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. 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 The longer the bypass time….the better chance of having some type of injury

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

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

Effects on the Lungs Considered to be the most serious injury as a result of CPB 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 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 The lungs are subject to injury by the activation of the blood compliment system by coming into contact with foreign substances

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

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

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

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

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

Effects on the Kidneys Another common effect of CPB is renal dysfunction 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 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

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

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

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

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

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

CT Scan Best method to determine extent of brain injury Best method to determine extent of brain injury

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

Major causes of cerebral injury Low flows Low flows Hypotension Hypotension Low pCO 2 …which leads to vasoconstriction of cerebral arteries Low pCO 2 …which leads to vasoconstriction of cerebral arteries High p0 2 …which also leads to vasoconstriction of cerebral arteries High p0 2 …which also leads to vasoconstriction of cerebral arteries

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

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

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

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

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

Major Effect on Endocrine System Insulin regulates the metabolism of glucose and regulates the processes for metabolism of fats, carb’s, and proteins 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. 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.

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

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