Are we doing everything we can to conserve blood during bypass? A national survey

Reduction of hemodilution in small adults undergoing open heart surgery: a prospective, randomized trial

Background. Given that there is an association between the degree of hemodilution during cardiopulmonary bypass (CPB) and postoperative complications, patients-outcome might be improved if the nadir hematocrit concentration is kept within an optimal range. Smaller patients are more likely to have a low hematocrit during CPB: this phenomenon may be related, at least partially, to the extreme hemodilution induced by a large fixed CPB priming volume. Methods. Forty patients with a body surface area (BSA) < 1.7 m2 undergoing open heart operations were randomized to either standard CPB with full prime volume (control group) or reduced prime extracorporeal circuit and vacuum-assisted venous drainage (VAVD) (study group). Results. There were no significant differences between the groups with respect to baseline characteristics, body surface area, hematologic profile and operative data. Clinical outcomes were similar. Nadir hematocrit and hemoglobin on bypass were significantly lower in the control group (22 ± 2.3 vs 24 ± 2.5%, p < 0.02 and 7.4 ± 0.7 vs 8 ± 0.9g/dl, p < 0.04, respectively).

Postoperative chest tube drainage was significantly higher in the control group (272 ± 253vs 139 ± 84ml, p < 0.04). There was no difference in blood transfusion in the two groups (0.5 ± 1.14 v 1.0 ± 1.77 units of packed red blood cells (PRBC), p = 0.29). Conclusions. Lowering CPB priming volume by means of using a small oxygenator and vacuum-assisted venous drainage (VAVD) resulted in a significant decrease of intraoperative hemodilution. This technique should be strongly considered for patients with a small BSA (<1.7 m2) undergoing open heart surgery. Perfusion (2007) 22, 317—322.

Is elimination of cardiotomy suction preferable in aortic valve replacement? Assessment of perioperative coagulation, fibrinolysis and inflammation

OBJECTIVES

Guidelines recommend the avoidance of direct return of pericardial blood based on evidence from coronary surgery. A continuous auto-transfusion system (CATS) can be a good alternative to cardiotomy suction by reinfusing aspirated pericardial blood without the necessity of intermittent collection. To clarify the effects of direct return of pericardial blood in aortic valve replacement (AVR), we compared the effects of cardiotomy suction and an alternative CATS on perioperative coagulofibrinolysis and inflammation systems, and clinical outcomes.

METHODS

In 40 AVR operations between April 2009 and April 2011, the retransfusion method of pericardial blood during cardiopulmonary bypass (CPB) was allocated to the use of cardiotomy suction (non-Cell-Saver group, n = 20) or CATS (Cell-Saver group, n = 20) under identical protocols of anticoagulation and transfusion. The blood from the left ventricular vent was returned to the venous reservoir. We obtained blood samples at nine points up to the morning after surgery.

RESULTS

Perioperative values for coagulofibrinolysis markers, such as thrombin-antithrombin III complex, fibrinogen degeneration products, D-dimer and plasmin-α2 plasmin inhibitor complex, were significantly lower in the Cell-Saver group than those in the non-Cell-Saver group from 1 h after the initiation of cardiopulmonary bypass to 3 or 6 h after termination of cardiopulmonary bypass (P < 0.05 for all markers). A fibrinolysis inhibition marker of plasminogen activator inhibitor-1 and the inflammation markers of interleukin-6, 8 and 10 as well as tumour necrosis factor-α were not significantly different. The amount of packed red blood cells required after the termination of CPB was significantly less in the Cell-Saver group compared with that in the non-Cell-Saver group (P = 0.004). There were no significant differences in the other clinical outcomes between the two groups.

CONCLUSIONS

In AVR, the avoidance of direct return of pericardial blood induced considerable suppressions of coagulofibrinolysis responses. A CATS is a favourable alternative for managing pericardial blood during cardiopulmonary bypass. Our results support the published guidelines and could help to establish ideal strategies for eliminating the use of cardiotomy suction, thus facilitating less-invasive valve surgeries with marked suppression of coagulofibrinolysis responses.

Pump blood processing, salvage and re-transfusion improves hemoglobin levels after coronary artery bypass grafting, but affects coagulative and fibrinolytic systems

Cell saving systems are commonly used during cardiac operations to improve hemoglobin levels and to reduce blood product requirements. We analyzed the effects of residual pump blood salvage through a cell saver on coagulation and fibrinolysis activation and on postoperative hemoglobin levels. Thirty-four elective coronary artery bypass graft (CABG) patients were randomized. In 17 patients, residual cardiopulmonary bypass (CPB) circuit blood was transfused after the cell saving procedure (cell salvage group). In the other 17 patients, residual CPB circuit blood was discarded (control group). Activation of the coagulative, fibrinolytic and inflammatory systems was evaluated pre-operatively (Pre), 2 hours after the termination of CPB (T0) and 24 hours postoperatively (T1), measuring prothrombin fragment 1.2 (PF 1.2), plasmin-anti-plasmin (PAP), plasminogen activator inhibitor-1 (PAI-1) and interleukin-6 (IL-6). The cell salvage group of patients had a significant improvement in hemoglobin levels after processed blood infusion (2.7 ± 1.7 g/dL vs 1.2 ± 1.1 g/dL; p=0.003). PF1.2 levels were significantly higher after infusion (T0: 1175 ± 770 pmol/L vs 730 ± 237 pmol/L; p=0.037; T1: 331 ± 235 pmol/L vs 174 ± 134 pmol/L; p=0.026). Also, PAP levels were higher in the cell salvage group, although not significantly (T0: 253 ± 251 ng/mL vs 168 ± 96 ng/mL; p: NS; T1: 95 ± 60 ng/mL vs 53 ± 32 ng/mL; p: NS). No differences were found for PAI-1, IL-6, heparin levels or for red blood cell (RBC) transfusions. The cell salvage group of patients had increased chest tube drainage (749 ± 320 vs 592 ± 264; p: NS) and fresh frozen plasma transfusion rate (5 (29%) pts vs 0 pts; p<0.04). Pump blood salvage with a cell saving system improved postoperative hemoglobin levels, but induced a strong thrombin generation, fibrinolysis activation and lower fibrinolysis inhibition. These conditions could generate a consumption coagulopathy.

Perfusion safety: new initiatives and enduring principles

Perfusion safety has been studied and discussed extensively for decades. Many initiatives occurred through efforts of professional organizations to achieve recognition, establish accreditation and certification, promote consensus practice guidelines, and develop peer-reviewed journals as sources for dissemination of clinical information. Newer initiatives have their basis in other disciplines and include systems approach, Quality Assurance/Quality Improvement processes, error recognition, evidence-based methodologies, registries, equipment automation, simulation, and the Internet. Use of previously established resources such as written protocols, checklists, safety devices, and enhanced communication skills has persisted to the present in promoting perfusion safety and has reduced current complication rates to negligible levels.

Pathophysiological aspects of cardiotomy suction usage

Cardiotomy suction is used for preservation of autologous blood during on-pump cardiac surgery at present. Controversially, the exclusion of cardiotomy suction in some types of operations (coronary artery bypass surgery) is not necessarily associated with an increased transfusion requirement. On the other hand, the use of cardiotomy suction causes an amplification of systemic inflammatory response and a resulting coagulopathy, as well as exacerbation of the microembolic load and hemolysis. This leads to a tendency towards increased blood loss, transfusion requirement and organ dysfunction. On the basis of these facts, it is appropriate to reconsider routine use of cardiotomy suction in on-pump coronary artery surgery.

The efficacy of an intraoperative cell saver during cardiac surgery: a meta-analysis of randomized trials

BACKGROUND

Cell salvage may be used during cardiac surgery to avoid allogeneic blood transfusion. It has also been claimed to improve patient outcomes by removing debris from shed blood, which may increase the risk of stroke or neurocognitive dysfunction. In this study, we sought to determine the overall safety and efficacy of cell salvage in cardiac surgery by performing a systematic review and meta-analysis of published randomized controlled trials.

METHODS

A comprehensive search was undertaken to identify all randomized trials of cell saver use during cardiac surgery. MEDLINE, Cochrane Library, EMBASE, and abstract databases were searched up to November 2008. All randomized trials comparing cell saver use and no cell saver use in cardiac surgery and reporting at least one predefined clinical outcome were included. The random effects model was used to calculate the odds ratios (OR, 95% confidence intervals [CI]) and the weighted mean differences (WMD, 95% CI) for dichotomous and continuous variables, respectively.

RESULTS

Thirty-one randomized trials involving 2282 patients were included in the meta-analysis. During cardiac surgery, the use of an intraoperative cell saver reduced the rate of exposure to any allogeneic blood product (OR 0.63, 95% CI: 0.43-0.94, P = 0.02) and red blood cells (OR 0.60, 95% CI: 0.39-0.92, P = 0.02) and decreased the mean volume of total allogeneic blood products transfused per patient (WMD -256 mL, 95% CI: -416 to -95 mL, P = 0.002). There was no difference in hospital mortality (OR 0.65, 95% CI: 0.25-1.68, P = 0.37), postoperative stroke or transient ischemia attack (OR 0.59, 95% CI: 0.20-1.76, P = 0.34), atrial fibrillation (OR 0.92, 95% CI: 0.69-1.23, P = 0.56), renal dysfunction (OR 0.86, 95% CI: 0.41-1.80, P = 0.70), infection (OR 1.25, 95% CI: 0.75-2.10, P = 0.39), patients requiring fresh frozen plasma (OR 1.16, 95% CI: 0.82-1.66, P = 0.40), and patients requiring platelet transfusions (OR 0.90, 95% CI: 0.63-1.28, P = 0.55) between cell saver and noncell saver groups.

CONCLUSIONS

Current evidence suggests that the use of a cell saver reduces exposure to allogeneic blood products or red blood cell transfusion for patients undergoing cardiac surgery. Subanalyses suggest that a cell saver may be beneficial only when it is used for shed blood and/or residual blood or during the entire operative period. Processing cardiotomy suction blood with a cell saver only during cardiopulmonary bypass has no significant effect on blood conservation and increases fresh frozen plasma transfusion.

The Cardiotomy Trial

Background— Reinfusion of unprocessed cardiotomy blood during cardiac surgery can introduce particulate material into the cardiopulmonary bypass circuit, which may contribute to postoperative cognitive dysfunction. On the other hand, processing of this blood by centrifugation and filtration removes coagulation factors and may potentially contribute to coagulopathy. We sought to evaluate the effects of cardiotomy blood processing on blood product use and neurocognitive functioning after cardiac surgery.

Methods and Results— Patients undergoing coronary and/or aortic valve surgery using cardiopulmonary bypass were randomized to receive unprocessed blood (control, n=134) or cardiotomy blood that had been processed by centrifugal washing and lipid filtration (treatment, n=132). Patients and treating physicians were blinded to treatment assignment. A strict transfusion protocol was followed. Blood transfusion data were analyzed using Poisson regression models. The treatment group received more intraoperative red blood cell transfusions (0.23±0.69 U versus 0.08±0.34 U, P =0.004). Both red blood cell and nonred blood cell blood product use was greater in the treatment group and postoperative bleeding was greater in the treatment group. Patients were monitored intraoperatively by transcranial Doppler and they underwent neuropsychometric testing before surgery and at 5 days and 3 months after surgery. There was no difference in the incidence of postoperative cognitive dysfunction in the 2 groups (relative risk: 1.16, 95% CI: 0.86 to 1.57 at 5 days postoperatively; relative risk: 1.05, 95% CI: 0.58 to 1.90 at 3 months). There was no difference in the quality of life nor was there a difference in the number of emboli detected in the 2 groups.

Conclusions— Contrary to expectations, processing of cardiotomy blood before reinfusion results in greater blood product use with greater postoperative bleeding in patients undergoing cardiac surgery. There is no clinical evidence of any neurologic benefit with this approach in terms of postoperative cognitive function.

Ultrafiltration reduces blood transfusions following cardiac surgery: a meta-analysis

BACKGROUND

Although used routinely in pediatric patients, ultrafiltration techniques that reverse hemodilution are infrequently used in adults. Data from small, unblinded clinical trials suggest that the use of ultrafiltration can reduce inflammatory mediators, improve cardiac function, and reduce hemodilution. We conducted a meta-analysis of randomized trials to evaluate the effects of ultrafiltration on blood transfusions and blood loss following adult cardiac surgery.

METHODS

Medline, EMBASE, and Cochrane databases were searched and randomized controlled trials evaluating modified and/or conventional ultrafiltration, meeting pre-determined selection criteria, were obtained. Quality evaluation and data extraction were performed by two independent observers blinded to study source. Random effects models were used to determine pooled effect estimates and sources of heterogeneity were explored using meta-regression.

RESULTS

One hundred and thirty two studies were screened and 10 randomized trials evaluating 1004 patients (control, n = 495; ultrafiltration, n = 509) were identified of which only two were double-blinded. The use of ultrafiltration was associated with a reduction in postoperative blood transfusions (weighted mean difference [95% CI] of -0.73 units [-1.16, -0.31]; p = 0.001). This reduction was greater in studies evaluating modified ultrafiltration. Use of ultrafiltration was also associated with reduced postoperative bleeding (-70 ml, [-118, -21]; p = 0.005), which was driven primarily by trials evaluating modified rather than conventional ultrafiltration.

CONCLUSIONS

Use of ultrafiltration is associated with a significant reduction in postoperative blood transfusions as well as reduced bleeding in adults undergoing cardiac surgery. The efficacy and cost-effectiveness of ultrafiltration as a blood conservations strategy should be evaluated in a large, randomized, double-blinded study.