What is the Role of Leukocyte Depletion in Cardiac Surgery?

Leukodepletion for patients undergoing heart valve surgery

BACKGROUND

There is some evidence for the benefits of leukodepletion in patients undergoing coronary artery surgery. Its effectiveness in higher risk patients, such as those undergoing heart valve surgery, particularly in terms of overall clinical outcomes, is currently unclear.

OBJECTIVES

To assess the beneficial and harmful effects of leukodepletion on clinical, patient-reported and economic outcomes in patients undergoing heart valve surgery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 3 of 12) in The Cochrane Library, the NHS Economic Evaluations Database (1960 to April 2013), MEDLINE Ovid (1946 to April week 2 2013), EMBASE Ovid (1947 to Week 15 2013), CINAHL (1982 to April 2013) and Web of Science (1970 to 17 April 2013) on 19 April 2013. We also searched the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), the US National Institutes of Health (NIH) clinical trials database and the International Standard Randomised Controlled Trial Number Register (ISRCTN) in April 2013 for ongoing studies. No language or time period restrictions were applied. We examined the reference lists of all included randomised controlled trials and contacted authors of identified trials. We searched the 'grey' literature at OpenGrey and handsearched relevant conference proceedings.

SELECTION CRITERIA

Randomised controlled trials comparing a leukocyte-depleting arterial line filter with a standard arterial line filter, on the arterial outflow of the heart-lung bypass circuit, in elective patients undergoing heart valve surgery.

DATA COLLECTION AND ANALYSIS

Data were collected on the study characteristics, three primary outcomes (1. post-operative in-hospital all-cause mortality within three months, 2. post-operative all-cause mortality excluding inpatient mortality < 30 days, 3. length of stay in hospital, 4. adverse events and serious adverse events) and seven secondary outcomes (1. tubular or glomerular kidney injury, 2. validated health-related quality of life scales, 3. validated renal injury scales, 4. use of continuous veno-venous haemo-filtration, 5. length of stay in intensive care, 6. costs of care). Data were extracted by one author and verified by a second author. Insufficient data were available to perform a meta-analysis or sensitivity analysis.

MAIN RESULTS

Eight studies were eligible for inclusion in the review but data on prespecified review outcomes were available from only one, modestly powered (24 participants) study (Hurst 1997). There were no differences between a leuko-depleting versus standard filter in length of stay in the intensive care unit (ICU) (mean difference (MD) 0.80 days; 95% confidence interval (CI) -0.24 to 1.84) or length of hospital stay (MD 0.20 days; 95% CI -1.78 to 2.18).

AUTHORS' CONCLUSIONS

There are currently insufficient good quality trials with valve surgery patients to inform recommendations for changes in clinical practice. A future National Institute for Health Research (NIHR)-funded feasibility study (recruiting mid-year 2013) comparing leukodepletion with a standard arterial line filter in patients undergoing elective heart valve surgery (the ROLO trial) will be the largest study to date and will make a significant contribution to future updates of this review.

Does leukocyte-depleted blood cardioplegia reduce myocardial reperfusion injury in cardiac surgery? A systematic review and meta-analysis

Blood cardioplegia in cardiac surgery contains leukocytes, which causes the inflammatory reaction and promotes myocardial reperfusion injury. The removal of leukocytes from the cardioplegia line, using specialized filters, has been proposed as one of the effective methods in attenuating the inflammatory response. We performed a two-level search to identify randomized, controlled trials concerning the effects of leukocyte-depleted blood cardioplegia on myocardial reperfusion injury. Sixteen studies, comprising 738 patients, met the selection criteria. There are significant reductions in creatinine kinase isoenzyme MB (CK-MB) during 4-8h postoperatively (SMD - 0.577; 95% CI -0.795 to -0.358; p=0.000), CK-MB peak (SMD - 0.713; 95% CI -1.027 to -0.400; p=0.000), troponin in the period of 4-8h postoperatively (SMD - 0.502; 95% CI -0.935 to -0.069; p=0.023), troponin peak (SMD - 0.826; 95% CI -1.373 to -0.279; p=0.003) and inotropic support (RR, 0.500; 95% CI 0.269 to 0.931; p=0.029). Leukocyte-depleted blood cardioplegia may reduce myocardial reperfusion injury in the early postoperative period, but there has been no evidence to support the clinically significant difference. Larger and more precise randomized control trials are needed to further elucidate the cardioprotective effects of cardioplegia leukofiltration.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Leukocyte depletion during cardiopulmonary bypass in routine adult cardiac surgery

OBJECTIVES

Cardiopulmonary bypass (CPB) elicits an inflammatory response which is potentially harmful and that is partly caused by activation of leukocytes. Despite promise from earlier studies, however, the value of intraoperative leukocyte-depletion (LD) remains equivocal. We studied the effect of LD during routine cardiac surgery.

METHODS

For a short period (2.5 months), all operations at our institution were performed with leukocyte filters (Pall, East Hills, NY, USA) in the arterial and cardioplegia lines of the CPB. Those patients operated immediately before and after this period served as controls.

RESULTS

In each group, 266 predominantly male (70%) patients were studied. A broad spectrum of operations including emergency surgery was evaluated, which was comparable between the groups (P=0.41). There were no significant differences regarding the preoperative data, but the preoperative leukocyte count tended to be lower in the leukodepletion-group (7961±2415 vs. 8444±2951, P=0.050). Despite this, no difference between the groups regarding the postoperative leukocyte count was observed. Significantly more LD-patients were extubated within 12 h postoperatively (69% vs. 60% in the control-group, P=0.029), but there were no significant differences regarding 30-day mortality (0.4% vs. 1.1%, P=0.37), transfusion requirements or major morbidity.

CONCLUSIONS

In a retrospective study on adding LD filters to all cardiac operations with CPB in adults, we did not observe a clear benefit of intraoperative LD with the strategy used (continuous filtration plus filtration of cardioplegia).

Leukocyte depletion for safe blood transfusion

Leukocytes have ability to distinguish between self cells (body own cells) and foreign (allogenic) cells on the basis of human leukocyte antigen (HLA) proteins that are present on the cell membrane and are effectively unique to a person. During allogenic blood transfusion a person receives large number of allogenic donor leukocytes and these are recognized as foreign cells by the recipient immune system which leads to several adverse reactions. To avoid such leukocyte-mediated adverse reactions leukodepleted blood transfusion is required. Leukocytes can be separated on the basis of size, dielectric properties, by affinity separation, freeze-thawing and centrifugation but all these methods are time consuming and costly. Filtration is another method for leukocyte depletion that is comparatively less expensive and more efficient as it gives more than 90% leukodepletion of blood along with minimal cell loss. However, present filtration procedures also have some limitations as they work efficiently with blood components but not with whole blood and show non-specific adhesion of large number of platelets and red blood cells along with leukocytes. All the currently available filters are costly, which has been a major reason for their limited application. Therefore, demand for a more efficient and cost-effective filter is high in medical community and scientists are attenpting to improve the efficiency of currently available filters. The present review gives an overview of the significance of leukodepleted blood transfusion and focuses on different methods for leukocyte depletion and challenges involved in all these technologies.