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The Effects of CPB

The Effects of CPB. Brian Schwartz, CCP November 5, 2002. Effects of CPB. To some degree or another, our patients who undergo CPB may suffer some type of injury. The longer the bypass time….the better chance of having some type of injury.

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The Effects of CPB

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  1. The Effects of CPB Brian Schwartz, CCP November 5, 2002

  2. Effects of CPB • To some degree or another, our patients who undergo CPB may suffer some type of injury. • The longer the bypass time….the better chance of having some type of injury

  3. Innovative products to help decrease the incidence of injury • Membrane oxygenators • Filters • Bubble detectors • Coated circuits

  4. Areas that are Effected The Lungs The Kidneys The Brain The Compliment System The Endocrine System The Hepatic System

  5. Effects on the Lungs • Considered to be the most serious injury as a result of CPB • By placing our patients on CPB the lungs automatically undergo some type of abnormal physiologic changes • The lungs are subject to injury by the activation of the blood compliment system by coming into contact with foreign substances

  6. Lungs (continued) • Compliment Activation of both C3a and C5a lead to the activation of leucocytes • Activation of Leucocytes • Leukoembolization may occur in the lungs with the release of oxygen free radicals and proteolytic enzymes released by the neutrophils

  7. Things we might see: • Pump Lung • Congested lungs with intraalveolar edema, interstitial edema, and atelectasis • Atelectasis • Collapsed lung • Smoking, chronic bronchitis, obesity, and pulmonary edema predispose patients for injury

  8. Donor Blood • Any time donor blood is added to the pump it should be filtered • It should be filtered mainly for leucocytes

  9. Thrombocytopenia • Defined as low platelet count • Platelet count usually decreases during CPB, sometimes even below 50,000 • Because of such a low platelet count we will see a large blood loss • Due to decreased amount of platelets and function

  10. Platelets (continued) • As the platelets are activated, they bind to the tubing, sequestered in the lungs, the spleen, and liver….all leading to thrombocytopenia

  11. Effects on the Kidneys • Another common effect of CPB is renal dysfunction • Normally, 25% of the total C.O. is sent to the kidneys. On pump this amount is reduced due to: low flows and low pressures

  12. Blood flow to kidneys is effected by: • Composition of Prime • The sympathetic nervous system • Hormones • Epinephrine • Angiotensin

  13. Renal Failure • Acute renal failure • Nitrogen wastes accumulate in the blood rapidly • Chronic renal failure • Urine decreases in amount and failure signs begin… • Increase in fluid intake doesn’t affect output, mental status changes, seizures, GI bleeding, and yellowing of the skin

  14. Best Indicator of Failure • Acute renal failure • Nitrogen wastes accumulate in the blood rapidly • mg/100ml • Elevated levels indicate creatine is not being expelled in the urine

  15. Reasons for poor function post-op • Long bypass run • Poor pre-op function • Addition of blood • Exposure of angiographic dyes • IABP

  16. Neurological Effects • These results are usually permanent as a result of an embolic event such as a CVA or Stroke • Embolus: defined as an air, blood clot, fat or calcium debris • Indicators of air embolism: • Seizures • Cardiac arrythmias • Ventricular dysfunction

  17. CT Scan • Best method to determine extent of brain injury

  18. Ways to prevent neurological injuries • Use filters • CO2 flush circuit • Watch temperature gradients • Vent heart when clamp is off

  19. Major causes of cerebral injury • Low flows • Hypotension • Low pCO2…which leads to vasoconstriction of cerebral arteries • High p02…which also leads to vasoconstriction of cerebral arteries

  20. Hematological Effects • Caused by exposing the patients to blood products in the circuit • Caused by using heparin • Caused by hemodiluting the patients

  21. Hematological Effects (continued) • Patients with pre-existing hematological problems are at even more of a risk when having heart surgery • Platelet dysfunction may be a result of diluting the patients and the blood interaction between air or pump circuit • Disseminated Intravascular Coagulation • Rare, but seen in long pump runs • Coagulation factors inappropriately activated and bleeding occurs systemically

  22. Effects on the Compliment System • CS involves complex proteins in the blood that bind with antibodies against infection and foreign bodies • When activated, over 18 plasma proteins are activated causing an immune response

  23. Activation of the CS • Release of anaphylatoxins that increase vascular permeability (edema) and smooth muscle contraction • C3a and C5a cause migration of neutrophils onto walls of vessels • Arachidonic acid causes increase vascular permeability • Chemotactic factors cause WBC’s to migrate to the area causing inflammation • Release of enzymes and oxygen free radicals that destroy tissue

  24. Effects on the Endocrine System • A system on ductless glands that secrete hormones directly into the blood • Adrenal: secretes epi/norepi • Thyroid: secretes T-3 and T-4 for metabolism • Pituitary: secretes vasopressin (ADH) • Pancreas: secretes insulin • Ovaries/Testis: maturation of eggs and sperm

  25. Major Effect on Endocrine System • Insulin regulates the metabolism of glucose and regulates the processes for metabolism of fats, carb’s, and proteins • Under hypothermic conditions the insulin response in decreased and thus one’s blood glucose levels increase. During the re-warming phases of bypass the insulin response increases.

  26. Hepatic Effects • The liver is the largest organ in the body • Consists of 4 lobes and supplied by 2 means • Hepatic artery- oxygen from the heart • Hepatic portal vein-nutrient filled blood from the stomach and intestines • Functions of the Liver • Processes glucose, proteins, and fats

  27. Hepatic Injury • Patient becomes jaundice…excessive bilirubin due to blood transfusions or blood trauma. • Jaundice may clear up by itself within a week • Elevated liver enzymes indicate injury • As long as you keep your flows about an 2.2 index, hepatic oxygenation is maintained and injury may be avoided

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