Inflammatory mediators in adults undergoing cardiopulmonary bypass: comparison of centrifugal and roller pumps

Cardiopulmonary bypass and internal thoracic artery: Can roller or centrifugal pumps change vascular reactivity of the graft? The IPITA study: A randomized controlled clinical trial

Background

Cardiopulmonary bypass (CPB) induces a systemic inflammatory response (SIRS) and affects the organ vascular bed. Experimentally, the lack of pulsatility alters myogenic tone of resistance arteries and increases the parietal inflammatory response. The purpose of this study was to compare the vascular reactivity of the internal thoracic arteries (ITAs) due to the inflammatory response between patients undergoing coronary artery bypass grafting (CABG) under CPB with a roller pump or with a centrifugal pump.

Methods

Eighty elective male patients undergoing CABG were selected using one or two internal thoracic arteries under CPB with a roller pump (RP group) or centrifugal pump (CFP group). ITA samples were collected before starting CPB (Time 1) and before the last coronary anastomosis during aortic cross clamping (Time 2). The primary endpoint was the endothelium-dependent relaxation of ITAs investigated using wire-myography. The secondary endpoint was the parietal inflammatory response of arteries defined by the measurements of superoxide levels, leukocytes and lymphocytes rate and gene expression of inflammatory proteins using. Terminal complement complex activation (SC5b-9) and neutrophil activation (elastase) analysis were performed on arterial blood at the same times.

Results

Exposure time of ITAs to the pump flow was respectively 43.3 minutes in the RP group and 45.7 minutes in the CFP group. Acetylcholine-dependent relaxation was conserved in the two groups whatever the time. Gene expression of C3 and C4a in the artery wall decreased from Time 1 to Time 2. No oxidative stress was observed in the graft. There was no difference between the groups concerning the leukocytes and lymphocytes rate. SC5b-9 and elastase increased between Time 1 and Time 2.

Conclusion

Endothelium-dependent relaxation of the internal thoracic arteries was preserved during CPB whatever the type of pump used. The inflammatory response observed in the blood was not found in the graft wall within this time frame.

Trial registration

Name of trial study protocol: IPITA

Registration number (ClinicalTrials.gov): NCT04168853.

Hemolysis and Inflammatory Response to Extracorporeal Circulation during On-Pump CABG: Comparison between Roller and Centrifugal Pump Systems

Objective

To compare the perioperative incidence rates of hemolysis and inflammatory response in patients undergoing coronary artery bypass grafting with the two main types of cardiopulmonary bypass, centrifugal and roller pumps, and establish correlations among hemolytic and inflammatory changes.

Methods

This was a prospective, randomized trial of 60 patients assigned to either roller pump (G1, n=30) or centrifugal pump (G2, n=30) bypass. Markers of hemolysis (serum haptoglobin, lactate dehydrogenase [LDH]) and inflammation (interleukin [IL]1ß, IL-6, and TNF-α) were measured and analyzed.

Results

There was no significant between-group difference in the variables of interest. In G1, there was a positive association with IL-6 and TNF-α (P<0.01 and P<0.05, respectively). In G2, there was a positive association with LDH in the postoperative period (P<0.5). At 24h post-cardiopulmonary bypass, there were positive associations between LDH and IL-1ß (P<0.05), LDH and TNF-α (P<0.01), haptoglobin and TNF-α (P<0.05), and LDH and TNF-α (P<0.01) in G1, and between LDH and IL-6 (P<0.01), LDH and TNF-α (P<0.01), and LDH and IL-6 (P<0.01) in G2.

Conclusion

There were no significant between-group differences in markers of hemolysis or inflammation. IL-6 and TNF-α were positively associated with duration of cardiopulmonary bypass in G1, while LDH was positively associated with duration of cardiopulmonary bypass in G2. The rate of significant associations between markers of hemolysis and inflammation was higher in the roller pump group (G1).

Registration number

ReBEC (RBR-92b9dg).

Cardiopulmonary bypass: development of John Gibbon's heart-lung machine

Objective

To provide a brief review of the development of cardiopulmonary bypass.

Methods

A review of the literature on the development of extracorporeal circulation techniques, their essential role in cardiovascular surgery, and the complications associated with their use, including hemolysis and inflammation.

Results

The advancement of extracorporeal circulation techniques has played an essential role in minimizing the complications of cardiopulmonary bypass, which can range from various degrees of tissue injury to multiple organ dysfunction syndrome. Investigators have long researched the ways in which cardiopulmonary bypass may insult the human body. Potential solutions arose and laid the groundwork for development of safer postoperative care strategies.

Conclusion

Steady progress has been made in cardiopulmonary bypass in the decades since it was first conceived of by Gibbon. Despite the constant evolution of cardiopulmonary bypass techniques and attempts to minimize their complications, it is still essential that clinicians respect the particularities of each patient's physiological function.

DEHP and its active metabolites: leaching from different tubing types, impact on proinflammatory cytokines and adhesion molecule expression. Is there a subsumable context?

Introduction: Di(2-ethylhexyl)phthalate (DEHP) is suspected to be toxic for several reasons. During contact with a lipophilic medium, DEHP leaks from polyvinylchloride (PVC), but its influence on inflammatory reactions remains unknown. We examined specific DEHP leaching out of different tubing types, the possibly modulated liberation of proinflammatory cytokines and the induction of adhesion molecule expression in primary endothelial cells.

Materials and Methods: Blood samples were circulated in traditional PVC, nodioctyl phthalate (DOP) PVC and heparin-coated PVC tubing within a Chandler loop model. The blood was tested for the concentration of DEHP and its active metabolites as well as the liberation of the proinflammatory cytokines TNFα and IL1ß. Furthermore, we exposed human endothelial cells to circulated blood and analysed them for the expression of the adhesion molecules ICAM-1, VCAM-1 and E-selectin.

Results: In contrast to the other tubing, PVC tubing showed significantly elevated DEHP levels, but no alteration was observed concerning a potential up-regulation of the cytokines or activation of the endothelial adhesion molecule receptors.

Conclusions: Our data conclude that there is no correlation between DEHP leaching and the inflammatory response after ECC support, but this study showed that even DEHP-free material is leaching DEHP and its toxic metabolites.

Clinical effectiveness of centrifugal pump to produce pulsatile flow during cardiopulmonary bypass in patients undergoing cardiac surgery

Although the centrifugal pump has been widely used as a nonpulsatile pump for cardiopulmonary bypass (CPB), little is known about its performance as a pulsatile pump for CPB, especially on its efficacy in producing hemodynamic energy and its clinical effectiveness. We performed a study to evaluate whether the Rotaflow centrifugal pump produces effective pulsatile flow during CPB and whether the pulsatile flow in this setting is clinically effective in adult patients undergoing cardiac surgery. Thirty-two patients undergoing CPB for elective coronary artery bypass grafting were randomly allocated to a pulsatile perfusion group (n = 16) or a nonpulsatile perfusion group (n = 16). All patients were perfused with the Rotaflow centrifugal pump. In the pulsatile group, the centrifugal pump was adjusted to the pulsatile mode (60 cycles/min) during aortic cross-clamping, whereas in the nonpulsatile group, the pump was kept in its nonpulsatile mode during the same period of time. Compared with the nonpulsatile group, the pulsatile group had a higher pulse pressure (P < 0.01) and a fraction higher energy equivalent pressure (EEP, P = 0.058). The net gain of pulsatile flow, represented by the surplus hemodynamic energy (SHE), was found much higher in the CPB circuit than in patients (P < 0.01). Clinically, there was no difference between the pulsatile and nonpulsatile groups with regard to postoperative acute kidney injury, endothelial activation, or inflammatory response. Postoperative organ function and the duration of hospital stay were similar in the two patient groups. In conclusion, pulsatile CPB with the Rotaflow centrifugal pump is associated with a small gain of EEP and SHE, which does not seem to be clinically effective in adult cardiac surgical patients.

LIFEBRIDGE B2T--a new portable cardiopulmonary bypass system

The LIFEBRIDGE B2T is a new portable cardiopulmonary bypass (CPB) system designed for temporary circulatory support. The LIFEBRIDGE B2T consists of a disposable patient unit with a CPB circuit, a control, and a base unit. The system weighs 20 kg. We used the LIFEBRIDGE B2T in four patients for circulatory support in beating heart coronary artery bypass graft for complete revascularization. The LIFEBRIDGE B2T was connected via femoral cannulation. Concentrations of free hemoglobin (fHb), interleukin (IL)-6, and -8 were measured. For venous blood drainage, 22-24 Fr cannulae and for arterial cannulation, 16-20 Fr cannulae were used. Average extracorporeal circulation (ECC) time was 61 +/- 18 minutes. During circulatory support, the system delivered an arterial blood flow between 3.1 and 4.1 L/min. The negative pressure at the venous drainage was between -79 and -45 mm Hg. During circulatory support, fHb concentration increased from 5.8 +/- 1.7 mg/dL to a maximum of 10.2 +/- 6.2 mg/dL. Also, IL-6 and -8 increased from 2.1 +/- 0.06 to 503.3 +/- 400.7 U/L and 5.9 +/- 0.9 to 66.5 +/- 46.8 U/L, respectively. The LIFEBRIDGE B2T is a new portable and safe circulatory support system. Connected via femoral cannulation, the system provides adequate arterial blood flow and an acceptable negative pressure at the venous cannula. The fHb concentration showed only a moderate increase during ECC.

Comparison of the centrifugal and roller pump in elective coronary artery bypass surgery—a prospective, randomized study with special emphasis upon platelet activation

Objective--Evaluation of the centrifugal pump vs roller pump concerning effects upon platelet function, hemolysis and clinical outcome in elective coronary artery bypass surgery. Design--Thirty-four patients were randomized to centrifugal or roller pump. Platelet activation was studied by flow cytometry before, during and up to 3 days after bypass. Results--Duration of bypass, ischemic period, peripheral anastomoses, hospital stay and mortality did not differ. In roller pump patients, platelet aggregates increased by 250% between end of bypass and 3 h postoperatively (p < 0.001). A secondary, fivefold increase in number of platelet aggregates was found on the 3rd postoperative day (p < 0.001). In the centrifugal pump group, these changes were not significant. Hemolysis increased (20%) at end of bypass and 3 h postoperatively (p < 0.005), and decreased to preoperative levels the next day without group difference. Conclusion--Platelet aggregation was significantly increased in roller compared with centrifugal pump patients, indicating higher susceptibility to postoperative thrombotic complications with the roller pump. Otherwise, there was no clinical evidence for superiority of the centrifugal pump.

[Inflammatory response and haematological disorders in cardiac surgery: toward a more physiological cardiopulmonary bypass]

The systemic inflammatory response in cardiac surgery is closely related to the haemostasis disturbances. It is responsible of a significant morbidity and mortality that was previously suspected to be caused by cardiopulmonary bypass alone. However, it is time now to clearly identify the factors that are material-dependent from that material-independent. From this point of view, off-pump surgery allowed for better comprehension of the multiple sources of the inflammatory response. Numerous pathways are activated, involving complement, platelets, neutrophiles and monocytes. The tissue pathway of the coagulation system, through tissue factor, is of major importance and has to be surgically considered in order to reduce the whole body inflammatory response postoperatively. The quality of the extracorporeal perfusion through its consequences on organ perfusion, particularly in the splanchnic area, also participates to this pathophysiological process. Beyond the progress of technology provided by the industry, particularly the minimally extracorporeal circulation derived from off-pump surgery evolution, the surgical approach is of major importance in the control of the systemic inflammatory response and must not be ignored yet.

Induction and detection of disturbed homeostasis in cardiopulmonary bypass

During cardiopulmonary bypass (CPB) haemodynamic alterations, haemostasis and the inflammatory response are the main causes of homeostatic disruption. Even with CPB procedures of short duration, the homeostasis of a patient is disrupted and, in many cases, requires intensive postoperative treatment to re-establish the physiological state of the patient. Although mortality is low, disruption of homeostasis may contribute to increased morbidity, particularly in high-risk patients. Over the past decades, considerable technical improvements in CPB equipment have been made to prevent the development of the systemic inflammatory response syndrome (SIRS). Despite all these improvements, only the inflammatory response, to some extent, has been reduced. The microcirculation is still impaired, as measured by tissue degradation products of various organs, indicating that CPB may still be considered as an unphysiological procedure. The question is, therefore, whether we can detect the pathophysiological consequences of CPB in each individual patient with valid bedside markers, and whether we can relate this to determinant factors in the CPB procedure in order to assist the perfusionist in improving the adequacy of CPB. The use of these markers could play a pivotal role in decision making by providing an immediate feedback on the determinant quality of perfusion. Therefore, we suggest validating the proposed markers in a nomogram to optimize not only the CPB procedure, but also the patient's safety.

Inflammation After Cardiopulmonary Bypass: Therapy for the Postpump Syndrome

Cardiopulmonary bypass (CPB) is used in most, but not all, complex heart operations. CPB is associated with a systemic inflammatory response in adults and children. Many materials-dependent (exposure of blood to non- physiologic surfaces and conditions) and materials-in dependent (surgical trauma, ischemia-perfusion to the organs, changes in body temperature, and release of endotoxin) factors during CPB have been implicated in the etiology of this complex response. The mechanisms involved may include complement activation, release of cytokines, leukocyte activation with expression of ad hesion molecules, and production of various vasoactive and immunoactive substances. Postpump inflamma tion may lead to postoperative complications and may result in respiratory failure, renal dysfunction, bleeding disorders, neurologic dysfunction, altered liver func tion, and ultimately multiple organ failure. Significant efforts are being made to decrease the generation and effects of postpump inflammation. Interventions to this end have included avoiding CPB when possible, im proving the biocompatibility of the involved mechani cal devices, and administering medications that main tain cellular integrity. This article provides an overview of the etiology, pathophysiology, and treatment of postpump inflammation. Perhaps with additional in sight into this syndrome, CPB can be made a safer and more efficacious modality of cardiorespiratory support. Copyright© 2001 by W.B. Saunders Company.

Oxygen free radical generation in healthy blood donors and cardiac patients: the protective effect of allopurinol

Cardiopulmonary bypass (CPB) activates the complement system, which leads to granulocyte activation and free radical production. Free radical activity during CPB has been associated with myocardial dysfunction. However, the relationship between cardiac enzymes and granulocytes to lipid peroxidation in cardiac surgery patients is unknown. Moreover, the effect of allopurinol on lipid peroxidation during mechanical trauma has to be explored. Thirty-four patients undergoing coronary bypass surgery and 26 healthy blood donors participated in this prospective study where granulocyte counts, cardiac enzymes and malondialdehyde (MDA) were measured and related. Allopurinol was used ex vivo, as scavenger, to explore its effect on lipid peroxidation. In the patient group, the mean preoperative MDA level (2.2 +/- 0.7, nmol/ml) significantly increased after 30 min of bypass (3.3 +/- 0.9 nmol/ml; p < 0.0001), and showed a second peak at aortic declamping (4.1 +/- 0.9 nmol/ml). There were significant correlations between MDA and granulocyte counts (r = 0.59, p < 0.0001) and cardiac enzymes (r = 0.55, p < 0.0001). In an ex vivo setting, further mechanical trauma to blood significantly increased the MDA levels, both in the control (p < 0.0001) and in the patient group (p < 0.0001) and this effect could be reduced by allopurinol (p < 0.0001). CPB and mechanical trauma generate oxygen free radicals. Allopurinol was found to reduce lipid peroxidation of red cells following mechanical trauma and this has to be further investigated regarding its ability to reduce morbidity in patients undergoing open heart surgery.

Heparin-coated circuits reduce occult myocardial damage during CPB: a randomized, single blind clinical trial

OBJECTIVES

Cardiopulmonary bypass is associated with a diffuse systemic inflammatory response that can cause considerable morbidity, including organ dysfunction and bleeding. Heparin-coated circuits have been shown to give a reduced inflammatory response with clinical benefits during open-heart surgery. However, the effects on lipid peroxidation, neutrophil activation and myocardial ischemic damage in the human have remained unknown.

METHODS

In a randomized single blind trial, complement activation, neutrophil counts, malondialdehyde, and cardiac enzymes were studied in 39 patients undergoing open-heart surgery. Two groups were perfused with cardiopulmonary bypass circuits with (n=20) or without heparin-coating (n=19).

RESULTS

The different complement factors (C3, C4, C3d, C3d/C3 and the C-function), neutrophil levels, MDA and the cardiac enzyme levels were comparable before CPB was started and significantly increased in both groups during bypass. There were significant intergroup differences in the neutrophil levels and MDA after reperfusion (P<0.0001). Furthermore, significant positive correlations between the lipid peroxidation, expressed as MDA levels, and the levels of neutrofils and the cardiac enzyme, CK-MB were seen within the groups.

CONCLUSIONS

Heparin coated circuits did lead to a decreased neutrophil response and MDA level. The correlations between CK-MB and neutrophil and MDA levels suggest neutrophil activation leading to lipid peroxidation that may influence myocardial damage. Heparin coating improved biocompatibility and was associated with less occult myocardial ischemic damage in patients undergoing open heart surgery.

Biocompatibility of silicone-coated oxygenator in cardiopulmonary bypass

BACKGROUND

This study was designed to analyze the biocompatibility of silicone-coated oxygenators using inflammatory response as the outcome measure, and to investigate whether the silicone-coated oxygenators perform better in terms of postoperative organ dysfunction.

METHODS

The 32 patients who underwent cardiopulmonary bypass (CPB) were divided into 3 groups: group A (n = 10), heparin-coated circuit with silicone-coated oxygenator; group B (n = 11), whole heparin-coated circuit; and group C (n = 11), whole untreated circuit. The plasma concentrations of the proinflammatory markers, made of inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, interleukin-8), terminal complement complex (C5b-9), and polymorphonuclear elastase (PMN-E), were measured by enzyme-linked immunosorbant assay.

RESULTS

All proinflammatory markers were significantly lower in groups A and B than in group C, especially C5b-9 and PMN-E concentrations, which were significantly lower in group A than in group B. The alveolar-arterial oxygen gradients (A-aDO2) and the respiratory index were significantly better in group A than in group C. In group B, however, only the A-aDO2 was significantly better than in group C. The duration of intubation and the length of stay in the intensive care unit stay were significantly shorter in groups A and B than in group C.

CONCLUSIONS

Silicone-coated oxygenators are biocompatible and prevent postoperative organ dysfunction.

Serotonin-Induced Coronary Contraction Increases After Blood Cardioplegia-Reperfusion

Background —Coronary contraction has been implicated in causing suboptimal myocardial function after coronary bypass surgery. Addition of blood to cardioplegic solutions has been shown to improve endothelial function after cardioplegia. In this study, the effects of blood cardioplegia and brief reperfusion on vascular reactivity in patients with coronary artery disease and the expression (mRNA and protein) of enzymes involved in vasomotor regulation were examined.

Methods and Results —The atrial appendages of patients undergoing coronary artery surgery were harvested before cardiopulmonary bypass (control, n=8) and after bypass from a nonischemic tissue atrial segment exposed to cold, hyperkalemic blood cardioplegia (mean, 60 minutes) and a brief period (10 minutes) of reperfusion (CP-Rep, n=8). Responses of atrial arterioles were studied in vitro with video-microscopy. Reverse-transcriptase polymerase chain reaction and Western blotting were used to examine the expressions and protein content, respectively, of enzymes involved in vasomotor regulation. Serotonin caused a minimal dilation under baseline conditions but after CP-Rep elicited a potent contractile response that was inhibited in the presence of the selective inducible cyclooxygenase (COX-2) inhibitor NS398. Substance P caused an endothelium-dependent relaxation of atrial arterioles through release of nitric oxide, and ADP caused relaxation mediated through release of prostaglandins. After CP-Rep, relaxation to substance P was impaired, whereas endothelium-independent relaxation to nitroprusside and response to ADP were unchanged. Expression and protein level of COX-2 were significantly increased after CP-Rep. In contrast, expression of inducible (nitric oxide synthase-2) or constitutive endothelial (nitric oxide synthase-3) nitric oxide synthase, prostacyclin synthase, and constitutive cyclooxygenase (COX-1) were not altered after CP-Rep.

Conclusions —CP-Rep increases serotonin-induced contraction of human microvessels caused by the release of products of COX-2 and the impaired release of nitric oxide. These findings have implications regarding altered coronary microvascular regulation and the cause of coronary spasm after cardiac surgery.

Complement deposition in early cardiac transplant biopsies is associated with ischemic injury and subsequent rejection episodes

BACKGROUND

Prolonged warm or cold ischemia is associated with poor survival of cardiac transplants, and ischemic changes in early posttransplantation endomyocardial biopsies correlate with the later development of chronic rejection. In animal models, tissue ischemia has been shown to activate complement.

METHODS

To determine whether ischemic changes in endomyocardial biopsies were associated with complement deposition, biopsies obtained 1-3 weeks after transplantation from 33 patients were evaluated immunohistologically for C4d and C3d deposition as well as for IgM, IgG, and IgA. The histological changes associated with ischemic injury were scored independently, using previously reported criteria without knowledge of the immunohistochemical results.

RESULTS

Diffuse capillary and pericapillary deposition of C4d or C3d were detected in endomyocardial biopsies of 14 of the 33 patients. The majority of biopsies (79%) with C4d or C3d deposits had histological evidence of ischemic injury, including eight of the nine biopsies containing both C4d and C3d deposition. In contrast, only 8 of 18 (45%) of the biopsies without C4d or C3d deposition had ischemic injury. Only trace amounts of IgM and no IgG or IgA were demonstrable in the biopsies. Only 2 of the 14 biopsies with C4d or C3d deposition had evidence of moderate acute rejection, whereas 5 of the 18 biopsies without C4d or C3d deposition had moderate acute rejection. However, C4d and C3d deposition did correlate with repeated acute rejection episodes on subsequent biopsies.

CONCLUSIONS

Thus, ischemic changes are associated with the activation of complement. Complement activation may in turn promote tissue injury and provide a potential target for future treatment.

Mechanisms of the systemic inflammatory response

The purpose of inflammation is to combat various agents that may injure the tissues. Conditions such as CPB can often cause systemic inflammation and dysfunction of major organs. Pulmonary, renal, myocardial and intestinal function may suffer various degrees of impairment during and after cardiac surgery. Although changes in major organs usually remain clinically insignificant, severe organ failure is not uncommon. The process of systemic inflammation proceeds through activation of serum proteins, activation of leucocytes and endothelial cells, secretion of cytokines, leucocyte-endothelial cell interaction, leucocyte extravasation and tissue damage. Several anti-inflammatory strategies have already been used, some of which have given promising results pertaining to further reduction in the rate of the inflammation-related complications in cardiac surgical patients.

Cardiopulmonary bypass: new strategies for weaning from cardiopulmonary bypass

This review focuses on weaning from cardiopulmonary bypass, a very critical time for patients and anaesthetists and frequently requiring major therapeutic effort. Few novel strategies for weaning have been described recently. Most drugs or approaches described during the review period are already well established. Emphasis is placed on the importance of non-cardiac factors, and on the importance of diastolic ventricular function as opposed to systolic function.