Miniaturized Cardiopulmonary Bypass in Coronary Artery Bypass Surgery: Marginal Impact on Inflammation and Coagulation but Loss of Safety Margins

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.

2021 MiECTiS focused update on the 2016 position paper for the use of minimal invasive extracorporeal circulation in cardiac surgery

The landmark 2016 Minimal Invasive Extracorporeal Technologies International Society (MiECTiS) position paper promoted the creation of a common language between cardiac surgeons, anesthesiologists and perfusionists which led to the development of a stable framework that paved the way for the advancement of minimal invasive perfusion and related technologies. The current expert consensus document offers an update in areas for which new evidence has emerged. In the light of published literature, modular minimal invasive extracorporeal circulation (MiECC) has been established as a safe and effective perfusion technique that increases biocompatibility and ultimately ensures perfusion safety in all adult cardiac surgical procedures, including re-operations, aortic arch and emergency surgery. Moreover, it was recognized that incorporation of MiECC strategies advances minimal invasive cardiac surgery (MICS) by combining reduced surgical trauma with minimal physiologic derangements. Minimal Invasive Extracorporeal Technologies International Society considers MiECC as a physiologically-based multidisciplinary strategy for performing cardiac surgery that is associated with significant evidence-based clinical benefit that has accrued over the years. Widespread adoption of this technology is thus strongly advocated to obtain additional healthcare benefit while advancing patient care.

Coagulation after paediatric miniaturised versus conventional cardiopulmonary bypass: Retrospective cohort study

BACKGROUND

Cardiopulmonary bypass (CPB) causes coagulation disorders after surgery. This study aimed to compare the coagulation parameters after congenital cardiac surgery with miniaturised CPB (MCPB) versus conventional CPB (CCPB).

METHODS

We gathered information about children who underwent cardiac surgery between 1/1/2016 and 12/31/2019. Using propensity score-matched data, we compared the coagulation parameters and postoperative outcomes of the MCPB and CCPB groups.

RESULTS

A total of 496 patients (327 with MCPB, 169 withCCPB) underwent congenital cardiac surgery, and 160 matched pairs in each group were enrolled in the analysis. Compared with CCPB children, MCPB children had a lowermean prothrombin time (14.9 ± 2.0 vs 16.4 ± 4.1; p < 0.001)and international normalised ratio (1.3 ± 0.2 vs. 1.4 ± 0.3; p < 0.001), but higher thrombin time (23.4 ± 20.4 vs 18.2 ± 4.4; p = 0.002). The CCPB group had greaterperioperative changes inprothrombin time, international normalised ratio, fibrinogen, and antithrombin III activity (all p < 0.01) but lower perioperative changesin thrombin time (p = 0.001) thanthe MCPB group. Ultra-fasttrack extubation and blood transfusionrates, postoperative blood loss, and intensive care unitlength of stay were considerably decreased in the MCPB group. There were no considerable intergroup differences in the activated partial thromboplastin time or platelet count.

CONCLUSIONS

Compared with CCPB, MCPB was associated with lower coagulation changes and better early outcomes, including shorter intensive care unit stay and less postoperative blood loss.

Physiological Changes in Subjects Exposed to Accidental Hypothermia: An Update

Background

Accidental hypothermia (AH) is an unintended decrease in body core temperature (BCT) to below 35°C. We present an update on physiological/pathophysiological changes associated with AH and rewarming from hypothermic cardiac arrest (HCA).

Temperature Regulation and Metabolism

Triggered by falling skin temperature, Thyrotropin-Releasing Hormone (TRH) from hypothalamus induces release of Thyroid-Stimulating Hormone (TSH) and Prolactin from pituitary gland anterior lobe that stimulate thyroid generation of triiodothyronine and thyroxine (T4). The latter act together with noradrenaline to induce heat production by binding to adrenergic β3-receptors in fat cells. Exposed to cold, noradrenaline prompts degradation of triglycerides from brown adipose tissue (BAT) into free fatty acids that uncouple metabolism to heat production, rather than generating adenosine triphosphate. If BAT is lacking, AH occurs more readily.

Cardiac Output

Assuming a 7% drop in metabolism per °C, a BCT decrease of 10°C can reduce metabolism by 70% paralleled by a corresponding decline in CO. Consequently, it is possible to maintain adequate oxygen delivery provided correctly performed cardiopulmonary resuscitation (CPR), which might result in approximately 30% of CO generated at normal BCT.

Liver and Coagulation

AH promotes coagulation disturbances following trauma and acidosis by reducing coagulation and platelet functions. Mean prothrombin and partial thromboplastin times might increase by 40–60% in moderate hypothermia. Rewarming might release tissue factor from damaged tissues, that triggers disseminated intravascular coagulation. Hypothermia might inhibit platelet aggregation and coagulation.

Kidneys

Renal blood flow decreases due to vasoconstriction of afferent arterioles, electrolyte and fluid disturbances and increasing blood viscosity. Severely deranged renal function occurs particularly in the presence of rhabdomyolysis induced by severe AH combined with trauma.

Conclusion

Metabolism drops 7% per °C fall in BCT, reducing CO correspondingly. Therefore, it is possible to maintain adequate oxygen delivery after 10°C drop in BCT provided correctly performed CPR. Hypothermia may facilitate rhabdomyolysis in traumatized patients. Victims suspected of HCA should be rewarmed before being pronounced dead. Rewarming avalanche victims of HCA with serum potassium > 12 mmol/L and a burial time >30 min with no air pocket, most probably be futile.

Modular minimally invasive extracorporeal circulation ensures perfusion safety and technical feasibility in cardiac surgery; a systematic review of the literature

INTRODUCTION

Despite extensive evidence that shows clinical of superiority of MiECC, worldwide penetration remains low due to concerns regarding air handling and volume management in the context of a closed system. The purpose of this study is to thoroughly investigate perfusion safety and technical feasibility of performing all cardiac surgical procedures with modular (hybrid) MiECC, as experienced from the perfusionist's perspective.

METHODS

We retrospectively reviewed perfusion charts of consecutive adult patients undergoing all types of elective, urgent, and emergency cardiac surgery under modular MiECC. The primary outcome measure was perfusion safety and technical feasibility, as evidenced in the need for conversion from a closed to an open circuit. A systematic review of the literature was conducted aiming to ultimately clarify whether there are any safety issues regarding MiECC technology.

RESULTS

We challenged modular MiECC use in a series of 403 consecutive patients of whom a significant proportion (111/403; 28%) underwent complex surgery including reoperations (4%), emergency repair of acute type A aortic dissection and composite aortic surgery (1.7%). Technical success rate was 100%. Conversion to an open circuit was required in 18/396 patients (4.5%), excluding procedures performed under circulatory arrest. Open configuration accounted for 40% ± 21% of total procedural perfusion time and was related to significant hemodilution and increase in peak lactate levels. Systematic review revealed that safety of the procedure challenged originated from a single report, while no clinical adverse event related to MiECC was identified.

CONCLUSIONS

Use of modular MiECC secures safety and ensures technical feasibility in all cardiac surgical procedures. It represents a type III active closed system, while its stand-by component is reserved for a small (<5%) proportion of procedures and for a partial procedural time. Thus, it eliminates any safety concern regarding air handling and volume management, while it overcomes any unexpected intraoperative scenario.

Impact of minimally invasive extracorporeal circulation on coagulation-a randomized trial

OBJECTIVES

Minimally invasive extracorporeal circulation (MiECC) is suggested to have favourable impact on blood loss compared to conventional extracorporeal circulation. We aimed to compare the impact of both systems on coagulation.

METHODS

Randomized trial comparing endogenous thrombin-generating potential early after elective coronary surgery employing either MiECC group (n = 30) or conventional extracorporeal circulation group (n = 30). Secondary outcomes were in vivo thrombin generation, bleeding end points and haemodilution, as well as morbidity and mortality up to 30-day follow-up.

RESULTS

Compared to the conventional extracorporeal circulation group, the MiECC group showed (i) a trend towards a higher early postoperative endogenous thrombin-generating potential (P = 0.06), (ii) lower intraoperative levels of thrombin-antithrombin complex and prothrombin fragment 1 + 2 (P < 0.001), (iii) less haemodilution early postoperatively as measured by haematocrit and weight gain, but without correlation to coagulation factors or bleeding end points. Moreover, half as many patients required postoperative blood transfusion in the MiECC group (17% vs 37%, P = 0.14), although postoperative blood loss did not differ between groups (P = 0.84). Thrombin-antithrombin complex levels (rs = 0.36, P = 0.005) and prothrombin fragment 1 + 2 (rs = 0.45, P < 0.001), but not early postoperative endogenous thrombin-generating potential (rs = 0.05, P = 0.72), showed significant correlation to increased transfusion requirements. The MiECC group demonstrated significantly lower levels of creatine kinase-MB, lactate dehydrogenase and free haemoglobin indicating superior myocardial protection, less tissue damage and less haemolysis, respectively. Perioperative morbidity and 30-day mortality did not differ between groups.

CONCLUSIONS

Conventional but not MiECC is associated with significant intraoperative thrombin generation despite full heparinization. No correlation between coagulation factors or bleeding end points with the degree of haemodilution could be ascertained.

CLINICALTRIALS.GOV IDENTIFIER

NCT03216720.

Air removal capacity of two different minimal invasive ECC systems: an in vitro comparison

Minimally invasive extracorporeal circulation systems are developed to decrease the deleterious effects of cardiopulmonary bypass. For instance, prime volume and foreign surface area are decreased in these systems. However, because of the lack of a venous reservoir in minimized systems, air handling properties of these minimally invasive extracorporeal circulation systems may be decreased as compared to conventional cardiopulmonary bypass systems. The aim of this in vitro study is to compare the air handling properties of two complete minimized cardiopulmonary bypass systems of two manufacturers, of which one system is provided with the air purge control. In an in vitro study, two minimally invasive extracorporeal circulation systems, Inspire Min.I manufactured by Sorin Group Italia, Mirandola, Italy (LivaNova, London, United Kingdom) and minimized extracorporeal circulation manufactured by Maquet, Rastatt, Germany (Getinge, Germany), were challenged with two types of air challenges; a bolus air challenge and a gaseous microemboli challenge. The air removal characteristics of the venous bubble traps and of the complete minimally invasive extracorporeal circulation systems were assessed by measuring the gaseous microemboli volume and number downstream of the venous bubble traps in the arterial line with a bubble counter. No significant differences were observed in air reduction between the venous bubble traps of Getinge (venous bubble traps) and LivaNova (Inspire venous bubble traps 8 in conjunction with the air purge control). Similarly, no significant differences were observed in volume and number of gaseous microemboli in the arterial line of both complete minimally invasive extracorporeal circulation systems. However, the gaseous microemboli load of the Inspire Min.I system was marginally lower after both the bolus air and the gaseous microemboli challenges. Both minimally invasive extracorporeal circulation systems assessed in this study, the LivaNova Inspire Min.I and the Getinge minimized extracorporeal circulation, showed comparable air removal properties, after both bolus and gaseous microemboli air challenges. Besides, air purge control automatic air removal system provided with the LivaNova Inspire Min.I. system may enhance patient's safety with the use of a minimally invasive extracorporeal circulation system. We consider both systems equally safe for clinical use.

Clinical and Biomaterial Evaluation of a new Condensed Dual-Function Extracorporeal Circuit in Reoperation for Coronary Artery Bypass Surgery

Purpose

This prospective, randomized study compared the clinical performance of three types of circuits: a newly introduced, fully-coated, interchangeable open-closed circuit with a dual configuration (hard shell with a bypass shunt), reduced length, and reduced prime of less than 800 cc (CondECC); a completely coated circuit (ECC); and a similar uncoated, open circuit with standard length and prime (CONT).

Methods

75 patients undergoing reoperation for coronary revascularization were randomly allocated into three groups (N=25): Group 1: CondECC with shortened tubing, components and an open-closed configuration of low priming volume with a centrifugal pump and a shunt which bypassed the reservoir for closed configuration; Group 2: ECC with a roller pump and hard-shell reservoir; Group 3: CONT. Blood samples for CBC, inflammatory mediators [Interleukin-2 (IL-2), Complement-3a (C3a)] and flow cytometry (CD11 b/CD18) were collected after induction (T1) and heparin administration (T2), 15 min after cardiopulmonary bypass (CPB) (T3), before cessation of CPB (T4), 15 min after reversal (T5), and the first postoperative day (T6).

Results

Leukocyte counts demonstrated significant increases at T4, T5 in CONT but remained stable in ECC and CondECC (p<0.05). Platelets were preserved better at T4, T5 in both ECC and CondECC study groups (p<0.05). IL-2 and C3a levels were significantly lower at T3, T4, T5 in CondECC and T4, T5 in ECC (p<0.05). Blood protein adsorption analysis demonstrated increased amount of microalbumin on CONT fibers (p<0.05).

Conclusions

The CondECC is a flexible, dual-function, open/closed configuration system that was easy to use, safe and achieved better biocompatibility when compared to coated and uncoated conventional circuits.

Modular minimal invasive extracorporeal circuits: another step toward universal applicability?

Introduction:

Safety concerns have been one of the main reasons opposing a wider acceptance of minimal invasive extracorporeal circuits (MiECC). Following an extensive experience and a multitude of modifications, we have set out to employ a modular MiECC as a universal extracorporeal circuit.

Methods:

A total of 129 cardiac surgical procedures were performed by a single surgeon in 2013. Excluding procedures done under circulatory arrest or with the potential need of such, the MiECC was utilized in almost 90% of surgeries. Of sixty-two (simple procedures) patients who underwent coronary artery bypass grafting (CABG), aortic valve replacement (AVR) or CABG + AVR, 82% were non-elective, 10% had a left ventricular ejection fraction (EF) <30% and most had an impaired renal function. Thirty-eight patients had more complex surgeries (complex procedures), 37% of which were urgent, 15% had an EF <30% and the majority had renal dysfunction.

Results:

The 30-day mortality was 5% in simple procedures and 2.5% in complex procedures. The incidence of postoperative atrial fibrillation was 13% and 16%, respectively. Optimum outcome was defined as a freedom from all complications and blood transfusions and was achieved in 52% and 42%, respectively.

Conclusions:

This report shows that modular MiECC can be employed with a high safety margin in cardiac surgery. Furthermore, it emphasizes the impact that minimal invasive philosophy could have in improving patient care.

Miniaturized cardiopulmonary bypass in adult cardiac surgery: a clinical update

INTRODUCTION

Cardiopulmonary bypass has undoubtedly been the cornerstone in the rapid development of cardiac surgery, allowing even the performance of procedures beyond the scope of cardiothoracic surgery. Its use however, is associated with significant complications that arise from the mechanical effects of the circuit on circulating blood components as well as the contact of blood with non-endothelial surfaces. Miniature cardiopulmonary bypass systems have been developed in an attempt to minimize these complications. Areas covered: Herein clinical outcomes from the most recent studies in adult cardiac surgery are discussed. The main benefits of miniaturisation as well as potential areas of further application are described. Expert commentary: Data is critically appraised in the context of current guidelines. Finally the need for further basic science in addition to large multi-centre randomized controlled trial data is highlighted.

Reduction of hemodilution in small adults undergoing open heart surgery: a prospective, randomized trial

Background. Given that there is an association between the degree of hemodilution during cardiopulmonary bypass (CPB) and postoperative complications, patients-outcome might be improved if the nadir hematocrit concentration is kept within an optimal range. Smaller patients are more likely to have a low hematocrit during CPB: this phenomenon may be related, at least partially, to the extreme hemodilution induced by a large fixed CPB priming volume. Methods. Forty patients with a body surface area (BSA) < 1.7 m2 undergoing open heart operations were randomized to either standard CPB with full prime volume (control group) or reduced prime extracorporeal circuit and vacuum-assisted venous drainage (VAVD) (study group). Results. There were no significant differences between the groups with respect to baseline characteristics, body surface area, hematologic profile and operative data. Clinical outcomes were similar. Nadir hematocrit and hemoglobin on bypass were significantly lower in the control group (22 ± 2.3 vs 24 ± 2.5%, p < 0.02 and 7.4 ± 0.7 vs 8 ± 0.9g/dl, p < 0.04, respectively).

Postoperative chest tube drainage was significantly higher in the control group (272 ± 253vs 139 ± 84ml, p < 0.04). There was no difference in blood transfusion in the two groups (0.5 ± 1.14 v 1.0 ± 1.77 units of packed red blood cells (PRBC), p = 0.29). Conclusions. Lowering CPB priming volume by means of using a small oxygenator and vacuum-assisted venous drainage (VAVD) resulted in a significant decrease of intraoperative hemodilution. This technique should be strongly considered for patients with a small BSA (<1.7 m2) undergoing open heart surgery. Perfusion (2007) 22, 317—322.

Miniature cardiopulmonary bypass — the Hammersmith experience

The decision to embark on a miniature cardiopulmonary bypass programme requires careful planning. The objective of this paper is to present our experience and initial findings for consideration by our multidisciplinary peers, who may wish to implement this technology at their own hospitals. The paper reviews the evolution of our programme over the first 150 clinical cases and our current position on the advantages and disadvantages of miniature cardiopulmonary bypass. Perfusion (2007) 22, 161—166.

Use of minimal invasive extracorporeal circulation in cardiac surgery: principles, definitions and potential benefits. A position paper from the Minimal invasive Extra-Corporeal Technologies international Society (MiECTiS)

Minimal invasive extracorporeal circulation (MiECC) systems have initiated important efforts within science and technology to further improve the biocompatibility of cardiopulmonary bypass components to minimize the adverse effects and improve end-organ protection. The Minimal invasive Extra-Corporeal Technologies international Society was founded to create an international forum for the exchange of ideas on clinical application and research of minimal invasive extracorporeal circulation technology. The present work is a consensus document developed to standardize the terminology and the definition of minimal invasive extracorporeal circulation technology as well as to provide recommendations for the clinical practice. The goal of this manuscript is to promote the use of MiECC systems into clinical practice as a multidisciplinary strategy involving cardiac surgeons, anaesthesiologists and perfusionists.

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.

Miniaturized extracorporeal circulation versus off-pump coronary artery bypass grafting: a meta-analysis of randomized controlled trials

BACKGROUND

Controversies exist whether off-pump coronary artery bypass (OPCAB) is superior to miniaturized extracorporeal circulation (MECC) in reducing deleterious effects of cardiopulmonary bypass as only a number of smaller randomized controlled trials (RCT) currently provide a limited evidence base. The main purpose of conducting the present meta-analysis was to overcome the expected low power in RCTs in an attempt to establish whether MECC is comparable to OPCAB.

METHODS

A MEDLINE/PubMed search was conducted to identify eligible RCTs. A pooled summary effect estimate was calculated by means of Mantel-Haenszel method.

RESULTS

The search yielded 7 RCTs included in this meta-analysis enrolling 271 patients in the OPCAB group and 279 in the MECC group. The OPCAB and MECC groups were comparable in terms of incidence of in-hospital mortality (Risk Difference [RD] 0.01; 95%CI -0.02, 0.03; P = 0.55; I(2) = 0%), stroke (RD -0.01; 95%CI -0.05, 0.04; P = 0.69; I(2) = 0%), need for renal replacement therapy (RD 0.00; -0.06, 0.06; P = 1; I(2) = 0%), postoperative atrial fibrillation (RD -0.03; -0.17, 0.10; P = 0.64; I(2) = 0%), re-exploration for bleeding (RD -0.01; 95%CI -0.03, 0.02; P = 0.65; I(2) = 0%), transfusion rate (RD -0.01; 95%CI -0.03, 0.02; P = 0.65; I(2) = 0%) and the amount of blood loss (weighted mean difference -25 mL; 95%CI -71, 21; P = 0.28; I(2) = 0%).

CONCLUSIONS

Using a meta-analytic approach, MECC achieves clinical results comparable to OPCAB including postoperative blood loss and blood transfusion requirement. On the basis of our findings, MECC should be considered as a valid alternative to OPCAB in order to reduce surgical morbidity of conventional cardiopulmonary bypass.

The inflammatory response between miniaturised and conventional cardiopulmonary bypass after cardiac surgery in an Asian population

INTRODUCTION

We compared the systemic inflammatory response of the MCPB system to the CCPB system with cell salvage and phosphorylcholine-coated tubing amongst Asian patients undergoing coronary artery bypass grafting.

METHODS

Seventy-eight patients were randomly assigned to the MCPB or the CCPB groups equally and followed up in a prospective, single-blinded, randomised, controlled trial. Levels of TNF-α, IL-6, CRP and LDH were measured peri-operatively.

RESULTS

The systemic inflammatory response was similar in both groups (TNF-α: p=0.222; IL-6: p=0.991; CRP: p=0.258). Only haemolysis was significantly higher in the CCPB group (LDH: p=0.011). The MCPB system was twice more expensive, but had a near 4-fold cost saving in tranfusions. Overall, the MCPB system cost 20% more than the modified CCPB system.

CONCLUSION

These results corroborate with studies that demonstrated the avoidance of cardiotomy suction rather than the MCPB system, itself, leads to an attenuated inflammatory response. The absence of obvious clinical benefit and the higher costs involved with the MCPB system would preclude its routine use.

Currently available biomaterials for use in cardiopulmonary bypass

Cardiopulmonary bypass (CPB) represents one of the most important technical innovations in healthcare history, yet the systemic responses to CPB remain a fundamentally unresolved problem. Study of the blood-biomaterial interaction and development of biocompatible materials is intimately related to efforts to optimize patient outcome following CPB. This article reviews the design innovations in biomaterial surfaces that have been introduced into clinical practice in an attempt to ameliorate the detrimental consequences of CPB, contrasting the actual clinical improvements and patient benefits achieved against those predicted on the basis of theory and in vitro testing. Some discussion of the underlying mechanisms of action as presently understood is provided and the current limitations of biomaterial-dependent strategies to improve outcome following CPB are addressed.

Miniaturized cardiopulmonary bypass: the Hammersmith technique

Background

Conventional Cardiopulmonary Bypass (cCPB) is a trigger of systemic inflammatory reactions, hemodilution, coagulopathy, and organ failure. Miniaturised Cardiopulmonary Bypass (mCPB) has the potential to reduce these deleterious effects. Here, we describe our standardised ‘Hammersmith’ mCPB technique, used in all types of adult cardiac operations including major aortic surgery.

Methods

The use of mCPB remains limited by the diversity of technologies which range from extremely complex, micro systems to ones very similar to cCPB. Our approach is designed around the principle of balancing the benefits of miniaturisation; reducing foreign surface area while maintaining patient safety.

Results

From January 2010 to March 2011, a single surgeon performed 184 consecutive operations (Euro score Logistic 8.4+/-9.9): 61 aortic valve replacements, 78 CABGs, 25 aortic valve replacement and CABG and 17 other procedures (major aortic surgery, re-do operations or double/triple valve replacements).

Our clinical experience suggests that:

i. Venous drainage is optimally maintained using kinetic energy.

ii. Venous collapse pressure depends on the patient’s anatomy and cannula size, but most importantly on the negative pressure generated by venous drainage.

iii. The patient-prime interaction is optimised with antegrade and retrograde autologous priming, which mixes the blood and prime away from the tissues and results in a reduced oncotic destabilization.

iv. mCPB is a safe and reproducible technique

Conclusion

The Hammersmith mCPB is a “next generation” system which uses standard commercially available components. It aims to maintain safety margin and the benefit of miniaturised system whilst reducing the human factor demands.

Brain emboli distribution and differentiation during cardiopulmonary bypass

OBJECTIVE

Cardiopulmonary bypass (CPB) is a lifesaving practice in cardiac surgery, but its use frequently is associated with cerebral injury and neurocognitive dysfunctions. Despite the involvement of numerous factors, microembolism occurring during CPB seems to be one of the main mechanisms leading to such alterations. The aim of the present study was to characterize the occurrence of cerebral microembolism with reference to microembolic amount, nature, and distribution in different combinations of cardiac procedures and CPB on the microembolic load.

DESIGN

A retrospective observational clinical study.

SETTING

A single-center regional hospital.

PARTICIPANTS

Fifty-five patients undergoing elective cardiac surgery with CPB.

INTERVENTIONS

Bilateral detection of the patients' middle cerebral arteries using a multifrequency transcranial Doppler.

MEASUREMENTS AND MAIN RESULTS

Patients were divided into 3 groups depending on the CPB circuit used (open, open with vacuum, or closed). There was a significant difference between the number of solid and gaseous microemboli (p<0.001), with the solid lower than the gaseous ones. The number of solid microemboli was affected by group (p< 0.05), CPB phase (p<0.001), and laterality (p<0.01). The number of gaseous microemboli was affected only by group (p<0.05) and CPB phase (p<0.001). Generally, the length of CPB phase did not affect the number of microemboli.

CONCLUSIONS

Surgical procedures combined with CPB circuits, but not the CPB phase length, affected the occurrence, nature, and laterality of microemboli.

Blood conservation strategies reduce the need for transfusions in ascending and aortic arch surgery

Introduction:

Ascending and aortic arch surgery is associated with higher levels of blood loss and subsequent need for allogeneic blood transfusions. We hypothesized that aggressive, comprehensive blood conservation strategies may limit the need for transfusions and, subsequently, improve postoperative outcomes.

Methods:

Over a five-year period, 189 patients underwent proximal aortic surgery at our institution. Fifty-one patients underwent surgery using a comprehensive blood conservation strategy (BCS), including preoperative hemoglobin optimization, antifibrinolytic therapy, intraoperative acute normovolemic hemodilution, cell salvage and meticulous surgical technique. The remaining 138 patients underwent surgery using conventional techniques (CONV).

Results:

Patients in the BCS group required fewer transfusions during their hospital stay compared to the conventional group (56.9% vs. 72.5%, p=0.041). When examining elective cases, this trend widens, with 40.0% of BCS patients requiring any transfusions compared to 72.9% patients in the conventional group (p=0.001). Red cell (47.1% vs. 62.3%, p=0.06), plasma (43.1% vs. 61.6%, p=0.02) and platelets (27.5% vs. 47.8%, p=0.01) were also less frequently required in the BCS group than the conventional group, respectively. When a transfusion was required, patients in the BCS group received significantly fewer units of red blood cells (2.8 ± 7.0 units) than the conventional group (5.81 ± 9.5 units; p=0.039). Mortality was similar in both groups (BCS 7.8%, conventional 10.9%, p=0.54); however, there was significantly less morbidity in the BCS group, using a composite of any of 10 major postoperative complications (23.5% vs. 39.1%; p=0.046). Median intensive care unit (ICU) and hospital lengths of stay were 2 and 7 days in the BCS group and 2 and 8 days in the CONV group (p=0.15), respectively.

Conclusions:

The aggressive use of a comprehensive blood conservation strategy in ascending and aortic arch surgery can significantly reduce the need for blood transfusions and is associated with less postoperative morbidity. Further evaluation with a randomized, controlled trial is warranted.

The early inflammatory response in a mini-cardiopulmonary bypass system: a prospective randomized study

OBJECTIVE

The aim of this study was to compare the early systemic inflammatory response of the Resting Heart System (RHS; Medtronic, Minneapolis, MN USA), a miniaturized cardiopulmonary bypass (CPB) system, with two groups using a standard extracorporeal circulation system during on-pump coronary artery bypass grafting (CABG) surgery.

METHODS

A total of 60 consecutive patients requiring CABG were prospectively randomized to undergo on-pump CABG using conventional CPB without cardiotomy suction (group A), conventional CPB with cardiotomy suction (group B), or the RHS (group C). Blood samples were collected at five time points: immediately before CPB, 30 minutes into CPB, immediately at the end of CPB, 30 minutes post-CPB, and 1 hour post-CPB. Inflammation was analyzed by changes in (a) levels of plasma proteins, including inflammatory cytokines (interleukin-6 [IL-6], IL-10, and tumor necrosis factor-α), chemokines (IL-8, monokine induced by interferon-γ, monocyte chemotactic protein-1, regulated on activation normal T cell expressed and secreted, and interferon-inducible protein-10), and acute phase proteins (C-reactive protein and complement protein 3); (b) biochemical variables (cardiac troponin I, hematocrit, and immunoglobulin G); and (c) cell numbers (leukocytes, neutrophils, and thrombocytes).

RESULTS

The RHS showed more delayed secretion of the cytokines tumor necrosis factor-α and IL-10, chemokines monokine induced by interferon-γ (P < 0.001); IL-8, and interferon-inducible protein-10; and complement protein 3 than conventional CPB systems did. Median thrombocyte numbers were higher in the RHS group. Levels of cardiac troponin I, monocyte chemotactic protein-1, and IL-6 were lower in both the RHS and conventional CPB without suction than with suction. Levels of C-reactive protein and regulated on activation normal T cell expressed and secreted, plus leukocyte and neutrophil numbers, were similar in all groups.

CONCLUSIONS

The Medtronic RHS may induce less systemic inflammation than conventional CPB systems, particularly when cardiotomy suction was used, but it did not result in improved clinical benefit.

Haemostasis alterations in coronary artery bypass grafting: comparison between the off-pump technique and a closed coated cardiopulmonary bypass system

OBJECTIVES

To compare coagulation and fibrinolysis activation in off-pump coronary artery bypass operation and in patients in whom a closed phosphorylcholine-coated cardiopulmonary bypass system was applied. Cardiopulmonary bypass induces activation of coagulative and fibrinolytic systems, which together with intraoperative haemodilution augment the risk of postoperative bleeding and transfusion of blood products.

METHODS

Thirty-six off-pump coronary artery bypass and 36 coronary artery bypass grafting patients in whom a closed, phosphorylcholine-coated cardiopulmonary bypass system with a closed-collapsible venous reservoir (Physio group) was used were prospectively enrolled. Activation of coagulation and fibrinolytic systems was assessed evaluating the release of prothrombin fragment 1.2 and plasmin-antiplasmin complex preoperatively (T0), 30 min after heparin administration (T1), 15 min after protamine administration (T2), 3 h after protamin administration (T3) and on postoperative days 1 (T4) and 5 (T5). Platelet function was evaluated through Platelet Function Analyzer 100(®).

RESULTS

During the operation, prothrombin fragment 1.2 and plasmin-antiplasmin levels were slightly higher in the Physio group, the difference being not statistically significant. In the off-pump coronary artery bypass group, prothrombin fragment 1.2 was significantly higher at T3 (618.7 ± 282.7 vs 416.6 ± 250.2 pmol/l; P = 0.006), T4 (416.7 ± 278.8 vs 310.2 ± 394.6 pmol/l; P < 0.001) and T5 (629.3 ± 295.2 vs 408.4 ± 409.7 pmol/l; P = 0.002), and plasmin-antiplasmin was significantly higher at T4 (731.1 ± 790 vs 334 ± 300.8 ng/ml; P = 0.019) and T5 (1744.4 ± 820.7 vs 860.1 ± 488.4 ng/ml; P = 0.003). Platelet Function Analyzer 100® closure time values were significantly higher in the Physio group patients at T3 (131.3 ± 105.7 vs 215.6 ± 58.9 s; P = 0.002). The off-pump coronary artery bypass patients had greater chest tube drainage (874.3 ± 371.5 vs 629.1 ± 334.5 ml; P = 0.005). The mean priming volume was 1240 ± 215 ml in the Physio group. Much more Physio patients received red blood cell transfusions (14 vs 25 patient; P = 0.009), because of higher intraoperative transfusion rates (6 vs 15 patients; P = 0.016). Despite similar preoperative haemoglobin levels (13 ± 1.2 vs 12.6 ± 1.4 g/dl; P = 0.2), postoperative haemoglobin levels were significantly lower in the Physio group.

CONCLUSIONS

The Physio cardiopulmonary bypass approach does not significantly alter haemostasis during the operation compared with off-pump coronary artery bypass providing a reduced activation in the postoperative period reducing also chest tube drainage. However, further priming volume reduction is required to decrease intraoperative red blood cell transfusion.

Minimized perfusion circuits: an alternative in the surgical treatment of Jehovah’s Witnesses

Objectives:

Jehovah’s Witnesses present a challenge to cardiac surgeons, as quality of care is not only defined by mortality and morbidity, but also by the avoidance of blood transfusions. Over the last years, minimized perfusion circuits (MPC) have contributed substantially to the achievement of this goal in our clinic. Presented is a retrospective analysis of our experience.

Methods:

Twenty-nine Jehovah’s Witnesses, aged 69 ± 10 years, have undergone cardiac surgery with a MPC in our institution since 2005. The ROCsafe (Reservoir Optional Circuit) MPC was used in most of these patients (n=27) as it offers the unique possibility of a speedy integration of a reservoir in the event of a major air leak, thereby, negligating any safety concerns.

Results:

There was no in-hospital or 30-day postoperative mortality. Mean ICU stay was 1.6 ± 2 days with a mean intubation time of 11.3 ± 9.1 hrs. Postoperative complications included one myocardial infarction with accompanying low cardiac output, one stroke, one transient delirium, one idiopathic thrombocytopenia and three re-operations (one sternal infection, one postoperative bleeding and one delayed tamponade). The mean postoperative hospital stay was 9.9 ± 2.3 days. Mean decrease in hemoglobin was 2.1 ± 1.3 g/dl during cardiopulmonary bypass and 3.4 ±1.4 g/dl at discharge. The lowest postoperative hemoglobin level was 9.3 ±1.8 (Range 6-12.9).

Conclusions:

These encouraging results emphasize the role MPCs can play in optimizing the quality of patient care. We hope that this report can serve as a stimulus for similar experiences.

Can minimized cardiopulmonary bypass systems be safer?

Although a growing body of evidence indicates superiority of minimized cardiopulmonary bypass (mCPB) systems over conventional CPB systems, limited venous return can result in severe fluctuations of venous line pressure which can result in gaseous emboli. In this study, we investigated the influence of sub-atmospheric pressures and volume buffer capacity added to the venous line on the generation of gaseous emboli in the mCPB circuit.

Two different mCPB systems (MEC - Maquet, n=7 and ECC.O - Sorin, n=8) and a conventional closed cardiopulmonary bypass (cCPB) system (n=12) were clinically evaluated. In the search for a way to increase volume buffer capacity of mCPB systems, we additionally evaluated the ‘Better Bladder’ (BB) in a mock circulation by simulating, repeatedly, decreased venous return while measuring pressure and gaseous embolic activity.

Arterial gaseous emboli activity during clinical perfusion with a cCPB system was the lowest in comparison to the mCPB systems (312±465 versus 311±421 with MEC and 1,966±1,782 with ECC.O, counts per 10 minute time interval, respectively; p=0.03). The average volume per bubble in the arterial line was the highest in cases with cCPB (12.5±8.3 nL versus 8.0±4.2 nL with MEC and 4.6±4.8 nL with ECC.O; p=0.04 for both). Significant cross-correlation was obtained at various time offsets from 0 to +35 s between sub-atmospheric pressure in the venous line and gaseous emboli activity in both the venous and arterial lines. The in vitro data showed that incorporation of the BB dampens fluctuations of venous line pressure by approximately 30% and decreases gaseous emboli by up to 85%.

In conclusion, fluctuations of sub-atmospheric venous line pressure during kinetic-assisted drainage are related to gaseous emboli. Volume buffer capacity added to the venous line can effectively dampen pressure fluctuations resulting from abrupt changes in venous return and, therefore, can help to increase the safety of minimized cardiopulmonary bypass by reducing gaseous microemboli formation resulting from degassing.

A case-controlled evaluation of the Medtronic Resting Heart System compared with conventional cardiopulmonary bypass in patients undergoing isolated coronary artery bypass surgery

The Medtronic Resting Heart System (RHS) is a heparin-coated, closed perfusion circuit. Clinical results indicate less haemodilution and reduced complement activation, when compared with a traditional circuit leading to fewer postoperative blood transfusions. We evaluated the potential clinical benefits, including reduced transfusion requirements, when using the RHS compared with conventional cardiopulmonary bypass (cCPB). The study group (n = 330) consisted of patients undergoing isolated coronary artery bypass grafting (CABG) using the RHS system during 2005-2009, matched with a control group (n = 609) including patients operated for isolated CABG during 2002-2009, utilizing cCPB. Significantly fewer patients received peri- and postoperative blood transfusions in the RHS group (25 vs. 37%, P < 0.001; mean 1.0 ± 2.6 vs. mean 1.6 ± 2.9 units of packed red blood cells). The incidence of reoperations due to bleeding was low, RHS 2% (n = 8) vs. cCPB 5% (n = 29), with a trend towards no significant difference between groups (P = 0.079). The duration of mechanical ventilation was shorter (mean 7 ± 16 vs. 9 ± 12 h, P < 0.001) for patients in the RHS group. This study demonstrates that CABG performed with the RHS reduces the incidence and magnitude of allogenic blood transfusion and results in a satisfactory clinical outcome.

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.

Perfusion safety: new initiatives and enduring principles

Perfusion safety has been studied and discussed extensively for decades. Many initiatives occurred through efforts of professional organizations to achieve recognition, establish accreditation and certification, promote consensus practice guidelines, and develop peer-reviewed journals as sources for dissemination of clinical information. Newer initiatives have their basis in other disciplines and include systems approach, Quality Assurance/Quality Improvement processes, error recognition, evidence-based methodologies, registries, equipment automation, simulation, and the Internet. Use of previously established resources such as written protocols, checklists, safety devices, and enhanced communication skills has persisted to the present in promoting perfusion safety and has reduced current complication rates to negligible levels.

Miniaturized extracorporeal circulation vs. off-pump coronary artery bypass grafting: What the evidence shows?

Recognition of the potentially deleterious effects of esxtracorporeal circulation led to off-pump coronary artery surgery (OPCAB) experiencing a surge in popularity in the initial decade after its conception. However, OPCAB has its own limitations and technical difficulties, such as coronary access, increased left ventricular size and reduced function, which may lead to the potential for suboptimal revascularization. As an alternative technique, miniaturized extracorporeal circulation (mECC) may provide a more controlled operative field in which the heart may be manipulated whilst minimizing the inflammatory, coagulopathic and haemodilutional effects of cardiopulmonary bypass. In this review, we outline the proposed benefits of the mECC system, discuss the pitfalls associated with mECC, and directly compare mECC to ‘off-pump’ coronary surgery for a variety of clinical and non-clinical outcomes.

Are minimized perfusion circuits the better heart lung machines? Final results of a prospective randomized multicentre study

Introduction: Minimized perfusion circuits (MPCs), although aiming at minimizing the adverse effects of cardiopulmonary bypass, have not yet gained popularity. This can be attributed to concerns regarding their safety, as well as lack of sufficient evidence of their benefit.

Methods: Described is a randomized, multicentre study comparing the MPC - ROCsafeRX to standard cardiopulmonary bypass in patients undergoing elective coronary artery bypass grafting and/ or aortic valve replacement.

Results: Five hundred patients were included in the study (252 randomized to the ROCsafeRX group and 248 to standard cardiopulmonary bypass). Both groups were well matched for demographic characteristics and type of surgery. No operative mortality and no device-related complications were encountered.

Transfusion requirement (333 ± 603 vs. 587 ± 1010 ml; p=0.001), incidence of atrial fibrillation (16.3% vs. 24.2%; p=0.03) and the incidence of major adverse events (9.1% vs. 16.5%; p=0.02) were all in favour of the MPC group.

Conclusion: These results confirm both the safety and efficacy of the ROCsafeRX MPC for a large variety of cardiac patients. Minimized perfusion circuits should, therefore, play a greater role in daily practice so that as many patients as possible can benefit from their advantages.

Management of intraoperative fluid balance and blood conservation techniques in adult cardiac surgery

Blood transfusions are associated with adverse physiologic effects and increased cost, and therefore reduction of blood product use during surgery is a desirable goal for all patients. Cardiac surgery is a major consumer of donor blood products, especially when cardiopulmonary bypass (CPB) is used, because hematocrit drops precipitously during CPB due to blood loss and blood cell dilution. Advanced age, low preoperative red blood cell volume (preoperative anemia or small body size), preoperative antiplatelet or antithrombotic drugs, complex or re-operative procedures or emergency operations, and patient comorbidities were identified as important transfusion risk indicators in a report recently published by the Society of Cardiovascular Anesthesiologists. This report also identified several pre- and intraoperative interventions that may help reduce blood transfusions, including off-pump procedures, preoperative autologous blood donation, normovolemic hemodilution, and routine cell saver use.A multimodal approach to blood conservation, with high-risk patients receiving all available interventions, may help preserve vital organ perfusion and reduce blood product utilization. In addition, because positive intravenous fluid balance is a significant factor affecting hemodilution during cardiac surgery, especially when CPB is used, strategies aimed at limiting intraoperative fluid balance positiveness may also lead to reduced blood product utilization.This review discusses currently available techniques that can be used intraoperatively in an attempt to avoid or minimize fluid balance positiveness, to preserve the patient's own red blood cells, and to decrease blood product utilization during cardiac surgery.

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.

Clinical Evaluation of the Air Removal Characteristics of an Oxygenator with Integrated Arterial Filter in a Minimized Extracorporeal Circuit

The use of minimized extracorporeal circuits (MECC) in cardiac surgery is an important measure to increase the biocompatibility of cardiopulmonary bypass during coronary artery bypass grafting (CABG). These circuits eliminate volume storage reservoirs and bubble traps to minimize the circuit. However, the reduction in volume may increase the risk of gaseous microemboli (GME). The MECC system as used by our group consists of a venous bubble trap, centrifugal pump, and an oxygenator. To further reduce the risk of introducing GME, an oxygenator with an integrated arterial filter was developed based on the concept of minimal volume and foreign surface. We studied the air removal characteristics of this oxygenator with and without integrated arterial filter. The quantity and volume of GME were measured with precision at both the inlet and outlet of the devices.

Our results showed that integration of an arterial filter into this oxygenator increased GME reducing capacity from 69.2% to 92%. Moreover, we were able to obtain data on the impact of an arterial filter on the exact size-distribution of GME entering the arterial line.

The present study demonstrates that an MECC system and oxygenator with integrated arterial filter significantly reduces the volume and size of GME. The use of an integrated arterial filter in an MECC system may protect the patient from the deleterious effects of CPB and may further improve patient safety.

Prospective, Randomized Study Comparing Two Different Minimized versus Conventional Cardiopulmonary Bypass Systems

Objective

Conventional cardiopulmonary bypass (CCPB) is a major trigger of inflammatory response. We aimed to assess the impact of two different minimized cardiopulmonary bypass systems (mini-CPB) with and without Bioline-coating compared with CCPB regarding organ function, inflammatory response, and early clinical outcome.

Methods

In a prospective, randomized study, 120 patients underwent elective coronary artery bypass grafting and were randomized into three groups: mini-CPB using a Bioline-coated (group A, n = 40) or an uncoated (group B, n = 40) circuit, or CCPB (group C, n = 40). Cytokines (interleukin-6, interleukin-8, and tumor necrosis factor-alpha), myocardial markers (creatine kinase [CK], CK-MB, and troponin-T), hematocrit, and platelet counts were measured up to 48 hours postoperatively. Early clinical outcome was assessed at 3 months postoperatively.

Results

Demographics, number of distal anastomoses, ventilation time, blood loss, intensive care unit, and hospital stay were comparable (P = not significant). Extracorporeal circulation and cross-clamp time were significantly longer in group A and B versus C (P < 0.005). No significant differences could be found in the release of interleukin-6, interleukin-8, and tumor necrosis factor-alpha among groups. Myocardial markers were significantly reduced in group A and B versus group C (P < 0.001). Hematocrit and platelet counts did not differ among the groups. No differences could be found in early clinical outcome up to 3 months.

Conclusions

This study showed significant better myocardial preservation with lower CK-MB and troponin-T levels in both mini-CPB groups. No significant differences could be found in terms of inflammation, hematologic effects, and early clinical outcome.

Mini extracorporeal circuit cardiopulmonary bypass system: a review

Improved knowledge of the pathophysiological processes experienced in response to cardiopulmonary bypass has led to new developments in extracorporeal technology and understanding. The use of mini extracorporeal circuits (MECC) is rapidly expanding in clinical practice. The mini extracorporeal circuit differs by a greatly reduced tubing length and the number of components when compared with current circuit designs. The MECC is believed to offer potential benefits to the surgical patient by reducing the systemic inflammatory response that remains strongly implicated in post-operative organ dysfunction. We present a review of the available literature and find the MECC to show an acceptable safety profile with a reduction in post-operative complications and transfusion requirements and no evidence of any negative impairment to the surgeon, anaesthetist or perfusionist. The observed post-bypass inflammatory response is seen to be lower after MECC bypass and this is of clear clinical benefit.

No clear clinical benefit of using mini-invasive extracorporeal circulation in coronary artery bypass grafting in low-risk patients

Background: Current research is engaged in innovative technologies of extracorporeal circulation (ECC) systems in an effort to eliminate negative effetcs. Some studies have shown that, due to the complexity of technical settings of mini-ECC, they invoke a weaker immune response compared to classic ECC. The clinical benefits of using these systems have not been clearly proven yet. Methods: A group of 54 patients who were indicated for elective coronary surgery were randomised into two groups — Group A (patients operated on using classic ECC - open modification) and Group B (patients operated on using mini-ECC). The concentrations of IL-6, PMN elastase and MCP-1 in both groups were monitored per- and postoperatively, along with the postoperative clinical course. Results: The groups did not differ in the basic pre- and peroperative characteristics. We recorded a lower priming for mini-ECC (p < 0.001) and significantly reduced hemodilution during ECC. There were no differences in the clinical outcome in either group. Serum concentrations of monitored markers of immune reaction towards ECC showed higher activity during standard ECC. Conclusion: New technologies used in mini-systems have proven to lower activation of the immune system, which can be monitored using kinetics of proinflammatory mediators. In spite of these comparable laboratory results, we did not find differences in short-term clinical results when comparing both these groups of low-risk patients.

Strategies to prevent intraoperative lung injury during cardiopulmonary bypass

During open heart surgery the influence of a series of factors such as cardiopulmonary bypass (CPB), hypothermia, operation and anaesthesia, as well as medication and transfusion can cause a diffuse trauma in the lungs. This injury leads mostly to a postoperative interstitial pulmonary oedema and abnormal gas exchange. Substantial improvements in all of the above mentioned factors may lead to a better lung function postoperatively. By avoiding CPB, reducing its time, or by minimizing the extracorporeal surface area with the use of miniaturized circuits of CPB, beneficial effects on lung function are reported. In addition, replacement of circuit surface with biocompatible surfaces like heparin-coated, and material-independent sources of blood activation, a better postoperative lung function is observed. Meticulous myocardial protection by using hypothermia and cardioplegia methods during ischemia and reperfusion remain one of the cornerstones of postoperative lung function. The partial restoration of pulmonary artery perfusion during CPB possibly contributes to prevent pulmonary ischemia and lung dysfunction. Using medication such as corticosteroids and aprotinin, which protect the lungs during CPB, and leukocyte depletion filters for operations expected to exceed 90 minutes in CPB-time appear to be protective against the toxic impact of CPB in the lungs. The newer methods of ultrafiltration used to scavenge pro-inflammatory factors seem to be protective for the lung function. In a similar way, reducing the use of cardiotomy suction device, as well as the contact-time between free blood and pericardium, it is expected that the postoperative lung function will be improved.

Clinical evaluation of minimized extracorporeal circulation in high-risk coronary revascularization: impact on air handling, inflammation, hemodilution and myocardial function

Objective: We examined intraoperative microembolic signals (GME), inflammatory response, hemolysis, perioperative regional cerebral oxygen saturation (rSO2), myocardial protection and desorbed protein amount on oxygenator fibers in high-risk patients undergoing coronary revascularization (CABG) with minimized and conventional cardiopulmonary bypass (CPB). Methods: Over a ten-month period, 40 Euroscore 6+ patients undergoing CABG were prospectively randomized to one of the two perfusion protocols (N=20): Group 1: minimized extracorporeal circuits (Mini-CPB) (ROCsafe MPC, Terumo, Ann Arbor, MI, USA) and Group 2: conventional extracorporeal circuits (CECC) (Capiox SX18, Terumo, USA). Serum creatinine kinase-MB (CKMB), free hemoglobin, interleukin-6 (IL-6) and C3a levels were measured. Blood samples were collected at T1: following induction of anesthesia; T2: thromboelastography control; T3:15 min after commencement of CPB; T4: before cessation of CPB; T5: 15 min after protamine reversal and T6: ICU. Results: Serum IL-6 levels were significantly lower in the Mini-CPB group at T4 and T5 and C3a levels were significantly less in the Mini-CPB group at T3, T4 and T5 vs. CECC (p<0.01). CKMB levels in coronary sinus blood demonstrated well preserved myocardium in the Mini-CPB group. Percentage expression of neutrophil CD11b/CD18 levels were significantly lower in the Mini-CPB group at T4 and T5 (p<0.05). There were no significant differences in air handling characteristics or free plasma hemoglobin levels in either circuit. rSO2 measurements were significantly better at T3 and T4 in the Mini-CPB vs. CECC (p<0.05) and always higher in the Mini-CPB during follow-up. Blood protein adsorption analysis of oxygenator membranes demonstrated a significantly increased amount of microalbumin on CECC fibers (p<0.05). Conclusion: Mini-CPB provided a comfort and safety level similar to conventional control via satisfactory air handling, attenuated inflammatory response and hemodilution, with a better clinical outcome in patients undergoing high-risk CABG.