Autotransfusion following cardiac operations: a randomized, prospective study

Cell salvage for minimising perioperative allogeneic blood transfusion in adults undergoing elective surgery

BACKGROUND

Concerns regarding the safety and availability of transfused donor blood have prompted research into a range of techniques to minimise allogeneic transfusion requirements. Cell salvage (CS) describes the recovery of blood from the surgical field, either during or after surgery, for reinfusion back to the patient.

OBJECTIVES

To examine the effectiveness of CS in minimising perioperative allogeneic red blood cell transfusion and on other clinical outcomes in adults undergoing elective or non-urgent surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, three other databases and two clinical trials registers for randomised controlled trials (RCTs) and systematic reviews from 2009 (date of previous search) to 19 January 2023, without restrictions on language or publication status.

SELECTION CRITERIA

We included RCTs assessing the use of CS compared to no CS in adults (participants aged 18 or over, or using the study's definition of adult) undergoing elective (non-urgent) surgery only.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 106 RCTs, incorporating data from 14,528 participants, reported in studies conducted in 24 countries. Results were published between 1978 and 2021. We analysed all data according to a single comparison: CS versus no CS. We separated analyses by type of surgery. The certainty of the evidence varied from very low certainty to high certainty. Reasons for downgrading the certainty included imprecision (small sample sizes below the optimal information size required to detect a difference, and wide confidence intervals), inconsistency (high statistical heterogeneity), and risk of bias (high risk from domains including sequence generation, blinding, and baseline imbalances). Aggregate analysis (all surgeries combined: primary outcome only) Very low-certainty evidence means we are uncertain if there is a reduction in the risk of allogeneic transfusion with CS (risk ratio (RR) 0.65, 95% confidence interval (CI) 0.59 to 0.72; 82 RCTs, 12,520 participants). Cancer: 2 RCTs (79 participants) Very low-certainty evidence means we are uncertain whether there is a difference for mortality, blood loss, infection, or deep vein thrombosis (DVT). There were no analysable data reported for the remaining outcomes. Cardiovascular (vascular): 6 RCTs (384 participants) Very low- to low-certainty evidence means we are uncertain whether there is a difference for most outcomes. No data were reported for major adverse cardiovascular events (MACE). Cardiovascular (no bypass): 6 RCTs (372 participants) Moderate-certainty evidence suggests there is probably a reduction in risk of allogeneic transfusion with CS (RR 0.82, 95% CI 0.69 to 0.97; 3 RCTs, 169 participants). Very low- to low-certainty evidence means we are uncertain whether there is a difference for volume transfused, blood loss, mortality, re-operation for bleeding, infection, wound complication, myocardial infarction (MI), stroke, and hospital length of stay (LOS). There were no analysable data reported for thrombosis, DVT, pulmonary embolism (PE), and MACE. Cardiovascular (with bypass): 29 RCTs (2936 participants) Low-certainty evidence suggests there may be a reduction in the risk of allogeneic transfusion with CS, and suggests there may be no difference in risk of infection and hospital LOS. Very low- to moderate-certainty evidence means we are uncertain whether there is a reduction in volume transfused because of CS, or if there is any difference for mortality, blood loss, re-operation for bleeding, wound complication, thrombosis, DVT, PE, MACE, and MI, and probably no difference in risk of stroke. Obstetrics: 1 RCT (1356 participants) High-certainty evidence shows there is no difference between groups for mean volume of allogeneic blood transfused (mean difference (MD) -0.02 units, 95% CI -0.08 to 0.04; 1 RCT, 1349 participants). Low-certainty evidence suggests there may be no difference for risk of allogeneic transfusion. There were no analysable data reported for the remaining outcomes. Orthopaedic (hip only): 17 RCTs (2055 participants) Very low-certainty evidence means we are uncertain if CS reduces the risk of allogeneic transfusion, and the volume transfused, or if there is any difference between groups for mortality, blood loss, re-operation for bleeding, infection, wound complication, prosthetic joint infection (PJI), thrombosis, DVT, PE, stroke, and hospital LOS. There were no analysable data reported for MACE and MI. Orthopaedic (knee only): 26 RCTs (2568 participants) Very low- to low-certainty evidence means we are uncertain if CS reduces the risk of allogeneic transfusion, and the volume transfused, and whether there is a difference for blood loss, re-operation for bleeding, infection, wound complication, PJI, DVT, PE, MI, MACE, stroke, and hospital LOS. There were no analysable data reported for mortality and thrombosis. Orthopaedic (spine only): 6 RCTs (404 participants) Moderate-certainty evidence suggests there is probably a reduction in the need for allogeneic transfusion with CS (RR 0.44, 95% CI 0.31 to 0.63; 3 RCTs, 194 participants). Very low- to moderate-certainty evidence suggests there may be no difference for volume transfused, blood loss, infection, wound complication, and PE. There were no analysable data reported for mortality, re-operation for bleeding, PJI, thrombosis, DVT, MACE, MI, stroke, and hospital LOS. Orthopaedic (mixed): 14 RCTs (4374 participants) Very low- to low-certainty evidence means we are uncertain if there is a reduction in the need for allogeneic transfusion with CS, or if there is any difference between groups for volume transfused, mortality, blood loss, infection, wound complication, PJI, thrombosis, DVT, MI, and hospital LOS. There were no analysable data reported for re-operation for bleeding, MACE, and stroke.

AUTHORS' CONCLUSIONS

In some types of elective surgery, cell salvage may reduce the need for and volume of allogeneic transfusion, alongside evidence of no difference in adverse events, when compared to no cell salvage. Further research is required to establish why other surgeries show no benefit from CS, through further analysis of the current evidence. More large RCTs in under-reported specialities are needed to expand the evidence base for exploring the impact of CS.

"Asanguinous" Open-Heart Surgery

"Asanguinous" open-heart surgery was initially performed by our team at our institution in January 1982 for mitral valve replacement in a Jehovah's Witness, whose religious beliefs precluded blood transfusion. Since then, we have applied this principle to all of our open-heart cases, with excellent results. Using an IBM 2991 blood cell processor and Sorensen Autologous Transfusion System, our institution has salvaged an average of 92.1 units of blood per month, from January 1982 to December of 1983, with a total of 650 units for 1982 and 1105 units for 1983. From January to August of 1984, a total of 645 units were saved, with an average of 80 units per month. This protocol involved 1121 patients with coronary bypass surgery, 32 of which had concommitant repair of IV aneurysm, and 27 with unilateral carotid endarterectomy. One hundred and sixty-eight underwent cardiac valve replacement, 109 mitral, 57 aortic, and 2 combined MVR-AYR. Eighty-six percent of our entire series did not require homologous, transfusion, other than their own, individual salvaged packed cells. "Asanguinous" open-heart surgery is not only possible and safe, but also a medically prudent technique that is cost-efficient and devoid of the usual hazards associated with homologous transfusion.

Transfusional quality of residual blood from heart—lung machine after extracorporeal circulation

After open-heart surgery using extracorporeal circulation, residual blood from the heart-lung machine was collected, treated by plasmaphaeresis and washed using a Haemonetics Cell Saver. Qualitative, quantitative and bacteriological aspects of the concentrated red cells were studied.

In 13 patients, an average of 500 ml of concentrated washed red cells (CWRC) was obtained with an average haematocrit of 62·3 %; bacteriological cultures were negative in all cases. As far as qualitative aspects were concerned (intraglobular ATP, 2, 3 DPG, deformability, filtrability and resistance to hypotonic solutions), these red cells were always compatible with immediate transfusion. However, the small volume of blood retrieved and the relatively high cost of this technique suggest that its use be restricted to cases of total haemodilution or for patients with rare blood groups, in whom homologous transfusion blood is scarce.

Conventional hemofiltration during cardiopulmonary bypass increases the serum lactate level in adult cardiac surgery

OBJECTIVE

To evaluate the effect of hemofiltration during cardiopulmonary bypass on lactate level in adult patients who underwent cardiac surgery.

DESIGN

An observational study.

SETTING

Prince Sultan cardiac center, Riyadh, Saudi Arabia.

PARTICIPANTS

The study included 283 patients classified into two groups: Hemofiltration group (n=138), hemofiltration was done during CPB. Control group (n = 145), patients without hemofiltration.

INTERVENTIONS

Hemofiltration during cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Monitors included hematocrit, lactate levels, mixed venous oxygen saturation, amount of fluid removal during hemofiltration and urine output. The lactate elevated in group H than group C (P < 0.05), and the PH showed metabolic acidosis in group H (P < 0.05). The mixed venous oxygen saturation decreased in group H than group C (P < 0.05). The number of transfused packed red blood cells was lower in group H than group C (P < 0.05). The hematocrit was higher in group H than group C (P < 0.05). The urine output was lower in group H than group C (P < 0.05).

CONCLUSIONS

Hemofiltration during cardiopulmonary bypass leads to hemoconcentration, elevated lactate level and increased inotropic support. There are some recommendations for hemofiltration: First; Hemofiltration should be limited for patients with impaired renal function, positive fluid balance, reduced response to diuretics or prolonged bypass time more than 2 hours. Second; Minimal amount of fluids should be administered to maintain adequate cardiac output and reduction of priming volumes is preferable to maintain controlled hemodilution. Third; it should be done before weaning of or after cardiopulmonary bypass and not during the whole time of cardiopulmonary bypass.

Management of intraoperative fluid balance and blood conservation techniques in adult cardiac surgery

Blood transfusions are associated with adverse physiologic effects and increased cost, and therefore reduction of blood product use during surgery is a desirable goal for all patients. Cardiac surgery is a major consumer of donor blood products, especially when cardiopulmonary bypass (CPB) is used, because hematocrit drops precipitously during CPB due to blood loss and blood cell dilution. Advanced age, low preoperative red blood cell volume (preoperative anemia or small body size), preoperative antiplatelet or antithrombotic drugs, complex or re-operative procedures or emergency operations, and patient comorbidities were identified as important transfusion risk indicators in a report recently published by the Society of Cardiovascular Anesthesiologists. This report also identified several pre- and intraoperative interventions that may help reduce blood transfusions, including off-pump procedures, preoperative autologous blood donation, normovolemic hemodilution, and routine cell saver use.A multimodal approach to blood conservation, with high-risk patients receiving all available interventions, may help preserve vital organ perfusion and reduce blood product utilization. In addition, because positive intravenous fluid balance is a significant factor affecting hemodilution during cardiac surgery, especially when CPB is used, strategies aimed at limiting intraoperative fluid balance positiveness may also lead to reduced blood product utilization.This review discusses currently available techniques that can be used intraoperatively in an attempt to avoid or minimize fluid balance positiveness, to preserve the patient's own red blood cells, and to decrease blood product utilization during cardiac surgery.

Time-related hemolysis in stored shed mediastinal blood after cardiopulmonary bypass

Reinfusion of mediastinal shed blood during cardiopulmonary bypass reportedly reduces the need for homologous blood transfusion. Although the fragility of blood components is thought to be amplified by shear stress during cardiopulmonary bypass and processing, the time-related deterioration of red blood cells (RBCs) in stored shed blood has not been studied extensively. In this study, we examined time-related hemolysis in shed blood stored at different temperatures. We examined processed shed blood collected from 15 patients (11 men and 4 women; mean age ± standard deviation, 71 ± 9 years) during cardiopulmonary bypass. The shed blood was collected and stored at 20°C (group A) or 4°C (group B). Stored blood collected by venipuncture at the end of the surgery was used as a control. Damage was assessed by measuring its free hemoglobin (Hb) levels, using a photometric assay. The free Hb levels in blood samples from each group were tested at 0, 3, 6, 12, 24, 36, and 48 h after surgery. The free Hb levels (g/dl) at 0, 12, and 24 h were 0.03 ± 0.01, 0.05 ± 0.02*, and 0.06 ± 0.02* in group A; 0.03 ± 0.02, 0.04 ± 0.03, and 0.05 ± 0.02* in group B; and 0.01 ± 0.01, 0.01 ± 0.01, and 0.01 ± 0.01 in the control group (*p < 0.05 vs. 0 h after surgery). The free Hb levels in stored shed blood significantly increased after 12 h in group A (20°C) and increased after 24 h in group B (4°C), whereas in drawn blood, they did not significantly increase over the first 24 h. Compared to storage at 20°C, storage at 4°C suppresses the increase in the free Hb levels.

The future of blood management

An evolving understanding of the consequences of allogeneic blood transfusion and escalating costs of providing allogeneic blood have resulted in an interest in blood management. Understanding the consequences of allogeneic transfusion includes a recognition of the immunosuppressive effects of allogeneic transfusion, a growing awareness of transfusion-related acute lung injury, and a rediscovery of transfusion-associated circulatory overload. More recently, interest has focused on the effect of stored blood on patient outcome. Although this discussion is not all-inclusive, it is intended to show that many techniques can be applied to decrease the exposure to allogeneic blood.

Cell salvage for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have prompted reconsideration of the use of allogeneic (from an unrelated donor) red blood cell (RBC) transfusion, and a range of techniques to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of cell salvage in reducing allogeneic blood transfusion and the evidence for any effect on clinical outcomes.

SEARCH STRATEGY

We identified studies by searching CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (1950 to June 2009), EMBASE (1980 to June 2009), the internet (to August 2009) and bibliographies of published articles.

SELECTION CRITERIA

Randomised controlled trials with a concurrent control group in which adult patients, scheduled for non-urgent surgery, were randomised to cell salvage (autotransfusion) or to a control group who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Data were independently extracted and the risk of bias assessed. Relative risks (RR) and weighted mean differences (WMD) with 95% confidence intervals (CIs) were calculated. Data were pooled using a random-effects model. The primary outcomes were the number of patients exposed to allogeneic red cell transfusion and the amount of blood transfused. Other clinical outcomes are detailed in the review.

MAIN RESULTS

A total of 75 trials were included. Overall, the use of cell salvage reduced the rate of exposure to allogeneic RBC transfusion by a relative 38% (RR 0.62; 95% CI 0.55 to 0.70). The absolute reduction in risk (ARR) of receiving an allogeneic RBC transfusion was 21% (95% CI 15% to 26%). In orthopaedic procedures the RR of exposure to RBC transfusion was 0.46 (95% CI 0.37 to 0.57) compared to 0.77 (95% CI 0.69 to 0.86) for cardiac procedures. The use of cell salvage resulted in an average saving of 0.68 units of allogeneic RBC per patient (WMD -0.68; 95% CI -0.88 to -0.49). Cell salvage did not appear to impact adversely on clinical outcomes.

AUTHORS' CONCLUSIONS

The results suggest cell salvage is efficacious in reducing the need for allogeneic red cell transfusion in adult elective cardiac and orthopaedic surgery. The use of cell salvage did not appear to impact adversely on clinical outcomes. However, the methodological quality of trials was poor. As the trials were unblinded and lacked adequate concealment of treatment allocation, transfusion practices may have been influenced by knowledge of the patients' treatment status potentially biasing the results in favour of cell salvage.

Cell salvage for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood, have prompted reconsideration of the use of allogeneic (blood from an unrelated donor) red blood cell (RBC) transfusion, and a range of techniques to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of cell salvage in reducing allogeneic blood transfusion and the evidence for any effect on clinical outcomes.

SEARCH STRATEGY

We identified studies by searching CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (1950 to June 2009), EMBASE (1980 to June 2009), the Internet (to August 2009) and bibliographies of published articles.

SELECTION CRITERIA

Randomised controlled trials with a concurrent control group in which adult patients, scheduled for non-urgent surgery, were randomised to cell salvage (autotransfusion), or to a control group, who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Data were independently extracted and the risk of bias assessed. Relative risks (RR) and weighted mean differences (WMD) with 95% confidence intervals (CIs) were calculated. Data were pooled using a random effects model. The primary outcomes were the number of patients exposed to allogeneic red cell transfusion, and the amount of blood transfused. Other clinical outcomes are detailed in the review.

MAIN RESULTS

A total of 75 trials were included. Overall, the use of cell salvage reduced the rate of exposure to allogeneic RBC transfusion by a relative 38% (RR=0.62: 95% CI 0.55 to 0.70). The absolute reduction in risk (ARR) of receiving an allogeneic RBC transfusion was 21% (95% CI 15% to 26%). In orthopaedic procedures the RR of exposure to RBC transfusion was 0.46 (95% CI 0.37 to 0.57) compared to 0.77 (95% CI 0.69 to 0.86) for cardiac procedures. The use of cell salvage resulted in an average saving of 0.68 units of allogeneic RBC per patient (WMD=-0.68; 95% CI -0.88 to -0.49). Cell salvage did not appear to impact adversely on clinical outcomes.

AUTHORS' CONCLUSIONS

The results suggest cell salvage is efficacious in reducing the need for allogeneic red cell transfusion in adult elective cardiac and orthopaedic surgery. The use of cell salvage did not appear to impact adversely on clinical outcomes. However, the methodological quality of trials was poor. As the trials were unblinded and lacked adequate concealment of treatment allocation, transfusion practices may have been influenced by knowledge of the patients' treatment status potentially biasing the results in favour of cell salvage.

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Cell salvage for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood, have prompted reconsideration of the use of allogeneic (blood from an unrelated donor) red blood cell (RBC) transfusion, and a range of techniques to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of cell salvage in reducing allogeneic blood transfusion and the evidence for any effect on clinical outcomes.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Current Contents and the websites of international health technology assessment agencies. The reference lists in identified trials and review articles were also searched, and study authors were contacted to identify additional studies. The searches were updated in January 2004.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to cell salvage, or to a control group, who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Two authors independently screened search results, extracted data and assessed methodological quality. The main outcomes measures were the number of patients exposed to allogeneic red cell transfusion, and the amount of blood transfused. Other outcomes measured were re-operation for bleeding, blood loss, post-operative complications (thrombosis, infection, non-fatal myocardial infarction, renal failure), mortality, and length of hospital stay (LOS).

MAIN RESULTS

Overall, the use of cell salvage reduced the rate of exposure to allogeneic RBC transfusion by a relative 39% (relative risk [RR] = 0.61: 95% confidence interval [CI] 0.52 to 0.71). The absolute reduction in risk (ARR) of receiving an allogeneic RBC transfusion was 23% (95% CI 16% to 30%). In orthopaedic procedures the RR of exposure to RBC transfusion was 0.42 (95% CI 0.32 to 0.54) compared to 0.77 (95% CI 0.68 to 0.87) for cardiac procedures. The use of cell salvage resulted in an average saving of 0.67 units of allogeneic RBC per patient (weighted mean difference was -0.64; 95% CI -0.89 to -0.45). Cell salvage did not appear to impact adversely on clinical outcomes.

AUTHORS' CONCLUSIONS

The results suggest cell salvage is efficacious in reducing the need for allogeneic red cell transfusion in adult elective surgery. However, the methodological quality of trials was poor. As the trials were unblinded and lacked adequate concealment of treatment allocation, transfusion practices may have been influenced by knowledge of the patients' treatment status biasing the results in favour of cell salvage.

Identifying Patients at Risk of Intraoperative and Postoperative Transfusion in Isolated CABG: Toward Selective Conservation Strategies

BACKGROUND

Allogeneic blood product use during cardiac operation is often reported to exceed 40% despite published guidelines and costly blood conservation strategies. We developed a predictive model, based on eight preoperative risk factors, of allogeneic blood product transfusion rates in patients undergoing a cardiac procedure.

METHODS

All 3,046 consecutive, isolated coronary artery bypass graft (CABG) procedures at a university hospital from 1995 to 1998 were included. A logistic regression model was created to identify independent predictors of allogeneic blood product transfusion. This model was validated using a prospective patient sample.

RESULTS

Overall use of allogeneic blood products was 23% with a crude operative mortality of 2.1%. In isolated, elective, first-time CABG cases, 16.9% received allogeneic blood products. Independent predictors of blood product usage in CABG patients were preoperative hemoglobin 12.0 or less, emergent operation, renal failure, female sex, age 70 years or older, left ventricular ejection fraction 0.40 or less, redo procedure, and low body surface area. Prospective validation of this model on 2,117 consecutive isolated CABG patients demonstrated an observed-to-expected allogeneic blood product transfusion rate ratio of 1.06.

CONCLUSIONS

This internally validated logistic regression risk model is a sensitive and specific predictor of allogeneic blood product use in patients undergoing isolated CABG. Utilization of this model allows for preoperative risk stratification and may allow for more rational resource allocation of costly blood conservation strategies and blood bank resources.

Blood conservation for critically ill patients

Anemia may be the most common illness of critically ill patients. The majority of critically ill patients are anemic at admission to the intensive care unit (ICU), and hemoglobin concentrations typically decline during the first 3 days of ICU stay. Hemoglobin continues to decline for patients with sepsis and higher severity of illness. This patient population may be at particular risk of adverse consequences of anemia given the cardiovascular, respiratory, and metabolic compromise frequently encountered during critical illness. The etiology of anemia of critical illness is multifactorial, resulting from phlebotomy, gastrointestinal bleeding, coagulation disorders, blood loss from vascular procedures, renal failure, nutritional deficiencies,bone marrow suppression, and impaired erythropoietin response.

Blood conservation in the intensive care unit

OBJECTIVE

To describe blood conservation strategies for critically ill patients.

DATA SOURCES

By using a predefined strategy, we searched the electronic databases of Medline, EMBASE, CINAHL, the Cochrane database of systematic reviews, Cochrane central register of controlled trials, ACP Journal Club, Database of abstracts of reviews and effects, and HealthSTAR for descriptions and evaluations of strategies of blood conservation among critically ill patients.

DATA SUMMARY

A number of blood conservation strategies have been used to prevent or treat anemia among critically ill patients. These include restrictive diagnostic phlebotomy using small-volume or pediatric phlebotomy tubes, point-of-care and inline bedside microanalysis, minimization of diagnostic sample waste, minimization of routine multiple daily phlebotomies, red blood cell salvage and antifibrinolytic agents for bleeding patients, consideration of removal of central venous and arterial catheters when no longer required for physiologic monitoring, threshold-based transfusion policy, and healthcare professional education.

CONCLUSIONS

There are many strategies of blood conservation for critically ill patients. The effects of these strategies on phlebotomy volumes, hemoglobin and hematocrit levels, transfusion requirements, clinical outcomes, as well as intensive care unit and laboratory resources and costs should be further evaluated.

Autotransfusion of Shed Mediastinal Blood *

RATIONALE

After the introduction of autotransfusion of shed mediastinal blood following cardiac surgery, the incidence of mediastinitis increased. The role of autotransfusion in the increased occurrence of this serious complication was examined.

METHODS

Using a case-control design, the preoperative, intraoperative, and postoperative characteristics of 11 patients with mediastinitis were compared to those of 33 randomly selected patients undergoing cardiac surgery between September 1, 2000, and April 15, 2001 (control subjects).

RESULTS

Patients with mediastinitis were significantly more likely to have a body mass index > 30 (unadjusted odds ratio [OR], 9.9; 95% confidence interval [CI], 2.3 to 42.5), to have received antibiotic therapy during the 2 weeks prior to cardiac surgery (OR, 12.0; 95% CI, 1.1 to 131), or to have required re-exploration within 24 h of the original operation (OR, 8.3; 95% CI, 1.8 to 39). Patients with mediastinitis had 3.4 known risk factors for mediastinitis, compared to only 1.4 risk factors per control subject (p = 0.0001), and longer duration of autotransfusion. After adjustment for other risk factors, autotransfusion for > 6 h was significantly associated with the development of mediastinitis (adjusted OR, 11.9; 95% CI, 1.4 to 97.2).

CONCLUSION

Retransfusion of shed mediastinal blood for > 6 h after cardiac surgery was an independent risk factor for mediastinitis.

Cell salvage for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood, have prompted reconsideration of the use of allogeneic (blood from an unrelated donor) red blood cell (RBC) transfusion, and a range of techniques to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of cell salvage in reducing allogeneic blood transfusion and the evidence for any effect on clinical outcomes.

SEARCH STRATEGY

Articles were identified by: computer searches of MEDLINE, EMBASE, Current Contents (to July 2002), the Cochrane Controlled Trials Register (Issue 2, 2002) and websites of international health technology assessment agencies. References in the identified trials and review articles were searched and authors contacted to identify additional studies.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to cell salvage, or to a control group, who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed using criteria proposed by Schulz et al. (Schulz 1995) and Jadad et al. (Jadad 1996). Main outcomes measured were: the number of patients exposed to allogeneic red cell transfusion, and the amount of blood transfused. Other outcomes measured were: re-operation for bleeding, blood loss, post-operative complications (thrombosis, infection, non-fatal myocardial infarction, renal failure), mortality, and length of hospital stay (LOS).

MAIN RESULTS

Overall, the use of cell salvage reduced the rate of exposure to allogeneic RBC transfusion by a relative 40% (relative risk [RR] = 0.60: 95% confidence interval [CI] = 0.51 to 0.70). The absolute reduction in risk (ARR) of receiving an allogeneic RBC transfusion was 23% (95%CI = 16% to 30%). In orthopaedic procedures the relative risk (RR) of exposure to RBC transfusion was 0.42 (95%CI = 0.32 to 0.54) compared to 0.78 (95%CI = 0.68 to 0.88) for cardiac procedures. The use of cell salvage resulted in an average saving of 0.64 units of allogeneic RBC per patient (weighted mean difference [WMD] = -0.64: 95%CI = -0.86 to -0.46). Cell salvage did not appear to impact adversely on clinical outcomes.

REVIEWER'S CONCLUSIONS

The results suggest cell salvage is efficacious in reducing the need for allogeneic red cell transfusion in adult elective surgery. However, the methodological quality of trials was poor. As the trials were unblinded and lacked adequate concealment of treatment allocation, transfusion practices may have been influenced by knowledge of the patient's treatment status biasing the results in favour of cell salvage.

Effectiveness of combined blood conservation measures in thoracic aortic operations with deep hypothermic circulatory arrest

BACKGROUND

The effectiveness of blood conservation measures for thoracic aortic operations with deep hypothermic circulatory arrest has not yet been documented.

METHODS

From July 1997 to December 2000, 148 thoracic aortic operations were performed in our department. Sixty-one cases involving patients who underwent elective thoracic aortic operation with deep hypothermic circulatory arrest were reviewed retrospectively.

RESULTS

Seventeen patients did not meet the criteria for the blood conservation program and were excluded from the present study. Therefore, 44 patients were analyzed in this study. Overall, 50% of patients did not require operative homologous blood transfusion (HBT) and 43% did not require in-hospital HBT. Smaller amounts of autologous donation, greater blood loss, and a longer operation time were independent risk factors for HBT requirement. Among 16 patients who had made an autologous donation of 1,600 mL or greater, 75% did not require intraoperative HBT and 69% did not require in-hospital HBT. The overall perioperative mortality rate was 4.5%. As for postoperative complications, prolonged intubation and postoperative infection were significantly more frequent among patients who required in-hospital HBT.

CONCLUSIONS

Our combined blood conservation measures were effective in avoiding HBT during major thoracic aortic operations with deep hypothermic circulatory arrest and may have reduced postoperative complications. The amount of the autologous donation was a strong predictor for avoiding HBT.

Troponin I concentrations of shed blood might influence monitoring of myocardial injury after coronary operations

In a prospective study we evaluated the concentration of cardiac troponin I (cTnI) and creatine kinase activities (CK) in shed mediastinal blood in the early postoperative period after coronary artery bypass grafting (CABG). Forty seven patients who underwent first time elective CABG were studied. CTnI levels and CK activities in arterial blood and shed mediastinal blood were measured after admission to the intensive care unit (ICU) and 6 h after unclamping the aorta. Mediastinal shed blood samples were drawn from 23 patients (group A) before the filter of the cardiotomy reservoir and from 24 patients (group B) behind. Additionally, both markers were measured in blood samples collected from the cell-saver. There were no significant differences between both groups (A and B) with regard to perioperative parameters. Mean loss of mediastinal shed blood in all patients was 207 +/- 127 ml within the first 6 h after operation. There was a positive correlation between CK activities and cTnI concentrations in serum and mediastinal shed blood, but shed blood contained significantly higher concentrations of cTnI as well as CK activities than the circulating blood after admission to the ICU and 6 h after unclamping the aorta. At both time points the cTnI-concentrations and CK activities in shed blood in group B were lower than those in group A but much higher than in serum. The effects of the use of a blood filter diminishes with time. Mediastinal shed blood contains extremely high cTnI concentrations and CK activities. Retransfusion of higher quantities of shed blood might lead to false-positive diagnosis of perioperative myocardial infarction.

Autologous transfusion of shed mediastinal blood after coronary artery bypass grafting and bacterial contamination

BACKGROUND

Autologous transfusion of shed mediastinal blood is often used after coronary artery bypass grafting (CABG). Shed blood has in a few studies been cultured during the first postoperative hours. However, autologous transfusion might in some cases be continued for several hours and no study has yet examined the bacterial contamination of shed blood later than 6 hours postoperatively.

METHODS

Seventy-five patients undergoing electively performed CABG were included. Cultures of shed blood were taken at initiation of the autologous transfusion and the following morning. Infection variables were measured preoperatively and postoperatively. Infectious complications during the first postoperative week were registered.

RESULTS

The frequency of patients with bacterial growth in the first culture was 0.22 (95% confidence interval: 0.12 to 0.31) compared with 0.04 (95% confidence interval: -0.044 to 0.087) in the second culture (p < 0.002). We found no significant difference in infection variables between patients with or without bacterial growth in the cultures. No patients suffered from early postoperative infectious complications.

CONCLUSIONS

There is no further contamination of the shed blood during the period between initiating the autologous transfusion and the following morning.

Autotransfusion decreases blood usage following cardiac surgery -- a prospective randomized trial

INTRODUCTION

10% of blood issued by the National Blood Service (220,000) is utilised in cardiac procedures. Transfusion reactions, infection risk and cost should stimulate us to decrease this transfusion rate. We tested the efficacy of autotransfusion of washed postoperative mediastinal fluid in a prospective randomized trial.

PATIENTS AND METHODS

166 patients undergoing coronary artery bypass grafting (CABG), valve or CABG + valve procedures were randomized into three groups. The indication for transfusion was a postoperative haemoglobin (Hb) < 10 g/l or a packed cell volume (PCV) < 30. When applicable, group A patients received washed post-operative drainage fluid. Group B all received blood processed from the cardiopulmonary bypass (CPB) circuit following separation from CPB and if appropriate washed post-operative drainage fluid. Group C were controls. Groups were compared using analysis of variance.

RESULTS

There was no significant difference in age, sex, type of operation, CPB time and preoperative Hb and PCV between the groups. Blood requirements were as shown. [table - see text] Twelve patients in group A and 10 in group B did not require a homologous transfusion following processing of the mediastinal drainage fluid.

CONCLUSION

Autotransfusion of washed postoperative mediastinal fluid can decrease the amount of homologous blood transfused following cardiac surgery. There was no demonstrable benefit in processing blood from the CPB circuit as well as mediastinal drainage fluid.

Transfusion medicine : support of patients undergoing cardiac surgery

There is still no alternative that is as effective or as well tolerated as blood; nevertheless, the search for ways to conserve, and even eliminate blood transfusion, continues. Based on hemoglobin levels, practice guidelines for the use of perioperative transfusion of red blood cells in patients undergoing coronary artery bypass grafting have been formulated by the National Institutes of Health and the American Society of Anesthesiologists. However, it has been argued that more physiologic indicators of adequacy of oxygen delivery should be used to assess the need for blood transfusion. Methods used for conserving blood during surgery include autologous blood donation, acute normovolemic hemodilution and intra- and postoperative blood recovery and reinfusion. The guidelines for the use of autologous blood transfusion are controversial and it does not appear to be cost effective compared with allogeneic blood transfusion in patients undergoing cardiac surgery. Similarly, the cost effectiveness of intra- and postoperative blood recovery and reinfusion need further evaluation. Treatment with recombinant human erythropoietin (rhEPO) remains unapproved in the US for patients undergoing cardiac or vascular surgery, but it is a valuable adjunct in Jehovah's Witness patients, for whom blood is unacceptable. The characterization of darbepoetin alfa, a novel erythropoiesis stimulating protein with a 3-fold greater plasma elimination half-life compared with rhEPO, is an important advance in this field. Darbepoetin alfa appears to be effective in treating the anemia in patients with renal failure or cancer and trials in patients with surgical anemia are planned. Desmopressin has been used to effectively reduce intraoperative blood loss. Topical agents to prevent blood loss, such as fibrin glue and fibrin gel, and agents that alter platelet function, such as aspirin (acetylsalicylic acid) or dipyridamole, need further evaluation in patients undergoing cardiac surgery. Aprotinin has been shown to preserve hemostasis and reduce allogeneic blood exposure to a greater extent than the antifibrinolytic agents tranexamic acid and aminocaproic acid. Controlled clinical trials comparing the costs of these agents with clinical outcomes, along with tolerability profiles in patients at risk for substantial perioperative bleeding are needed.

Reinfusion of mediastinal blood after heart surgery

BACKGROUND

Several authors studying autotransfusion of shed mediastinal blood in patients undergoing heart operations have published conflicting results regarding reduction of the need for homologous blood transfusion. The effect on coagulation parameters is also unclear.

METHODS

In a prospective randomized study, 198 patients who underwent coronary artery bypass grafting or a valvular operation were divided into 2 groups: a group with autotransfusion of shed mediastinal blood after an operation and a control group. Continuous reinfusion of mediastinal blood was done until no drainage was present or for a period of 12 hours after the operation. The amount of blood lost and autotransfused, the number of homologous blood products transfused, and the coagulation parameters were monitored.

RESULTS

The number of patients requiring homologous blood transfusion was significantly different between the 2 groups (54/98 [55%] in autotransfused patients vs 73/100 [73%] in the control group, P =.01). The number of re-explorations for excessive bleeding was similar in the 2 groups (7/98 [7.1%] vs 8/100 [8%]), but the amount of blood collected postoperatively was higher in the autotransfused patients compared with control patients (1200 +/- 201 mL vs 758 +/- 152 mL, P =.0007). Coagulation parameters analyzed and complication rates were similar in the 2 groups after the operations.

CONCLUSION

Autotransfusion of shed mediastinal blood reduces the need for homologous blood transfusion in patients undergoing various cardiac operations. The cause of increased shed blood in patients undergoing autotransfusion remains unclear.

Institutional variability in red blood cell conservation practices for coronary artery bypass graft surgery. Institutions of the MultiCenter Study of Perioperative Ischemia Research Group

OBJECTIVE

To assess whether substantial institutional variability exists in red blood cell conservation practices associated with coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective, randomized patient enrollment and data collection.

SETTING

Twenty-four U.S. academic institutions participating in the Multicenter Study of Perioperative Ischemia.

PARTICIPANTS

A well-defined subset of primary CABG surgery patients (n = 713) expected to be at low risk for bleeding and exposure to allogeneic transfusion.

INTERVENTIONS

None (observational study).

MEASUREMENTS AND MAIN RESULTS

Frequency of use of red blood cell conservation techniques was determined among institutions. Correlation was determined between use of each technique and transfusion of allogeneic red blood cells and between use of each technique and median institutional blood loss. Significant variability (p < 0.01) was detected in institutional transfusion practice with respect to the use of predonated autologous whole blood, normovolemic hemodilution, red cell salvage, and reinfusion of shed mediastinal blood. The frequency of institutional use of these techniques was not associated with allogeneic transfusion (r2 < 0.15) or blood loss (r2 < 0.10) in the low-risk population of patients examined.

CONCLUSIONS

Institutions vary significantly in perioperative blood conservation practices for CABG surgery. Further study to determine the appropriate use of these techniques is warranted.

A meta-analysis of the effectiveness of cell salvage to minimize perioperative allogeneic blood transfusion in cardiac and orthopedic surgery. International Study of Perioperative Transfusion (ISPOT) Investigators

Concern about risks of allogeneic transfusion has led to an interest in methods for decreasing perioperative transfusion. To determine whether cell salvage reduces patient exposure to allogeneic blood, we performed meta-analyses of randomized trials, evaluating the effectiveness and safety of cell salvage in cardiac or orthopedic elective surgery. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Twenty-seven studies were included in the meta-analyses. Cell salvage devices that do not wash salvaged blood were marginally effective in cardiac surgery patients when used postoperatively (relative risk [RR] = 0.85, 95% confidence interval [CI] = 0.79-0.92). Devices that wash or do not wash salvaged blood considerably decreased the proportion of orthopedic surgery patients who received allogeneic transfusion (RR = 0.39, 95% CI = 0.30-0.51 and RR = 0.35, 95% CI 0.26-0.46, respectively). No studies of cell savers that wash salvaged blood during cardiac surgery were included. Cell salvage did not appear to increase the frequency of adverse events. We conclude that cell salvage in orthopedic surgery decreases the risk of patients' exposure to allogeneic blood transfusion perioperatively. Postoperative cell salvage in cardiac surgery, with devices that do not wash the salvaged blood, is only marginally effective.

IMPLICATIONS

This meta-analysis of all published randomized trials provides the best current estimate of the effectiveness of cell salvage and is useful in guiding clinical practice. We conclude that cell salvage in orthopedic surgery decreases the proportion of patients requiring allogeneic blood transfusion perioperatively, but postoperative cell salvage is only marginally effective in cardiac surgery.

Autotransfusion in coronary artery bypass grafting: disparity in laboratory tests and clinical performance

OBJECTIVE

Autotransfusion during and after cardiac surgery is widely performed, but its effects on coagulation, fibrinolysis, and inflammatory response have not been known in detail.

METHODS

Hemostatic and inflammatory markers were extensively studied in 40 coronary artery bypass patients undergoing a consistent intraoperative and postoperative autotransfusion protocol. An identical autotransfusion protocol was applied to 4916 consecutive coronary patients and the overall clinical results were evaluated in this large patient population.

RESULTS

The autologous blood pooled before bypass remained nearly inactivated after storage. A slight elevation of thrombin-antithrombin complex and prothrombin fragment 1.2, as well as plasmin/alpha(2)-antiplasmin complex was found in the content of the extracorporeal circuit after surgery, indicating thrombin formation and fibrinolytic activity. Also some increase of beta-thromboglobulin was present. In the mediastinal shed blood, complete coagulation, as evidenced by the absence of fibrinogen, had taken place and all parameters described above were extremely elevated. However, no thrombin activity was detected. As for the inflammatory response, moderately increased levels of complement activation products, terminal complement complex, and interleukin-6 traced in the extracorporeal circuit reached very high levels in mediastinal shed blood. Autotransfusion of the residual extracorporeal circuit blood and the mediastinal drainage was followed by elevation of most of these markers in circulating plasma. On the other hand, no correlating harmful effects were recorded in the study patients or in the consecutive 4916 patients. Coagulation disturbances were rare and allogeneic transfusions were required in fewer than 4% of all patients.

CONCLUSIONS

The hemostatic and immunologic systems were moderately activated in the autologous blood remaining in the extracorporeal circuit, whereas the mediastinal shed blood was highly activated in all aspects. However, autotransfusion had no correlating clinical side-effects and the subsequent exposure to allogeneic blood products was minimal.

A meta-analysis of the effectiveness of cell salvage to minimize perioperative allogeneic blood transfusion in cardiac and orthopedic surgery. International Study of Perioperative Transfusion (ISPOT) Investigators

Concern about risks of allogeneic transfusion has led to an interest in methods for decreasing perioperative transfusion. To determine whether cell salvage reduces patient exposure to allogeneic blood, we performed meta-analyses of randomized trials, evaluating the effectiveness and safety of cell salvage in cardiac or orthopedic elective surgery. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Twenty-seven studies were included in the meta-analyses. Cell salvage devices that do not wash salvaged blood were marginally effective in cardiac surgery patients when used postoperatively (relative risk [RR] = 0.85, 95% confidence interval [CI] = 0.79-0.92). Devices that wash or do not wash salvaged blood considerably decreased the proportion of orthopedic surgery patients who received allogeneic transfusion (RR = 0.39, 95% CI = 0.30-0.51 and RR = 0.35, 95% CI 0.26-0.46, respectively). No studies of cell savers that wash salvaged blood during cardiac surgery were included. Cell salvage did not appear to increase the frequency of adverse events. We conclude that cell salvage in orthopedic surgery decreases the risk of patients' exposure to allogeneic blood transfusion perioperatively. Postoperative cell salvage in cardiac surgery, with devices that do not wash the salvaged blood, is only marginally effective.

IMPLICATIONS

This meta-analysis of all published randomized trials provides the best current estimate of the effectiveness of cell salvage and is useful in guiding clinical practice. We conclude that cell salvage in orthopedic surgery decreases the proportion of patients requiring allogeneic blood transfusion perioperatively, but postoperative cell salvage is only marginally effective in cardiac surgery.

Safety and efficacy of shed mediastinal blood transfusion after cardiac surgery: a multicenter observational study. Multicenter Study of Perioperative Ischemia Research Group

OBJECTIVE

To examine the efficacy and safety of shed mediastinal blood (SMB) transfusion in preventing allogenic red blood cell (RBC) transfusion.

DESIGN

An observational clinical study.

SETTING

Twelve US academic medical centers.

PARTICIPANTS

Six hundred seventeen patients undergoing elective primary coronary artery bypass grafting.

INTERVENTIONS

Patients were administered SMB transfusion or not, according to institutional and individual practice, without random assignment.

MEASUREMENTS AND RESULTS

The independent effect of SMB transfusion on postoperative RBC transfusion was examined by multivariable modeling. Potential complications of SMB transfusion, such as bleeding and infection, were examined. Three hundred twelve of the study patients (51%) received postoperative SMB transfusion (mean volume, 554 +/- 359 mL). Patients transfused with SMB had significantly lower volumes of RBC transfusion than those not receiving SMB (0.86 +/- 1.50 v 1.08 +/- 1.65 units; p < 0.05). However, multivariable analysis showed that SMB transfusion was not predictive of postoperative RBC transfusion. Demographic factors (older age, female sex), institution, and postoperative events (greater chest tube drainage, lower hemoglobin level on arrival to the intensive care unit, and use of inotropes) were significant predictors of RBC transfusion. The volume of chest tube drainage on the operative day (707 +/- 392 v 673 +/- 460 mL; p = 0.30), reoperation for hemorrhage (3.1% v2.5%; p = 0.68), and overall frequency of infection (5.8% v 6.6%; p = 0.81) were similar between patients receiving and not receiving SMB, respectively. However, in patients who did not receive allogenic RBC transfusion, there was a significantly greater frequency of wound infection in the SMB group (3.6% v0%; p = 0.02).

CONCLUSION

These data suggest that SMB is ineffective as a blood conservation method and may be associated with a greater frequency of wound infection.

Autotransfusion of washed shed mediastinal fluid decreases the requirement for autologous blood transfusion following cardiac surgery: a prospective randomized trial

OBJECTIVES

The National Blood Service issues 2.2 million units of blood per year, 10% of these (220000) are utilized in cardiac procedures. Transfusion reactions, infection risk and cost should stimulate us to decrease this transfusion rate. We test the efficacy of autotransfusion following surgery in a prospective randomized trial.

METHODS

One hundred and twelve patients undergoing CABG, valve or CABG + valve procedures were randomized into two groups. Group A received washed postoperative drainage fluid and group C were controls. The indication for transfusion was a postoperative haemoglobin (Hb) < 10 g/l or a PCV < 30. There was no significant difference in preoperative and operative variables between the groups.

RESULTS

Twenty-eight patients in group A and 46 in group C required homologous transfusion (P = 0.0008). Group A patients required 298+/-49 ml of banked blood per patient, group C 508+/-49 ml (P = 0.003). There was no difference in total blood required (volume autotransfused + volume banked blood transfused) between the groups (group A 404+/-50 ml, group C 508+/-50 ml) or in mean total mediastinal fluid drainage (group A 652+/-51 ml, group C 686+/-50ml). The mean Hb concentration was significantly higher in group A on day 1 (11.2 g/dl+/-51 vs. 10.6 g/dl+/-13 (P = 0.002)). No morbidity was associated with autotransfusion.

CONCLUSION

Autotransfusion can decrease the amount of homologous blood transfused following cardiac surgery. This represents a benefit to the patient and a decrease in cost to the health service.

The effect of postoperative normovolaemic anaemia and autotransfusion on blood saving after internal mammary artery bypass surgery

The efficacy of two blood conservation techniques in decreasing and in preventing the use of homologous blood products was retrospectively studied in 150 patients undergoing internal mammary artery bypass surgery. Patients were matched according to prebypass blood haemoglobin (Hb) content and body surface area and were allocated to one of three groups: in the patients of group 1 (n = 50), normovolaemic anaemia (NA) was accepted postoperatively (haematocrit [Hct] was accepted to a minimum level of 25%); the patients of group 2 (n = 50) were treated with postoperative autotransfusion (AT) of mediastinal shed blood and acceptance of NA. Group 3 (n = 50) contained control patients, not treated with NA or with AT (Hct was accepted to a minimum level of 30%). Patients of group 1 required 3.0 +/- 0.3 units of homologous blood products, but the patients of groups 2 and 3 received significantly more (p less than 0.01) units: 3.9 +/- 0.2 and 4.5 +/- 0.3 units. No donor blood products were needed in 36%, 9% and 5% of the patients in groups 1, 2 and 3 respectively. The net postoperative blood loss was similar in the groups: 1229 +/- 92 ml in group 1, 1098 +/- 74 ml in group 2 and 1243 +/- 72 ml in group 3. However, total blood loss (1982 +/- 135 ml), including the retransfused part (954 +/- 89 ml), was significantly larger (p less than 0.01) in group 2, than in groups 1 and 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Does heparin coating improve biocompatibility? A study on complement, blood cells and postoperative morbidity during cardiac surgery

To evaluate whether the effect of heparin coating the extracorporeal circuit resulted in differences in patient outcome and haemostatic alteration, 24 patients undergoing elective, isolated coronary artery bypass were randomized prospectively to cardiopulmonary bypass (CPB) with heparin-coated circuits (group H, n = 12) or uncoated circuits (group C, n = 12). The technique of CPB, heparinization and its reversal were the same in both groups. We studied complement status (C3d, C3, C3d/C3, C4 and C-function), white blood cell counts with differentiation and the postoperative morbidity. The results confirmed that CPB activates complement and increases neutrophils in both the H and C groups. A significantly lower level of leucocytosis was seen in group H compared to the C group (p < 0.05). The complement function via the classical pathway (C-function), expressed as a percentage of the function of a reference serum pool (the values of normal sera were 75-125%), was significantly reduced in both heparin-coated and uncoated circuits (p < 0.05). There was no significant intergroup difference regarding C3, C3d/C3, C4 and C-function during the study period. A lower frequency of postoperative morbidity was present in the H group. We conclude that heparin-coated surfaces elicit less leucocytosis and decrease postoperative morbidity in patients undergoing cardiac surgery but do not cause a significant difference regarding activation of the complement system as reported by many other investigators.

The omnipotent platelet. Part II: Further observations

Observation of platelet responses during acute injury or pathology can provide important information. The initial response is thrombocytopenia followed by thrombocytosis. In the case of injury with negative X-ray and appropriate thrombocytosis, a bone scan is indicated. The platelet responds like a sedimentation rate, which indicates the course of the injury or pathology.

Fatal air embolism due to perioperative blood recovery

This study was initiated to investigate the incidence of acute mortality from air embolism associated with perioperative blood recovery and the causative factors and common characteristics of such fatalities. All facilities providing transfusion services in New York State are required to report severe adverse reactions to, and the total number of, transfusion and blood recovery procedures performed. Relevant data for the period from January 1990 to June 1995 were tabulated. During this time, 127,586 perioperative blood recovery procedures were performed, and 8,955,619 conventional blood components were transfused. The frequency of fatal air embolism after readministration of recovered blood was approximately 1:30,000-1:38,000; none followed conventional transfusion. Characteristics common to the fatalities (including an additional case reported before the study interval) were examined; all involved reinfusion of recovered blood under pressure. In the population studied, the incidence of fatal air embolism after the perioperative readministration of recovered blood was significantly higher than that after conventional transfusion. A model of such a system demonstrated that as much as 200 mL of air could enter the circulation in as little as 4 s, rendering visual detection and intervention extremely difficult. Education and guidelines to reduce the risk and mortality associated with this procedure are recommended.

Blood Conservation in Open-Heart Surgery

At the All India Institute of Medical Sciences, in a 6-week period between October and November 1995, 57 patients with preoperative hemoglobin levels of more than 10 g/100mL were included in a blood conservation protocol. Autologous blood trans-fusion, total body hemodilution to a minimum hematocrit of 20%, and retransfusion of pump blood, along with meticulous intraoperative hemostasis, were performed. Forty-eight, patients (84%) did not require transfusion of homologous blood or blood products. The remaining 9 patients (including 2 who underwent reoperation, 2 who had reexploration, and 2 with preoperative renal failure) received blood or blood products when their hemoglobin fell below 8 g/100mL. No patient had postoperative hemodynamic instability or delayed recovery. All patients were discharged on oral hematinics. Blood conservation techniques are safe and easy to implement. When used in combination, they provide satisfactory results, avoid transfusion-related problems, and conserve blood supplies.

Reinfusion of mediastinal blood in CABG patients: impact on homologous transfusions and rate of re-exploration

BACKGROUND

Reinfusion of mediastinal shed blood after cardiac surgery has been used in some centers to reduce exposure to homologous blood transfusions. The method has not been widely applied mostly because some studies have failed to demonstrate a significant benefit.

METHODS

A group of 675 consecutive patients undergoing first-time, isolated coronary artery bypass surgery (CABG) was studied. Prospective data was collected on the first 375 patients receiving autotransfusion (ATS) of mediastinal shed blood. The charts of 338 patients immediately preceding the institution of the ATS program at our institution (NO ATS group) were retrospectively reviewed. Transfusion of homologous blood products and rate of re-exploration for bleeding were closely monitored.

RESULTS

The two groups were identical. The net blood loss was significantly less in the ATS group than in the NO ATS group (1013 +/- 431 cc vs 1371 +/- 631 cc, p < 0.0001). Rate of exploration for postoperative bleeding was 1.5% in the ATS group and 5.0% in the NO ATS group (p < 0.01). In the ATS group, 51.9% of patients were not exposed to any homologous blood product (vs 17.8% in the NO ATS group, p < 0.0001). The ATS patients received on the average 2.9 +/- 7.2 units of blood products versus 6.4 +/- 9.7 units in the NO ATS group (p < 0.0001).

CONCLUSION

Reinfusion of mediastinal shed blood significantly reduces exposure to homologous blood transfusions and rate of reexploration. The ATS system reduces the number of re-explorations for coagulopathy-related postoperative hemorrhage.

Adverse effects of postoperative infusion of shed mediastinal blood

BACKGROUND

Postoperative infusion of shed mediastinal blood has been used in an effort to decrease blood usage after cardiac operations. Recent experience has suggested that this practice may actually lead to a delayed increase in bleeding.

METHODS

In a prospective, randomized study, 40 patients undergoing coronary artery bypass grafting with shed mediastinal blood collected in a cardiotomy reservoir were divided into two equal groups and studied during their first 4 hours in the intensive care unit. Shed mediastinal blood was directly infused in group I (n = 20), whereas in group II (n = 20), it was not. In group II, if a sufficient volume of red cells was present to allow processing (n = 5), washed red cells were infused. Variables studied before and after infusion were the amount of blood lost and infused, homologous blood transfused, complete blood count and differential, serum fibrinogen, fibrin split products, D-dimers, clotting factors, prothrombin time, activated partial thromboplastin time, thromboelastograms, plasma-free hemoglobin, complement factors C3 and C4, creatine kinase and its MB isoenzyme, and body temperature.

RESULTS

After infusion of shed mediastinal blood, elevated levels of fibrin split products and D-dimers were found in significantly more patients in group I. The thromboelastogram index was normal in 76% of patients in group II but in only 12.5% in group I. Group I also had an increase in band neutrophils, a greater number of febrile patients, higher serum levels of creatine kinase, its MB isoenzyme, and plasma-free hemoglobin, and greater blood loss during hours 3, 4, and 5 in the intensive care unit. The volume of red cells in shed mediastinal blood (hematocrit, 9% to 10%) was small, resulting in clinically insignificant autotransfusion when infused directly, and insufficient for cell processing in most patients.

CONCLUSIONS

These data support those in previous studies that direct infusion of shed mediastinal blood does not save substantial amounts of autologous red cells and can cause a delayed coagulopathy and other adverse effects that may be harmful to patients postoperatively.

Autotransfused shed mediastinal blood has normal erythrocyte survival

BACKGROUND

Autotransfusion of shed mediastinal blood may reduce the need for homologous blood transfusions in cardiac surgery. In an earlier study we have shown that the red blood cells (RBCs) of shed mediastinal blood have a normal membrane stability (osmotic fragility) compared with circulating RBCs after coronary artery bypass grafting and better than stored RBCs. This indicates that RBCs in shed mediastinal blood are not damaged further during salvage. It remains to be determined how autotransfusion affects the survival of RBCs from shed mediastinal blood.

METHODS

We performed a prospective, randomized, and controlled study involving 26 patients having elective, uncomplicated coronary artery bypass grafting. Dual-isotope labeling technique (chromium 51 and technetium 99m) was used to investigate the 24-hour survival of RBCs from shed mediastinal blood and RBCs from circulating blood, and to estimate the mean survival time of RBCs.

RESULTS

There was no significant difference between the 24-hour survival of shed mediastinal RBCs and circulating RBCs. The estimated mean cell lifespan was 20.5 days (range, 11.6 to 29.0 days) for shed mediastinal RBCs and 22.7 days (range, 14.4 to 36.2 days) for circulating RBCs.

CONCLUSIONS

The survival of RBCs from shed mediastinal blood after autotransfusion is comparable with the survival of RBCs in the patients' circulating blood.

Intraoperative and postoperative blood salvage

Surgical patients present unique opportunities for reducing allogeneic transfusions via perioperative blood salvage. Intraoperative cell saver techniques enable the collection of autologous blood from the surgical field and cardiopulmonary bypass circuit for return to the patient. Washing and hemoconcentration creates a product with an average hematocrit of 50% that carries normal erythrocyte survival, with minimal coagulation factors of platelets. Postoperative autotransfusion of shed blood from chest tubes or surgical drains enables additional blood conservation, reducing allogeneic transfusions by as much as 50%. Both intermittent and continuous autotransfusion systems using standard chest drainage equipment are available that require minimal setup and maintenance at the bedside. The hematocrit of shed blood is 20-25%, with depletion of clotting factors and platelet function. Potential advantages of perioperative blood salvage include the ready availability of large volumes of patient-compatible blood, with optimal oxygen-carrying capacity, that is virtually free from the risk of viral contamination. Specific indications, contraindications, and techniques for the salvage and administration of these vital products are presented.

Autotransfusion after coronary artery bypass grafting halves the number of patients needing blood transfusion

BACKGROUND

Several randomized studies about autotransfusion of shed mediastinal blood in patients undergoing coronary artery bypass grafting have resulted in divergent findings concerning reduction of the need for homologous blood transfusions. Most of these studies used less strict criteria for homologous blood transfusion than applied in daily clinical practice.

METHODS

A prospective, randomized, controlled study involving 120 patients having elective, uncomplicated coronary artery bypass grafting was performed. The autotransfusion group received transfusion of shed mediastinal blood for 18 hours. Criteria for homologous blood transfusion were hemoglobin concentration less than 5.0 mmol/L in the intensive care unit and less than 5.5 mmol/L during the rest of the hospital stay.

RESULTS

Twenty-eight percent of patients in the autotransfusion group received homologous blood transfusion versus 55% in the control group (p = 0.007). Ninety-five percent of the shed mediastinal blood was transfused. In the autotransfusion group, a total of 26 units of homologous blood was used versus 78 units in the control group (p < 0.001).

CONCLUSIONS

Autotransfusion of shed mediastinal blood in patients undergoing elective, uncomplicated coronary artery bypass grafting halves the number of patients needing homologous blood and reduces the amount of homologous blood given.

Conservation of blood during cardiovascular surgery

Conservative use of allogeneic red blood cell (RBC) transfusion is a growing trend in cardiovascular surgery. Recent advances in blood conservation measures have reduced, and in some cases eliminated, the need for allogeneic RBC transfusions in some of these patients. Reduced reliance on allogeneic RBC transfusion requires close collaboration among the clinical pathology, anesthesia, and surgery services managing the patient. Preoperative conservation measures include donation of autologous blood and treatment with recombinant human erythropoietin (Epoetin alfa). Meticulous surgical technique, moderate hemodilution, aprotinin, hemostatic techniques, blood salvage, and autotransfusion are intraoperative measures that can reduce blood loss. Postoperatively, even severe blood deficits can often be restored with adequate diet and rest and the use of actinics.

Autotransfusion after open heart surgery: quality of shed mediastinal blood compared to banked blood

The need to conserve a patient's own blood and avoid homologous transfusion is now well recognized. Therefore, techniques designed to reduce requirements for homologous blood transfusions have been developed. One of the methods is autotransfusion of shed mediastinal blood after open-heart surgery. The objectives of the present study were to investigate osmotic fragility and oxygen transport capacity of shed mediastinal blood compared to patient blood and stored packed red blood cells (SAGM). Shed mediastinal blood from ten consecutive patients undergoing elective cardiac surgery (coronary bypass grafting) was studied and compared to patient blood, 10 units of 3 weeks old and 10 units of 5 weeks old stored packed red blood cells (SAGM). Oxygen transport capacity was investigated by calculation of p50 for oxygen by use of the oxygen status algorithm (OSA 2.0) programme and measurement of 2,3-diphosphoglycerate (2,3-DPG) concentrations. The osmotic fragility was determined using increasing concentrations of saline. 2,3-DPG concentrations in shed mediastinal blood (5.3 mikromol/ml erythrocyte) were within the range measured in patient blood, but significantly higher than SAGM blood (P < 0.001). P50 for oxygen (3.5 kPa) in shed mediastinal blood was not significantly different compared to patient blood, but significantly higher (P < 0.01) compared with stored SAGM blood. The osmotic fragility in shed mediastinal blood was not significantly different compared to patient blood, but significantly lower (P < 0.001) than the osmotic fragility in stored SAGM blood. This suggests that red cells saved from shed mediastinal blood have better oxygen transport capacity and may have longer survival compared to stored blood.

Autotransfusion after open heart surgery: the oxygen delivery capacity of shed mediastinal blood is maintained

Autotransfusion of mediastinal shed blood after open heart surgery has become a common and accepted procedure in reducing the need for homologous transfusion during the last 15 years. The objectives of the present study were to investigate the oxygen delivery capacity of autotransfused shed mediastinal blood, compared to patient-blood, during cardiopulmonary bypass and in the postoperative period. Ten consecutive patients undergoing elective cardiac surgery were studied. Mediastinal shed blood was collected in the cardiotomy reservoir and retransfused during the first 18 postoperative hours. The oxygen delivery capacity of the blood to the tissues was calculated by use of the oxygen status algorithm (OSA 2.0) programme and measurement of the 2,3-diphosphoglycerate (2,3-DPG) concentration. Autotransfusion volume ranged from 450-1530 ml per patient (median 824 ml). Shed blood had a mean haemoglobin level of 8.8 g/dl and 7.4 g/dl at 1 h and 6 h of autotransfusion, respectively. There were no significant changes of 2,3-DPG concentration in the patient-blood during cardiopulmonary bypass or after autotransfusion compared to preoperative values. P50 for oxygen (3.6 and 3.6 kPa) and 2,3-DPG concentrations (5.3 and 5.1 mikromol/ml erythrocyte) in shed mediastinal blood (1h and 6h postoperatively) were not significantly different compared to patient-blood. The results demonstrate that the oxygen delivery capacity of shed mediastinal blood is maintained and that the oxygen affinity of patient-blood is not influenced by autotransfusion.