Leukocyte filtration and postoperative infections

How do we forecast tomorrow's transfusion? - Next generation transfusion practices to improve recipient safety

Recipient safety measures play a key role in overall transfusion efficacy. The key advances in safety over the first century of transfusion medicine have been the development of techniques to prevent hemolytic transfusion reactions, hemolytic disease of the newborn and transmission of viral pathogens. While these risks remain important, they affect many fewer patients than previously. We propose that some of the most important current safety issues relate to toxicities broadly encompassed by the immunomodulatory effects of allogeneic transfusion. These include (1) universal leukoreduction to mitigate nosocomial infections, inflammation and organ injury, (2) removal of stored supernatant and its attendant toxic contents that cause dysfunctional immunity and organ injury, (3) avoiding infusing ABO incompatible antigen and antibody that can lead to bleeding, platelet refractoriness and inflammation, (3) minimizing prophylactic transfusions (particularly of plasma and platelets) except where benefit is proven, and (4) avoiding use of normal saline which is linked to renal failure and possibly hemolysis. Accompanying these safety measures will be the continued growth of one of the most important safety measures, patient blood management, which has as one benefit the avoidance of unnecessary and harmful transfusions. Reducing the toxicity of transfusions will enhance the improved clinical outcomes seen with patient blood management.

Allogeneic red cell transfusion and its influence on relevant humoral and cellular immunological parameters: A prospective observational trial

BACKGROUND

It is assumed that transfusion of allogeneic red cells is associated with increased peri-operative mortality and morbidity. Also assumed is the theory of transfusion-related immunomodulation.

OBJECTIVE

The aim of this study was to investigate the hypothesis that red cell transfusion specifically leads to an immunological response in surgical patients.

DESIGN

Prospective observational study.

SETTING

Departments of Orthopedic Surgery and Anaesthesia, University Hospital, Thailand.

PATIENTS

Low-risk, noncancer patients, aged 18 to 75 years undergoing elective major spine surgery, with and without red cell transfusion therapy.

INTERVENTIONS

Blood specimens were withdrawn four times (prior to surgery and on days 1, 3 and 5).

MAIN OUTCOME MEASURES

Assessment of immunocompetent cells and cytokines in transfused and nontransfused patients using flow cytometry and multiplex ELISA.

RESULTS

From a total of 78 patients, 61 met the requirements and were analysed in three groups: 19 with no transfusion and 26 and 16 transfused intra-operatively and on day 1 or 2, respectively. No patient experienced peri-operative haemorrhage. Postoperative infection or thrombosis occurred in 5.5% of nontransfused patients and 16.6% of transfused patients; the difference was not significant. There was no significant immunomodulatory effect of red cell transfusion: of 45 immunological parameters, only five little-relevant cytokines were significantly affected, although slightly and nonspecifically.

CONCLUSION

Our data indicate that red cell transfusion alone does not create an immunological response in otherwise healthy surgical patients. Our findings do not generally contradict the transfusion-related immunomodulation phenomenon, which has, however, primarily been observed in patients with an already weakened or procedure-deteriorated immune system, such as from malignant disease, significant comorbidity, extensive abdominal/thoracic surgery and cardiopulmonary bypass.

TRIAL REGISTRATION

The study was registered on 15 May 2014, before enrolment of the first patient, at www.ClinicalTrials.gov, NCT02140216.

Blood management in total knee arthroplasty: state-of-the-art review

Total blood loss from primary total knee arthroplasty may exceed 2 L with greater blood loss during revision procedures. Blood loss and allogeneic transfusion are strongly associated with adverse outcomes from surgery including postoperative mortality, thromboembolic events and infection. Strategies to reduce blood loss and transfusion rates improve patient outcomes and reduce healthcare costs. Interventions are employed preoperatively, intraoperatively and postoperatively. The strongest predictor for allogeneic blood transfusion is preoperative anaemia. Over 35% of patients are anaemic when scheduled for primary and revision knee arthroplasty, defined as haemoglobin <130 g/L for men and women, and the majority of cases are secondary to iron deficiency. Early identification and treatment of anaemia can reduce postoperative transfusions and complications. Anticoagulation must be carefully managed perioperatively to balance the risk of thromboembolic event versus the risk of haemorrhage. Intraoperatively, tranexamic acid reduces blood loss and is recommended for all knee arthroplasty surgery; however, the optimal route, dose or timing of administration remains uncertain. Cell salvage is a valuable adjunct to surgery with significant expected blood loss, such as revision knee arthroplasty. Autologous blood donation is not recommended in routine care, sealants may be beneficial in select cases but further evidence of benefit is required, and the use of a tourniquet remains at the discretion of the surgeon. Postoperatively, restrictive transfusion protocols should be followed with a transfusion threshold haemoglobin of 70 g/L, except in the presence of acute coronary syndrome. Recent studies report no allogeneic transfusions after primary knee arthroplasty surgery after employing blood conservation strategies. The current challenge is to select and integrate different blood conserving interventions to deliver an optimal patient pathway with a multidisciplinary approach.

Indications for red cell transfusions in pediatric patients

Red cell transfusions are amongst the most common therapeutic procedures in seriously ill children, particularly in the inpatient setting. This is despite the fact that there is no evidence base for most clinical settings, with the exception of patients with hemoglobinopathies, particularly thalassemia and sickle cell anemia. Obviously exsanguinating hemorrhage and life threatening anemia are urgent indications for which no other therapeutic approach is currently available. Most transfusions are, however, given prophylactically to prevent the complications of hypoxia or hemodynamic stability, based upon expert opinion and a faith in the oxygen carrying capacity and beneficial hemodynamic properties of transfused red cells. The question confronting current day pediatric practice is to what extent transfused red cells prevent adverse events, other than in thalassemia and sickle cell anemia, as opposed to causing them. Do transfusions of red cells prevent organ failure, stroke, etc. or not? There is epidemiologic evidence in the adult randomized trial literature that liberal red cell transfusion likely causes more such adverse events than it prevents. The relevance of such studies to children, particularly neonates, is uncertain. Randomized trials in critically ill neonates have yielded little to no evidence that liberal red cell transfusion is beneficial, but the data are not definitive. In critically ill older children the data suggest there is no benefit to liberal red cell transfusion, but the indications for red cell transfusion are uncertain. Most practitioners would agree that combining laboratory data such hemoglobin/hematocrit with clinical indications for transfusions (evidence of end organ hypoxia such as tachycardia, shortness of breath, etc.) is the only viable strategy at present, until more definitive randomized trial data are available.

The effects of storage of red blood cells on the development of postoperative infections after noncardiac surgery

BACKGROUND

Prolonged storage of red blood cells (RBCs) is a potential risk factor for postoperative infections. The objective of this study was to examine the effect of age of RBCs transfused on development of postoperative infection.

STUDY DESIGN AND METHODS

In this prospective, double-blind randomized trial, 199 patients undergoing elective noncardiac surgery and requiring RBC transfusion were assigned to receive nonleukoreduced RBCs stored for not more than 14 days ("fresh blood" group, n = 101) or for more than 14 days ("old blood" group, n = 98). The primary outcome was occurrence of infection within 28 days after surgery; secondary outcomes were postoperative acute kidney injury (AKI), in-hospital and 90-day mortality, admission to intensive care unit, and hospital length of stay (LOS). As older blood was not always available, an "as-treated" (AT) analysis was also performed according to actual age of the RBCs transfused.

RESULTS

The median [interquartile range] storage time of RBCs was 6 [5-10] and 15 [11-20] days in fresh blood and in old blood groups, respectively. The occurrence of postoperative infection did not differ between groups (fresh blood 22% vs. old blood 25%; relative risk [RR], 1.17; confidence interval [CI], 0.71-1.93), although wound infections occurred more frequently in old blood (15% vs. 5%; RR, 3.09; CI, 1.17- 8.18). Patients receiving older units had a higher rate of AKI (24% vs. 6%; p < 0.001) and, according to AT analysis, longer LOS (mean difference, 3.6 days; CI, 0.6-7.5).

CONCLUSION

Prolonged RBC storage time did not increase the risk of postoperative infection. However, old blood transfusion increased wound infections rate and incidence of AKI.