIOPLEGIA CANNULA THESE CANNULAS ARE USED TO DELIVER CARDIOPLEGIA TO THE PATIENTS

41. Myocardial Protection To provide a motionless field for the surgeon, the heart is arrested in diastole by the administration of a potassium-enriched cardioplegia solution to the heart. Potassium-induced arrest alone reduces the heart's myocardial oxygen consumption by 90%.

42. Myocardial Protection The combined influence of potassium arrest and myocardial temperatures lower than 22°C reduces myocardial oxygen consumption by 97% and enables the tissue to withstand complete interruption of blood flow for periods of 20 to 40 minutes

43. CARDIOPLEGIA Antegrade cardioplegia is delivered through a small cannula in the aortic root or via handheld cannulas directly into the coronary ostia when the aortic valve is exposed Retrograde cardioplegia is delivered through a cuffed catheter inserted blindly into the coronary sinus

44. Temperature Deliberate hypothermia is a reliable method of neuroprotection and is often used during routine CPB. Temp can be estimated from tympanic, nasopharyngeal, esophageal , rectal, bladder, skin surface, pulmonary arterial, or jugular venous bulb temperature

45. HEATER COOLER UNIT The heater cooler unit commonly known as Haemotherm (or) Temperature control unit Used to warm or cool and to maintain the temperature during CPB

46. SUCTIONS Blood accumalating in the surgical field is collected in the reservoir in CPB Machine and returned to the body.

47. Complications of Cardio- Pulmonary Bypass Duration of bypass Age Cardiac function

48. End Organs That Can Be Adversely Affected by CPB Heart Brain  Kidneys Gastrointestinal tract Endocrine system