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Bleeding hearts
Bleeding Fawzv
G. Estafanous,
H
EARTS BLEED for different reasons. At the cmotional level, they bleed without blood loss after disappointments or failures. They also can bleed a lot during and after cardiac surgery. The sympathetic response is the same, but therapy is different. In the 1990s almost 50 years after the initial experiences with cardiac surgery, results are better than ever, but it has been a long, tedious learning process. Blood requirements per cardiac case in the early 1950s were 20 to 30 units, and by the late 1960s and early 1970s the average number of units of blood per case was approximately 10. Currently there are approximately 300,000 cardiac operations per year. Had blood requirements remained the same as the 1970s standards, cardiac cases would have required 3 million units of blood or approximately 25% of the total transfusions in the United States. That would have paralyzed this country’s blood banks. The use of such large amounts of blood also resulted in an increased incidence of intraoperative and postoperative bleeding. In addition, before appropriate testing for hepatitis, the large blood usage caused a high incidence of postoperative hepatitis. This was not recognized immediately after surgery, but definitely increased morbidity and affected the overall outcome following cardiac surgery. The increased number of cardiac operations could not have been done without the progress made in blood use; however, several challenges still remain. CARDIOPULMONARY
BYPASS
The design of early oxygenators was primitive and required the use of large amounts of blood for priming. The oxygenators along with the early pumps and tubing damaged almost all of the blood components. Currently, hollow fiber membrane oxygenators require no more than 2 L of fluid for priming, and provide excellent gas exchange with negligible damage to blood components. Roller pumps are more efficient and less traumatic, and new heparin-coated tubing is being developed. BLOOD CONSERVATION
AND USE
By the early 1970s Jehovah’s Witnesses demanded heart surgery without use of blood transfusion. In addition, the number of coronary artery bypass procedures began to increase dramatically, as did reoperations that required an even larger number of units of blood. The Red Cross and blood banks made it clear that they could not supply enough blood for the increasing number of cardiac operations if use remained the same. The merits of acute normovolemic anemia or hemodilution were popularized and emphasized. These include a
From the Division of Anesthesia, Cleveland Clinic, Cleveland, OH. Address reprint requests to Fawzy G. Estafanous, MD, Chairman, Division of Anesthesia, Cleveland Clinic, 950 Euclid Ave, Cleveland, OH 44106. Copyright o 1991 by W.B. Saunders Company 1053-077019110506-1002$03.00/0 2
Hearts MD
compensatory increase in the cardiac output, maintained oxygen transportation, decreased systemic vascular resistance (SVR), and a decreased incidence of postoperative bleeding. All major centers started to compete with each other for the largest percent of operations performed without blood use. These competitions and challenges stimulated the search for and development of blood conservation programs. In principle, they were about how to use less and save more blood. These programs included (1) preoperative screening for blood diseases; (2) discontinuation of anticoagulation medications, eg aspirin; (3) preoperative group typing rather than full cross-matching; (4) preoperative blood donation; (5) autologous blood transfusions during surgery; (6) the use of blood washing machines to reuse suctioned blood during surgery; (7) retransfusion of shed blood postoperatively; and (8) the use of blood components. Credit should also go to the surgeons because they modified their hemostasis techniques. The percentage of reoperations for surgical bleeding decreased in most institutions. As our experience with blood use matured at the Cleveland Clinic, we realized that presurgical blood donation was impractical and unnecessary. Intraoperative autotransfusion did not have an impact on postoperative hematocrit values, and, frequently, there was not enough suctioned blood that required washing and retransfusion. However, we currently do transfuse postoperatively shed blood by a computerized system that delivers the blood back to the patient as it is lost. This maintains better hemodynamic stability and we have eliminated whole blood transfusion after surgery. In the 1980s the challenges for surgeons and anesthesiologists changed. Because of advancements in medical therapy and the development of percutaneous transluminal coronary angioplasty (PTCA), patients required surgery later in life. Therefore, we began dealing with older patients, more complicated procedures, more patients with impaired ventricular function, and up to 30% of patients having reoperations. During reoperations, bypass time is prolonged, and there is more blood oozing than active bleeding. In the older patients and those with impaired ventricular function, acute normovolemic anemia is less tolerated than in younger patients with good ventricular function. Pathophysiological studies reemphasized the need for higher hematocrit values, between 27% and 29% in patients with impaired ventricular function to ensure better hemodynamics. We also demonstrated that hemodilution may decrease the effectiveness of vasopressors and inotropes, and larger doses are needed to produce the same effect in hemodiluted patients compared with nonhemodiluted patients. Postoperative oozing can be very significant following reoperations, even with the use of membrane oxygenators, because of the adhesions and prolonged bypass time. This blood loss is related to decreases in platelet count and function. This challenge stimulated the development of new therapeutic modalities such as (1) fibrin glue for local
Journalof Cardiotboracic and
Vascular Anesthesia, Vol5,
No 6,
Suppl1 (December),
1991:
pp 2-3
3
BLEEDING HEARTS
hemostasis; (2) intraoperative platelet concentrating chines; (3) desmopressin; and (4) aprotinin. The use of desmopressin did not last long because its effects are significant and the advantages are limited. use of intraoperative platelet retrieval and salvage
ma-
chines can have some advantages, but they are associated with high cost and very complicated procedures. The use of
side The ma-
fibrin glue definitely decreases oozing and bleeding. Clinical observations of the effectiveness of aprotinin are currently being evaluated in widespread clinical trials.
G. Estafanous,
H
EARTS BLEED for different reasons. At the cmotional level, they bleed without blood loss after disappointments or failures. They also can bleed a lot during and after cardiac surgery. The sympathetic response is the same, but therapy is different. In the 1990s almost 50 years after the initial experiences with cardiac surgery, results are better than ever, but it has been a long, tedious learning process. Blood requirements per cardiac case in the early 1950s were 20 to 30 units, and by the late 1960s and early 1970s the average number of units of blood per case was approximately 10. Currently there are approximately 300,000 cardiac operations per year. Had blood requirements remained the same as the 1970s standards, cardiac cases would have required 3 million units of blood or approximately 25% of the total transfusions in the United States. That would have paralyzed this country’s blood banks. The use of such large amounts of blood also resulted in an increased incidence of intraoperative and postoperative bleeding. In addition, before appropriate testing for hepatitis, the large blood usage caused a high incidence of postoperative hepatitis. This was not recognized immediately after surgery, but definitely increased morbidity and affected the overall outcome following cardiac surgery. The increased number of cardiac operations could not have been done without the progress made in blood use; however, several challenges still remain. CARDIOPULMONARY
BYPASS
The design of early oxygenators was primitive and required the use of large amounts of blood for priming. The oxygenators along with the early pumps and tubing damaged almost all of the blood components. Currently, hollow fiber membrane oxygenators require no more than 2 L of fluid for priming, and provide excellent gas exchange with negligible damage to blood components. Roller pumps are more efficient and less traumatic, and new heparin-coated tubing is being developed. BLOOD CONSERVATION
AND USE
By the early 1970s Jehovah’s Witnesses demanded heart surgery without use of blood transfusion. In addition, the number of coronary artery bypass procedures began to increase dramatically, as did reoperations that required an even larger number of units of blood. The Red Cross and blood banks made it clear that they could not supply enough blood for the increasing number of cardiac operations if use remained the same. The merits of acute normovolemic anemia or hemodilution were popularized and emphasized. These include a
From the Division of Anesthesia, Cleveland Clinic, Cleveland, OH. Address reprint requests to Fawzy G. Estafanous, MD, Chairman, Division of Anesthesia, Cleveland Clinic, 950 Euclid Ave, Cleveland, OH 44106. Copyright o 1991 by W.B. Saunders Company 1053-077019110506-1002$03.00/0 2
Hearts MD
compensatory increase in the cardiac output, maintained oxygen transportation, decreased systemic vascular resistance (SVR), and a decreased incidence of postoperative bleeding. All major centers started to compete with each other for the largest percent of operations performed without blood use. These competitions and challenges stimulated the search for and development of blood conservation programs. In principle, they were about how to use less and save more blood. These programs included (1) preoperative screening for blood diseases; (2) discontinuation of anticoagulation medications, eg aspirin; (3) preoperative group typing rather than full cross-matching; (4) preoperative blood donation; (5) autologous blood transfusions during surgery; (6) the use of blood washing machines to reuse suctioned blood during surgery; (7) retransfusion of shed blood postoperatively; and (8) the use of blood components. Credit should also go to the surgeons because they modified their hemostasis techniques. The percentage of reoperations for surgical bleeding decreased in most institutions. As our experience with blood use matured at the Cleveland Clinic, we realized that presurgical blood donation was impractical and unnecessary. Intraoperative autotransfusion did not have an impact on postoperative hematocrit values, and, frequently, there was not enough suctioned blood that required washing and retransfusion. However, we currently do transfuse postoperatively shed blood by a computerized system that delivers the blood back to the patient as it is lost. This maintains better hemodynamic stability and we have eliminated whole blood transfusion after surgery. In the 1980s the challenges for surgeons and anesthesiologists changed. Because of advancements in medical therapy and the development of percutaneous transluminal coronary angioplasty (PTCA), patients required surgery later in life. Therefore, we began dealing with older patients, more complicated procedures, more patients with impaired ventricular function, and up to 30% of patients having reoperations. During reoperations, bypass time is prolonged, and there is more blood oozing than active bleeding. In the older patients and those with impaired ventricular function, acute normovolemic anemia is less tolerated than in younger patients with good ventricular function. Pathophysiological studies reemphasized the need for higher hematocrit values, between 27% and 29% in patients with impaired ventricular function to ensure better hemodynamics. We also demonstrated that hemodilution may decrease the effectiveness of vasopressors and inotropes, and larger doses are needed to produce the same effect in hemodiluted patients compared with nonhemodiluted patients. Postoperative oozing can be very significant following reoperations, even with the use of membrane oxygenators, because of the adhesions and prolonged bypass time. This blood loss is related to decreases in platelet count and function. This challenge stimulated the development of new therapeutic modalities such as (1) fibrin glue for local
Journalof Cardiotboracic and
Vascular Anesthesia, Vol5,
No 6,
Suppl1 (December),
1991:
pp 2-3
3
BLEEDING HEARTS
hemostasis; (2) intraoperative platelet concentrating chines; (3) desmopressin; and (4) aprotinin. The use of desmopressin did not last long because its effects are significant and the advantages are limited. use of intraoperative platelet retrieval and salvage
ma-
chines can have some advantages, but they are associated with high cost and very complicated procedures. The use of
side The ma-
fibrin glue definitely decreases oozing and bleeding. Clinical observations of the effectiveness of aprotinin are currently being evaluated in widespread clinical trials.