Platelet-rich plasma sequestration, with therapeutic platelet yields, reduces allogeneic transfusion in complex cardiac surgery

Platelet dysfunction is the most common cause of nonsurgical bleeding after cardiopulmonary bypass (CPB). We hypothesized that reinfusion of a therapeutic quantity of platelets sequestered before CPB would decrease the need for allogeneic platelet transfusion, as well as decrease bleeding and total allogeneic transfusion, in cardiac surgery patients at moderately high risk for bleeding. Fifty-five patients undergoing either reoperative coronary artery bypass (CABG) or combined CABG and valve replacement were randomized to control or platelet-rich plasma sequestration (pheresis) groups. All patients received intraoperative epsilon-aminocaproic acid infusions. There was no significant difference between groups with respect to preoperative characteristics, duration of CPB, or target postoperative hematocrit. Mean platelet yields were 6.2 +/- 2.1 units (3.1 x 10(11) platelets). Mean pheresis time was 44 min. Allogeneic platelets (range = 6-12 units) were transfused to 28% of control patients, compared with 0% of pheresis patients (P < 0.01). Allogeneic packed red blood cells were transfused to 45% of control patients (1.2 units per patient) versus 31% of pheresis patients (0. 7 unit per patient) (P = 0.35). Total allogeneic units transfused were significantly reduced in the pheresis group (P < 0.02). Mediastinal chest tube drainage was not significantly decreased in the pheresis group. In this prospective, randomized study, therapeutic platelet yields were obtained before CPB. In contrast with recent studies with low platelet yields, these data support the conclusion that platelet-rich plasma sequestration is effective in reducing allogeneic platelet transfusions and total allogeneic units transfused in cardiac surgery patients at moderately high risk for post-CPB coagulopathy and bleeding. IMPLICATIONS: Transfusion of allogeneic blood products, including platelets, is common during complex cardiac surgical procedures. In the present prospective, randomized study, a significant reduction in allogeneic platelet transfusion and total allogeneic units transfused was observed after the reinfusion of a therapeutic quantity of autologous platelets sequestered before cardiopulmonary bypass.     

A comparison of bleeding and transfusion in patients who undergo coronary artery bypass grafting via sternotomy with and without cardiopulmonary bypass

OBJECTIVE: To determine whether there is a difference between on-pump cardiopulmonary bypass (CABG) and off-pump coronary artery bypass grafting (OPCAB) without heparin reversal with regard to bleeding, transfusion requirements, and incidence of surgical re-exploration of the mediastinum. DESIGN: Retrospective chart review. SETTING: A large academic medical center. PARTICIPANTS: Two hundred adult patients undergoing cardiac surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: One hundred CABG patients were compared with 100 OPCAB patients. Statistical significance was measured with P values of 相似文献   

Effect of autologous platelet-rich plasma (PRP) in cardiac surgery

Autologous platelet-rich plasma (PRP) was harvested before cardiopulmonary bypass (CPB). After heparin neutralization, it was returned to patients. The purpose of this study was to examine platelet function and the amount of blood loss and blood transfusion after transfusion of PRP. Twenty-eight patients undergoing elective coronary artery bypass grafting and other procedures were divided into three groups: group A; patients undergoing CAGB between May and October 1997 (n = 10), group B; patients undergoing other between May and October 1997 (n = 8), group C; patients undergoing CAGB before May 1997 (n = 10). Blood cell count, platelet aggregation in response to ADP, and platelet adhesion were measured before CPB, just after CPB, after infusion of protamine and PRP, 24 hrs after CPB and 48 hrs after CPB. Blood loss and blood transfusion in group. A and group C were examined after CPB. There was no significant difference in platelet count between group A and group B. There was significant difference in platelet aggregation in group A. There was no significant difference in blood loss after CPB between group A and group C, but there was a significant difference in blood transfusion between group A and group C. These results suggest that PRP was useful to preserve platelet function and to decrease blood loss after CPB in cardiac surgery.     

The effect of prophylactic epsilon-aminocaproic acid on bleeding, transfusions, platelet function, and fibrinolysis during coronary artery bypass grafting.

BACKGROUND: Antifibrinolytic medications administered before skin incision decrease bleeding after cardiac surgery. Numerous case reports indicate thrombus formation with administration of epsilon-aminocaproic acid (epsilon-ACA). The purpose of this study was to examine the efficacy of epsilon-ACA administered after heparinization but before cardiopulmonary bypass in reducing bleeding and transfusion requirements after primary coronary artery bypass surgery. METHODS: Seventy-four adult patients undergoing primary coronary artery bypass surgery were randomized to receive 125 mg/kg epsilon-ACA followed by an infusion of 12.5 mg x kg(-1) x h(-1) or an equivalent volume of saline. Coagulation studies, thromboelastography, and platelet aggregation tests were performed preoperatively, after bypass, and on the first postoperative day. Mediastinal drainage was recorded during the 24 h after surgery. Homologous blood transfusion triggers were predefined and transfusion amounts were recorded. RESULTS: One patient was excluded for surgical bleeding and five patients were excluded for transfusion against predefined criteria One patient died from a dysrhythmia 2 h postoperatively. Among the remaining 67, the epsilon-ACA group had less mediastinal blood loss during the 24 h after surgery, 529+/-241 ml versus 691+/-286 ml (mean +/- SD), P < 0.05, despite longer cardiopulmonary bypass times and lower platelet counts, P < 0.05. Platelet aggregation was reduced in both groups following cardiopulmonary bypass but did not differ between groups. Homologous blood transfusion was similar between both groups. CONCLUSIONS: Prophylactic administration of epsilon-ACA after heparinization but before cardiopulmonary bypass is of minimal benefit for reducing blood loss postoperatively in patients undergoing primary coronary artery bypass grafting.     

A comparative study of the effect of autologous platelet-rich plasma and fresh autologous whole blood on haemostasis after cardiac surgery

The effects of fresh autologous platelet-rich plasma and autologous whole blood on haemostasis afer cardiopulmonary bypass were examined in adult cardiac surgery patients. Platelet count, adenosine diphosphate 10 μM maximum aggregation rate and clotting Factor VIII were greater in the platelet-rich plasma group (n = 11) than in the whole blood group (n = 8) after platelet-rich plasma or whole blood reinfusion. Blood loss after heparin neutralization was less in the platelet-rich plasma group than in the whole blood group, Blood loss from heparin neutralization to 12h after surgery was correlated with platelet count, fibrinogen and ADP aggregation rate. The number of patients who required homologous blood transfusion was less in the platelet-rich plasma group. In conclusion, the reinfusion of autologous platelet-rich plasma improves haemostasis after cardiopulmonary bypass, and may enable surgery to be performed without homologous blood transfusion.     

The Effect of Prophylactic [Greek small letter epsilon]-Aminocaproic Acid on Bleeding, Transfusions, Platelet Function, and Fibrinolysis during Coronary Artery Bypass Grafting

Background: Antifibrinolytic medications administered before skin incision decrease bleeding after cardiac surgery. Numerous case reports indicate thrombus formation with administration of [Greek small letter epsilon]-aminocaproic acid ([Greek small letter epsilon]-ACA). The purpose of this study was to examine the efficacy of [Greek small letter epsilon]-ACA administered after heparinization but before cardiopulmonary bypass in reducing bleeding and transfusion requirements after primary coronary artery bypass surgery.

Methods: Seventy-four adult patients undergoing primary coronary artery bypass surgery were randomized to receive 125 mg/kg [Greek small letter epsilon]-ACA followed by an infusion of 12.5 mg [middle dot] kg-1 [middle dot] h-1 or an equivalent volume of saline. Coagulation studies, thromboelastography, and platelet aggregation tests were performed preoperatively, after bypass, and on the first postoperative day. Mediastinal drainage was recorded during the 24 h after surgery. Homologous blood transfusion triggers were predefined and transfusion amounts were recorded.

Results: One patient was excluded for surgical bleeding and five patients were excluded for transfusion against predefined criteria. One patient died from a dysrhythmia 2 h postoperatively. Among the remaining 67, the [Greek small letter epsilon]-ACA group had less mediastinal blood loss during the 24 h after surgery, 529 +/- 241 ml versus 691 +/- 286 ml (mean +/- SD), P < 0.05, despite longer cardiopulmonary bypass times and lower platelet counts, P < 0.05. Platelet aggregation was reduced in both groups following cardiopulmonary bypass but did not differ between groups. Homologous blood transfusion was similar between both groups.     

Effects of autologous platelet concentrate reinfusion after open heart surgery in patients with congenital heart disease

BACKGROUND: Plasma pheresis and reinfusion of platelet-rich plasma has not been shown to reduce blood loss in cardiac patients. Recently, freshly prepared autologous platelet concentrates (PC) can be made from patient's blood and has a higher concentration than conventional platelet rich plasma. In this study, the effects of autologous PC reinfusion were examined after open heart surgery in patients with congenital heart disease. METHODS: Eight patients with noncyanotic congenital heart disease, who underwent open heart surgery and reinfusion of autologous PC, were classified as the PC group. Eight other patients with noncyanotic congenital heart disease, who underwent only open heart surgery, were defined as the control group. Ages ranged from 2 to 24 years and were not significantly different between the two groups (9.3 +/- 5.1 years in the PC group and 12.6 +/- 7.9 years in the control group, p = 0.33). In the PC group, blood was collected from the femoral vein through a 6F catheter introducer; 9 to 20 U (13.0 +/- 5.4 U, 0.42 +/- 0.22 U/kg) of autologous PC were prepared and were reinfused after protamine administration. The time course of platelet counts was examined until postoperative day 7. Aggregation responses to adenosine diphosphate; (4 micromol/L and 8 micromol/L), collagen (1 micromol/L and 5 micromol/L), and epinephrine (5 micromol/L and 10 micromol/L) were evaluated after induction of anesthesia (individual references), after protamine administration, at the end of the operation; these responses were shown as recovery ratios. RESULTS: Blood loss during surgery in the PC group was significantly less than in the control group (4.8 +/- 3.0 mL/kg versus 7.8 +/- 1.7 mL/kg, p = 0.044). Similarly blood loss on postoperative day 1 in the PC group was significantly less than in the control group (3.6 +/- 1.2 mL/kg versus 7.2 +/- 3.1 mL/kg, p = 0.013). The platelet counts in the PC group were larger than those in the control group until postoperative day 5, after reinfusion of prepared autologous PC. The recovery ratios of the aggregation responses to adenosine diphosphate, collagen, and epinephrine after protamine administration were not significantly different between the two groups. However, recovery in the PC group after reinfusion of the prepared autologous PC was greater than in the control group. CONCLUSIONS: Reinfusion of the freshly prepared autologous PC was followed by good aggregation responses and low blood loss in patients with noncyanotic congenital heart disease after open heart surgery. This procedure may be useful in pediatric open heart surgery without blood transfusion or with little administration of homologous blood products.     

Reduction in blood loss and blood use after cardiopulmonary bypass with high-dose aprotinin versus autologous fresh whole blood transfusion.

Ninety patients undergoing cardiac surgery were randomly divided into three groups of 30 patients to compare the effects on bleeding and transfusion requirements of either intraoperative infusion of high-dose aprotinin (GpI) or reinfusion of autologous fresh whole blood (GpII) versus a control group (GpIII). Standardized anesthetic, perfusion, and surgical techniques were used. Platelet counts, hemoglobin concentration, hematocrit, fibrinogen, and Ivy-Nelson bleeding times determined at fixed times perioperatively did not differ among the three groups. The total loss from the chest drains was significantly reduced in GpI (328 +/- 28 mL; mean +/- SEM) as compared with the loss in GpII and GpIII (775 +/- 75 mL and 834 +/- 68 mL, respectively). There was a threefold difference in the total hemoglobin loss (GpI, 14.2 +/- 1.7 g; GpII, 50.1 +/- 5.0 g; GpIII, 45.0 +/- 5.2 g). GpI patients also received less banked blood: 250 +/- 53 mL versus 507 +/- 95 mL in GpII and 557 +/- 75 mL in GpIII. No GpI patient required transfusion of platelets or fresh frozen plasma. Fresh whole autologous blood transfusions had no significant hemostatic effect and failed to reduce the homologous blood requirement. Conversely, high-dose aprotinin reduced blood loss and transfusion requirements.     

Influence of modified ultrafiltration on coagulation, fibrinolysis and blood loss in adult cardiac surgery.

OBJECTIVES: Modified ultrafiltration (MUF) significantly reduce blood loss and transfusion requirements in pediatric cardiac surgery presumably by a reduction in inflammatory mediators which decrease the inflammatory axes and decrease the cross-activation of fibrinolysis and thrombosis. The influence of MUF on blood loss and homologous blood transfusion in adult cardiac surgery has not yet been determined. Furthermore, data about the influence on routine coagulation tests, platelet activation as well as the coagulation and fibrinolytic systems are limited. METHODS: In a prospective randomized study 48 patients scheduled for elective myocardial revascularization were randomized into a control group (n=16), a conventional ultrafiltration (CUF) group (n=16) and a MUF group (n=16). Perioperatively, serial blood samples were drawn at specific intervals to evaluate coagulation, fibrinolysis, and platelet function. RESULTS: Neither the coagulation nor the fibrinolytic system was positively influenced by MUF or CUF. The routine clotting tests were comparable except for a significantly higher antithrombin III activity after MUF compared to the CUF control group persisting 24 h postoperatively. Platelet factor 4 activity and platelet counts showed no differences among the groups. MUF considerably reduced the postoperative blood loss (MUF, 6.4+/-1.7 ml/kg bw per 24 h vs. CUF, 9.2+/-2.5 ml/kg bw per 24 h (P=0.003) vs. control, 8.9+/-2.2 ml/kg bw per 24 h (P=0.008)) and allogeneic blood transfusion (MUF, 2.0+/-3.4 ml/kg bw per 24 h vs. CUF, 6.9+/-5.1 ml/kg bw per 24 h (P=0.034) vs. control, 7.0+/-6.3 ml/kg bw per 24 h (P=0.029)). CONCLUSIONS: MUF in adult cardiac surgery significantly reduces postoperative blood loss and transfusion requirements. The mechanism for reduced blood loss could not be elucidated in this study.     

Platelet concentrates transfusion in cardiac surgery and platelet function assessment by multiple electrode aggregometry

Background: Platelet dysfunction contributes to the pathophysiology of bleeding complications during and after cardiac surgery. In most surgical institutions, no peri-operative point-of-care monitoring of platelet function is used. We evaluated the usefulness of the Multiplate^® platelet function analyser based on impedance aggregometry for identifying groups of patients at a high risk of transfusion of platelet concentrates (PC).
Methods: Platelet function parameters were determined in 60 patients before and after routine cardiac surgery. Impedance aggregometry measurements were performed on Multiplate^® using ADP (ADPtest), collagen (COLtest) and thrombin receptor activating peptide (TRAPtest) as platelet activators. The correlations between the aggregometry results and the transfusion of PC were calculated. The results of the aggregation tests were also divided into tertiles and the differences in PC transfusion between the low and the high tertile were assessed.
Results: Low aggregometry delimited groups of patients with significantly higher PC transfusion. In the receiver operating characteristic curve, low pre-operative aggregation in the ADPtest identified patients with high total transfusion of PC (area under the curve 0.74, P =0.001), while the ADPtest performed at the end of the operation identified patients with high PC transfusion on the intensive care unit (ICU) (area under the curve 0.76, P =0.002).
Conclusions: Near-patient platelet aggregation may allow the identification of patients with enhanced risk of PC transfusion, both pre-operatively and upon arrival on the ICU.     

The effect of transfusion of fresh whole blood versus platelet concentrates after cardiac operations. A scanning electron microscope study of platelet aggregation on extracellular matrix

To evaluate the effect of fresh whole blood transfusion versus platelet concentrates transfusion on platelet aggregation after cardiac operations, 24 patients were randomized to receive either one unit of fresh whole blood (12 patients) or 10 platelet units (12 patients) after cardiopulmonary bypass. Platelet aggregation on extracellular matrix, platelet count, and mean platelet volume were studied preoperatively, at termination of cardiopulmonary bypass, after protamine administration, and after the transfusion of fresh whole blood or after transfusion of each two platelet units. Extracellular matrix produced by cultured bovine corneal cells closely resembles the vascular subendothelial basal lamina, and is an ideal in vitro model in the study of platelet interaction with the subendothelium. Platelet aggregation on extracellular matrix, studied by a scanning electron microscope, was graded from 1 to 4, wherein grade 1 represents nonactivated platelets and grade 4 a mature platelet aggregate. With this grading system, the two groups were similar in preoperative values (3.3 +/- 0.9 versus 3.7 +/- 0.4) and values after cardiopulmonary bypass (1.5 +/- 1.0 in both groups). One unit of fresh whole blood restored platelet aggregation on extracellular matrix to preoperative status (3.0 +/- 1.0), whereas eight platelet units were needed for the same result (3.2 +/- 0.8). One unit of fresh whole blood increased platelet count in a manner similar to that achieved by six platelet units and increased mean platelet volume to a level higher than that achieved by 10 platelet units. These results suggest that the effect of one unit of fresh whole blood on platelet aggregation after cardiopulmonary bypass is at least equal, if not superior, to the effect of 8 to 10 platelet units.     

Intraoperative use of platelet-plasmapheresis in vascular surgery

STUDY OBJECTIVE: To determine, in a pilot study, whether pheresis of plasma and platelets before surgical blood loss, with reinfusion of the autologous plasma and platelets after completion of the aortic reconstruction, will result in decreased bleeding and decreased transfusion of allogenic blood components in patients undergoing elective aortic reconstruction. DESIGN: Randomized study. SETTING: University medical center. INTERVENTIONS: Patients were randomized to perioperative (acute) platelet plasmapheresis (APP group) versus conventional blood component therapy (control group). In the APP group, blood was withdrawn after induction of anesthesia, to sequester approximately 300 mL of platelet rich plasma (PRP); platelet poor plasma (PPP) and red blood cells (RBC) were sequestered as well. An autotransfusion device was used to collect and re-infuse autologous RBC during the course of the operation in both groups. After completion of the aortic reconstruction, autologous PRP and PPP were re-infused in the APP group. Blood loss, volume of blood component transfusions, and preoperative and postoperative hemoglobin (Hb), hematocrit (Hct), platelet, international normalized ratio (INR), and activated partial thromboplastin time (aPTT) were recorded. MEASUREMENTS AND MAIN RESULTS: There was no difference between groups in demographics, preoperative laboratory values, or surgical procedures, although more patients were treated for aneurysms (73% vs. 60%) and fewer for occlusive disease (20% vs. 40%) in the control versus APP group. Also, there were no differences between the control and APP groups in duration of operation, blood loss, volume of colloid infused, or volume of allogenic RBC and plasma transfused. Patients in the APP group received a greater volume of crystalloid solution (9.1 +/- 3.4 L vs. 6.8 +/- 3.0 L; p = 0.002), but fewer units of allogenic platelets than the control group (0.7 +/- 1.0 units vs. 0.2 +/- 0.4 units; p < 0.04). There were no differences in postoperative Hb, Hct, INR, aPTT, or fibrinogen. The platelet count was lower in the APP group than in the control group (123 +/- 40 x 10(3)/mm(3) vs. 182 +/- 51 x 10(3)/mm(3); p = 0.004). CONCLUSIONS: Perioperative platelet plasmapheresis led to fewer allogenic platelet transfusions in patients undergoing elective aortic reconstruction. However, there was no decrease in blood loss and no reduction in transfusion of allogenic RBC or plasma. Perioperative platelet plasmapheresis is not recommended for routine use in elective aortic reconstruction.     

Near-patient platelet function testing in patients undergoing coronary artery surgery: a pilot study

Platelet dysfunction after cardiopulmonary bypass contributes to microvascular bleeding and is associated with blood transfusion and resternotomy. Platelet count can be readily performed, but currently there are no standardised, reproducible, rapidly available platelet function tests. We studied platelet function as measured by multiple electrode platelet aggregometery (multiplate) and light transmission aggregometry in 44 patients undergoing routine coronary artery surgery. Platelet aggregation as measured by multiplate was reduced during and after cardiopulmonary bypass compared with baseline with evidence of partial recovery by the time of transfer to ITU. In patients transfused blood, platelet aggregation measured by multiplate was reduced during chest closure with adenosine diphosphate (18 U vs 29 U, p = 0.01) and thrombin receptor agonist peptide-6 agonist (65 U vs 88 U, p = 0.01) compared with patients not transfused. This suggests that multiplate, a new point of care analyser, can detect platelet dysfunction in this setting.     

Tranexamic acid reduces postoperative bleeding in off-pump coronary artery bypass grafting

OBJECTIVE: Tranexamic acid (TA) reduces blood loss in coronary artery surgery with cardiopulmonary bypass. The present prospective study was designed to investigate its hemostatic effect in off-pump coronary artery bypass (OPCAB). METHOD: Seventy-six patients undergoing elective OPCAB were randomized into two groups, received TA (0.75 g loading dose before surgery and 250 mg/h during surgery, gross dose: 1.5 g, n=36) and saline solution (control, n=40), respectively. Perioperative blood samples were collected. Hematochemical parameters including platelet adhesion rate, D-dimer and fibrinopeptide-A (FPA) were analysis. Volume of blood loss, blood transfusion and other clinical data were recorded throughout the perioperative period. RESULTS: Cumulative blood loss was significantly reduced in the TA group as compared to the controls postoperatively (6 hrs (median [25th-75th]): TA: 200.0 [140.0-230.0] ml, Control: 225.0 [200.0-347.5.0] ml, p=0.009; 24 hrs: TA: 440.0 [270.0-605.0] ml, Control: 655.0 [500.0-920.0] ml, p<0.001). Number of patients received blood transfusion in each group was similar. Levels of D-dimer rose significantly after surgery, and were significantly lower in the TA group than that in controls. Platelet adhesion rate and FPA levels remained at baseline levels after the operation in two groups. Early clinical outcomes were similar between groups. CONCLUSION: The results indicated that tranexamic acid limits fibrinolysis and reduces blood loss after off-pump coronary artery bypass surgery.     

Serial changes in primary hemostasis after massive transfusion

Primary hemostasis was studied in 22 injured patients in the operating room (OR) after a minimum of 10 transfusions, 6 and 15 hours after surgery, on postoperative days 2 and 4 and during convalescence (mean 25 days after surgery). The platelet count was low in the OR and continued to fall after surgery through the second postoperative day; it began to rise by day 4 and was above normal at convalescence. Most patients had prolonged bleeding time through day 4. Platelet aggregation with adenosine diphosphate and collagen was depressed in the OR and platelet aggregation remained depressed. The platelet-specific proteins, beta-thromboglobulin and platelet factor 4, were elevated in the OR and fell throughout the first 4 postoperative days. A secondary rise in these proteins occurred at convalescence. Despite severe alterations in both the number and function of platelets after massive transfusion for injury, no patient had clinical oozing. Therefore the routine administration of platelets in comparable patients without "medical bleeding" is unwarranted.     

Point-of-care platelet function testing

Cardiopulmonary bypass has unpredictably deleterious effects on platelet function. Patients with cardiovascular disease have treatments aimed at reducing platelet aggregation and are at risk of excessive bleeding during surgery. Transfusion of blood products, particularly platelets, probably causes increased morbidity and mortality. Conversely, patients with excessive platelet aggregation are at risk of thrombotic complications--undesirable outcomes in the context of myocardial revascularization and prevention of stroke. Platelet function is difficult to monitor. Laboratory tests take time, and the results are not immediately available. Point-of-care (POC) testing of platelet function should facilitate the clinical management of bleeding patients by rationalizing platelet transfusion and avoiding unnecessary transfusion. Furthermore, POC platelet function could alert the clinician to risks of excessive platelet activation and measure the efficacy of antiplatelet therapy. This article outlines some of the POC platelet function monitors available as well as their potential applications.     

Coagulation tests during cardiopulmonary bypass correlate with blood loss in children undergoing cardiac surgery.

OBJECTIVES: To examine whether coagulation tests, sampled before and during cardiopulmonary bypass (CPB), are related to blood loss and blood product transfusion requirements, and to determine what test value(s) provide the best sensitivity and specificity for prediction of excessive hemorrhage. DESIGN: Prospective. SETTING: University-affiliated, pediatric medical center. PARTICIPANTS: Four hundred ninety-four children. INTERVENTIONS: Coagulation tests. MEASUREMENTS AND MAIN RESULTS: Demographic, coagulation test, blood loss, and transfusion data were noted in consecutive children undergoing cardiac surgery. Laboratory tests included hematocrit (Hct), prothrombin time, partial thromboplastin time (PTT), platelet count, fibrinogen concentration, and thromboelastography. Stepwise linear regression analysis indicated that platelet count during CPB was the variable most significantly associated with intraoperative blood loss (in milliliters per kilogram) and 12-hour chest tube output (in milliliters per kilogram). Other independent variables associated with blood loss were thromboelastography maximum amplitude (MA) during CPB, preoperative PTT, preoperative Hct, and preoperative thromboelastography angle and shear modulus values. Thromboelastography MA during CPB was the only variable associated with total products transfused (in milliliters per kilogram). Of all tests studied, platelet count during CPB (< or = 108,000/microL) provided the maximum sensitivity (83%) and specificity (58%) for prediction of excessive blood loss (receiver operating characteristic analysis). Blood loss was inversely related to patient age; neonates received the most donor units (median, 8 units; range, 6 to 10 units). CONCLUSIONS: During cardiac surgery, coagulation tests (including thromboelastography) drawn pre-CPB and during CPB are useful to identify children at risk for excessive bleeding. Platelet count during CPB was the variable most significantly associated with blood loss.     

Platelet function after coronary artery bypass grafting: is there a procoagulant activity after off-pump compared with on-pump surgery?

OBJECTIVE: After off-pump coronary artery bypass (OPCAB) haemostasis might be better preserved compared with on-pump coronary artery bypass grafting (CABG). The aim of this study was to investigate whether this possibly better preserved haemostasis results in a procoagulant activity of the platelets. DESIGN: Thirty patients were studied prospectively, 15 undergoing on-pump CABG and 15 undergoing OPCAB. Platelet function was evaluated four times within the first 24 h: preoperatively, postoperatively, 4 h and 1 day after surgery with a bedside whole blood clotting test. RESULTS: A significant increase of platelet-activating-factor-induced platelet aggregation was observed postoperatively after OPCAB (p < 0.01). Only two patients did not reach preoperative values within 1 day postoperatively and four patients had a more than twofold increase. Platelet aggregation immediately after on-pump CABG was reduced to near half of preoperative values, but within 1 day postoperatively normal platelet aggregation was regained in half of the patients. CONCLUSION: This study has mainly indicated that platelets after OPCAB were more easily activated in the early postoperative period. After CABG with cardiopulmonary bypass we found a temporary platelet dysfunction which seemed to be overcome within the first postoperative day.     

Acute normovolemic hemodilution and intraoperative cell salvage in aortic surgery

OBJECTIVE: The objective of this study was to report current transfusion requirements and outcomes in patients undergoing elective aortic surgery with autologous transfusion. METHODS: This was a retrospective review of transfusion practice in infrarenal aortic surgery in a tertiary vascular unit with a longstanding interest in autologous transfusion. One hundred and ten consecutive patients underwent infrarenal aortic surgery with a combination of acute normovolemic hemodilution (ANH) and intraoperative cell salvage (ICS). All patients underwent hemodilution to a target hemoglobin concentration of 11 g/dL and underwent ICS with a centrifugal device. RESULTS: Median blood loss was 1140 mL (interquartile range [IQR], 683 to 1609 mL) in 78 aneurysm repairs and 775 mL (IQR, 400 to 1225 mL) in 32 aortobifemoral bypasses for occlusive disease (P =.02), resulting in a median salvaged red cell volume of 403 mL (IQR, 256 to 563 mL) for aneurysm repairs and 250 mL (IQR, 200 to 290 mL) in bypass surgery (P =.001). Thirty-six patients (33%) needed transfusion of stored blood, for a total of 115 units, with just four patients needing more than five units. The mortality rate was 8% (9/110). With multivariate analysis, low hemoglobin level (P =.006) and low platelet count (P =.023) were associated with stored blood transfusion. CONCLUSION: Blood loss is too small to justify ICS in surgery for occlusive disease; ANH alone may be a suitable strategy. With appropriate experience, the combination of ANH and ICS may render crossmatching unnecessary, even in aortic aneurysm surgery.     

Platelet Function and Adrenoceptors during and after Induced Hypotension using Nitroprusside

Background: Hypotension induced by sodium nitroprusside can minimize intraoperative blood loss. The release of endogenous catecholamines can influence adrenoceptors of platelets and thus might change the ability of platelets to aggregate.

Methods: Forty patients undergoing nasal septum, tympanoplastic, or sphenoid sinus surgery were randomly divided into two groups, those having controlled hypotension (A) and those serving as controls (B). Blood samples were drawn before the operation, after induction of anesthesia, 1 h after the start of the operation, and on the day after surgery.

Results: Epinephrine-induced platelet aggregation only increased in the controls on the day after surgery (A: from 49 +/- 25% to 47 +/- 29%; B: from 53 +/- 24% to 72 +/- 14%; mean +/- SD; P < 0.01). Spontaneous platelet aggregation increased in the controls from a median of 1.2 Ohm/h to 2.4 during the operation and 2.9 on the day after surgery but not after hypotension. On the day after surgery, alpha2 receptors reached their maximum (A: 238 +/- 164; B: 234 +/- 80 per platelet). During the operation, the norepinephrine concentrations were significantly greater in group A (median, 419 pg/ml) than in group B (median, 217 pg/ml; P < 0.05). Blood loss was greater in the controls (A: 180 +/- 75; B: 379 +/- 120 ml; P < 0.05).