Reinfusion of autologous platelet-rich plasma improves hemostasis after cardiopulmonary bypass]

Although it is reported that postoperative bleeding is reduced by reinfusing autologous platelet-rich plasma (PRP) after cardiopulmonary bypass (CPB), the effect of PRP on hemostasis is not reported in detail. We prepared PRP and fresh whole blood (WB) from the blood of seven patients each prior to their undergoing CPB, and reinfused them autologously to the patients intravenously after the CPB was terminated. In this article, the effect on hemostasis of autologous PRP and WB was described. Platelet aggregation rates and blood coagulation factors were examined before, during and after bypass. Platelet counts, ADP-induced platelet aggregation and the activities of coagulation factors II, V and VII-X were significantly greater in prepared PRP than in WB (p less than 0.01 or p less than 0.05). A mean volume of 724 +/- 109 ml of PRP or 401 +/- 63 ml of WB was reinfused within about 30 minutes after heparin was neutralized by protamine sulfate. The platelet counts increased from 4.3 +/- 1.4 x 10(4)/mm3 to 14.1 +/- 1.6 x 10(4)/mm3 after PRP reinfusion and the platelet aggregation rates increased significantly (p less than 0.01) after PRP reinfusion compared to WB transfusion. The activities of coagulation factors VII-X also increased significantly (p less than 0.05) after reinfusion of PRP when compared to transfusion of WB. The activated partial thromboplastin time decreased to 1.2 times the baseline in the PRP group but remained 1.5 times the baseline in the WB group (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

In vitro effect of fresh frozen plasma on the activated coagulation time in patients undergoing cardiopulmonary bypass

The in vitro effect of fresh frozen plasma (FFP) on the whole blood activated coagulation time (ACT) was examined in 18 patients undergoing cardiopulmonary bypass (CPB) during coronary artery bypass graft surgery. The addition of FFP to whole blood in vitro, after systemic heparinization, significantly prolonged the ACT from 451 +/- 21 seconds (mean +/- SE) to 572 +/- 41 seconds (P less than 0.05). There was no significant correlation between the plasma antithrombin III activity and the prolongation in ACT after systemic heparinization, with or without addition of FFP. The addition of FFP to whole blood in three of the six patients who exhibited heparin resistance (ACT less than 400 seconds after administration of 350 unit/kg heparin) did not prolong the ACT to greater than 400 seconds. These observations suggest that infusion of FFP will further prolong the ACT after heparin administration in most patients including some with initial heparin resistance.     

Recombinant hirudin anticoagulation for aortic valve replacement in heparin-induced thrombocytopenia

PURPOSE: To report the case of a patient with HIT that received a prolonged infusion of r-hirudin (lepirudin; Refludan; Hoechst, France) before, during and after cardiopulmonary bypass (CPB) for aortic surgery. Although administration of r-hirudin for CPB anticoagulation has previously been reported, many questions persist concerning the best therapeutic regimen for CPB anticoagulation as well as the time of onset and the doses for postoperative anticoagulation. CLINICAL FEATURES: A 65-yr-old man was admitted for surgery of aortic stenosis after an episode of acute pulmonary edema complicated by deep venous thrombosis in the context of documented HIT. The patient received r-hirudin for 13 dy before surgery at doses (0.4 mg x kg(-1) bolus followed by 0.15 mg x kg(-1) x hr(-1) continuous infusion) that maintained activated partial thromboplastin time (aPTT) ratios between 2 and 2.5. Anticoagulation for CPB was performed with r-hirudin given as 0.1 mg x kg(-1) i.v. bolus and 0.2 mg kg(-1) in the CPB priming volume. Anticoagulation during CPB was monitored with the whole blood activated coagulation time and ecarin clotting time (ECT) performed in the operating room with values corresponding to r-hirudin concentrations >5 microg x ml(-1) during CPB. Anticoagulation during CPB was uneventful. Two bleeding episodes, related to the r-hirudin regimen and necessitating allogeneic blood transfusion, occurred after surgery. CONCLUSION: This case report confirms previous experience of the use of r-hirudin for anticoagulation during CPB and provides additional information in the context of prolonged r-hirudin infusion before and after CPB.     

Heparin-coated versus uncoated extracorporeal circuit in patients undergoing coronary artery bypass graft surgery

OBJECTIVE: To assess the effect of heparin-coated circuits on bleeding, transfusion, and platelet count in patients undergoing primary coronary artery bypass grafting with full heparinization. DESIGN: Randomized, double-blind study. SETTING: Tertiary-care academic medical center. PARTICIPANTS: Eighty-eight patients undergoing coronary artery bypass grafting requiring cardiopulmonary bypass (CPB) without previous sternotomy. INTERVENTIONS: Subjects received either a heparin-coated or an uncoated extracorporeal circuit for CPB. Heparin, 300 micro/kg, was administered, and supplemental amounts were administered to maintain an activated coagulation time of greater than 480 seconds. Platelet counts were determined during CPB. Mediastinal chest tube drainage was collected in the intensive care unit for 24 hours. MEASUREMENTS AND MAIN RESULTS: The mean platelet counts were similar between the groups during CPB. There was no significant difference in 24-hour mediastinal chest tube drainage (mean +/- standard deviation; median) between the heparin-coated (n = 44, 1096 +/- 401, 1015 mL) and uncoated group (n = 44, 1150 +/- 548, 1040 mL; p = 0.91). The heparin-coated group received less allogeneic packed red blood cells (0.9 +/- 1.6, 0.0 v 1.5 +/- 1.8, 1.0 U; p = 0.04). CONCLUSIONS: The use of a heparin-coated or uncoated cardiopulmonary bypass circuit and full heparinization marginally reduced only red blood cell transfusion but was not associated with platelet sparing or reduced perioperative bleeding.     

Tranexamic acid in primary CABG surgery: high vs low dose

AIM: Prophylactic administration of tranexamic acid decreases bleeding and transfusions after cardiac procedures but it is still unclear what the best dose and the most appropriate timing to get the best results are. METHODS: We enrolled 250 patients scheduled for elective, primary coronary revascularization. They were randomly divided into 2 groups. Group H received tranexamic 30 mg x kg(-1) soon after the induction of anaesthesia and a further same dose was added to the prime solution of cardiopulmonary bypass (CPB). Group L received tranexamic acid 15 mg x kg(-1) after systemic heparinization followed by an infusion of 1 mg x kg(-1) h(-1) till the end of the operation. Transfusions of bank blood products, bleeding in the postoperative period and coagulation profile were recorded. RESULTS: We did not find any difference between the groups either with respect to transfusion requirements or with respect to blood loss. CONCLUSION: For elective, first time coronary artery bypass surgery, both dosages of tranexamic acid are equally effective. Theoretically, it seems safer to administer it when patients are protected from thrombus formation by full heparinization.     

Failure of autologous fresh frozen plasma to reduce blood loss and transfusion requirements in coronary artery bypass surgery

BACKGROUND: Previous studies failed to demonstrate any benefit from prophylaxis with fresh frozen plasma (FFP) after cardiopulmonary bypass (CPB). The results, however, were limited by either retrospective study design or use of FFP in subtherapeutic doses (2-3 units). The authors evaluated whether a therapeutic dose (15 ml/kg) of FFP reduces blood loss and transfusion requirements in elective coronary artery bypass surgery. The risks of multiple allogeneic blood donor exposure were circumvented by using autologous plasma. METHODS: Sixty adult patients scheduled for elective primary coronary artery bypass grafting were randomized to receive, after CPB, an intravenous infusion of 15 ml/kg of either autologous FFP (30 patients) or 6% hydroxyethyl starch 450/0.7 (HES; 30 patients). Autologous plasma was obtained by platelet-poor plasmapheresis several weeks before surgery. Perioperative blood transfusions were administered per protocol. Postoperative blood loss was defined as the chest tube drainage during the first 24 h after surgery. RESULTS: The data from 56 patients (FFP group, 27 patients; HES group, 29 patients) who completed the study according to protocol were analyzed. Median postoperative blood loss was 630 ml (range, 450-1,840 ml) and 830 ml (range, 340-1,980 ml) in the FFP and HES groups, respectively (P = 0.08). Both postoperative (0-24 h) and total perioperative erythrocyte transfusion requirements did not differ significantly between the groups (P = 0.32 and 0.14, respectively). CONCLUSION: The prophylactic administration of a therapeutic dose (15 ml/kg) of autologous FFP after CPB failed to reduce blood loss and transfusion requirements in patients undergoing uncomplicated, elective, primary coronary artery bypass surgery.     

Influence of high-dose aprotinin treatment on blood loss and coagulation patterns in patients undergoing myocardial revascularization.

Intraoperative administration of the proteinase inhibitor aprotinin causes reduction in blood loss and homologous blood requirement in patients undergoing cardiac surgery. To ascertain the blood-saving effect of aprotinin and to obtain further information about the mode of action, 40 patients undergoing primary myocardial revascularization were randomly assigned to receive either aprotinin or placebo treatment. Aprotinin was given as a bolus of 2 x 10(6) kallikrein inactivator units (KIU) before surgery followed by a continuous infusion of 5 x 10(5) KIU/h during surgery. Additionally, 2 x 10(6) KIU were added to the pump prime. Strict criteria were used to obtain a homogeneous patient selection. Total blood loss was reduced from 1,431 +/- 760 ml in the control group to 738 +/- 411 ml in the aprotinin group (P less than 0.05) and the homologous blood requirement from 838 +/- 963 ml to 163 +/- 308 ml (P less than 0.05). In the control group, 2.3 +/- 2.2 U of homologous blood or blood products were given, and in the aprotinin group, 0.63 +/- 0.96 U were given (P less than 0.05). Twenty-five percent of patients in the control group and 63% in the aprotinin group did not receive banked blood or homologous blood products. The activated clotting time as an indicator of inhibition of the contact phase of coagulation was significantly increased before heparinization in the aprotinin group (141 +/- 13 s vs. 122 +/- 25 s) and remained significantly increased until heparin was neutralized after cardiopulmonary bypass (CPB).(ABSTRACT TRUNCATED AT 250 WORDS)     

Vecuronium pharmacokinetics and pharmacodynamics during hypothermic cardiopulmonary bypass in infants and children

PURPOSE: To determine the effect of moderate and deep hypothermic cardiopulmonary bypass (CPB) on the pharmacokinetic and pharmacodynamic behaviour of vecuronium in infants and children. METHODS: We studied 12 patients undergoing surgery for congenital heart disease under narcotic-nitrous oxide anesthesia. Neuromuscular blockade was maintained constant (TI 4-10% by Datex electromyograph) by adjusting a vecuronium infusion. Plasma vecuronium concentrations (Cpss) were analysed by HPLC to describe a pseudosteady-state during each of the pre-CPB, CPB and post-CPB phases. Paired arterial blood samples were taken 20 min apart after at least 20 min of constant infusion. RESULTS: Nine cases were analysed, mean age 20 mo, mean weight 9 kg. Three patients had deep and six moderate hypothermia. In the pre-CPB phase Cpss fell into two groups (mean +/- SD: 330 +/- 42 ng x ml(-1); 127 +/- 27 ng x ml(-1); P < 0.001); similarly the clearances showed a bimodal distribution (mean +/- SD: 5.08 +/- 0.94; 11.51 +/- 0.2 ml x min(-1) x kg(-1) P < 0.001), although in different patients. During CPB this bimodal distribution disappeared. Vecuronium infusion rate (VIR) decreased by 84% and 92% from pre-CPB to CPB phase in deep and moderate hypothermia groups respectively (P < 0.05), paralleled by decreases in Cpss of 36% (P > 0.05) and 52% (P < 0.05). CONCLUSION: Changes in vecuronium requirements and plasma concentrations during CPB demonstrate that vecuronium pharmacokinetics and pharmacodynamics are both affected by hypothermic CPB in infants. The finding of bimodal distributions for plasma vecuronium and vecuronium clearance highlights the need for individual monitoring of neuromuscular blockade in this age group.     

Pharmacokinetics of epsilon-aminocaproic acid in patients undergoing aortocoronary bypass surgery.

BACKGROUND: Epsilon-aminocaproic acid (EACA) is commonly infused during cardiac surgery using empiric dosing schemes. The authors developed a pharmacokinetic model for EACA elimination in surgical patients, tested whether adjustments for cardiopulmonary bypass (CPB) would improve the model, and then used the model to develop an EACA dosing schedule that would yield nearly constant EACA blood concentrations. METHODS: Consenting patients undergoing elective coronary artery surgery received one of two loading doses of EACA, 30 mg/kg (group I, n = 7) or 100 mg/kg (group II, n = 6) after CPB, or (group III) a 100 mg/kg loading dose before CPB and a 10 mg x kg(-1) x h(-1) maintenance infusion continued for 4 h during and after CPB (n = 7). Two patients with renal failure received EACA in the manner of group III. Blood concentrations of EACA, measured by high-performance liquid chromatography, were subjected to mixed-effects pharmacokinetic modeling. RESULTS: The EACA concentration data were best fit by a model with two compartments and corrections for CPB. The elimination rate constant k10 fell from 0.011 before CPB to 0.0006 during CPB, returning to 0.011 after CPB. V1 increased 3.8 l with CPB and remained at that value thereafter. Cl1 varied from 0.08 l/min before CPB to 0.007 l/min during CPB and 0.13 l/min after CPB. Cl2 increased from 0.09 l/min before CPB to 0.14 l/min during and after CPB. Two patients with renal failure demonstrated markedly reduced clearance. Using their model, the authors predict that an EACA loading infusion of 50 mg/kg given over 20 min and a maintenance infusion of 25 mg x kg(-1) x h(-1) would maintain a nearly constant target concentration of 260 microg/ml. CONCLUSIONS: EACA clearance declines and volume of distribution increases during CPB. The authors' model predicts that more stable perioperative EACA concentrations would be obtained with a smaller loading dose (50 mg/kg given over 20 min) and a more rapid maintenance infusion (25 mg x kg(-1) x h(-1)) than are typically employed.     

Hematological assessment of patients undergoing plasmapheresis during cardiac surgery

Methods of reducing patient exposure to homologous blood transfusions include the technique of intraoperative plasmapheresis for the production of platelet rich plasma (PRP). The present study was designed to determine the patient benefits of PRP by examining hemostatic changes in coagulation screens and viscoelastic whole blood monitoring (Thrombelastography, [TEG]). One hundred fifteen patients undergoing elective cardiac surgery were prospectively randomized into a blinded study. Sixty-three patients had 20 percent of the circulating plasma volume sequestered prior to heparinization and pheresed into PRP, which was reinfused 10 minutes following heparin reversal with protamine. The control (CTR) group of 52 patients were exposed to no sequestration procedure. Patients were followed to discharge and 112 parameters, including anthropometric, operative, and postoperative factors, were measured. There were no significant differences between patient groups in preoperative, cardiopulmonary bypass (CPB), or surgical parameters. Average PRP volume was 600+/-100 ml with a total platelet yield of 1.1 billion platelets per patient. TEG indices were determined at four distinct times during the surgical procedure. The CTR group had significantly higher pre-CPB TEG indices of 2.3+/-1.2 and 2.1+/-1.2 (mean+/-SD), vs. 1.8+/-1.5 and 1.4+/-1.7 in the PRP group (p less than .04). Following heparin reversal, pre-PRP reinfusion TEG values were similar between groups, although both groups had significantly decreased indices when compared to pre-CPB values. Thirty minutes post-PRP infusion the treatment group had significantly improved TEG recovery when compared to the CTR group, 1.0+/-1.2 vs. 0.3+/-1.7 (p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemostatic consequences of a non-fresh or reconstituted whole blood small volume cardiopulmonary bypass prime in neonates and infants

Objectives: Despite aggressive measures to miniaturize the cardiopulmonary bypass (CPB) circuit in neonates and infants, the CPB prime volume is often at least as large as the patients’ blood volume. We conducted an observational study to characterize the hemostatic consequences of a CPB prime consisting of either non‐fresh or reconstituted whole blood. Methods: Hematocrit, fibrinogen, platelet count, plasminogen, anti‐thrombin III (AT‐III), and factors (F) II, V, VII, IX, and X of 30 neonates and infants undergoing cardiac surgery with CPB utilizing either a non‐fresh or reconstituted whole blood prime were prospectively evaluated at eight time points. Following protamine administration, microvascular bleeding was treated by protocol. Results: The hemostatic composition of the CPB prime was the same following the use of either non‐fresh or reconstituted whole blood. The CPB prime platelet count (mean ± sd ) was 5.87 ± 2.84 × 10³ μl^?1 when compared to a preoperative platelet count of 298 ± 142 × 10³ μl^?1 (P < 0.0001). Twenty patients received 17.3 ± 9.2 ml·kg^?1 (0.86 ± 0.46 units·kg^?1) of platelets with significant improvement in platelet count. Nine patients received 16.7 ± 13.4 ml·kg^?1 (0.84 ± 0.67 units·kg^?1) of cryoprecipitate with significant improvements in FVIII and fibrinogen. Conclusions: Non‐fresh or reconstituted whole blood as a component of a small volume CPB prime in neonates and infants induces clinically significant dilutional thrombocytopenia in conjunction with less significant reductions in fibrinogen, FII, FV, FVII, FVIII, FIX, FX, plasminogen, and AT‐III.     

Perflubron emulsion (AF0144) augments harvesting of autologous blood: a phase II study in cardiac surgery

OBJECTIVE: To assess tolerance and preliminary efficacy of a perfluorocarbon emulsion (AF0144) used with acute normovolemic hemodilution to reduce allogeneic blood transfusion for patients undergoing coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB). DESIGN: Controlled, single-blind, parallel-group phase II dose escalation trial. SETTING: Single-institution university medical center. PARTICIPANTS: Adult patients undergoing elective CABG surgery (n = 36). INTERVENTIONS: A calculated volume of autologous whole blood was harvested for each patient with a target on-bypass hematocrit of 20% to 22%. Placebo, low-dose (1.8 g/kg) AF0144, or high-dose (2.7 g/kg) AF0144 was infused. During CPB, blood was transfused at protocol-defined triggers (hematocrit <15%, PvO(2) <30 mmHg, SvO(2) <60%). After CPB, all autologous whole blood was reinfused. Allogeneic red blood cells were transfused if a trigger was reached. MEASUREMENTS AND MAIN RESULTS: Safety assessments (vital signs, hematology, blood chemistry, coagulation, and adverse events) were monitored through postoperative day 21. Efficacy endpoints included percentage of patients reaching a transfusion trigger and number of allogeneic units of red blood cells transfused. During CPB, <25% of subjects reached a transfusion trigger. During hospitalization, significantly fewer (p < 0.01) high-dose subjects (33%) reached a trigger than did control patients (91%). Allogeneic red blood cell transfusion did not differ significantly among groups. Safety assessments indicated AF0144 was well tolerated. CONCLUSION: The data suggest that AF0144 when used with acute normovolemic hemodilution is well tolerated and may be effective when used to enhance oxygen delivery for patients undergoing CABG surgery. Confirmation of safety and efficacy in a larger phase III clinical trial is warranted.     

Failure of Autologous Fresh Frozen Plasma to Reduce Blood Loss and Transfusion Requirements in Coronary Artery Bypass Surgery

Background: Previous studies failed to demonstrate any benefit from prophylaxis with fresh frozen plasma (FFP) after cardiopulmonary bypass (CPB). The results, however, were limited by either retrospective study design or use of FFP in subtherapeutic doses (2-3 units). The authors evaluated whether a therapeutic dose (15 ml/kg) of FFP reduces blood loss and transfusion requirements in elective coronary artery bypass surgery. The risks of multiple allogeneic blood donor exposure were circumvented by using autologous plasma.

Methods: Sixty adult patients scheduled for elective primary coronary artery bypass grafting were randomized to receive, after CPB, an intravenous infusion of 15 ml/kg of either autologous FFP (30 patients) or 6% hydroxyethyl starch 450/0.7 (HES; 30 patients). Autologous plasma was obtained by platelet-poor plasmapheresis several weeks before surgery. Perioperative blood transfusions were administered per protocol. Postoperative blood loss was defined as the chest tube drainage during the first 24 h after surgery.

Results: The data from 56 patients (FFP group, 27 patients; HES group, 29 patients) who completed the study according to protocol were analyzed. Median postoperative blood loss was 630 ml (range, 450-1,840 ml) and 830 ml (range, 340-1,980 ml) in the FFP and HES groups, respectively (P = 0.08). Both postoperative (0-24 h) and total perioperative erythrocyte transfusion requirements did not differ significantly between the groups (P = 0.32 and 0.14, respectively).     

The effect of acute normovolemic hemodilution on homologous blood requirements and total estimated red blood cell volume lost

Background: Acute normovolemic hernodilution combined with retransfusion is one of the various techniques proposed to avoid homologous blood transfusion in cardiac surgery. The purpose of the present paper is to study the effect of the volume of autologous blood collected pre-cardiopulmonary bypass (CPB) on homologous blood requirements and total estimated red blood cell (RBC) volume lost in coronary artery bypass grafting (CABG) surgery.
Methods: Following induction of anesthesia, sequestration of one (5–8 ml/kg; Group I, n=14) or two units (12–15 ml/kg; Group 11, n=14) of fresh autologous blood was performed under electrocardiographic and hernodynamic control. Group III (n= 14) was designated as the control group. Autologous blood was reinfused at the conclusion of CPB.
Results: The use of homologous blood in the study groups was significantly less than in the control group. High-volume phlebotomy did not make a significant difference in the requirement of the homologous blood, while causing a mild increase in the total estimated RBC volume lost. No significant differences could be demonstrated in preoperative, post-CPB and discharge hematocrit levels and postoperative blood drainage between the groups.
Conclusion: Acute intraoperative hemodilution with high- and low-volume phlebotomy reduced the homologous blood requirements similarly regardless of the amount of phlebotomy.     

乌司他丁对体外循环心内直视手术婴儿围术期肾功能的影响

目的 评价乌司他丁对体外循环心内直视手术婴儿围术期肾功能的影响.方法 择期拟行心内直视手术的室间隔缺损伴肺动脉高压婴儿40例,月龄3～5月,体重5.3～6.8kg,ASA分级Ⅱ级,性别不限.随机分为2组(n=20):对照组(C组)和乌司他丁组(U组).U组将乌司他丁20 000 U/kg溶于20 ml生理盐水中,颈内静脉注射1/3量,体外循环开始时和主动脉开放即刻预充液中各充入1/3量;C组用生理盐水替代.分别于切皮前30 min(T1)、主动脉阻断前5 min(T2)、主动脉开放后5 min(T3)、术毕(T4)、术后24 h(T5)和48 h(T6)时,留取新鲜尿液,并采集颈内静脉血样,测定尿β2-微球蛋白(β2-MG)浓度和N-乙酞-β-D-葡萄糖苷酶(NAG)活性、血清Cr和BUN的浓度.结果 两组血清BUN和Cr浓度组内和组间比较差异无统计学意义(P＞0.05).与T1时比较,两组T2-6时尿NAG活性和β2-MG浓度升高(P＜0.05);与C组比较,U组T3-5时尿NAG活性和β2-MG浓度降低(P＜0.05).结论 乌司他丁可保护体外循环心内直视手术婴儿围术期的肾功能.     

Lepirudin during cardiopulmonary bypass in a patient with heparin-induced thrombocytopenia

Lepirudin is an alternative anticoagulant therapy in heparin-induced thrombocytopenia (HIT) during cardiopulmonary bypass (CPB). We report a case of a female patient with HIT referred for aortocoronary bypass graft despite persistence of antibodies to platelet factor 4-heparin complexes. Anticoagulation management is described. Whole blood hirudin concentration attempted during CPB was above 4 microg ml(-1). To obtain this concentration, lepirudin administration was managed as follows: 0.1 mg kg(-1) h(-1) lepirudin during preoperative course, 0.2 mg kg(-1) bolus just before CPB and 0.2 mg kg(-1) in the priming solution, complementary boluses of 5 and 10 mg during procedure (according to whole blood ecarin clotting time). Aprotinin was administered simultaneously according to Royston protocol. Anticoagulation was monitored with whole blood ecarin time performed in the operation room (patient's whole blood was diluted one half and one third with normal whole blood; in vitro calibration curve was constructed using normal whole blood spiked with lepirudin). CPB duration was 73 min. When measured, whole blood hirudin concentration was 3.8-5.8 microg ml(-1). Total lepirudin administration was 44 mg. No haemorrhagic or thrombotic events were observed during surgical procedure and postoperative course. Despite lepirudin administration is not yet clearly precise for CPB procedure, its use seems adapted and safe in subjects without renal insufficiency but requiring precise coordination for anaesthesiological, surgical and biological teams.     

Preoperative autologous blood donation in elderly patients with cardiovascular surgery

BACKGROUND: During the cardiovascular surgeries in elderly people, only a few cases can avoid the homologous blood transfusion, because of their preoperative anemic tendency and low hemopoietic abilities. We examined the capability to avoid the homologous blood transfusion in over 75 year old patients by the preoperative autologous blood collection. Sixty-six patients underwent scheduled cardiovascular surgery between January 1996 and December 1999. The groups were divided into three categories of preoperatively collected autologous blood amounts: high-amount (800-1,200 ml), medium-amount (200-800 ml), and low-amount (0 ml). Each group was divided into two subgroups in according to the use of cardiopulmonary bypass (CPB). There were no differences among the each group in age, body weight, or preoperative and postoperative day-7 hematocrit values. RESULTS: Only 21.2% of patients could donate the expected blood amounts preoperatively. Mean volume was 641 ml. In groups used CPB, no patient was transfused homologous blood in high-amount group. On the contrary, 100% patients were donated in medium and low amount groups. In groups operated without CPB, homologous blood transfusion was required 14.3% in high-amount group, 25.0% in medium-amount group, and 83.3% in low-amount group. CONCLUSION: It seems that predonation of more than 800 ml may be sufficient to avoid the homologous blood transfusion in using CPB operation and more than 400 ml in non using CPB operation.     

Maintenance of blood heparin concentration rather than activated clotting time better preserves the coagulation system in hypothermic cardiopulmonary bypass

In cardiopulmonary bypass (CPB), despite heparin regimens in which the activated clotting time (ACT) is kept at more than 400 s, there is biochemical evidence of thrombin generation indicating activation of the coagulation system and increased fibrinolytic activity. Therefore, to reduce the coagulant activation has been one of the main issues in the improvement of CPB. The purpose of this study was to compare the heparin concentration with the ACT and to evaluate the effect of keeping higher heparin concentration on the coagulation and fibrinolytic systems during hypothermic CPB, employing moderate hypothermia (MHT) or deep hypothermic circulatory arrest (DHT). Heparin was either administered to maintain an ACT >400 s (ACT group) or to maintain a whole blood heparin concentration of 3 mg/kg (heparin group). At the lowest core temperature during CPB, the ACT and the heparinase ACT (unrelated to heparin concentration) were increased the most whereas the whole blood heparin concentration was less than half the initial concentration in both ACT groups of MHT and DHT. The thrombin-antithrombin III (TAT) content just after CPB in both MHT and DHT was significantly lower in the heparin group than in the ACT group. In conclusion, ACT does not reflect the whole blood heparin concentration during hypothermic CPB. Furthermore, maintenance of the higher heparin concentration during hypothermic CPB may suppress the activation of the coagulation system via thrombin inhibition. That effect was more remarkable in deep hypothermic CPB. Therefore, we believe that anticoagulation management during hypothermic CPB should be based on the maintenance of the higher blood heparin concentration.     

Heparinless cardiopulmonary bypass with argatroban in dogs.

OBJECTIVES: Systemic heparinization is usually required for cardiopulmonary bypass (CPB). However, problems such as heparin-induced thrombocytopenia, protamine shock, and antithrombin III deficiency exist related to CPB with heparinization. The aim of this study was to evaluate argatroban (ARG) as a substitute for heparin during CPB. METHODS: In the pilot study, blood samples were sequentially obtained from dogs with continuous infusion of ARG at a dose of 10 (n = 6), 20 (n = 6), or 30 (n = 6) microg/kg per min for 2 h without CPB. In the main study, dogs underwent CPB for 2 h with 10 (n = 6) or 30 (n = 6) microg/kg per min of ARG or with heparin with blood samples obtained sequentially. Thrombogenicity in each group was evaluated by observation of the blood-contacting surfaces of the CPB circuits with scanning electron microscopy (SEM). Evidence of thromboembolism in the dogs was also investigated in histological specimens of the kidney and spleen in addition to microscopic observation at autopsy. RESULTS: In the pilot study, the activated coagulation time (ACT) reached a maximum level dose-dependently after continuous infusion of ARG for 30 min. ACT returned to the baseline value within 60 min after the termination of continuous infusion. In the main study, CPB with 30 microg/kg per min of ARG achieved thrombin-antithrombin III complex (TAT) level similar to that achieved by CPB with heparin. Platelet count with 30 microg/kg per min of ARG tended to be higher than that with heparin or 10 microg/kg per min of ARG. The SEM appearance of blood-contacting surfaces of the CPB circuits after infusion with 30 microg/kg per min of ARG appeared to be similar to that after infusion with heparin. Depositions on the blood-contacting surfaces of the CPB circuits were also frequently observed with 10 microg/kg per min of ARG. CONCLUSIONS: Coagulability related to CPB was controlled by the appropriate ARG dosage without the use of heparin in dogs. ARG may be a substitute for heparin in CPB.     

Heparin management protocol for cardiopulmonary bypass influences postoperative heparin rebound but not bleeding.

A group of 63 adult patients undergoing cardiac surgical procedures requiring cardiopulmonary bypass (CPB) were studied to examine the relationship between heparin doses administered and postoperative bleeding. Patients were randomly assigned either to receive heparin 200 U/kg and additional heparin as needed to reach and maintain an activated clotting time (ACT) greater than 400 s for CPB (group A, n = 30), or to receive heparin 400 U/kg and additional heparin as needed to reach and maintain a whole blood heparin concentration greater than 4.0 U/ml for CPB (group H, n = 33). Groups were compared for the amount of postoperative bleeding, heparin rebound, homologous transfusion requirements, and standard laboratory coagulation tests. In the last 33 patients studied, additional tests of platelet aggregation and plasma levels of beta thromboglobulin (BTG), antithrombin III, and several markers of fibrinolysis were measured and compared by group. The mean heparin dose was 28,000 +/- 4,800 U for group A and 57,000 +/- 10,700 U for group H (P less than 0.05 for group A vs. group H). At 8 and 24 h postoperatively, mediastinal drainage did not differ significantly between groups (mean 24-h drainage +/- SD = 901 +/- 414 ml in group A, 1035 +/- 501 ml in group H), nor did the incidence of transfusion with homologous blood products.(ABSTRACT TRUNCATED AT 250 WORDS)