Does blood transfusion harm cardiac surgery patients?

Role of preoperative intravenous iron therapy to correct anemia before major surgery: study protocol for systematic review and meta-analysis

BACKGROUND

Preoperative anemia is a common and potentially serious hematological problem in elective surgery and increases the risk for perioperative red blood cell (RBC) transfusion. Transfusion is associated with postoperative morbidity and mortality. Preoperative intravenous (IV) iron therapy has been proposed as an intervention to reduce perioperative transfusion; however, studies are generally small, limited, and inconclusive.

METHODS/DESIGN

We propose performing a systematic review and meta-analysis. We will search MEDLINE, EMBASE, EBM Reviews, Cochrane-controlled trial registry, Scopus, registries of health technology assessment and clinical trials, Web of Science, ProQuest Dissertations and Theses, and conference proceedings in transfusion, hematology, and surgery. We will contact our study drug manufacturer for unpublished trials. Titles and abstracts will be identified and assessed by two reviewers for potential relevance. Eligible studies are: randomized or quasi-randomized clinical trials comparing preoperative administration of IV iron with placebo or standard of care to reduce perioperative blood transfusion in anemic patients undergoing major surgery. Screening, data extraction, and quality appraisal will be conducted independently by two authors. Data will be presented in evidence tables and in meta-analytic forest plots. Primary efficacy outcomes are change in hemoglobin concentration and proportion of patients requiring RBC transfusion. Secondary outcomes include number of units of blood or blood products transfused perioperatively, transfusion-related acute lung injury, neurologic complications, adverse events, postoperative infections, cardiopulmonary complications, intensive care unit (ICU) admission/readmission, length of hospital stay, acute kidney injury, and mortality. Dichotomous outcomes will be reported as pooled relative risks and 95% confidence intervals. Continuous outcomes will be reported using calculated weighted mean differences. Meta-regression will be performed to evaluate the impact of potential confounding variables on study effect estimates.

DISCUSSION

Reducing unnecessary RBC transfusions in perioperative medicine is a clinical priority. This involves the identification of patients at risk of receiving transfusions along with blood conservation strategies. Of potential pharmacological blood conservation strategies, IV iron is a compelling intervention to treat preoperative anemia; however, existing data are uncertain. We propose performing a systematic review and meta-analysis evaluating the efficacy and safety of IV iron administration to anemic patients undergoing major surgery to reduce transfusion and perioperative morbidity and mortality.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015016771.

Evaluating the ‘next generation’ of cell salvage - will it make a difference?

Introduction: Donor blood supplies are diminishing, becoming more costly and these transfusions lead to higher mortality in cardiac patients. The transfusion risks and the literature highlight the need for an alternative similar to cell salvage to be routinely considered. The Xtra is the first cell saver to be launched since 2001 and will undoubtedly initiate evolution towards the ‘next generation’ of cell savers. It is also the first to be launched in a new era where the demand for electronic perfusion data management (EPDM) has grown.

Results: The user interface (UI) was easy to use. The increased data entry options improved the quality of the recordable data. The integrated data management system (DMS) was comprehensive. Data was easy to manage and enabled central data compilation, which reduces repeated data, the risk of inconsistent data inventory and provides the potential for research and analyses. The haematocrit of the processed blood is a key quality indicator for cell salvage. The comparison of the manufacturer’s integrated protocol, Popt, to our team’s own protocol showed that Popt delivered a higher haematocrit on its ‘1st bowl’ (59.1% compared to 57.3%) and its ‘total process’ end product haematocrit was 0.68% higher. The Popt cycle took an average of 330s, whereas our own settings completed in just over 300s.

Conclusion: The Xtra is a device which will lead the evolution of ‘next generation’ cell saver technology. The user interface and data management system provide export options and the ability to record the level of data required for good EPDM. This is essential to ‘future proof’ cell salvage technology. The manufacturer’s integrated protocol achieved a higher end product haematocrit than our perfusion team’s best practice. The design of the Xtra is contemporary, but the DMS equips this cell saver for the new era that faces both Perfusion and Cardiac Surgery.

Erythropoietin is equally effective as fresh-blood transfusion at reducing infarct size in anemic rats

OBJECTIVE

We recently demonstrated that transfusion of anemic animals up to 100 g/L hemoglobin with fresh blood protects the heart from ischemic injuries following myocardial infarction. Erythropoietin has cardioprotective effects independent of its erythropoietic activity. The objective of this study was to compare the cardioprotective effects of erythropoietin treatment to fresh-blood transfusion in anemic rats after acute myocardial infarction.

DESIGN

Randomized animal study.

SETTING

University laboratory.

SUBJECTS

Male Sprague-Dawley rats weighing 200-300 g.

INTERVENTION

Myocardial infarction was induced by coronary artery ligation in 76 rats, 55 of which were anemic (80-90 g/L) and 21 of which had normal hemoglobin levels. Animals were randomized to erythropoietin (2000 units/kg), fresh-blood transfusion to 100 g/L hemoglobin, or saline-treatment groups immediately following myocardial infarction.

MEASUREMENTS AND MAIN RESULTS

At 24 hrs after myocardial infarction, cardiac function and infarct size were determined. Myocardial apoptosis was determined by caspase-3 activity and terminal deoxynucleotidyl transferase d-UTP nick end labeling (TUNEL) assay. Infarct size was significantly decreased in anemic rats treated with erythropoietin or blood transfusion compared to those in the saline-treatment group. Cardiac function, as measured by maximal positive and minimal negative first derivatives of left ventricular pressure, was better preserved in the normal hemoglobin groups and the erythropoietin- or transfusion-treated anemic animals compared to saline-treated anemic animals. Myocardial caspase-3 activity and TUNEL-positive nuclei were significantly increased in anemic rats but were decreased by erythropoietin treatment or red blood cell transfusion.

CONCLUSIONS

Erythropoietin treatment is equally effective as fresh-blood transfusion in anemic rats after acute myocardial infarction at reducing infarct size, myocardial apoptosis, and improving cardiac function.