Systemic inflammatory response to coronary artery bypass graft surgery

Platelet transfusion enhances pro-aggregatory status shortly after coronary artery bypass grafting (CABG while modulating platelet pro-inflammatory state 1-week post-surgery

During coronary artery bypass grafting (CABG), the surgical procedure, particularly the manipulation of the major arteries of the heart, induces a significant inflammatory state that may compromise platelet function to the extent that platelet transfusion is required. Given stored platelets as a major source of biological mediators, this study investigates the effects of platelet transfusion on the major pro-aggregatory, pro-inflammatory and immunomodulatory markers of platelets. Platelets from 20 patients, 10 who received platelet transfusion and 10 without, were subjected to flow cytometery where P-selectin and CD40 ligand (CD40L) expressions and PAC-1 binding (activation-specific anti GPIIb/GPIIIa antibody) analysed at five-time points of 24 h before surgery, immediately, 2 h, 24 h and 1 week after surgery. Analysis of intra-platelet transforming growth factor-beta-1 (TGF-β1) was also conducted using western blotting. Patients with platelet transfusion showed increased levels of P-selectin, CD40L and intra-platelet TGF-β1 2-h after surgery compared to those without transfusion (p < 0.05). PAC-1 binding was increased 24 h after surgery in transfused patients (p < 0.05). Given the significant post-transfusion elevation of platelet TGF-β1, P-sel/CD40L reduction in transfused patients a week after was of much interest. This study showed for the first time the significant effects of platelet transfusion on the pro-inflammatory, pro-aggeregatory and immunomodulatory state of platelets in CABG patients, which manifested with immediate, midterm and delayed consequences. While the increased pro-inflammatory conditions manifested as an immediate effect of platelet transfusion, the pro-aggregatory circumstances emerged 24 h post-transfusion. A week after surgery, attenuations of pro-inflammatory markers of platelets in transfused patients were shown, which might be due to the immunomodulatory effects of TGF-β1.

Enhanced Recovery After Cardiac Surgery: Where Do We Stand?

Purpose of Review

Enhanced recovery after surgery (ERAS) protocols are multimodal and multi-professional strategies to enhance postoperative convalescence and thereby reduce the length of hospital stay and hospital-associated complications. This review provides an up-to-date overview about basic principles of enhanced recovery after surgery protocols, their transfer into cardiac surgery, and their current state of evidence. It is supposed to offer clinical implications for further adaptations and implementations of such protocols in cardiac surgery.

Recent Findings

ERAS protocols are a story of success in numerous surgical disciplines and led to a paradigm shift in perioperative care and the establishment of ERAS Cardiac Society, a non-profit organization that provides evidence-based guidelines and recommendations for further development of enhanced recovery protocols, trying to harmonize the many existing efforts of individual approaches for cardiac surgery.

Summary

Promising results from comprehensive ERAS protocols in cardiac surgery emerged. Nevertheless, there is a paucity of high-quality data about holistic approaches in cardiac surgery and further efforts need to be promoted.

Inhibition of metalloproteinases in therapy for severe lung injury due to COVID-19

Since its first appearance in December 2019 in the Chinese province of Wuhan, COVID-19 has spread rapidly throughout the world and poses a serious threat to public health. Acute respiratory failure due to widespread lung inflammation progress to acute respiratory distress syndrome (ARDS) with an altered pulmonary and alveolar function that can lead to disability, prolong hospitalizations, and adverse outcomes.

While there is no specific treatment for severe acute lung injury (ALI) and ARDS due to the COVID-19 and the management is mostly supportive, it is very important to better understand the pathophysiological processes activated by the inflammatory mediators such as cytokines and metalloproteinases with the aim of their subsequent inhibition in the course of the complex treatment.

Herein, we will discuss the pathophysiological mechanisms of ALI/ARDS, with a focus on the pivotal role played by matrix metalloproteinases (MMP) and the kinin-kallikrein system (KKS), and the effects of the possible pharmacological interventions.

Aprotinin is a nonspecific protease inhibitor especially of trypsin, chymotrypsin, plasmin, and kallikrein, and it is many years in clinical use. Aprotinin inhibits the release of pro-inflammatory cytokines and involved in the process of glycoprotein homeostasis. Experimental data support that the use of aprotinin to inhibit MMPs and KKS may be a new potential approach to the treatment of ALI / ARDS.

Tranexamic acid in cardiac surgery: a systematic review and meta-analysis (protocol)

INTRODUCTION

Bleeding during cardiac surgery is associated with increased morbidity and mortality. Tranexamic acid is an antifibrinolytic with proven efficacy in major surgeries. Current clinical practice guidelines recommend intraoperative use in cardiac procedures. However, several complications have been reported with tranexamic acid including seizures. This review intends to summarise the evidence examining the efficacy and safety of tranexamic acid in patients undergoing cardiac surgery.

METHODS/DESIGN

We will search MEDLINE, Embase, PubMED, ACPJC, CINAHL and the Cochrane trial registry for eligible randomised controlled trials, the search dates for all databases will be from inception until 1 January 2019, investigating the perioperative use of topical and/or intravenous tranexamic acid as a stand-alone antifibrinolytic agent compared with placebo in patients undergoing open cardiac surgery. We categorised outcomes as patient critical or patient important. Selected patient-critical outcomes are: mortality (intensive care unit, hospital and 30-day endpoints), reoperation within 24 hours, postoperative bleeding requiring transfusion of packed red blood cells, myocardial infarction, stroke, pulmonary embolism, bowel infarction, upper or lower limb deep vein thrombosis and seizures. Those outcomes, we perceived as clinical experts to be most patient valued and patients were not involved in outcomes selection process. We will not apply publication date, language, journal or methodological quality restrictions. Two reviewers will independently screen and identify eligible studies using predefined eligibility criteria and then review full reports of all potentially relevant citations. A third reviewer will resolve disagreements if consensus cannot be achieved. We will present the results as relative risk with 95% CIs for dichotomous outcomes and as mean difference or standardised mean difference for continuous outcomes with 95% CIs. We will assess the quality of evidence using the Grading of Recommendations, Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

Formal ethical approval is not required as primary data will not be collected. The results will be disseminated through a peer-reviewed publication TRIAL REGISTRATION NUMBER: CRD42018105904.

Bioactive Sphingolipids, Complement Cascade, and Free Hemoglobin Levels in Stable Coronary Artery Disease and Acute Myocardial Infarction

BACKGROUND

Acute myocardial infarction (AMI) and coronary artery bypass graft (CABG) surgery are associated with a pathogen-free inflammatory response (sterile inflammation). Complement cascade (CC) and bioactive sphingolipids (BS) are postulated to be involved in this process.

AIM

The aim of this study was to evaluate plasma levels of CC cleavage fragments (C3a, C5a, and C5b9), sphingosine (SP), sphingosine-1-phosphate (S1P), and free hemoglobin (fHb) in AMI patients treated with primary percutaneous coronary intervention (pPCI) and stable coronary artery disease (SCAD) undergoing CABG.

PATIENTS AND METHODS

The study enrolled 37 subjects (27 male) including 22 AMI patients, 7 CABG patients, and 8 healthy individuals as the control group (CTRL). In the AMI group, blood samples were collected at 5 time points (admission to hospital, 6, 12, 24, and 48 hours post pPCI) and 4 time points in the CABG group (6, 12, 24, and 48 hours post operation). SP and S1P concentrations were measured by high-performance liquid chromatography (HPLC). Analysis of C3a, C5a, and C5b9 levels was carried out using high-sensitivity ELISA and free hemoglobin by spectrophotometry.

RESULTS

The plasma levels of CC cleavage fragments (C3a and C5b9) were significantly higher, while those of SP and S1P were lower in patients undergoing CABG surgery in comparison to the AMI group. In both groups, levels of CC factors showed no significant changes within 48 hours of follow-up. Conversely, SP and S1P levels gradually decreased throughout 48 hours in the AMI group but remained stable after CABG. Moreover, the fHb concentration was significantly higher after 24 and 48 hours post pPCI compared to the corresponding postoperative time points. Additionally, the fHb concentrations increased between 12 and 48 hours after PCI in patients with AMI.

CONCLUSIONS

Inflammatory response after AMI and CABG differed regarding the release of sphingolipids, free hemoglobin, and complement cascade cleavage fragments.

Pyruvate Dehydrogenase Activity and Quantity Decreases After Coronary Artery Bypass Grafting: a Prospective Observational Study

INTRODUCTION

Pyruvate dehydrogenase (PDH) is a key gatekeeper enzyme in aerobic metabolism. The main purpose of this study was to determine if PDH activity is affected by major stress in the form of coronary artery bypass grafting (CABG), which has previously been used as a model of critical illness.

METHODS

We conducted a prospective, observational study of patients undergoing CABG at an urban, tertiary care hospital. We included adult patients undergoing CABG with or without concomitant valve surgery. Measurements of PDH activity and quantity and thiamine were obtained prior to surgery, at the completion of surgery, and 6 h after surgery.

RESULTS

Fourteen patients were enrolled (aged 67 ± 10 years, 21% female). Study subjects had a mean 41.7% (SD, 27.7%) reduction in PDH activity after surgery and a mean 32.0% (SD, 31.4%) reduction 6h after surgery (P < 0.001). Eight patients were thiamine deficient (≤ 7 nmol/L) after surgery compared with none prior to surgery (P = 0.002). Thiamine level was significantly associated with PDH quantity at all time points (P = 0.01). Postsurgery lactate levels were inversely correlated with postsurgery thiamine levels (r = -0.58 and P = 0.04).

CONCLUSION

The stress of major surgery causes decreased PDH activity and quantity and depletion of thiamine levels.

COMT-Val158Met-polymorphism is not a risk factor for acute kidney injury after cardiac surgery

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) depicts a major complication after cardiac surgery using cardiopulmonary bypass (CPB).

OBJECTIVE

CSA-AKI has clearly been linked to increased perioperative morbidity and mortality. Dysregulations of vasomotor tone are assumed to be causal for CSA-AKI. While catechol-O-methyltransferase (COMT) is involved in metabolizing catecholamines, a single-nucleotide polymorphism (SNP) in the COMT gene leads to different enzyme activities according to genotype. Pilot studies found associations between those COMT genotypes and CSA-AKI.

METHODS

We prospectively included 1741 patients undergoing elective cardiac surgery using cardiopulmonary bypass (CPB). Patients were genotyped for COMT-Val158Met-(G/A) polymorphism (rs4680).

RESULTS

Demographic characteristics and procedural data revealed no significant differences between genotypes. No association between COMT genotypes and the RIFLE criteria could be detected. A multiple linear regression analysis for postoperative creatinine increase revealed highly significant associations for aortic cross-clamp time (P < 0.001), CPB time (P < 0.001), norepinephrine (P < 0.001), and age (P < 0.001). No associations were found for COMT genotypes or baseline creatinine. With an R (2) = 0.39 and a sample size of 1741, the observed power of the regression analysis was >99%.

CONCLUSIONS

Based on our results, we can rule out an association between the COMT-Val158Met-(G/A) polymorphism and the appearance of CSA-AKI.

Albumin limits mesenteric endothelial dysfunction and inflammatory response in cardiopulmonary bypass

The aim of this study was to investigate the potential anti-inflammatory and endothelial protective properties of albumin during cardiopulmonary bypass (CPB) in an experimental porcine model. Two groups underwent CPB for 90 min (n = 7 in each group), and a baseline (BL) control group did not undergo CPB (n = 7). Priming consisted of a gelatin solution (4% gelofusine, CPBG group) or colloid solution (5% albumin, CPBA group). Mesenteric arterial segments were isolated and exposed in vitro to phenylephrine (with or without nitric oxide synthase inhibition) to assess contractility, and exposed to acetylcholine and sodium nitroprusside to assess relaxation. Plasma tumor necrosis factor (TNF)-α levels, intestinal and pulmonary TNF-α and heme oxygenase (HO)-1 mRNA expression, and organ injury were studied. Upon sacrifice, TNF-α levels were significantly higher in the CPBG group than in the CPBA and BL groups. The contractile response was significantly higher in the CPBG group, whereas the response to acetylcholine was significantly lower in the CPBG group than in the other groups. HO-1 mRNA expression was significantly higher in intestine samples in the CPBA group than in the CPBG and BL groups. HO-1 mRNA expression was significantly higher in lung samples in the CPBA group than in the CPBG group. Leukocyte infiltration was significantly higher in intestine and lung samples in the CPBG group than in the CPBA and BL groups. Albumin priming reduced CPB-induced mesenteric vascular dysfunction and prevented the development of a systemic inflammatory response by modeling HO-1 expression in target organs.

Risk factors for late extubation after coronary artery bypass grafting

OBJECTIVE

To evaluate the independent risk factors for late extubation after coronary artery bypass grafting (CABG).

METHODS

Preoperative, intraoperative, and postoperative characteristics of patients undergoing isolated CABG between June 2005 and June 2008 at the Tongji Hospital were retrospectively analyzed. Elapsed time between CABG and extubation of more than 8hours was defined as late extubation.

RESULTS

The incidence of late extubation after CABG was 69.23% (288/416). Through univariate and logistic regression analysis, the independent risk factors for late extubation after CABG were older age (odds ratio [OR]=4.804), duration of cardiopulmonary bypass (OR=2.426), perioperative use of intra-aortic balloon pump (OR=1.451), preoperative arterial oxygen partial pressure (OR=.204), and postoperative hemoglobin level (OR=.793).

CONCLUSION

Older age, prolonged cardiopulmonary bypass time, perioperative intra-aortic balloon pump requirement, low preoperative arterial oxygen partial pressure, and low postoperative hemoglobin level were identified as the 5 independent risk factors for late extubation after CABG.

Two large preoperative doses of erythropoietin do not reduce the systemic inflammatory response to cardiac surgery

OBJECTIVES

Cardiac surgery and cardiopulmonary bypass (CPB) induce an inflammatory reaction that may lead to tissue injury. Experimental studies suggest that recombinant human erythropoietin (EPO) independent of its erythropoietic effect may be used clinically as an anti-inflammatory drug. This study tested the hypothesis that 2 large doses of EPO administered shortly before CPB ameliorate the systemic inflammatory response to CPB.

DESIGN AND SETTING

A prospective, double-blind, placebo-controlled and randomized study at a single tertiary care hospital.

PARTICIPANTS

Patients scheduled for coronary artery bypass graft surgery with CPB.

INTERVENTIONS

EPO (epoetin alfa, 500 IU/kg intravenously, n = 22) or placebo (n = 21) was administered 12 to 18 hours preoperatively and again at the induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

CPB in both groups greatly increased plasma concentrations of tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, IL-1beta receptor antagonist, IL-6, IL-10, and N-terminal probrain natriuretic peptide (NT-proBNP). Compared with placebo, EPO at day 3 after CPB augmented the TNF-alpha response (p < 0.05) and at 2 hours after CPB increased NT-proBNP (p < 0.05). Also, EPO tended to enhance the CPB-induced increase in IL-1beta receptor antagonist (p = 0.057). Otherwise, EPO had no effect on pro- and antiinflammatory mediators compared with placebo.

CONCLUSIONS

Two large doses of EPO given shortly before CPB do not reduce perioperative release of inflammatory cytokines. In contrast, EPO may augment the TNF-alpha and NT-proBNP response. Although the long-term clinical impact remains unknown, the findings do not support use of EPO as an anti-inflammatory drug in patients undergoing cardiac surgery.

Factors associated with excessive bleeding in cardiopulmonary bypass patients: a nested case-control study

Introduction

Excessive bleeding (EB) after cardiopulmonary bypass (CPB) may lead to increased mortality, morbidity, transfusion requirements and re-intervention. Less than 50% of patients undergoing re-intervention exhibit surgical sources of bleeding. We studied clinical and genetic factors associated with EB.

Methods

We performed a nested case-control study of 26 patients who did not receive antifibrinolytic prophylaxis. Variables were collected preoperatively, at intensive care unit (ICU) admission, at 4 and 24 hours post-CPB. EB was defined as 24-hour blood loss of >1 l post-CPB. Associations of EB with genetic, demographic, and clinical factors were analyzed, using SPSS-12.2 for statistical purposes.

Results

EB incidence was 50%, associated with body mass index (BMI)< 26.4 (25–28) Kg/m², (P = 0.03), lower preoperative levels of plasminogen activator inhibitor-1 (PAI-1) (P = 0.01), lower body temperature during CPB (P = 0.037) and at ICU admission (P = 0.029), and internal mammary artery graft (P = 0.03) in bypass surgery. We found a significant association between EB and 5G homozygotes for PAI-1, after adjusting for BMI (F = 6.07; P = 0.02) and temperature during CPB (F = 8.84; P = 0.007). EB patients showed higher consumption of complement, coagulation, fibrinolysis and hemoderivatives, with significantly lower leptin levels at all postoperative time points (P = 0.01, P < 0.01 and P < 0.01).

Conclusion

Excessive postoperative bleeding in CPB patients was associated with demographics, particularly less pronounced BMI, and surgical factors together with serine protease activation.

Bioinformatics analysis of the early inflammatory response in a rat thermal injury model

Background

Thermal injury is among the most severe forms of trauma and its effects are both local and systemic. Response to thermal injury includes cellular protection mechanisms, inflammation, hypermetabolism, prolonged catabolism, organ dysfunction and immuno-suppression. It has been hypothesized that gene expression patterns in the liver will change with severe burns, thus reflecting the role the liver plays in the response to burn injury. Characterizing the molecular fingerprint (i.e., expression profile) of the inflammatory response resulting from burns may help elucidate the activated mechanisms and suggest new therapeutic intervention. In this paper we propose a novel integrated framework for analyzing time-series transcriptional data, with emphasis on the burn-induced response within the context of the rat animal model. Our analysis robustly identifies critical expression motifs, indicative of the dynamic evolution of the inflammatory response and we further propose a putative reconstruction of the associated transcription factor activities.

Results

Implementation of our algorithm on data obtained from an animal (rat) burn injury study identified 281 genes corresponding to 4 unique profiles. Enrichment evaluation upon both gene ontologies and transcription factors, verifies the inflammation-specific character of the selections and the rationalization of the burn-induced inflammatory response. Conducting the transcription network reconstruction and analysis, we have identified transcription factors, including AHR, Octamer Binding Proteins, Kruppel-like Factors, and cell cycle regulators as being highly important to an organism's response to burn response. These transcription factors are notable due to their roles in pathways that play a part in the gross physiological response to burn such as changes in the immune response and inflammation.

Conclusion

Our results indicate that our novel selection/classification algorithm has been successful in selecting out genes with play an important role in thermal injury. Additionally, we have demonstrated the value of an integrative approach in identifying possible points of intervention, namely the activation of certain transcription factors that govern the organism's response.