White blood cell-containing allogeneic blood transfusion, postoperative infection and mortality: a meta-analysis of observational 'before-and-after' studies

A pilot study evaluating the effects of prestorage leukoreduction on markers of inflammation in critically ill dogs receiving a blood transfusion

OBJECTIVES

To compare markers of inflammation after transfusion of leukoreduced (LR) packed RBCs (pRBCs) versus non-LR pRBCs in dogs with critical illness requiring blood transfusion, and to report survival to discharge and rates of transfusion reactions in these dogs.

DESIGN

Prospective randomized blinded clinical study June 2014-September 2015.

SETTING

University veterinary teaching hospital.

ANIMALS

Twenty-three client-owned critically ill dogs, consecutively enrolled.

INTERVENTIONS

Dogs requiring a single pRBC transfusion were randomized into the LR or non-LR pRBC group. Exclusion criteria included: requirement for multiple blood products, history of previous blood transfusion, and administration of anti-inflammatory or immunosuppressive medication prior to enrollment.

MEASUREMENTS

Blood samples were obtained immediately prior to transfusion, then 2 and 24 hours following transfusion. Parameters measured at each time point included: PCV, WBC count, segmented and band neutrophil counts, fibrinogen, and plasma lactate and C-reactive protein concentrations. Acute patient physiologic and laboratory evaluation fast score was calculated on admission.

RESULTS

Eleven dogs were included in the LR group and 12 in the non-LR group; scores of illness severity were not significantly different between groups. Total WBC count was significantly higher in the non-LR versus LR group 24 hours following pRBC transfusion, but this difference was not evident 2 hours following transfusion. No other inflammatory parameters at any time point were significantly different between LR versus non-LR pRBC transfused dogs. Survival rates to discharge for LR and non-LR groups were 8/11 and 9/12, respectively. Acute transfusion reactions were identified in 1/11 and 2/12 dogs in the LR and non-LR group, respectively. All transfused blood was stored ≤12 days.

CONCLUSIONS

Most markers of inflammation did not significantly increase following transfusion of LR versus non-LR pRBCs stored ≤12 days in ill dogs. Further prospective, randomized trials are needed in clinically ill dogs to determine the benefit of prestorage leukoreduction.

The impact of two different transfusion strategies on patient immune response during major abdominal surgery: a preliminary report

Blood transfusion is associated with well-known risks. We investigated the difference between a restrictive versus a liberal transfusion strategy on the immune response, as expressed by the production of inflammatory mediators, in patients subjected to major abdominal surgery procedures. Fifty-eight patients undergoing major abdominal surgery were randomized preoperatively to either a restrictive transfusion protocol or a liberal transfusion protocol (with transfusion if hemoglobin dropped below 7.7 g dL(-1) or 9.9 g dL(-1), respectively). In a subgroup of 20 patients randomly selected from the original allocation groups, blood was sampled for measurement of IL-6, IL-10, and TNFα. Postoperative levels of IL-10 were higher in the liberal transfusion group on the first postoperative day (49.82 ± 29.07 vs. 15.83 ± 13.22 pg mL(-1), P < 0.05). Peak postoperative IL-10 levels correlated with the units of blood transfused as well as the mean duration of storage and the storage time of the oldest unit transfused (r(2) = 0.38, P = 0.032, r(2) = 0.52, P = 0.007, and r(2) = 0.68, P<0.001, respectively). IL-10 levels were elevated in patients with a more liberal red blood cell transfusion strategy. The strength of the association between anti-inflammatory IL-10 and transfusion variables indicates that IL-10 may be an important factor in transfusion-associated immunomodulation. This trial is registered under ClinicalTrials.gov Identifier: NCT02020525.

Postsurgical inflammatory neuropathy: a report of five cases

BACKGROUND

Clinical and pathologic descriptions of postsurgical inflammatory neuropathy have been reported but this condition is still under recognized.

METHODS

We reviewed 5 cases of a biopsy-proven inflammatory neuropathy that occurred within 30 days after surgical procedures. These patients were seen at one center in a 2-year period.

RESULTS

All patients developed neuropathy symptoms with time delay between the surgery and the neuropathy onset. In all, the symptoms progressed up to the time of evaluation. Electrophysiological studies revealed mononeuropathy or asymmetrical polyneuropathy with active denervation. Nerve biopsies showed ischemic injury and perivascular inflammatory collections in all cases. All patients were treated with intravenous methylprednisolone and four of them showed clinical improvement. The non-responsive patient did not receive immunotherapy until 2 years after neuropathy onset.

CONCLUSIONS

The report illustrates that focal or asymmetrical neuropathy is typical of postsurgical inflammatory neuropathy and has a favorable outcome after intravenous corticosteroid treatment. The report underscores the importance for considering potentially treatable inflammatory neuropathies in the post-surgical setting.

Leucocytosis following Transfusion with Leucodepleted Red Cells to Non-Bleeding Critically Ill Patients

Previous studies have shown that transfusion of non-leucodepleted red blood cells can cause leucocytosis in recipients. A small study suggested that pre-storage leucodepletion removed this phenomenon, but has not been further substantiated. We explored whether recipient leucocytosis occurs when leucodepleted red blood cells were transfused to non-bleeding intensive care patients. We used routinely collected data for 95 transfusions in 54 patients. Overall, no leucocytosis was found on the first routine blood sample following transfusion (mean change 0.6 × 109/L; 95% confidence interval - 0.2 to 1.3; p=0.145). However, for the 32 transfusions in patients with normal pre-transfusion leucocyte count there was a clinically small but statistically significant leucocytosis following transfusion, unlikely to have occurred by chance (mean change 1.5 × 109/L; 0.5 to 2.5; p=0.005). No significant change was observed in patients with pre-transfusion leucocytosis. We found no relation between leucocytosis and storage age of red cells. Our data suggest that transfusions with leucodepleted red cells can increase leucocyte counts in recipients. The mechanism of this effect and its clinical importance are uncertain.

Anemia in critical illness: insights into etiology, consequences, and management

Anemia is common in the intensive care unit, and may be associated with adverse consequences. However, current options for correcting anemia are not without problems and presently lack convincing efficacy for improving survival in critically ill patients. In this article we review normal red blood cell physiology; etiologies of anemia in the intensive care unit; its association with adverse outcomes; and the risks, benefits, and efficacy of various management strategies, including blood transfusion, erythropoietin, blood substitutes, iron therapy, and minimization of diagnostic phlebotomy.

Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have led to the development of a range of interventions to minimise blood loss during major surgery. Anti-fibrinolytic drugs are widely used, particularly in cardiac surgery, and previous reviews have found them to be effective in reducing blood loss, the need for transfusion, and the need for re-operation due to continued or recurrent bleeding. In the last few years questions have been raised regarding the comparative performance of the drugs. The safety of the most popular agent, aprotinin, has been challenged, and it was withdrawn from world markets in May 2008 because of concerns that it increased the risk of cardiovascular complications and death.

OBJECTIVES

To assess the comparative effects of the anti-fibrinolytic drugs aprotinin, tranexamic acid (TXA), and epsilon aminocaproic acid (EACA) on blood loss during surgery, the need for red blood cell (RBC) transfusion, and adverse events, particularly vascular occlusion, renal dysfunction, and death.

SEARCH STRATEGY

We searched: the Cochrane Injuries Group's Specialised Register (July 2010), Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 3), MEDLINE (Ovid SP) 1950 to July 2010, EMBASE (Ovid SP) 1980 to July 2010. References in identified trials and review articles were checked and trial authors were contacted to identify any additional studies. The searches were last updated in July 2010.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of anti-fibrinolytic drugs in adults scheduled for non-urgent surgery. Eligible trials compared anti-fibrinolytic drugs with placebo (or no treatment), or with each other.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. This version of the review includes a sensitivity analysis excluding trials authored by Prof. Joachim Boldt.

MAIN RESULTS

This review summarises data from 252 RCTs that recruited over 25,000 participants. Data from the head-to-head trials suggest an advantage of aprotinin over the lysine analogues TXA and EACA in terms of reducing perioperative blood loss, but the differences were small. Compared to control, aprotinin reduced the probability of requiring RBC transfusion by a relative 34% (relative risk [RR] 0.66, 95% confidence interval [CI] 0.60 to 0.72). The RR for RBC transfusion with TXA was 0.61 (95% CI 0.53 to 0.70) and was 0.81 (95% CI 0.67 to 0.99) with EACA. When the pooled estimates from the head-to-head trials of the two lysine analogues were combined and compared to aprotinin alone, aprotinin appeared more effective in reducing the need for RBC transfusion (RR 0.90; 95% CI 0.81 to 0.99).Aprotinin reduced the need for re-operation due to bleeding by a relative 54% (RR 0.46, 95% CI 0.34 to 0.62). This translates into an absolute risk reduction of 2% and a number needed-to-treat (NNT) of 50 (95% CI 33 to 100). A similar trend was seen with EACA (RR 0.32, 95% CI 0.11 to 0.99) but not TXA (RR 0.80, 95% CI 0.55 to 1.17). The blood transfusion data were heterogeneous and funnel plots indicate that trials of aprotinin and the lysine analogues may be subject to publication bias.When compared with no treatment aprotinin did not increase the risk of myocardial infarction (RR 0.87, 95% CI 0.69 to 1.11), stroke (RR 0.82, 95% CI 0.44 to 1.52), renal dysfunction (RR 1.10, 95% CI 0.79 to 1.54) or overall mortality (RR 0.81, 95% CI 0.63 to 1.06). Similar trends were seen with the lysine analogues, but data were sparse. These data conflict with the results of recently published non-randomised studies, which found increased risk of cardiovascular complications and death with aprotinin. There are concerns about the adequacy of reporting of uncommon events in the small clinical trials included in this review.When aprotinin was compared directly with either, or both, of the two lysine analogues it resulted in a significant increase in the risk of death (RR 1.39, 95% CI 1.02, 1.89), and a non-significant increase in the risk of myocardial infarction (RR 1.11 95% CI 0.82, 1.50). Most of the data contributing to this added risk came from a single study - the BART trial (2008).

AUTHORS' CONCLUSIONS

Anti-fibrinolytic drugs provide worthwhile reductions in blood loss and the receipt of allogeneic red cell transfusion. Aprotinin appears to be slightly more effective than the lysine analogues in reducing blood loss and the receipt of blood transfusion. However, head to head comparisons show a lower risk of death with lysine analogues when compared with aprotinin. The lysine analogues are effective in reducing blood loss during and after surgery, and appear to be free of serious adverse effects.

Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have led to the development of a range of interventions to minimise blood loss during major surgery. Anti-fibrinolytic drugs are widely used, particularly in cardiac surgery, and previous reviews have found them to be effective in reducing blood loss, the need for transfusion, and the need for re-operation due to continued or recurrent bleeding. In the last few years questions have been raised regarding the comparative performance of the drugs. The safety of the most popular agent, aprotinin, has been challenged, and it was withdrawn from world markets in May 2008 because of concerns that it increased the risk of cardiovascular complications and death.

OBJECTIVES

To assess the comparative effects of the anti-fibrinolytic drugs aprotinin, tranexamic acid (TXA), and epsilon aminocaproic acid (EACA) on blood loss during surgery, the need for red blood cell (RBC) transfusion, and adverse events, particularly vascular occlusion, renal dysfunction, and death.

SEARCH STRATEGY

We searched: the Cochrane Injuries Group's Specialised Register (July 2010), Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 3), MEDLINE (Ovid SP) 1950 to July 2010, EMBASE (Ovid SP) 1980 to July 2010. References in identified trials and review articles were checked and trial authors were contacted to identify any additional studies. The searches were last updated in July 2010.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of anti-fibrinolytic drugs in adults scheduled for non-urgent surgery. Eligible trials compared anti-fibrinolytic drugs with placebo (or no treatment), or with each other.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

This review summarises data from 252 RCTs that recruited over 25,000 participants. Data from the head-to-head trials suggest an advantage of aprotinin over the lysine analogues TXA and EACA in terms of reducing perioperative blood loss, but the differences were small. Compared to control, aprotinin reduced the probability of requiring RBC transfusion by a relative 34% (relative risk [RR] 0.66, 95% confidence interval [CI] 0.60 to 0.72). The RR for RBC transfusion with TXA was 0.61 (95% CI 0.53 to 0.70) and was 0.81 (95% CI 0.67 to 0.99) with EACA. When the pooled estimates from the head-to-head trials of the two lysine analogues were combined and compared to aprotinin alone, aprotinin appeared more effective in reducing the need for RBC transfusion (RR 0.90; 95% CI 0.81 to 0.99).Aprotinin reduced the need for re-operation due to bleeding by a relative 54% (RR 0.46, 95% CI 0.34 to 0.62). This translates into an absolute risk reduction of 2% and a number needed-to-treat (NNT) of 50 (95% CI 33 to 100). A similar trend was seen with EACA (RR 0.32, 95% CI 0.11 to 0.99) but not TXA (RR 0.80, 95% CI 0.55 to 1.17). The blood transfusion data were heterogeneous and funnel plots indicate that trials of aprotinin and the lysine analogues may be subject to publication bias.When compared with no treatment aprotinin did not increase the risk of myocardial infarction (RR 0.87, 95% CI 0.69 to 1.11), stroke (RR 0.82, 95% CI 0.44 to 1.52), renal dysfunction (RR 1.10, 95% CI 0.79 to 1.54) or overall mortality (RR 0.81, 95% CI 0.63 to 1.06). Similar trends were seen with the lysine analogues, but data were sparse. These data conflict with the results of recently published non-randomised studies, which found increased risk of cardiovascular complications and death with aprotinin. There are concerns about the adequacy of reporting of uncommon events in the small clinical trials included in this review.When aprotinin was compared directly with either, or both, of the two lysine analogues it resulted in a significant increase in the risk of death (RR 1.39, 95% CI 1.02, 1.89), and a non-significant increase in the risk of myocardial infarction (RR 1.11 95% CI 0.82, 1.50). Most of the data contributing to this added risk came from a single study - the BART trial (2008).

AUTHORS' CONCLUSIONS

Anti-fibrinolytic drugs provide worthwhile reductions in blood loss and the receipt of allogeneic red cell transfusion. Aprotinin appears to be slightly more effective than the lysine analogues in reducing blood loss and the receipt of blood transfusion. However, head to head comparisons show a lower risk of death with lysine analogues when compared with aprotinin. The lysine analogues are effective in reducing blood loss during and after surgery, and appear to be free of serious adverse effects.

Ectosomes as immunomodulators

Considerable progress has been made in recognizing microvesicles as important mediators of intercellular communication rather than irrelevant cell debris. Microvesicles released by budding directly from the cell membrane surface (i.e., ectocytosis) either spontaneously or in response to various stimuli are called shed vesicles or ectosomes. Ectosomes are rightside-out vesicles with cytosolic content, and they expose phosphatidylserine in the outer leaflet of their membrane. Depending on their cellular origin, ectosomes have been associated with a broad spectrum of biological activities. In the light of recent findings, we now know that ectosomes derived from polymorphonuclear leukocytes, erythrocytes, platelets, and tumor cells have profound effects on the innate immune system, as well as on the induction of the adaptive immunity, globally reprogramming cells such as macrophages or dendritic cells toward an immunosuppressive and possibly tolerogenic phenotype. Although the effects observed in the circulation are mainly procoagulant and pro-inflammatory, ectosomes might be anti-inflammatory/immunosuppressive in local inflammation.

Blood still kills: six strategies to further reduce allogeneic blood transfusion-related mortality

After reviewing the relative frequency of the causes of allogeneic blood transfusion-related mortality in the United States today, we present 6 possible strategies for further reducing such transfusion-related mortality. These are (1) avoidance of unnecessary transfusions through the use of evidence-based transfusion guidelines, to reduce potentially fatal (infectious as well as noninfectious) transfusion complications; (2) reduction in the risk of transfusion-related acute lung injury in recipients of platelet transfusions through the use of single-donor platelets collected from male donors, or female donors without a history of pregnancy or who have been shown not to have white blood cell (WBC) antibodies; (3) prevention of hemolytic transfusion reactions through the augmentation of patient identification procedures by the addition of information technologies, as well as through the prevention of additional red blood cell alloantibody formation in patients who are likely to need multiple transfusions in the future; (4) avoidance of pooled blood products (such as pooled whole blood-derived platelets) to reduce the risk of transmission of emerging transfusion-transmitted infections (TTIs) and the residual risk from known TTIs (especially transfusion-associated sepsis [TAS]); (5) WBC reduction of cellular blood components administered in cardiac surgery to prevent the poorly understood increased mortality seen in cardiac surgery patients in association with the receipt of non-WBC-reduced (compared with WBC-reduced) transfusion; and (6) pathogen reduction of platelet and plasma components to prevent the transfusion transmission of most emerging, potentially fatal TTIs and the residual risk of known TTIs (especially TAS).

Blood management in total knee arthroplasty: a comparison of techniques

Patients undergoing total knee arthroplasty (TKA) are at high risk for postoperative anemia and allogeneic blood transfusions. Risks associated with allogeneic blood exposure (ie, infection, fluid overload, and longer hospital stays) have prompted alternative blood management strategies. The main goal of this study was to evaluate whether a single change in the clinical blood management of patients undergoing TKA reduced the severity of postoperative anemia or the need for allogeneic blood transfusions. A second goal of this study was to assess the financial impact of the change on the institution. This study compared perioperative cell salvage, preoperative autologous blood donation, and the practice of using allogeneic blood alone in patients undergoing TKA. Clinical and financial data of 154 unique cases of primary TKA at the Mayo Clinic Arizona were retrospectively reviewed. Transfusion rates were 25%, 18%, and 52% respectively for patients in the cell salvage, preoperative autologous blood donation, and allogeneic blood only groups. Respective relative risk reductions were 51.9% (P=.007) and 65.4% (P=.002) with the use of cell salvage or preoperative autologous blood donation versus allogeneic alone. Cell salvage and preoperative autologous blood donation were found to significantly reduce the requirements for allogeneic blood transfusions; these techniques were found to be roughly equivalent in clinical benefit when compared to the use of allogeneic blood alone. The logistical advantages of cell salvage (ie, no preoperative blood donation, no risk of wasting blood units) were associated with greater costs to the institution.

Erythrocyte-derived ectosomes have immunosuppressive properties

Several clinical studies have suggested that blood transfusions are immunosuppressive. Whereas there have been reports describing immunosuppression induced by leukocytes or fragments thereof, the possibility that microparticles, released by erythrocytes during storage, are also involved was not investigated. We present evidence here that such microparticles have all the properties of ectosomes including size, the presence of a lipid membrane, and the specific sorting of proteins. These erythrocyte-derived ectosomes (E-ecto) fixed C1q, which was followed by activation of the classical pathway of complement with binding of C3 fragments. Similarly to ectosomes released by PMN, they express phosphatidylserine on their surface membrane, suggesting that they may react with and down-regulate cells of the immune system. In vitro, they were taken up by macrophages, and they significantly inhibited the activation of these macrophages by zymosan A and LPS, as shown by a significant drop in TNF-alpha and IL-8 release (respectively, 80% and 76% inhibitions). In addition, the effect of E-ecto was not transient but lasted for at least 24 h. In sum, E-ecto may interfere with the innate immune system/inflammatory reaction. Therefore, E-ecto transfused with erythrocytes may account for some of the immunosuppressive properties attributed to blood transfusions.

Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have led to the development of a range of interventions to minimise blood loss during major surgery. Anti-fibrinolytic drugs are widely used, particularly in cardiac surgery and previous reviews have found them to be effective in reducing blood loss and the need for transfusion. Recently, questions have been raised regarding the comparative performance of the drugs and the safety of the most popular agent, aprotinin.

OBJECTIVES

To assess the comparative effects of the anti-fibrinolytic drugs aprotinin, tranexamic acid (TXA), and epsilon aminocaproic acid (EACA) on blood loss during surgery, the need for red blood (RBC) transfusion, and adverse events, particularly vascular occlusion, renal dysfunction, and death.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE, and the internet. References in identified trials and review articles were checked and trial authors were contacted to identify any additional studies. The searches were last updated in July 2006.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of anti-fibrinolytic drugs in adults scheduled for non-urgent surgery. Eligible trials compared anti-fibrinolytic drugs with placebo (or no treatment), or with each other.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

This review summarises data from 211 RCTs that recruited 20,781 participants. Data from placebo/inactive controlled trials, and from head-to-head trials suggest an advantage of aprotinin over the lysine analogues TXA and EACA in terms of operative blood loss, but the differences were small. Aprotinin reduced the probability of requiring RBC transfusion by a relative 34% (relative risk [RR] 0.66, 95% confidence interval [CI] 0.61 to 0.71). The RR for RBC transfusion with TXA was 0.61 (95% CI 0.54 to 0.69) and it was 0.75 (95% CI 0.58 to 0.96) with EACA. When the pooled estimates from the head-to-head trials of the two lysine analogues were combined and compared to aprotinin alone, aprotinin appeared superior in reducing the need for RBC transfusion: RR 0.83 (95% CI 0.69 to 0.99). Aprotinin reduced the need for re-operation due to bleeding: RR 0.48 (95% CI 0.35 to 0.68). This translates into an absolute risk reduction of just under 3% and a number needed-to-treat (NNT) of 37 (95% CI 27 to 56). Similar trends were seen with TXA and EACA, but the data were sparse and the differences failed to reach statistical significance. The blood transfusion data were heterogeneous and funnel plots indicate that trials of aprotinin and the lysine analogues may be subject to publication bias. Evidence of publication bias was not observed in trials reporting re-operation rates. Adjustment for these effects reduced the magnitude of estimated benefits but did not negate treatment effects. However, the apparent advantage of aprotinin over the lysine analogues was small and may be explained by publication bias and non-equivalent drug doses. Aprotinin did not increase the risk of myocardial infarction (RR 0.92, 95% CI 0.72 to 1.18), stroke (RR 0.76, 95% CI 0.35 to 1.64) renal dysfunction (RR 1.16, 95% CI 0.79 to 1.70) or overall mortality (RR 0.90, 95% CI 0.67 to 1.20). The analyses of myocardial infarction and death included data from the majority of subjects recruited into the clinical trials of aprotinin. However, under-reporting of renal events could explain the lack of effect seen with aprotinin. Similar trends were seen with the lysine analogues but data were sparse. These results conflict with the results of recently published non-randomised studies.

AUTHORS' CONCLUSIONS

Anti-fibrinolytic drugs provide worthwhile reductions in blood loss and the need for allogeneic red cell transfusion. Based on the results of randomised trials their efficacy does not appear to be offset by serious adverse effects. In most circumstances the lysine analogues are probably as effective as aprotinin and are cheaper; the evidence is stronger for tranexamic acid than for aminocaproic acid. In high risk cardiac surgery, where there is a substantial probability of serious blood loss, aprotinin may be preferred over tranexamic acid. Aprotinin does not appear to be associated with an increased risk of vascular occlusion and death, but the data do not exclude an increased risk of renal failure. There is no need for further placebo-controlled trials of aprotinin or lysine analogues in cardiac surgery. The principal need is for large comparative trials to assess the relative efficacy, safety and cost-effectiveness of anti-fibrinolytic drugs in different surgical procedures.

Leukocyte Reduction's Role in the Attenuation of Infection Risks among Transfusion Recipients

Despite advances in the screening of donated blood for infectious agents, the risk of transmitting viral, bacterial, and protozoal infections, as well as newly emerging diseases, via transfusion persists. A complementary approach is leukocyte reduction (LR), the removal of leukocytes from donated blood by filtration. Published evidence, establishing the benefit of LR in reducing the risk of febrile nonhemolytic reactions, cytomegalovirus transmission, and human leukocyte antigen alloimmunization has led to its use for some time for the care of immunosuppressed and other individuals considered to be at high risk for such complications. Recent literature suggests that LR may be effective in reducing the risk of transmission of a number of additional transfusion-transmitted infectious agents, including herpesviruses, retroviruses, bacteria, protozoa, and prions. There is also evidence that LR may reduce the risk of transfusion-related immunomodulation, further contributing to protection against infections that would complicate treatment. With the mounting evidence of potential benefit, a number of countries, as well as many hospitals and blood centers in the United States, have adopted a policy of performing LR for all donated blood. Physicians who care for immunosuppressed patients and those who are responsible for institutional infection-control practices should remain informed of the growing body of literature on LR.

Transfusion-related immunomodulation (TRIM): an update

Allogeneic blood transfusion (ABT)-related immunomodulation (TRIM) encompasses the laboratory immune aberrations that occur after ABT and their established or purported clinical effects. TRIM is a real biologic phenomenon resulting in at least one established beneficial clinical effect in humans, but the existence of deleterious clinical TRIM effects has not yet been confirmed. Initially, TRIM encompassed effects attributable to ABT by immunomodulatory mechanisms (e.g., cancer recurrence, postoperative infection, or virus activation). More recently, TRIM has also included effects attributable to ABT by pro-inflammatory mechanisms (e.g., multiple-organ failure or mortality). TRIM effects may be mediated by: (1) allogeneic mononuclear cells; (2) white-blood-cell (WBC)-derived soluble mediators; and/or (3) soluble HLA peptides circulating in allogeneic plasma. This review categorizes the available randomized controlled trials based on the inference(s) that they permit about possible mediator(s) of TRIM, and examines the strength of the evidence available for relying on WBC reduction or autologous transfusion to prevent TRIM effects.

Blood transfusions and postoperative infections in patients undergoing elective surgery

BACKGROUND

Postoperative infections result from the interactions of bacteria, the surgical technique, and host defense mechanisms. Thus, identifying single determinant factors has proved difficult.

MAGNITUDE OF THE RISK

In a recent survey of 2,809 colorectal resections, transfusion was the single most powerful risk factor for postoperative infection. In patients undergoing primary hip or knee prosthesis insertion, the transfusion of allogeneic blood increased the risk of a deep-seated infection by a factor of 12.

MECHANISMS

Several host defense mechanisms are impaired by blood products. The initial hypothesis incriminated the transfused white blood cells, but this paradigm has since been challenged. The effects of free serum iron, the blood storage time, and the presence in stored blood of bioactive substances such as inhibitors of metalloproteinase-1 may also be important.

CONCLUSION

It is worth pursuing efforts to emphasize autologous blood transfusion and the reinfusion of shed blood as blood conservation strategies, as these practices reduce the risk of infectious complications.

Long-term Outcome After Anesthesia and Surgery: Remarks on the Biology of a Newly Emerging Principle in Perioperative Care

There is a strong possibility that the risk from anesthesia and surgery carries over from the immediate perioperative period to more remote time points. This extended risk seems to influence the progression, severity, and complication rate of certain chronic illnesses, such as vascular heart disease and some of the malignancies, although other disease processes might be affected as well. With the recognition that the perioperative process could be responsible for later adverse events comes the need to reassess existing patient safety models, because some of the risk could be preventable. To confront these challenges, it is necessary to understand the underlying biology of this association, and immunology should be particularly helpful in this pursuit. It will be of special importance to integrate our knowledge of the host immune response to anesthesia and surgery with the recent revelations on the role of immunity in the progression of many of the chronic diseases. Additionally, we need to examine how genetic diversity or acquired defects alter the immune response to tissue injury and infection so that we can improve risk stratification and preemptive therapies. In the meantime, we must strive to improve short- and long-term outcomes by expanding our efforts to reduce disease activity preoperatively, to control the surgical stress response and infection rate, and to use tissue-preserving surgical techniques. Long-term patient safety after anesthesia and surgery is not a specialty-by-specialty endeavor; it requires a highly collaborative, institutional, and national effort to foster innovative research and health care process improvements.

Pneumonia as a complication of blood product transfusion in the critically ill: Transfusion-related immunomodulation (TRIM)

BACKGROUND

An increased risk of postoperative infection (including pneumonia) attributable to the receipt of allogeneic blood transfusion has been investigated as a possible manifestation of transfusion-related immunomodulation (TRIM) in 16 randomized controlled trials (RCTs) and approximately 40 observational studies.

OBJECTIVES

This review categorizes RCTs and observational studies with regard to the inference that they permit about possible mediators of TRIM-allogeneic white cells (WBCs), WBC-derived soluble mediators, and/or allogeneic plasma-and examines whether the totality of the clinical evidence supports an association between allogeneic blood transfusion and postoperative infection.

RESULTS

When all available studies are considered together in meta-analyses, three types of studies show no increased risk of postoperative infection in association with allogeneic blood transfusion: a) RCTs comparing recipients of buffy-coat-reduced and prestorage-filtered, WBC-reduced allogeneic red cells; b) RCTs comparing recipients of allogeneic and autologous blood; and c) observational studies comparing patients transfused before and after implementation of WBC reduction. RCTs comparing recipients of nonbuffy-coat-reduced and WBC-reduced red blood cells may point to a TRIM effect, but they cannot yet be subjected to formal meta-analysis.

CONCLUSIONS

No overwhelming clinical evidence has been presented to establish the existence of a TRIM effect that relates allogeneic blood transfusion to postoperative infection.

Perioperative blood transfusion and outcome

PURPOSE OF REVIEW

As a result of advances in pathogen testing and transfusion standards over the last decade, the risk of disease transmission through allogeneic blood transfusions has decreased markedly. The effects of allogeneic blood transfusions on the immune system, however, have received more attention, as they appear to influence outcome. The following review summarizes the effects of allogeneic blood transfusions on selected outcome parameters and the influence of white blood cell reduction on these parameters.

RECENT FINDINGS

Adverse effects of allogeneic blood transfusions on outcome variables such as postoperative infection, cancer recurrence, pulmonary function, length of stay, and mortality have been shown in multiple trials, but most were not randomized or blinded. One proposed approach to reduce unwanted side-effects is to reduce the donor's white blood cell count before transfusion. This can be done either by individual bedside filtration or by pre-storage (or post-storage) universal white blood cell reduction. Studies investigating this approach have yielded conflicting results.

SUMMARY

Although the results of a number of studies suggest a negative impact of allogeneic blood transfusions on immune function and consequently outcome parameters, this has not been proven in rigorously controlled randomized trial, or in meta-analyses. Reduction of white blood cells might be beneficial in selected patient populations, but at this time does not appear warranted in the general surgical population. As universal white blood cell reduction is a very costly process, it probably should not be implemented until such a benefit is proven.

Transfusion Safety: Where Are We Today?

Over the past decades, the incidence of clinically significant transfusion-transmitted diseases has been dramatically reduced. These reductions have occurred because of a multifocal approach to the collection, processing, and release of blood and blood components. Research has focused on characterizing specific pathogens and their infectious patterns, especially the early viremic phase. Donor motivation and characteristics have been investigated, and restrictive eligibility criteria have been established. Regulatory oversight has been strengthened in the United States and hemovigilance systems established in many countries of the European Union, Canada, and Japan to identify new and emerging infectious and noninfectious transfusion risks. Such systems are required because many emerging pathogens will elude the stringent and sensitive donor testing already in place which, unfortunately, requires advanced technologies. Despite the remarkable progress, the processes of delivering a transfusion to a patient provide additional opportunity for risk, but have been less- well studied and the solutions have been less-well defined. Specific areas of concern include the collection and correct identification of patient samples, selection of modified or unique products, blood administration process, and establishment of specific indications for transfusion. In this chapter, we review the status of transfusion safety in the United States and discuss some emerging infectious and noninfectious risks of transfusion that will become future areas for basic and translational research. The disparities that exist in blood safety in developing countries' red cell alloimmunization and autoimmunity will not be covered.

Cost-effectiveness of leucocyte-depleted erythrocyte transfusion in cardiac valve surgery

Cost-effectiveness of leucodepleted erythrocytes (LD) over buffy-coat-depleted packed cells (PC) is estimated from the primary dataset of a recently reported randomized clinical trial involving valve surgery (+/-CABG) patients. Data on the patient level of 474 adult patients who were randomized double-blind to LD or PC were used in order to calculate the healthcare costs and longevity per patient. The incremental cost-effectiveness ratio (ICER) in net costs per life-year gained was established from the healthcare perspective. Bootstrapping and cost-effectiveness acceptability curves were used in order to determine the confidence interval (CI) of the ICER. The longevity of patients in the PC and LD group was 10.6 and 11.4 years, respectively. Relative to PC, LD yielded an estimated 0.8 (95% CI = -0.27 to 1.84) life-year in the baseline. Adjusted for age and sex differences, health gains for LD are 0.4 life-year gained (95% CI = -0.67 to 1.44). Healthcare costs per patient averaged 10163 US dollars per patient in the PC group and 9949 US dollars in the LD group. Average cost-savings were 214 US dollars (95% CI = -1536 to 1964) per patient. Acceptability curves constructed from bootstrap simulations showed a probability of being cost-saving of 59% for universal leucodepletion from the healthcare perspective. The probability of adopting leucodepletion regardless of the costs reaches 92.7%. LD in patients receiving four or more transfusions showed the highest cost-savings and health gains. Leucodepletion of erythrocytes is a cost-saving strategy in cardiac valve (+/-CABG) patients. However, probablistic analysis failed to show a significant difference with buffy-coat-depleted PC.