Effects of a leukocyte depleting arterial line filter on perioperative morbidity in patients undergoing cardiac surgery: a controlled randomized trial

Leukocyte filtration and leukocyte modulation therapy during extracorporeal cardiopulmonary resuscitation in a porcine model of prolonged cardiac arrest

Extracorporeal cardiopulmonary resuscitation (ECPR) is emerging as a feasible and effective rescue strategy for prolonged cardiac arrest (CA). However, prolonged total body ischemia and reperfusion can cause microvascular occlusion that prevents organ reperfusion and recovery of function. One hypothesized mechanism of microvascular "no-reflow" is leukocyte adhesion and formation of neutrophil extracellular traps. In this study we tested the hypothesis that a leukocyte filter (LF) or leukocyte modulation device (L-MOD) could reduce NETosis and improve recovery of heart and brain function in a swine model of prolonged cardiac arrest treated with ECPR. Thirty-six swine (45.5 ± 2.5 kg, evenly distributed sex) underwent 8 min of untreated ventricular fibrillation CA followed by 30 min of mechanical CPR with subsequent 8 h of ECPR. Two females were later excluded from analysis due to CPR complications. Swine were randomized to standard care (Control group), LF, or L-MOD at the onset of CPR. NET formation was quantified by serum dsDNA and citrullinated histone as well as immunofluorescence staining of the heart and brain for citrullinated histone in the microvasculature. Primary outcomes included recovery of cardiac function based on cardiac resuscitability score (CRS) and recovery of neurologic function based on the somatosensory evoked potential (SSEP) N20 cortical response. In this model of prolonged CA treated with ECPR we observed significant increases in serum biomarkers of NETosis and immunohistochemical evidence of microvascular NET formation in the heart and brain that were not reduced by LF or L-MOD therapy. Correspondingly, there were no significant differences in CRS and SSEP recovery between Control, LF, and L-MOD groups 8 h after ECPR onset (CRS = 3.1 ± 2.7, 3.7 ± 2.6, and 2.6 ± 2.6 respectively; p = 0.606; and SSEP = 27.9 ± 13.0%, 36.7 ± 10.5%, and 31.2 ± 9.8% respectively, p = 0.194). In this model of prolonged CA treated with ECPR, the use of LF or L-MOD therapy during ECPR did not reduce microvascular NETosis or improve recovery of myocardial or brain function. The causal relationship between microvascular NETosis, no-reflow, and recovery of organ function after prolonged cardiac arrest treated with ECPR requires further investigation.

Pumping O2 with no N2: An Overview of Hollow Fiber Membrane Oxygenators with Integrated Arterial Filters

The advancement of cardiac surgery benefits from the continual technological progress of cardiopulmonary bypass (CPB). Every improvement in the CPB technology requires further clinical and laboratory tests to prove its safety and effectiveness before it can be widely used in clinical practice. In order to reduce the priming volume and eliminate a separate arterial filter in the CPB circuit, several manufacturers developed novel hollow-fiber membrane oxygenators with integrated arterial filters (IAF). Clinical and experimental studies demonstrated that an oxygenator with IAF could reduce total priming volume, blood donor exposure and gaseous microemboli delivery to the patient. It can be easily set up and managed, simplifying the CPB circuit without sacrificing safety. An oxygenator with IAF is expected to be more beneficial to the patients with low body weight and when using a minimized extracorporeal circulation system. The aim of this review manuscript was to discuss briefly the concept of integration, the current oxygenators with IAF, and the in-vitro / in-vivo performance of the oxygenators with IAF.

Deep Hypothermia and Circulatory Arrest in Adults

Brain protection during cardiopulmonary bypass has been the subject of intense research. Deep hypothermic circulatory arrest (DHCA) continues to be used for that goal during complex aortic arch and large intracranial aneurysm surgeries. The anesthetic management for adult patients undergoing these types of procedures requires specific knowledge and expertise. Based on our experience and review of the current literature, the authors highlight the key areas of the anesthetic plan, discussing the risk factors associated with adverse neurologic outcome as well as the rationale for decisions regarding specific monitors and medications. In the conclusion an anesthetic protocol for adult patients undergoing DHCA is suggested.

Leucocyte-depleted Blood Cardioplegia

The effect of the depletion of leucocytes from cardioplegic and initial myocardial reperfusion blood on the inflammatory response and myocardial protection in patients with unstable angina undergoing cardiopulmonary bypass (CPB) was studied. Patients were allocated randomly to a leucocyte-depleted (LD) group or a control group. The LD group received continuous retrograde LD isothermic blood cardioplegia and the control group received isothermic blood cardioplegia. Blood samples were collected at seven time-points before, during and after the procedure. Total leucocyte counts of cardioplegia blood in the LD group were significantly lower than in the control group, but systemic leucocyte and neutrophil counts after CPB did not differ between the groups. The levels of adhesion molecules, cytokines, elastase and malondialdehyde were significantly increased after CPB in both groups and reached peak values 2-6 h after surgery; no other significant differences were found. LD cardioplegia and myocardial reperfusion did not attenuate the endothelial and neutrophil-mediated components of the CPB-induced inflammatory response, which may lead to myocardial reperfusion injury.

Pharmacological Neuroprotection During Cardiac Surgery

Despite more than 30 years of aggressive neuroprotective research by many investigators, neuropsychological deficit after cardiac surgery remains an important cause of postoperative morbidity. Although the neurological outcome is a result of a multifactorial etiology, many physicians world-wide have recognized the importance of this problem, and extensive efforts have been made in attempting to minimize the incidence of neurological and neurocognitive dysfunction. Pharmacological intervention is one of the important potential methods of neuroprotection during cardiac surgery. In vitro studies have identified drugs that are effective protectants against focal cerebral ischemia, hemorrhage, and global ischemia. However, at present there is no solid agreement on the need for prophylactic neuroprotectants in cardiac surgery. Researchers and clinicians must become more cognizant of the pitfalls and paradoxes that have arisen in attempting to translate the results of animal studies into clinical trial, with regard to neuroprotective therapy during cardiac surgery. There is an extensive need for new pharmacological approaches directed at reducing neurologic and neurocognitive injury during cardiac surgery. This article reviews past and present neuroprotective efforts and interventions during cardiac surgery.

Leukoreduction for the prevention of adverse reactions from allogeneic blood transfusion

BACKGROUND

A blood transfusion is an acute intervention, implemented to solve life and health-threatening conditions on a short-term basis. However, blood transfusions have adverse events, some of them potentially related to immune modulation or to a direct transmission of infectious agents (e.g. cytomegalovirus). Leukoreduction is a process in which the white blood cells are intentionally reduced in packed red blood cells (PRBCs) in order to reduce the risk of adverse reactions. The potential benefits of leukoreduced PRBCs in all types of transfused patients for decreasing infectious and non-infectious complications remain unclear.

OBJECTIVES

To determine the clinical effectiveness of leukoreduction of packed red blood cells for preventing adverse reactions following allogeneic blood transfusion.

SEARCH METHODS

We ran the most recent search on 10th November 2015. We searched the Cochrane Injuries Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library), MEDLINE (OvidSP), Embase(OvidSP), CINAHL Plus (EBSCO), LILACS (BIREME), and clinical trials registers. In addition, we checked the reference lists of all relevant trials and reviews identified in the literature searches.

SELECTION CRITERIA

Randomised clinical trials including patients of all ages requiring PRBC allogeneic transfusion. Any study was eligible for inclusion, regardless of the length of participant follow-up or country where the study was performed. The primary outcome was transfusion-related acute lung injury (TRALI). Secondary outcomes were death from any cause, infection from any cause, non-infectious complications and any other adverse event.

DATA COLLECTION AND ANALYSIS

At least two review authors independently performed study selection, 'Risk of bias' assessments and data extraction. We estimated pooled relative risk for dichotomous outcomes, and we measured statistical heterogeneity using I² statistic. The random-effects model was used to synthesise results. We conducted a trial sequential analysis to assess the risk of random errors in cumulative meta-analyses.

MAIN RESULTS

Thirteen studies, most including adult patients, met the eligibility criteria. We found no clear evidence of an effect of leukoreduced PRBC versus non-leukoreduced PRBC in patients that were randomised to receive transfusion for the following outcomes: TRALI: RR 0.96, 95% CI 0.67 to 1.36, P = 0.80 from one trial reporting data on 1864 trauma patients. The accrued information of 1864 participants constituted only 28.5% of the diversity-adjusted required information size (DARIS) of 6548 participants. The quality of evidence was low. Death from any cause: RR 0.81, 95% CI 0.58 to 1.12, I² statistic = 63%, P = 0.20 from nine trials reporting data on 6485 cardiovascular surgical patients, gastro-oncology surgical patients, trauma patients and HIV infected patients. The accrued information of 6485 participants constituted only 55.3% of the DARIS of 11,735 participants. The quality of evidence was very low. Infection from any cause: RR 0.80, 95% CI 0.62 to 1.03, I² statistic = 84%, P = 0.08 from 10 trials reporting data on 6709 cardiovascular surgical patients, gastro-oncology surgical patients, trauma patients and HIV infected patients. The accrued information of 6709 participants constituted only 60.6% of the DARIS of 11,062 participants. The quality of evidence was very low. Adverse events: The only adverse event reported as an adverse event was fever (RR 0.81, 95% CI 0.64 to 1.02; I² statistic= 0%, P = 0.07). Fever was reported in two trials on 634 cardiovascular surgical and gastro-oncology surgical patients. The accrued information of 634 participants constituted only 84.4% of the DARIS of 751 participants. The quality of evidence was low. Incidence of other non-infectious complications: This outcome was not assessed in any included trial.

AUTHORS' CONCLUSIONS

There is no clear evidence for supporting or rejecting the routine use of leukoreduction in all patients requiring PRBC transfusion for preventing TRALI, death, infection, non-infectious complications and other adverse events. As the quality of evidence is very low to low, more evidence is needed before a definitive conclusion can be drawn.

The effect of systemic arterial-line leukocyte filtration on the outcome of adult patients undergoing cardiac surgery

BACKGROUND

It is known that cardiopulmonary bypass causes an inflammatory reaction with associated morbidity and mortality. Several anti-inflammatory strategies have been implemented to reduce this response, including leukocyte removal from the circulation using specialized filters.

OBJECTIVES

The aim of this randomized clinical study was to assess the impact of arterial-line systemic leukocyte filtration on the postoperative outcome of adult patients undergoing elective cardiac surgery.

PATIENTS AND METHODS

114 patients undergoing CABG or valve replacement in Baqiyatallah hospital, Tehran, Iran from May to August 2011 were randomly assigned to two groups: with and without leukocyte filtration and their outcomes were compared.

RESULTS

The postoperative intubation time was significantly shorter in patients with leukocyte filters (0.014). There was no significant difference between two groups regarding other outcome relatedvariables.

CONCLUSIONS

Systemic arterial leukocyte filtration reduces the intubation time but has no other beneficial effect on the outcome of patients undergoing CABG or valve 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.

Pathogenesis of myocardial ischemia-reperfusion injury and rationale for therapy

Since the initial description of the phenomenon by Jennings et al 50 years ago, our understanding of the underlying mechanisms of reperfusion injury has grown significantly. Its pathogenesis reflects the confluence of multiple pathways, including ion channels, reactive oxygen species, inflammation, and endothelial dysfunction. The purposes of this review are to examine the current state of understanding of ischemia-reperfusion injury, as well as to highlight recent interventions aimed at this heretofore elusive target. In conclusion, despite its complexity our ongoing efforts to mitigate this form of injury should not be deterred, because nearly 2 million patients annually undergo either spontaneous (in the form of acute myocardial infarction) or iatrogenic (in the context of cardioplegic arrest) ischemia-reperfusion.

Does Systemic Leukocyte Filtration Affect Perioperative Hemorrhage in Cardiac Surgery? A Systematic Review and Meta-Analysis

Cardiopulmonary bypass causes a systemic inflammatory reaction. Activation of leukocytes is an important part of this process, and is known to directly contribute to the development of postoperative coagulopathy, and thus hemorrhage. The removal of leukocytes from the cardiopulmonary bypass circulation, using specialized filters, has been proposed as one method for attenuating this inflammatory response. However, there is no consensus on its effectiveness. We used meta-analytical techniques to systematically assess the literature reporting on the potential effect of systemic leukofiltration on perioperative hemorrhage. Random effects modeling was used to calculate overall estimate, and heterogeneity was assessed. Systemic leukofiltration made no significant impact on chest tube drainage in the first 24 hours (weighted mean difference [WMD], x23.9 ml; 95% confidence interval [CI], x95.48-47.61; p = 0.51) or on the total packed red cell transfusion requirements of each patient (WMD, 7.84 ml; 95% CI, x80.13-95.81; p = 0.86). The studies performed in this area thus far are highly heterogeneous, due in part to relatively poor-quality design and inadequate matching of their study groups. Although further high-quality trials on systemic leukofiltration may be appropriate, other strategies to reduce the coagulopathy associated with cardiopulmonary bypass should be sought and evaluated.

The effects of various leukocyte filtration strategies in cardiac surgery

It is known that cardiopulmonary bypass causes an inflammatory reaction with an associated morbidity and mortality. Several anti-inflammatory strategies have been implemented to reduce this response, including leukocyte removal from the circulation using specialised filters. The aim of this study is to systematically review the available evidence on leukocyte filtration in cardiac surgery, focusing on its effect on systemic inflammation and whether this has influenced clinical outcomes. Five electronic databases were systematically searched for studies reporting the effect of leukocyte filtration at any point within the cardiopulmonary bypass circuit in humans. Reference lists of all identified studies were checked for any missing publications. Two authors independently extracted the data from the included studies. Whilst systemic leukodepleting filters do not appear to consistently lower leukocyte counts, they may preferentially remove activated leukocytes. Small improvements in early post-operative lung function in patients receiving systemic leukodepletion have been reported, but this does not lead to reduced hospital stay or decreased mortality. There is substantial evidence that cardioplegic leukocyte filtration attenuates the reperfusion injury at a cellular level, but this has not been translated into clinical improvements. Finally, whilst various strategies involving multiple leukocyte filters, or the incorporation of pharmacological agents into leukocyte-depleting protocols have been evaluated, the current available results are not conclusive. Our study suggests that there is not enough high quality or consistent evidence to draw guidelines regarding the use of leukocyte-depleting filters within routine cardiac surgical practice.

Leukocyte Filter Enhances Neutrophil Activation during Combined Aortic Valve and Coronary Artery Bypass Surgery

OBJECTIVE

Cardiopulmonary bypass-induced systemic inflammatory reaction involving the expression of neutrophil surface adhesion molecules is the main mechanism leading to myocardial ischemia-reperfusion injury as well as multiorgan dysfunction. Patients undergoing prolonged cardiopulmonary bypass are especially at risk in this regard. The aim of this prospective, randomized study was to evaluate the impact of continuous leukocyte filtration on the perioperative expression of neutrophil adhesion molecules along with the markers of systemic inflammation during combined coronary artery revascularization and aortic valve surgery due to aortic stenosis.

PATIENT AND METHODS

Twenty patients scheduled for combined coronary artery revascularization and aortic valve surgery due to aortic stenosis were randomized to undergo cardiopulmonary bypass with or without a leukocyte filter (LeukoGuard LG6). The expression of neutrophil adhesion molecules and proinflammatory cytokine response were measured.

RESULTS

The use of the leukocyte filter significantly increased neutrophil CD11b expression (Pg = .003) compared to the control group, which was followed by a faster rise in interleukin-6 levels 5 minutes (median, 125 versus 34 pg/mL) and 2 hours after cardiopulmonary bypass (median, 158 versus 92 pg/mL, Pt x g < .001), respectively. No marked differences in terms of levels of CD11a, CD62L, cardiac troponin-I, or oxyhemodynamics were observed.

CONCLUSIONS

The observed increased neutrophil activation and enhanced inflammatory response do not support the use of continuous leukofiltration in patients undergoing prolonged cardiopulmonary bypass.