Impact of minimal invasive extracorporeal circulation on systemic inflammatory response - a randomized trial

BACKGROUND

Extracorporeal circulation causes a systemic inflammatory response, that may cause postoperative haemodynamic instability and end-organ dysfunction. This study aimed to investigate the impact of minimal invasive extracorporeal circulation (MiECC) on the systemic inflammatory response compared with conventional extracorporeal circulation (CECC).

METHODS

Patients undergoing coronary artery bypass grafting were randomized to MiECC (n = 30) and CECC (n = 30). Primary endpoint was tumor necrosis factor-α. Secondary endpoints were other biochemical markers of inflammation (IL1β, IL6 and IL8, C-reactive protein, leukocytes), and markers of inadequate tissue perfusion and tissue damage (lactate dehydrogenase, lactate and creatine kinase-MB). In addition, we registered signs of systemic inflammatory response syndrome, haemodynamic instability, atrial fibrillation, respiratory dysfunction, and infection.

RESULTS

Patients treated with MiECC showed significantly lower levels of tumor necrosis factor-α than CECC during and early after extracorporeal circulation (median: MiECC 3.4 pg/mL; CI 2.2-4.5 vs. CECC 4.6 pg/mL; CI 3.4-5.6; p = 0.01). Lower levels of creatine kinase-MB and lactate dehydrogenase suggested less tissue damage. However, we detected no other significant differences in any other markers of inflammation, tissue damage or in any of the clinical outcomes.

CONCLUSIONS

Lower levels of TNF-α after MiECC compared with CECC may reflect reduced inflammatory response, although other biochemical markers of inflammation were comparable. Our results suggest better end-organ protection with MiECC compared with CECC. Clinical parameters related to systemic inflammatory response were comparable in this study.

CLINICAL REGISTRATION NUMBER

NCT03216720.

Effects of interventions targeting the systemic inflammatory response to cardiac surgery on clinical outcomes in adults

BACKGROUND

Organ injury is a common and severe complication of cardiac surgery that contributes to the majority of deaths. There are no effective treatment or prevention strategies. It has been suggested that innate immune system activation may have a causal role in organ injury. A wide range of organ protection interventions targeting the innate immune response have been evaluated in randomised controlled trials (RCTs) in adult cardiac surgery patients, with inconsistent results in terms of effectiveness.

OBJECTIVES

The aim of the review was to summarise the results of RCTs of organ protection interventions targeting the innate immune response in adult cardiac surgery. The review considered whether the interventions had a treatment effect on inflammation, important clinical outcomes, or both.

SEARCH METHODS

CENTRAL, MEDLINE, Embase, conference proceedings and two trial registers were searched on October 2022 together with reference checking to identify additional studies.

SELECTION CRITERIA

RCTs comparing organ protection interventions targeting the innate immune response versus placebo or no treatment in adult patients undergoing cardiac surgery where the treatment effect on innate immune activation and on clinical outcomes of interest were reported.

DATA COLLECTION AND ANALYSIS

Searches, study selection, quality assessment, and data extractions were performed independently by pairs of authors. The primary inflammation outcomes were peak IL-6 and IL-8 concentrations in blood post-surgery. The primary clinical outcome was in-hospital or 30-day mortality. Treatment effects were expressed as risk ratios (RR) and standardised mean difference (SMD) with 95% confidence intervals (CI). Meta-analyses were performed using random effects models, and heterogeneity was assessed using I2.

MAIN RESULTS

A total of 40,255 participants from 328 RCTs were included in the synthesis. The effects of treatments on IL-6 (SMD -0.77, 95% CI -0.97 to -0.58, I2 = 92%) and IL-8 (SMD -0.92, 95% CI -1.20 to -0.65, I2 = 91%) were unclear due to heterogeneity. Heterogeneity for inflammation outcomes persisted across multiple sensitivity and moderator analyses. The pooled treatment effect for in-hospital or 30-day mortality was RR 0.78, 95% CI 0.68 to 0.91, I2 = 0%, suggesting a significant clinical benefit. There was little or no treatment effect on mortality when analyses were restricted to studies at low risk of bias. Post hoc analyses failed to demonstrate consistent treatment effects on inflammation and clinical outcomes. Levels of certainty for pooled treatment effects on the primary outcomes were very low.

AUTHORS' CONCLUSIONS

A systematic review of RCTs of organ protection interventions targeting innate immune system activation did not resolve uncertainty as to the effectiveness of these treatments, or the role of innate immunity in organ injury following cardiac surgery.

Conventional versus miniaturized cardiopulmonary bypass: A systematic review and meta-analysis

Objective

A meta-analysis of randomized controlled trials was performed to compare the effects of miniaturized extracorporeal circulation (MECC) and conventional extracorporeal circulation (CECC) on morbidity and mortality rates after cardiac surgery.

Methods

A comprehensive literature search was conducted using Ovid, PubMed, Medline, EMBASE, and the Cochrane databases. Randomized controlled trials from the year 2000 with n > 40 patients were considered. Key search terms included variations of "mini," "cardiopulmonary," "bypass," "extracorporeal," "perfusion," and "circuit." Studies were assessed for bias using the Cochrane Risk of Bias tool. The primary outcomes were postoperative mortality and stroke. Secondary outcomes included arrhythmia, myocardial infarction, renal failure, blood loss, and a composite outcome comprised of mortality, stroke, myocardial infarction and renal failure. Duration of intensive care unit, and hospital stay was also recorded.

Results

The 42 studies eligible for this study included a total of 2154 patients who underwent CECC and 2196 patients who underwent MECC. There were no significant differences in any preoperative or demographic characteristics. Compared with CECC, MECC did not reduce the incidence of mortality, stroke, myocardial infarction, and renal failure but did significantly decrease the composite of these outcomes (odds ratio, 0.64; 95% confidence interval [CI], 0.50-0.81; P = .0002). MECC was also associated with reductions in arrhythmia (odds ratio, 0.67; 95% CI, 0.54-0.83; P = .0003), blood loss (mean difference [MD], -96.37 mL; 95% CI, -152.70 to -40.05 mL; P = .0008), hospital stay (MD, -0.70 days; 95% CI, -1.21 to -0.20 days; P = .006), and intensive care unit stay (MD, -2.27 hours; 95% CI, -3.03 to -1.50 hours; P < .001).

Conclusions

MECC demonstrates clinical benefits compared with CECC. Further studies are required to perform a cost-utility analysis and to assess the long-term outcomes of MECC. These should use standardized definitions of endpoints such as mortality and renal failure to reduce inconsistency in outcome reporting.

Comparison of two technics of cardiopulmonary bypass (conventional and mini CPB) in the trans-and postoperative periods of cardiac surgery

OBJECTIVE

This study aimed to compare the effects of two different perfusion techniques: conventional cardiopulmonary bypass and miniature cardiopulmonary bypass in patients undergoing cardiac surgery at the University Hospital of Santa Maria--RS.

METHODS

We perform a retrospective, cross-sectional study, based on data collected from the patients operated between 2010 and 2013. We analyzed the records of 242 patients divided into two groups: Group I: 149 patients undergoing cardiopulmonary bypass and Group II - 93 patients undergoing the miniature cardiopulmonary bypass.

RESULTS

The clinical profile of patients in the preoperative period was similar in the cardiopulmonary bypass and miniature cardiopulmonary bypass groups without significant differences, except in age, which was greater in the miniature cardiopulmonary bypass group. The perioperative data were significant of blood collected for autotransfusion, which were higher in the group with miniature cardiopulmonary bypass than the cardiopulmonary bypass and in transfusion of packed red blood cells, which was higher in cardiopulmonary bypass than in miniature cardiopulmonary bypass. In the immediate, first and second postoperative period the values of hematocrit and hemoglobin were higher and significant in miniature cardiopulmonary bypass than in the cardiopulmonary bypass, although the bleeding in the first and second postoperative days was higher and significant in miniature cardiopulmonary bypass than in the cardiopulmonary bypass.

CONCLUSION

The present results suggest that the miniature cardiopulmonary bypass was beneficial in reducing the red blood cell transfusion during surgery and showed slight but significant increase in hematocrit and hemoglobin in the postoperative period.

Versatile minimized system--a step towards safe perfusion

A growing body of evidence indicates the superiority of minimized cardiopulmonary bypass (CPB) systems compared to conventional systems in terms of inflammatory reactions and transfusion requirements. Evident benefits of minimized CPB systems, however, do not come without consequences. Kinetic-assisted drainage, as used in these circuits, can result in severe fluctuations of venous line pressures and, consequently, fluctuation of the blood flow delivered to the patient. Furthermore, subatmospheric venous line pressures can cause gaseous microemboli. Another limitation is the absence of cardiotomy suction, which can lead to excessive blood loss via a cell saver. The most serious limitation of minimized circuits is that these circuits are very constrained in the case of complications or changing of the surgery plan. We developed a versatile minimized system (VMS) with a priming volume of about 600 ml. A compliance chamber in the venous line decreases peaks of pressure fluctuations. This chamber also acts as a bubble trap. Additionally, the open venous reservoir is connected parallel to the venous line and excluded from the circulation during an uncomplicated CPB. This reservoir can be included in the circulation via a roller pump and be used as a cardiotomy reservoir. The amount and rate of returned blood in the circulation is regulated by a movable level detector. Further, the circuit can easily be converted to an open system with vacuum-assisted venous drainage in the case of unexpected complications. The VMS combines the benefits of minimized circuits with the versatility and safety of a conventional CPB system. Perfusionists familiar with this system can secure an adequate and timely response at expected and unexpected intraoperative complications.

What We have Learned about Minimized Extracorporeal Circulation versus Conventional Extracorporeal Circulation: An Updated Meta-Analysis

Introduction

The benefits of minimized extracorporeal circulation (MECC) compared with conventional extracorporeal circulation (CECC) are still in debate.

Methods

PubMed, EMBASE and the Cochrane Library were searched until November 10, 2014. After quality assessment, we chose a fixed-effects model when the trials showed low heterogeneity, otherwise a random-effects model was used. We performed univariate meta-regression and sensitivity analysis to search for the potential sources of heterogeneity. Cumulative meta-analysis was performed to access the evolution of outcome over time.

Results

41 RCTs enrolling 3744 patients were included after independent article review by 2 authors. MECC significantly reduced atrial fibrillation (RR, 0.76; 95% CI, 0.66 to 0.89; P<0.001; I2 = 0%), and myocardial infarction (RR, 0.43; 95% CI, 0.26 to 0.71; P = 0.001; I2 = 0%). In addition, the results regarding chest tube drainage, transfusion rate, blood loss, red blood cell transfusion volume, and platelet count favored MECC as well.

Conclusions

MECC diminished morbidity of cardiovascular complications postoperatively, conserved blood cells, and reduced allogeneic blood transfusion.

A retrospective comparative study of minimally invasive extracorporeal circulation versus conventional extracorporeal circulation in emergency coronary artery bypass surgery patients: a single surgeon analysis

OBJECTIVES

At the moment, the main application of minimally invasive extracorporeal circulation (MiECC) is reserved for elective cardiac operations such as coronary artery bypass grafting (CABG) and/or aortic valve replacement. The purpose of this study was to compare the outcome of emergency CABG operations using either MiECC or conventional extracorporeal circulation (CECC) in patients requiring emergency CABG with regard to the perioperative course and the occurrence of major adverse cardiac and cerebral events (MACCE).

METHODS

We analysed the emergency CABG operations performed by a single surgeon, between January 2007 and July 2013, in order to exclude the differences in surgical technique. During this period, 187 emergency CABG patients (113 MiECC vs 74 CECC) were investigated retrospectively with respect to the following parameters: in-hospital mortality, MACCE, postoperative hospital stay and perioperative transfusion rate.

RESULTS

The mean logistic European System for Cardiac Operative Risk Evaluation was higher in the CECC group (MiECC 12.1 ± 16 vs CECC 15.0 ± 20.8, P = 0.15) and the number of bypass grafts per patient was similar in both groups (MiECC 2.94 vs CECC 2.93). There was no significant difference in the postoperative hospital stay or in major postoperative complications. The in-hospital mortality was higher in the CECC group 6.8% versus MiECC 4.4% (P = 0.48). The perioperative transfusion rate was lower with MiECC compared with CECC (MiECC 2.6 ± 3.2 vs CECC 3.8 ± 4.2, P = 0.025 units of blood per patient).

CONCLUSIONS

In our opinion, the use of MiECC in urgent CABG procedures is safe, feasible and shows no disadvantages compared with the use of CECC. Emergency operations using the MiECC system showed a significantly lower blood transfusion rate and better results concerning the unadjusted in-hospital mortality.

TLR2 AND TLR4 EXPRESSION ON BLOOD MONOCYTES AND GRANULOCYTES OF CARDIAC SURGICAL PATIENTS IS NOT AFFECTED BY THE USE OF CARDIOPULMONARY BYPASS

Cardiac surgery is inseparably linked to the activation of innate immunity cells recognizing danger signals of both endogenous and exogenous origin via pattern recognition receptors such as TLR receptors. Therefore, we followed by flow cytometry TLR2 and TLR4 expression on blood monocytes and granulocytes of patients who underwent coronary artery bypass grafting using beating heart surgery (off-pump, n = 34), with use of standard cardiopulmonary bypass (CPB), (on-pump, n = 30), and miniinvasive CPB (mini on-pump, n = 25), respectively, before, during surgery, and up to 7th postoperative day. TLR2 and TLR4 expression both on monocytes and granulocytes was significantly diminished already at the end of CPB being highly significantly decreased at the end of surgery in all patients’ groups. TLR2 and TLR4 expression reached preoperative value at the 1st postoperative day being significantly higher at the 3rd postoperative day. Using intracellular staining we found the peak of TLR2 and TLR4 expression inside of monocytes and granulocytes at the first postoperative day in a subgroup of on-pump patients. In conclusion, TLR2 and TLR4 expression is significantly modulated in patients undergoing coronary artery bypass grafting as a part of adaptive homeostatic mechanisms induced by major surgery. The very surgical trauma is responsible for TLR2 and TLR4 modulation. Surprisingly, cardiopulmonary bypass itself was little contributing to the modulation of TLR2 and TLR4 expression.

Mini cardiopulmonary bypass: Anesthetic considerations

This review article is going to elaborate on the description, components, and advantages of mini-cardiopulmonary bypass (mini-CPB), with special reference to the anesthetic management and fast track anesthesia with mini-CPB. There are several clinical advantages of mini-CPB like, reduced inflammatory reaction to the pump, reduced need for allogenic blood transfusion and lower incidence of postoperative neurological complications. There are certainly important points that have to be considered by anesthesiologists to avoid sever perturbation in the cardiac output and blood pressure during mini-CPB. Fast-track anesthesia provides advantages regarding fast postoperative recovery from anesthesia, and reduction of postoperative ventilation time. Mini bypass offers a sound alternative to conventional CPB, and has definite advantages. It has its limitations, but even with that it has a definite place in the current practice of cardiac surgery.

Comparison of the use of minimized cardiopulmonary bypass with conventional techniques on the incidence of retinal microemboli during aortic valve replacement surgery

OBJECTIVES

Minimized cardiopulmonary bypass (MCPB) circuits have been shown to reduce cerebral and retinal microembolisation during coronary artery bypass graft (CABG) surgery compared to conventional CPB (CCPB) circuits. Our aim was to evaluate whether the reduction of microembolisation is sustained in aortic valve surgery, as well as to evaluate the effects of MCPB on inflammatory, endothelial, and platelet activation markers.

MATERIAL AND METHODS

Patients were randomized to undergo aortic valve replacement (AVR), with or without CABG, with MPCB (n=20) or CCPB (n=20). After anaesthesia induction and termination of CPB, standardized digital retinal fluorescein angiography images were obtained on both eyes and analyzed in a blinded fashion. Blood samples were collected at eight time points until the third postoperative day.

RESULTS

Fewer patients in the MCPB group showed evidence of microembolic perfusion defects on postperfusion retinal fluorescein angiographs compared to the CCPB group (37% vs. 63%, absolute difference 26%, 95% CI -5% -51%, P = 0.194). Polymorphonuclear leukocyte (PMN) elastase and von Willebrand factor release were statistically significantly reduced in the MCPB group, but there were no significant differences in other markers of inflammation, coagulation or endothelial activation. A significantly higher three-fold increase in the amount of shed blood was collected to the cell saver with a higher rate of intraoperative platelet transfusion in the MCPB group compared to CCPB.

CONCLUSIONS

The use of MCPB was associated statistically insignificantly with less retinal microemboli compared to CCPB. MCPB was complicated by excess bleeding and need for transfusion. The feasibility of MCPB techniques in valve surgery requires further studies.

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.

Expression of CD200/CD200R regulatory molecules on granulocytes and monocytes is modulated by cardiac surgical operation

Aims: Cardiac surgical operation is inseparably linked to the induction of an inflammatory response. Both humoral and cellular regulatory mechanisms are operating to maintain body homeostasis. We followed the changes in the expression of CD200/CD200R regulatory molecules on monocytes and granulocyte of cardiac surgical patients operated on using either standard (OP) or modified “mini-invasive” cardiopulmonary bypass (MOP).

Methods: Expression of CD200/CD200R regulatory molecules was determined by flow cytometry.

Results: The expression of CD200R on granulocytes was increased after surgery in both groups of patients, but the increase was statistically significant only in OP patients (p<0.01). At this time point, there was a significant difference in CD200R expression on granulocytes when comparing OP to MOP patients, being higher in the former group (p<0.01). The expression of CD200R on monocytes was diminished after surgery and during an early postoperative period in both groups of patients. The expression of CD200 on monocytes was significantly diminished after surgery in both groups (p<0.01). Nonetheless, we observed an increase in CD200 expression in OP patients at the 3rd postoperative day. There was a statistically significantly increased CD200 expression on monocytes of OP patients (p<0.001) at the 3rd postoperative day when we compared OP and MOP groups. The expression of CD200 on granulocytes was significantly higher after surgery and at the 3rd postoperative day in OP when compared to MOP patients.

Conclusions: CD200R expression on granulocytes was significantly increased, while CD200 and CD200R expression on monocytes was decreased after cardiac surgery.