A new practical technique to reduce allogeneic blood exposure and hospital costs while preserving clotting factors after cardiopulmonary bypass: the Hemobag®

A novel autotransfusion device saving erythrocytes and platelets used in a 72 h survival swine model of surgically induced controlled blood loss

BACKGROUND

The purpose of this study was to develop a swine model of surgically induced blood loss to evaluate the performances of a new autotransfusion system allowing red blood cells and platelets preservation while collecting, washing and concentrating hemorrhagic blood intraoperatively.

METHODS

Two types of surgically induced blood loss were used in 12 minipigs to assess system performance and potential animal complications following autotransfusion: a cardiac model (cardiopulmonary bypass) and a visceral model (induced splenic bleeding). Animal clinical and hematological parameters were evaluated at different time-points from before bleeding to the end of a 72-hour post-transfusion period and followed by a post-mortem examination. System performances were evaluated by qualitative and quantitative parameters.

RESULTS

All animals that received the autotransfusion survived. Minimal variations were seen on the red blood cell count, hemoglobin, hematocrit at the different sampling times. Coagulation tests failed to show any hypo or hypercoagulable state. Gross and histologic examination didn't reveal any thrombotic lesions. Performance parameters exceeded set objectives in both models: heparin clearance (≥ 90%), final heparin concentration (≤ 0.5 IU/mL), free hemoglobin washout (≥ 90%) and hematocrit (between 45% and 65%). The device treatment rate of diluted blood was over 80 mL/min.

CONCLUSIONS

In the present study, both animal models succeeded in reproducing clinical conditions of perioperative cardiac and non-cardiac blood loss. Sufficient blood was collected to allow evaluation of autotransfusion effects on animals and to demonstrate the system performance by evaluating its capacity to collect, wash and concentrate red blood cells and platelets. Reinfusion of the treated blood, containing not only concentrated red blood cells but also platelets, did not lead to any postoperative adverse nor thrombogenic events. Clinical and comparative studies need to be conducted to confirm the clinical benefit of platelet reinfusion.

A comparison of haemostatic biomarkers during low-risk patients undergoing cardiopulmonary bypass using either conventional centrifugal cell salvage or the HemoSep device

BACKGROUND

Cardiac surgery using cardiopulmonary bypass (CPB) is associated with a coagulopathy due to haemodilution, thrombocytopenia and platelet dysfunction and the activation of coagulation and fibrinolysis, despite the use of large doses of unfractionated heparin. Conventional red cell salvage may exacerbate post-operative bleeding as plasma containing haemostatic factors is discarded. We hypothesized that a novel cell salvage device (HemoSep) may attenuate haemostatic changes associated with red cell salvage. We studied haemostatic markers following autologous transfusion from conventional cell salvage or the HemoSep device.

METHODS

This randomised, controlled trial compared haemostatic markers in patients undergoing coronary artery bypass grafting or aortic valve replacement who received autologous blood returned from cell salvage (control) or HemoSep (study). Blood samples were taken pre-operatively, end of CPB, post-transfusion of salvaged blood and 3 hours post-operatively and analysed for full blood count (FBC), prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, D-dimer and endogenous thrombin potential (ETP).

RESULTS

Fifty-four patients were recruited (n=28 control, n=26 study). Processed blood volume for transfusion was significantly (p<0.001) higher in the HemoSep group. In the HemoSep group, the PT was shorter (18.7±0.3 vs 19.9±0.3 sec; p<0.05) post-operatively and the aPTT was longer (48.6±3.8 vs 37.3±1.0 sec; p<0.01) following autologous transfusion. In the control group, D-dimer and ETP levels were higher (1903±424 vs.1088±151; p<0.05 and 739±46 vs. 394±60; p<0.001, respectively) following autologous transfusion.

CONCLUSIONS

Although centrifuged cell salvage is known to adequately haemoconcentrate and remove unwanted substrates and bacteriological contamination, the process can exacerbate coagulopathy. The HemoSep device demonstrated some increase in haemostatic markers when used in low-risk cardiac surgery patients.

Comparative evaluation of blood salvage techniques in patients undergoing cardiac surgery with cardiopulmonary bypass

BACKGROUND

The primary objective of this study was to test and compare the efficacy of currently available intraoperative blood salvage systems via a demonstration of the level of increase in percentage concentration of red blood cells (RBC), white blood cells 9WBC) and platelets (Plt) in the end product.

METHODS

In a prospective, randomized study, data of 80 patients undergoing elective cardiac surgery with cardiopulmonary bypass in a 6-month period was collected, of which the volume aspirated from the surgical field was processed by either the HemoSep Novel Collection Bag (Advancis Surgical, Kirkby-in-Ashfield, Notts, UK) (N=40) (Group 1) or a cell- saver (C.A.T.S Plus Autotransfusion System, Fresenius Kabi, Bad Homburg, Germany) (N=40) (Group 2).

RESULTS

Hematocrit levels increased from 23.05%±2.7 to 43.02%±12 in Group 1 and from 24.5±2 up to 55.2±9 in Group 2 (p=0.013). The mean number of platelets rose to 225200±47000 from 116400 ±40000 in the HemoSep and decreased from 125200±25000 to 96500±30000 in the cell-saver group (p=0.00001). The leukocyte count was concentrated significantly better in Group 1 (from 10100±4300 to 18120±7000; p=0.001). IL-6 levels (pg/dL) decreased from 223±47 to 83±21 in Group 1 and from 219±40 to 200±40 in Group 2 (p=0.001). Fibrinogen was protected significantly better in the HemoSep group (from 185±35 to 455±45; p=0.004).

CONCLUSIONS

Intraoperative blood salvage systems functioned properly and the resultant blood product was superior in terms of red blood cell species. The HemoSep group had significantly better platelet and leukocyte concentrations and fibrinogen content.

Dialyzer-based cell salvage system: a superior alternative to conventional cell salvage in off-pump coronary artery bypass grafting

Objectives

Our goal was to test the hypothesis that the use of a dialyzer-based cell salvage system during off-pump coronary artery bypass grafting (OPCABG) reduces requirements for homologous blood transfusions (HBT) and improves postoperative haemtochemical parameters.

Methods

Data were prospectively collected for 222 patients who had OPCABG using 3 different cell salvage techniques: (1) dialyzer-based cell salvage (DBCS) ( n  = 75), (2) conventional cell salvage (CCS) ( n  = 73) and (3) without cell salvage (WCS) ( n  = 74). Salvaged blood was transfused at the end of the operation. The primary outcome of the study was the amount of homologous blood transfused. Secondary outcomes were changes in haemtochemical parameters, postoperative bleeding, need for non-invasive ventilation (NIV), postoperative complications, renal dysfunction, clotting derangement, duration of intensive care unit (ICU) and hospital stay and mortality rates.

Results

There were no deaths. In patients with >1000 ml blood loss, there was a significant reduction in HBT in the DBCS group (300 ± 161 ml) compared with the WCS group (550 ± 85 ml) ( P  <   0.0001). Postoperative changes in haemtochemical parameters were significantly fewer in the DBCS group compared with the other 2 groups. The incidence of NIV ( P  =   0.002), renal dysfunction ( P  =   0.009) and postoperative complications ( P  =   0.003) was least in the DBCS group and highest in the WCS group. Mean ICU stays were comparable ( P  =   0.208); however, the mean hospital stay was significantly shorter in the DBCS group (6.08 ± 3.12 days) compared with the WCS group (7.54 ± 4.46 days) ( P  =   0.022). There was no significant increase in coagulopathy in any group as suggested by comparable chest tube drainage ( P  =   0.285) and comparable prothrombin time.

Conclusions

The use of the DBCS system in OPCABG resulted in a significant reduction in HBT, improvement in postoperative levels of haemoglobin, platelets and albumin and reduction in complications without increased risk of coagulopathy.

Evaluation of coagulation factors and platelet function from an off-line modified ultrafiltration technique for post-cardiopulmonary bypass circuit blood recovery

Modified ultrafiltration (MUF) is a technique that hemoconcentrates residual CPB circuit blood and the patient at the same time. Hemoconcentration and MUF are Class 1-A recommendations in the anesthesia and surgical blood conservation guidelines. This study evaluated the off-line MUF process of the Hemobag (HB, Global Blood Resources, Somers, CT, USA) to quantitate coagulation factor levels, platelet (PLT) count and function in one facility and cellular growth factor concentrations of the final product that were transfused to the patient in another facility

In two cardiac surgery facilities, after decannulation, the extracorporeal circuit (ECC) blood from 22 patients undergoing cardiac surgery was processed with the HB device. In eleven patients from the first facility by the study design, blood samples for coagulation factor levels and PLT aggregation were drawn from the reservoir of the MUF device pre- and post-processing. The samples (n = 11) were sent to a reference laboratory where testing for prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT), reptilase time, fibrinogen, clotting factors II, V, VII, VIII, IX, X, ADAMTS-13, protein C, protein S, antithrombin III, von Willebrand Factor (vWF), and platelet (PLT) aggregation were performed. A portion of the final concentrated HB blood samples (n = 5-10) from the second facility by design were evaluated for transforming and platelet-derived cellular growth factor concentrations.

On average, approximately 800 – 2000 mls of whole blood were removed from the ECC post-CPB for processing in the HB device. After processing, there was, on the average, approximately 300 – 950 mls of concentrated whole blood salvaged for reinfusion. The PT and INR were significantly lower in the post-processing product compared to the pre-processing samples while the aPTT times were not significantly different. All coagulation factors and natural anti-coagulants were significantly increased in the final product. The PLT number, although increased by 24%, was not statistically significant. While PLT function assays showed a statistically significant decrease in the levels post-processing, there was substantial platelet function in the MUF product. Overall, the decrease in function was in the range of 10% to 15%. Final product PDGF-αβ and TGF-β1 averaged 11,048 and 2,040 pg/ml, respectively.

In these two case series, (ECC) circuit blood concentrated using the HB device showed coagulation studies with significantly lower PT and INR and significantly increased levels of all clotting factors. The findings are similar to trends reported in other studies utilizing conventional MUF and the HB. Functioning platelets remain in the final product, with growth factor concentrations similar to some methods employed to create platelet concentrates to enhance coagulation. Based on the ability of the HB off-line MUF procedure to concentrate circuit blood, the clinical utility of the HB device to decrease allogeneic blood product exposure should be evaluated in a prospective randomized clinical trial.

The Hemobag: the modern ultrafiltration system for patients undergoing cardiopulmonary by pass

BACKGROUND

The return of extracorporeal circuit blood at the termination of cardiopulmonary bypass (CPB) is an important feature of blood conservation during cardiac surgery procedures globally. We report our initial clinical evaluation of the Hemobag system a blood-salvaging device designed for whole blood recovery of residual post-CPB volume.

METHODS

Residual whole blood is hemoconcetrated through the multipass "recovery loop" circuit separate from the CPB and collected in the Hemobag System. This allows the surgeons to continue with surgery, decannulate, and administer protamine simultaneously while the Hemobag is in use and the CPB circuit remains safely primed. We have compared 25 patients receiving the Hemobag to a control group of 25 patients treated with the cell washer that represented our previous standard of care method of circuit blood-salvaging technique.

RESULTS

The Hemobag system provided significantly higher hemoglobin, hematocrit, fibrinogen, albumin, and total protein levels in the final product reducing the amount of wasted autologous blood cells. There were no device-related complications. There were no significant differences in terms of blood utilization, chest tube drainage and clinical outcomes over the entire postoperative period among groups.

CONCLUSIONS

These results suggest that the Hemobag system is a safe and efficient method to multipass hemoconcentrate the residual diluted blood of the CPB circuit. The Hemobag has demonstrated its ability to maximize the composition of the residual CPB volume to achieve the best possible post-CPB hemoglobin, plasma protein and coagulation factors profile for the patient respect to CW.

2011 update to the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists blood conservation clinical practice guidelines

BACKGROUND

Practice guidelines reflect published literature. Because of the ever changing literature base, it is necessary to update and revise guideline recommendations from time to time. The Society of Thoracic Surgeons recommends review and possible update of previously published guidelines at least every three years. This summary is an update of the blood conservation guideline published in 2007.

METHODS

The search methods used in the current version differ compared to the previously published guideline. Literature searches were conducted using standardized MeSH terms from the National Library of Medicine PUBMED database list of search terms. The following terms comprised the standard baseline search terms for all topics and were connected with the logical 'OR' connector--Extracorporeal circulation (MeSH number E04.292), cardiovascular surgical procedures (MeSH number E04.100), and vascular diseases (MeSH number C14.907). Use of these broad search terms allowed specific topics to be added to the search with the logical 'AND' connector.

RESULTS

In this 2011 guideline update, areas of major revision include: 1) management of dual anti-platelet therapy before operation, 2) use of drugs that augment red blood cell volume or limit blood loss, 3) use of blood derivatives including fresh frozen plasma, Factor XIII, leukoreduced red blood cells, platelet plasmapheresis, recombinant Factor VII, antithrombin III, and Factor IX concentrates, 4) changes in management of blood salvage, 5) use of minimally invasive procedures to limit perioperative bleeding and blood transfusion, 6) recommendations for blood conservation related to extracorporeal membrane oxygenation and cardiopulmonary perfusion, 7) use of topical hemostatic agents, and 8) new insights into the value of team interventions in blood management.

CONCLUSIONS

Much has changed since the previously published 2007 STS blood management guidelines and this document contains new and revised recommendations.

Intraoperative blood salvage and retransfusion from citrate treated wounds is safe and feasible

OBJECTIVES

Allogenic blood transfusions are associated with increased morbidity and mortality in surgical patients. The study objective was to investigate the feasibility and safety of intraoperative autotransfusion of unwashed shed whole blood using a novel method.

DESIGN

Twenty pigs were randomised to autotransfusion or crystalloid volume replacement. In two separate surgical wounds, the surfaces and 400 ml of shed blood were treated in situ with citrate, delivered with an equipment transforming suction to positive pressure. Central haemodynamics were monitored with a pulmonary artery catheter. Effects on oxygen-carrying capacity, formed blood elements, haemolysis, inflammation, metabolism, and coagulation were evaluated with biochemical analyses.

RESULTS

No clinically relevant adverse effects on haemodynamics were encountered, apart from a decrease in cardiac output and mixed venous saturation similar to that in control animals. Haemoglobin level was better preserved in the autotransfused group (97 vs. 86 g/L, p=0.0007). There were no major differences in biochemical variables and no macroscopic clot formation precluding autotransfusion.

CONCLUSIONS

The technique was safe and feasible for intraoperative blood salvage and autotransfusion. Haemodynamics and biochemical variables were similar to controls. The technique warrants further studies in humans, as it may contribute towards a reduction of allogenic blood transfusions.

Efficacy and cost-effectiveness of cell saving blood autotransfusion in adult lumbar fusion

The objective of this study was to explore the use of cell saver blood autotransfusion in spinal surgery and to evaluate the efficacy and cost-effectiveness of cell saver blood autotransfusion during lumbar spine fusion in adults. Specific indications for the use of cell saver in adult lumbar fusion surgery have not yet been clearly determined. A total of 50 consecutive candidates for posterolateral fusion with internal fixation were prospectively randomized into either receiving perioperatively cell saving autotransfusion (Group A: 25 patients) or not (Group B: 25 patients). The use of cell saving technique did not exclude the use of allogenic blood transfusion. Surgical indications were spinal stenosis, spondylolisthesis, adolescent idiopathic scoliosis, degenerative scoliosis and fractures. Medical and financial data were recorded. A cost-analysis was performed. Patients in Group A received 880 +/- 216 mL from cell saver and 175 +/- 202 mL allogenic blood. The patients in Group B received 908 +/- 244 mL allogenic blood. Blood volumes data collected were expressed in mean +/- SD values. The cost of blood transfusion in Group A was 995 +/-euro447 per patient and 1220 +/- 269 in Group B (P < 0.05). In elective lumbar fusion blood requirements can be satisfied with the use of autotransfusion. The use of cell saver appears to be useful and cost-effective during most elective lumbar fusions.

Does Re-operation have an Effect on Outcome Following Heart Transplantation?

OBJECTIVE

Previous cardiac operation has traditionally been considered as a potential risk factor for patients undergoing heart transplantation. This study aimed to evaluate the outcome of patients undergoing heart transplantation as a second cardiac procedure and compare it with primary heart transplantation, using meta-analytical methodology.

METHODS

A literature search was undertaken to identify relevant comparative studies. Outcomes of interest were classified into four categories: (a) intra-operative times; (b) post-operative outcomes; (c) resources; (d) actuarial outcomes.

RESULTS

Seven studies matched the selection criteria, reporting on 1004 patients. Six hundred and twenty-three had transplantation as primary operation and 381 as re-operation. The 1-year, 2-year, and 5-year mortality were similar for the two groups (HR=0.85, p=0.54; HR=0.97, p=0.88; and HR=1.04, p=0.92, respectively). Total operative, cold-ischaemic, by-pass, and cross-clamp times were significantly longer for the re-operation group by 59.44 (p<0.001), 14.62 (p=0.05), 25.24 (p<0.001), and 7.93 (p<0.001)min, respectively. Both ICU and hospital stay were longer for the re-operation group but only the former was statistically significant (WMD=1.37; p=0.02). Post-operative complications were similar, except re-exploration rate and blood transfusion requirement, which were higher in the re-operation group (OR=3.51; p<0.001 and WMD=2.21; p<0.001, respectively).

CONCLUSIONS

Heart transplantation following previous cardiac operation is technically demanding requiring longer operative times compared to primary heart transplantation. It does not, however, add a significant risk to the survival of the patient, and associated morbidity is not significantly compromised.