Inflammatory response to cardiopulmonary bypass: mechanisms involved and possible therapeutic strategies

Endocytosis of peroxiredoxin 1 links sterile inflammation to immunoparalysis in pediatric patients following cardiopulmonary bypass

After cardiopulmonary bypass (CPB), the occurrence of systemic inflammatory response is often accompanied by a persistent compensatory anti-inflammatory response syndrome that can lead to a compromised immune competence termed immunoparalysis, rendering the patients susceptible to infections which is a leading complication following cardiac surgery. However, the underlying mechanisms of CPB-elicited immunoparalysis remain obscure. In this study we showed that peroxiredoxin 1 (Prdx1), a putative cytosolic antioxidant, was released immediately after CPB in a cohort of pediatric patients receiving congenital cardiac surgery. This increased Prdx1 was correlated to a reduced human leukocyte antigen-DR expression and an elevated interleukin-10 (IL-10) production, as well as a hypo-responsiveness of macrophages to endotoxin and a higher incidence of nosocomial infection. We demonstrated that substitution of Ser⁸³ for Cys⁸³ prevented Prdx1 from oligomerization and subsequent binding and internalization to macrophages. These effects mitigated Prdx1-induced IL-10 induction and endotoxin tolerance. Furthermore, after engagement with toll-like receptor (TLR) 4, clathrin-dependent endocytosis is crucial for Prdx1 to elicit IL-10 production in phagocytes. Congruently, inhibition of Prdx1/TLR4 endocytosis in phagocytes reversed the Prdx1/IL-10-mediated hypo-responsiveness to endotoxin. Our findings unveiled the possible mechanisms by which Prdx1 undertakes to cause immunoparalysis, and targeting endocytosis of Prdx1 could be a novel therapeutic approach for postoperative infections associated with CPB.

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Cardiopulmonary bypass-elicited ischemia/reperfusion injury causes release of Prdx1.

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High molecular weight forms of Prdx1 interact with TLR4 to initiate sterile inflammation.

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Endocytosis of Prdx1/TLR4 induces IL-10 production that leads to immunoparalysis and subsequent septic inflammation.

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Inhibition of Prdx1/TLR4 endocytosis reverses Prdx1/IL-10-mediated hypo-responsiveness to endotoxin in phagocytes.

Identifying Risk Factors for Complicated Post-operative Course in Tetralogy of Fallot Using a Machine Learning Approach

Introduction: Tetralogy of Fallot (TOF) repair is associated with excellent operative survival. However, a subset of patients experiences post-operative complications, which can significantly alter the early and late post-operative course. We utilized a machine learning approach to identify risk factors for post-operative complications after TOF repair.

Methods: We conducted a single-center prospective cohort study of children <2 years of age with TOF undergoing surgical repair. The outcome was occurrence of post-operative cardiac complications, measured between TOF repair and hospital discharge or death. Predictors included patient, operative, and echocardiographic variables, including pre-operative right ventricular strain and fractional area change as measures of right ventricular function. Gradient-boosted quantile regression models (GBM) determined predictors of post-operative complications. Cross-validated GBMs were implemented with and without a filtering stage non-parametric regression model to select a subset of clinically meaningful predictors. Sensitivity analysis with gradient-boosted Poisson regression models was used to examine if the same predictors were identified in the subset of patients with at least one complication.

Results: Of the 162 subjects enrolled between March 2012 and May 2018, 43 (26.5%) had at least one post-operative cardiac complication. The most frequent complications were arrhythmia requiring treatment (N = 22, 13.6%), cardiac catheterization (N = 17, 10.5%), and extracorporeal membrane oxygenation (ECMO) (N = 11, 6.8%). Fifty-six variables were used in the machine learning analysis, of which there were 21 predictors that were already identified from the first-stage regression. Duration of cardiopulmonary bypass (CPB) was the highest ranked predictor in all models. Other predictors included gestational age, pre-operative right ventricular (RV) global longitudinal strain, pulmonary valve Z-score, and immediate post-operative arterial oxygen level. Sensitivity analysis identified similar predictors, confirming the robustness of these findings across models.

Conclusions: Cardiac complications after TOF repair are prevalent in a quarter of patients. A prolonged surgery remains an important predictor of post-operative complications; however, other perioperative factors are likewise important, including pre-operative right ventricular remodeling. This study identifies potential opportunities to optimize the surgical repair for TOF to diminish post-operative complications and secure improved clinical outcomes. Efforts toward optimizing pre-operative ventricular remodeling might mitigate post-operative complications and help reduce future morbidity.

Effect of aortic cross-clamp time on late survival after isolated aortic valve replacement

OBJECTIVES

Longer aortic cross-clamp (ACC) time is associated with decreased early survival after cardiac surgery. Because maximum follow-up in previous studies on this subject is confined to 28 months, it is unknown whether this adverse effect is sustained far beyond this term. We aimed to determine whether longer ACC time was independently associated with decreased late survival after isolated aortic valve replacement in patients with severe aortic stenosis during 25 years of follow-up.

METHODS

In this retrospective cohort study, multivariable analysis was performed to identify possible independent predictors of decreased late survival, including ACC and cardiopulmonary bypass (CPB) time, in a cohort of 456 consecutive patients with severe aortic stenosis, who had undergone isolated aortic valve replacement between 1990 and 1993.

RESULTS

Mean follow-up was 25.3 ± 2.7 years. Median (interquartile range) and mean ACC times were normal: 63.0 (20.0) and 64.2 ± 16.1 min, respectively. Age, operative risk scores and New York Heart Association class were similar in patients with ACC time above, versus those with ACC time below the median. Longer ACC time was independently associated with decreased late survival: hazards ratio (HR) 1.01 per minute increase of ACC time (95% confidence interval [CI] 1.00-1.02; P = 0.012). Longer CPB time was not associated with decreased late survival (HR 1.00 per minute increase of CPB time [95% CI 1.00-1.00; P = 0.30]).

CONCLUSIONS

Longer ACC time, although still within normal limits, was independently associated with decreased late survival after isolated aortic valve replacement in patients with severe aortic stenosis.

The impact of exogenous nitric oxide during cardiopulmonary bypass for cardiac surgery

OBJECTIVES

Cardiac surgery using cardiopulmonary bypass frequently provokes a systemic inflammatory response syndrome. This can lead to the development of low cardiac output syndrome (LCOS). Both of these can affect morbidity and mortality. This study is a systematic review of the impact of gaseous nitric oxide (gNO), delivered via the cardiopulmonary bypass (CPB) circuit during cardiac surgery, on post-operative outcomes. It aims to summarise the evidence available, to assess the effectiveness of gNO via the CPB circuit on outcomes, and highlight areas of further research needed to develop this hypothesis.

METHODS

A comprehensive search of Pubmed, Embase, Web of Science and the Cochrane Library was performed in May 2020. Only randomised control trials (RCTs) were considered.

RESULTS

Three studies were identified with a total of 274 patients. There was variation in the outcomes measures used across the studies. These studies demonstrate there is evidence that this intervention may contribute towards cardioprotection. Significant reductions in cardiac troponin I (cTnI) levels and lower vasoactive inotrope scores were seen in intervention groups. A high degree of heterogeneity between the studies exists. Meta-analysis of the duration of mechanical ventilation, length of ICU stay and length of hospital stay showed no significant differences.

CONCLUSION

This systematic review explored the findings of three pilot RCTs. Overall the hypothesis that NO delivered via the CPB circuit can provide cardioprotection has been supported by this study. There remains a significant gap in the evidence, further high-quality research is required in both the adult and paediatric populations.

Nuclear factor erythroid 2-related factor 2 (Nrf2), tumor necrosis factor alpha protein (TNF-α), heme oxygenase-1 (HO-1) gene expressions during cardiopulmonary bypass

OBJECTIVE

During extracorporeal circulation, blood is in contact with nonendothelial surfaces. The increase in the amount of blood touching the non-endothelial surface increases the damage to the blood elements. This initiates and increases oxidative stress. Increased oxidative stress leads to the activation of antioxidant systems. These two systems work gradually in the process of Cardiopulmonary Bypass. This study aims to investigate the changes of TNF-α, Nrf2 and HO-1 gene expression in extracorporeal circulation.

MATERIALS AND METHODS

Fifteen patients who underwent open heart surgery were included in the study. Blood samples were taken preoperatively, during cardiopulmonary bypass (CPB) and 24 hours postoperatively. TNF-α, Nrf2 and HO-1 gene expressions in plasma samples were studied by using appropriate kits. Changes in gene expressions were compared.

RESULTS

TNF-α gene expression increased during CPB compared to preoperative levels (p <0.05). Similarly, Nrf-2 gene expression increased significantly during CPB (p <0.001) and decreased postoperatively (p <0.001). There was a significant increase in HO-1 gene expression during CPB (p <0.01). Postoperatively, this increase was found to decrease similar to Nrf2 (p <0.05).

CONCLUSIONS

According to the results, TNF-α, Nrf2, HO-1 gene expressions increase during CPB and these values decrease after the operation. This shows that oxidative stress and inflammatory processes start with CPB and antioxidant processes start similarly. With the termination of CPB, both processes are terminated. This has been demonstrated by gene expressions. Future studies will make it easier to understand these processes.

Safety and Efficacy of Human Chorionic Gonadotropin Hormone-Derivative EA-230 in Cardiac Surgery Patients: A Randomized Double-Blind Placebo-Controlled Study

OBJECTIVES

To determine the safety and efficacy of human chorionic gonadotropin hormone-derivative EA-230 in cardiac surgery patients. Cardiac surgery induces systemic inflammation and may impair renal function, affecting patient outcome. EA-230 exerted immunomodulatory and renoprotective effects in preclinical models and was safe and showed efficacy in phase I and II human studies.

DESIGN

Double-blinded, placebo-controlled, randomized study.

SETTING

Collaboration of the Cardiothoracic Surgery, Anesthesiology, and the Intensive Care departments of a tertiary hospital in the Netherlands.

PATIENTS

One hundred eighty patients undergoing an on-pump coronary artery bypass procedure with or without concomitant valve surgery.

INTERVENTIONS

Ninety mg/kg/hr EA-230 or placebo administered during surgery.

MEASUREMENTS AND MAIN RESULTS

During the study, no safety concerns emerged. EA-230 did not modulate interleukin-6 plasma concentrations (area under the curve 2,730 pg/mL × hr [1,968-3,760] vs 2,680 pg/mL × hr [2,090-3,570] for EA-230 and placebo group, respectively; p = 0.80). Glomerular filtration rate increased following surgery (mean ± sem increase in the EA-230 vs placebo groups: glomerular filtration rateiohexol measured using iohexol plasma clearance: 19 ± 2 vs 16 ± 2 mL/min/1.73 m2; p = 0.13 and estimated glomerular filtration rate with the Modification of Diet in Renal Disease equation using creatinine: 6 ± 1 vs 2 ± 1 mL/min/1.73 m2; p = 0.01). The "injury" stage of the Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease criteria for acute kidney injury was 7% in the EA-230 group versus 18% in the placebo group (p = 0.07). In addition, EA-230-treated patients had a less positive fluid balance compared with placebo-treated patients (217 ± 108 vs 605 ± 103 mL; p = 0.01), while the use of vasoactive agents was similar in both groups (p = 0.39). Finally, hospital length of stay was shorter in EA-230 treated patients (8 d [7-11] vs 10 d [8-12]; p = 0.001). Efficacy results were more pronounced in patients that had longer duration of surgery and thus longer duration of study drug infusion.

CONCLUSIONS

EA-230 was safe in patients undergoing on-pump cardiac surgery. It did not modulate interleukin-6 plasma concentrations but appeared to exert beneficial renal and cardiovascular effects and shortened in-hospital length of stay.

Perioperative management after elective cardiac surgery: the predictive value of procalcitonin for infective and noninfective complications

Objective: Procalcitonin (PCT) has been associated with adverse outcomes after cardiac surgery. Nevertheless, there is no consensus on thresholds and timing of PCT measurement to predict adverse outcomes. Materials & methods: A total of 960 patients undergoing elective cardiac surgery were retrospectively evaluated. PCT levels were measured from the first to the seventh postoperative day (POD). The onset of complications was recorded. Results: Complications occurred in 421 (44%) patients. PCT on the third POD was associated with the occurrence of any kind of complications (odds ratio: 1.06; p: 0.037), and noninfectious complications (odds ratio: 1.05; p: 0.035), after adjusting. PCT above the median value at the third POD (>0.33 μg/l) predicted postoperative complications (incidence rate ratio: 1.13; p = 0.035). Conclusion: PCT seems to predict postoperative complications in cardiac surgery. The determination at the third POD yields the greatest sensitivity and specificity.

Elevated Monocyte Chemoattractant Protein-1 as the Independent Risk Factor of Delirium after Cardiac Surgery. A Prospective Cohort Study

BACKGROUND

The pathogenesis of postoperative delirium is largely unknown. The primary objective of this study is to assess whether increased levels of monocyte chemoattractant protein-1 (MCP-1) and high-sensitivity C-reactive protein (hsCRP) are associated with postoperative delirium in patients who have undergone cardiac surgery. The secondary objective is to investigate whether any association between raised inflammatory biomarkers levels and delirium is related to surgical and anesthetic procedures or mediated by pre-existing psychiatric conditions associated with raised pro-inflammatory markers levels.

METHODS

The patients were screened for cognitive impairment one day preoperatively with the use of the Mini-Mental State Examination Test and the Clock Drawing Test. A diagnosis of major depressive disorder (MDD) and anxiety disorders was established on the basis of Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria. Blood samples were collected pre- and postoperatively for hsCRP and chemokine levels.

RESULTS

Postoperative delirium developed in 34% (61 of 177) of patients. Both pre- and postoperative hsCRP, and preoperative MCP-1 levels were associated with postoperative delirium in univariate comparisons; p = 0.001; p < 0.001; p < 0.001, respectively. However, according to a multivariable logistic regression analysis, only a raised MCP-1 concentration before surgery was independently associated with postoperative delirium, and related to advancing age, preoperative anxiety disorders and prolonged intubation.

CONCLUSIONS

The present study suggests that an elevated preoperative MCP-1 concentration is associated with delirium after cardiac surgery. Monitoring of this inflammatory marker may reveal the cardiovascular disease (CVD) patients who are at risk of neuropsychiatric syndromes development.

A comparison of cardiopulmonary bypass versus extracorporeal membrane oxygenation: Does intraoperative circulatory support strategy affect outcomes in pediatric lung transplantation?

OBJECTIVE

Data on adult lung transplantation suggest perioperative benefits of intraoperative extracorporeal membrane oxygenation (ECMO) compared to cardiopulmonary bypass (CPB). Information regarding their pediatric counterparts, however, is limited. This study compares outcomes of intraoperative ECMO versus CPB in pediatric lung transplantation.

METHODS

We reviewed all pediatric lung transplants at our institution from 2014 to 2019 and compared those supported intraoperatively on ECMO (n = 13) versus CPB (n = 22), plus a conditional analysis excluding re-transplantations (ECMO [n = 13] versus CPB [n = 20]). We evaluated survival, surgical times, intraoperative transfusions, postoperative support, complications, and duration of hospitalization.

RESULTS

Total time on ECMO support was significantly less than that of CPB support (P = .018). Intraoperatively, the ECMO group required fewer transfusions of fresh-frozen plasma (8.9 [5.8-22.3] vs 16.6 [11.4-39.0] mL/kg, P = .049) and platelets (4.2 [0.0-6.7] vs 8.0 [3.5-14.0] mL/kg, P = .049). When excluding re-transplantations, patients on ECMO required fewer packed red blood cells intraoperatively (12.6 [2.1-30.7] vs 28.2 [14.0-54.0] mL/kg, P = .048). There were no differences in postoperative support requirements, complications, or mortality at one, six, and twelve months.

CONCLUSIONS

Intraoperative ECMO support during pediatric lung transplantation appears to decrease intraoperative transfusion requirements when compared to CPB. Data from additional institutions may strengthen these observations.

Bag-1L Protects against Cell Apoptosis in an In Vitro Model of Lung Ischemia-Reperfusion Injury through the C-Terminal "Bag" Domain

Bcl-2-associated athanogene 1 (Bag-1) is a multifunctional and antiapoptotic protein that binds to the antiapoptosis regulator Bcl-2 and promotes cell survival. To investigate the protective function of Bag-1, we examined the effects of Bag-1L, one isoform of Bag-1, in an in vitro cell culture model of lung ischemia-reperfusion injury (LIRI) generated by treatment of A549 cells with hypoxia/reoxygenation. Overexpression of full-length Bag-1L increased the viability of A549 cells and reduced cell apoptosis in response to 6 h of hypoxia/reoxygenation treatment. Furthermore, Bag-1L overexpression enhanced the heat shock protein 70 (HSP70) and Bcl-2 protein levels, increased the phosphorylation of AKT, decreased Bax and cleaved caspase-3 levels, and was able to overcome cell cycle arrest. These effects were not observed in A549 cells overexpressing a truncated form of Bag-1L lacking the "Bag domain," denoted Bag-1L△C. The "Bag domain" is the C-terminal 47 amino acids. Taken together, the results of this study suggest that Bag-1L overexpression can protect against oxidative stress and apoptosis in an in vitro LIRI model, with a dependence on the Bag domain.

Preoperative Lymphocyte-to-Monocyte Ratio as a Prognostic Predictor of Long-Term Mortality in Cardiac Surgery Patients: A Propensity Score Matching Analysis

Aims: To evaluate the prognostic value of the preoperative lymphocyte-to-monocyte ratio (LMR) in patients who underwent cardiac surgery. Methods: Clinical data were extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) database. The optimal cutoff value of LMR was determined by X-tile software. The Cox proportional hazard model was applied for the identification of independent prognostic factors of 4-year mortality and survival curves were estimated using the Kaplan-Meier method. In order to balance the influence of potential confounding factors, a 1:1 propensity score matching (PSM) method was performed. Results: A total of 1,701 patients were included. The X-tile software indicated that the optimal cutoff value of the LMR for 4-year mortality was 3.58. After PSM, 489 pairs of score-matched patients were generated. The Cox proportional hazard model showed that patients with an LMR < 3.58 had a significantly higher 4-year mortality than patients with an LMR ≥ 3.58 in the entire cohort (HR = 1.925, 95%CI: 1.509-2.456, p < 0.001) and the PSM subset (HR = 1.568, 95%CI: 1.2-2.05, p = 0.001). The survival curves showed that patients with an LMR < 3.58 had a significant lower 4-year survival rate in the entire cohort (71.7 vs. 88.5%, p < 0.001) and the PSM subset (73.2 vs. 81.4%, p = 0.002). Conclusions: A lower LMR (<3.58) was associated with a higher risk of 4-year mortality and can serve as a prognostic predictor of the long-term mortality in cardiac surgery patients.

The Future Directions of Research in Cardiac Anesthesiology

This article provides an overview of knowledge gaps that need to be addressed in cardiac anesthesia, including mitigating the inflammatory effects of cardiopulmonary bypass, defining myocardial infarction after cardiac surgery, improving perioperative neurologic outcomes, and the optimal management of patients undergoing valve replacement. In addition, emerging approaches to research conduct are discussed, including the use of new analytical techniques like machine learning, pragmatic trials, and adaptive designs.

Effect of modified ultrafiltration on cytokines and hemoconcentration in dogs undergoing cardiopulmonary bypass

Cardiac surgery using cardiopulmonary bypass (CPB) generates severe inflammatory reactions secondary to hemodilution and surgical stress. This study was conducted to evaluate whether modified ultrafiltration (MUF) could be performed safely and to clarify its effects during mitral valve repair in dogs in terms of hemodilution and the status of inflammatory cytokines. We retrospectively studied 38 dogs with mitral valve disease who underwent MUF immediately after mitral valve repair under CPB. To determine the effect of MUF, we measured the pre- and post-MUF blood dilution and blood cytokine levels. The levels of red blood cells, hematocrit (HCT), and albumin were significantly increased after MUF, whereas interleukin (IL)-6 levels were significantly increased from 24.3 (range 9.6–54.6) to 32.3 (15.9–65.1) pg/ml. The levels of IL-8 and IL-10 declined significantly after MUF, from 368.2 (246.1–669.4) and 45.4 (28.6–76.1) to 272.2 (174.1–414.4) and 28.8 (18.8–44.5) pg/ml, respectively. Our results demonstrated that MUF can be applied in dogs undergoing CPB and is effective in achieving hemoconcentration. Moreover, MUF may be useful for the removal of cytokines. Further studies are needed to validate these findings and clarify the effects of inflammatory cytokines after CPB.

Cardiopulmonary Bypass Induces Acute Lung Injury via the High-Mobility Group Box 1/Toll-Like Receptor 4 Pathway

During cardiopulmonary bypass (CPB), pulmonary ischemia/reperfusion (I/R) injury can cause acute lung injury (ALI). Our previous research confirmed that abnormal high-mobility group box 1 (HMGB1) release after CPB was closely related to ALI. However, the mechanism underlying the HMGB1-mediated induction of ALI after CPB is unclear. Our previous study found that HMGB1 binds Toll-like receptor 4 (TLR4), leading to lung injury, but direct evidence of a role for these proteins in the mechanism of CPB-induced lung injury has not been shown. We examined the effects of inhibiting HMGB1 or reducing TLR4 expression on CPB-induced lung injury in rats administered anti-HMBG1 antibody or TLR4 short-hairpin RNA (shTLR4), respectively. In these rat lungs, we studied the histologic changes and levels of interleukin- (IL-) 1β, tumour necrosis factor- (TNF-) α, HMGB1, and TLR4 after CPB. After CPB, the lung tissues from untreated rats showed histologic features of injury and significantly elevated levels of IL-1β, TNF-α, HMGB1, and TLR4. Treatment with anti-HMGB1 attenuated the CPB-induced morphological inflammatory response and protein levels of IL-1β, TNF-α, HMGB1, and TLR4 in the lung tissues and eventually alleviated the ALI after CPB. Treatment with shTLR4 attenuated the CPB-induced morphological inflammatory response and protein levels of IL-1β, TNF-α, and TLR4 in the lung tissues and eventually alleviated the ALI after CPB, but could not alleviate the HMGB1 protein levels induced by CPB. In summary, the present study demonstrated that the HMGB1/TLR4 pathway mediated the development of ALI induced by CPB.

Potential risks in using midodrine for persistent hypotension after cardiac surgery: a comparative cohort study

Background

Persistent hypotension is a frequent complication after cardiac surgery with cardiopulmonary bypass (CPB). Midodrine, an orally administered alpha agonist, could potentially reduce intravenous vasopressor use and accelerate ICU discharge of otherwise stable patients. The main objective of this study was to explore the clinical impacts of administering midodrine in patients with persistent hypotension after CPB. Our hypothesis was that midodrine would safely accelerate ICU discharge and be associated with more days free from ICU at 30 days.

Results

We performed a retrospective cohort study that included all consecutive patients having received midodrine while being on vasopressor support in the ICU within the first week after cardiac surgery with CPB, between January 2014 and January 2018 at the Montreal Heart Institute. A contemporary propensity score matched control group that included patients who presented similarly prolonged hypotension after cardiac surgery was formed.

After matching, 74 pairs of patients (1:1) fulfilled inclusion criteria for the study and control groups. Midodrine use was associated with fewer days free from ICU (25.8 [23.7–27.1] vs 27.2 [25.9–28] days, p = 0.002), higher mortality (10 (13.5%) vs 1 (1.4%), p = 0.036) and longer ICU length of stay (99 [68–146] vs 68 [48–99] hours, p = 0.001). There was no difference in length of intravenous vasopressors (63 [40–87] vs 44 [26–66] hours, p = 0.052), rate of ICU readmission (6 (8.1%) vs 2 (2.7%), p = 0.092) and occurrence of severe kidney injury (11 (14.9%) vs 10 (13.5%) patients, p = 0.462) between groups.

Conclusion

The administration of midodrine for sustained hypotension after cardiac surgery with CPB was associated with fewer days free from ICU and higher mortality. Routine prescription of midodrine to hasten ICU discharge after cardiac surgery should be used with caution until further prospective studies are conducted.

Model of Magnetic Particle Capture Under Physiological Flow Rates for Cytokine Removal During Cardiopulmonary Bypass

OBJECTIVE

The objective of this study is to design a physical model of a magnetic filtration system which can separate magnetic nanoparticle (MNP)-tagged cytokines from fluid at physiologically relevant flow rates employed during cardiopulmonary bypass (CPB) procedures.

METHODS

The Navier-Stokes equations for the pressure driven flow in the chamber and the quasistatic stray magnetic field produced by an array of permanent magnets were solved using finite element analysis in COMSOL Multiphysics for 2D and 3D representations of the flow chamber. Parameters affecting the drag and magnetic forces including flow chamber dimensions, high gradient magnet array configurations, and particle properties, were changed and evaluated for their effect on MNP capture.

RESULTS

Flow chamber dimensions which achieve appropriate flow conditions for CPB were identified, and magnetic force within the chamber decreased with increased chamber height. A magnetic "block" array produced the highest magnetic force within the chamber. Polymeric microparticles loaded with MNPs were shown to have increased particle capture with increased hydrodynamic diameter.

CONCLUSION

The model achieved a predicted efficiency up to 100% capture in a single-pass of fluid flowing at 1.75 L/min.

SIGNIFICANCE

This work is an important step in designing a magnetic flow chamber that can remove the magnetically tagged cytokines under high flow employed during CPB. Cytokines have been shown to stimulate the systemic inflammatory response (SIR) associated with CPB and are an established therapeutic target to mitigate the SIR. In the long term, this work aims to guide researchers in the more accurate design of magnetic separation systems.

Nitric oxide added to the sweep gas of the oxygenator during cardiopulmonary bypass in infants: A pilot randomized controlled trial

Our objective was to assess the effect of nitric oxide added to the sweep gas of the oxygenator during cardiopulmonary bypass (CPB) in infants on platelet count, platelet function, clinical outcomes, and safety. A randomized, double-blinded, placebo-controlled clinical trial in infants less than a year of age undergoing cardiac surgery requiring CPB was undertaken. Nitric oxide at a dose of 20 ppm was added to the sweep gas in the treatment group. Blood was collected at baseline and prior to separation from CPB to measure platelet count and function as determined by responsiveness to specific agonists. Clinical outcomes were observed through hospital discharge. Methemoglobin levels were measured preoperatively, at the conclusion of CPB, and upon admission to the ICU. Forty patients consented and were randomized in the trial. Eighteen patients were randomized to the treatment group and 22 were included in the placebo group. The groups were similar in terms of age, weight, gender, and surgical complexity. No significant differences were found in measures of platelet count, platelet response to agonist, or clinical outcomes. Patients in the treatment group had higher methemoglobin levels after receiving nitric oxide, but no levels approached toxicity (maximum 2.4%). Nitric oxide added to the sweep gas of the oxygenator during CPB in infants did not have an appreciable effect on the preservation of platelet count, platelet responsiveness to agonist, or clinical outcomes. Methemoglobin levels were increased after receiving nitric oxide but were far below a toxic level of 15%.

Mannitol Is Associated with Less Postoperative Delirium after Aortic Valve Surgery in Patients Treated with Bretschneider Cardioplegia

Background  Heart surgery with extracorporeal circulation (ECC) often leads to postoperative delirium (POD). This is associated with increased morbidity resulting in longer hospital stay and associated costs. The purpose of our study was to analyze the effect of intraoperative mannitol application on POD in patients undergoing elective aortic valve replacement (AVR).

Materials and Method s In our retrospective single-center study, 259 patients underwent elective AVR, using Bretschneider cardioplegic solution for cardiac arrest, between 2014 and 2017. Patients were divided in mannitol ( n  = 188) and nonmannitol ( n  = 71) groups. POD was assessed using the confusion assessment method for the intensive care unit (ICU). Statistical significance was assumed at p  < 0.05.

Results  Baseline patient characteristics did not differ between the groups. Incidence of POD was significantly higher in the nonmannitol group (33.8 vs. 13.8%; p  = 0.001). These patients required longer ventilation time (24.1 vs. 17.1 hours; p  = 0.021), higher reintubation rate (11.3 vs. 2.7%; p  = 0.009), ICU readmission (12.7 vs. 4.8%; p  = 0.026), prolonged ICU (112 vs. 70 hours; p  = 0.040), and hospital stay (17.8 vs. 12.6 days; p  < 0.001), leading to higher expenses (19,349 € vs. 16,606 €, p  < 0.001). A 30-day mortality was not affected, but nonmannitol group showed higher Simplified Acute Physiology Score II score (32.2 vs. 28.7; p  < 0.001). Mannitol substitution was independently associated with lower incidence of POD (odds ratio: 0.40; 95% confidence interval: 0.18–0.89; p  = 0.02).

Conclusion  Treatment with mannitol during ECC was associated with decreased incidence of POD. This was accompanied by shorter ventilation time, ICU and hospital stay, and lower treatment expenses.

Impact of minimal invasive extracorporeal circulation on atrial fibrillation after coronary artery bypass surgery

Postoperative atrial fibrillation (POAF) is the most common arrhythmia after cardiac surgery with an incidence between 15% and 50% and pathophysiology not fully known. By choosing the method of extracorporeal circulation with focus on the reduction of systemic inflammatory response, one can potentially decrease the risk of POAF. In this prospective, randomized trial, we compared minimal invasive extracorporeal circulation (MiECC) with conventional extracorporeal circulation (CECC) in the prevention of POAF after coronary artery bypass surgery (CABG). A total of 240 patients who were scheduled for their first on-pump CABG, were randomized to MiECC or CECC. The primary outcome measure was the incidence of first POAF during the first 84 hours after surgery. POAF occurred in 42/120 (35.0%) MiECC patients and 43/120 (35.8%) CECC patients with nonsignificant difference between the groups (OR 1.043, 95% CI 0.591-1.843, P = .884). The first postoperative creatine kinase-MB mass (CK-MBm) value was lower in the MiECC group, 13.95 [10.5-16.7] (median [IQR]) than in the CECC group, 15.30 [11.4-18.9] (P = .036), whereas the use of perioperative dobutamine was higher in the MiECC group, 18/120 (15.0%), than in the CECC group 8/120 (6.7%) (P = .038). The incidence of a stroke, perioperative myocardial infarction, and resternotomy caused by bleeding did not differ in the MiECC and CECC groups. Age (OR 1.08, 95% CI 1.04-1.13, P = .000) and peak postoperative CK-MBm (OR 1.57, 95% CI 1.06-2.37, P = .026) were independent predictors of POAF. MiECC compared to CECC was not effective in reducing the incidence of POAF in patients undergoing CABG.

Myocardial Fluid Balance and Pathophysiology of Myocardial Edema in Coronary Artery Bypass Grafting

Myocardial edema is one of the most common complications of coronary artery bypass grafting (CABG) that is linearly related to many coronary artery diseases. Myocardial edema can cause several consequences including systolic dysfunction, diastolic dysfunction, arrhythmia, and cardiac tissue fibrosis that can increase mortality in CABG. Understanding myocardial fluid balance and tissue and systemic fluid regulation is crucial in order to ultimately link how coronary artery bypass grafting can cause myocardial edema in such a setting. The identification of susceptible patients by using imaging modalities is still challenging. Future studies about the technique of imaging modalities, examination protocols, prevention, and treatment of myocardial edema should be carried out, in order to limit myocardial edema occurrence and prevent complications.

Infection profile in neonatal patients during extracorporeal membrane oxygenation

OBJECTIVES

To describe risk factors for acquired infection during neonatal extracorporeal membrane oxygenation and to examine the predictive value of inflammatory markers in the diagnosis of infection.

METHODS

A retrospective study was conducted with data for patients under 30 days supported with extracorporeal membrane oxygenation from 2003 to April 2016, in a neonatal intensive care unit.

RESULTS

Our study included 160 neonatal patients, the average age of connection was 8.5 days and the duration of extracorporeal membrane oxygenation support was 9.7 days. The incidence of confirmed infection was 23%. Patients with confirmed infection present more frequently: vaginal delivery, lower birth weight, female sex, diagnosis of congenital diaphragmatic hernia, and longer duration of extracorporeal membrane oxygenation. When comparing the group of patients with confirmed infection and suspicion of infection, there were no significant differences in the inflammatory markers. When calculating the slope for each one, the difference in white blood cell count slope 72 h before the infection is significant; in patients with confirmed infection, the count of white blood cell increases (slope: 0.25), versus the group of patients with suspected infection in whom the count decreases (slope: -0.39). No differences were found in other variables.

CONCLUSION

Our study describes that the factors that increase the risk of infection are lower birth weight, vaginal birth, duration of extracorporeal membrane oxygenation, and a positive trend of white blood cell 72 h prior to infection/suspicion. Further studies are necessary to include or definitively rule out the use of these factors and the biomarkers as predictors of infection in neonatal patients supported with extracorporeal membrane oxygenation.

Interleukin -17 Serum Levels and Polymorphisms in Acute Kidney Injury Patients

BACKGROUND

Cardiopulmonary bypass (CPB) has been demonstrated to provoke a systemic inflammatory response believed to be responsible for some of the serious postoperative complications such as renal dysfunction. Therefore, we tested the hypothesis suggesting that the serum levels of IL- 17A (IL-17), as an inflammatory cytokine, and its gene variants are associated with acute kidney injury after CPB (AKI-CPB).

METHODS

A total of 135 Iranian patients undergoing cardiopulmonary bypass were included in this study, of whom 65 (48.1%) developed AKI. Blood specimens were collected preoperatively and at 12 hours postoperatively. The IL-17 gene polymorphisms (rs2275913 and rs3819024) were determined using sequence-specific primers (PCR-SSP) technique.Pre- and postoperative IL-17 levels were measured and analyzed in relation to polymorphisms.

RESULTS

IL-17 concentrations in CBP subjects, were increased after cardiopulmonary bypass (P<0.00001)but there were no statistically significant differences in IL-17 serum level between AKI and non-AKI groups. Different genotypes of IL-17 rs2275913 SNP (G→A) were associated with different circulating IL-17 levels before bypass and also after AKI development. There were no associations between gene polymorphisms (rs2275913and rs3819024) and incidence of AKI- CPB. There was an association between thers2275913 SNP and the severity of AKI.

CONCLUSION

This study clarified that the rs2275913 SNP to some extent determines plasma IL-17 concentrations in CPB patients. No significant association was found between IL-17 levels or gene polymorphisms (rs2275913and rs3819024) and incidence of AKI-CPB. Our results suggest that there is an association between rs2275913 and the severity of AKI- CPB.

Patients over 70 years of age with moderate ischemic mitral regurgitation undergoing surgical revascularization plus mitral valve repair: insights from a single-center study of propensity-matched data

Background

Elderly patients, compared with the young, have a higher burden of surgical risk factors with reduced functional capacity and increased comorbidities conditions, and may have worse clinical outcomes. So far, few reports have focused on clinical outcomes of patients over 70 years of age with moderate chronic ischemic mitral regurgitation (IMR) undergoing mitral valve repair at the time of coronary artery bypass grafting (CABG). This single-center study of propensity-matched data attempts to answer a question: compared with patients with age of 70 or less, whether patients over 70 years of age with moderate IMR undergoing CABG plus mitral valve repair receive poor outcomes.

Methods

All eligible patients were included in this study and were entered into either an elderly group (n=142) or a control group (n=182) according to patients' age. In-hospital outcomes (consisting of surgical mortality and major postoperative morbidity) and midterm clinical outcomes (including all-cause mortality and recurrent mitral regurgitation) were compared after propensity score matching (1:1).

Results

Using propensity-score matching, 103 pairs of patients were successfully established in a 1:1 ratio. No significant differences between the two matched groups were found with regard to surgical mortality (5.8% vs. 3.9%, P=0.754) and major postoperative morbidity. A total of 184 patients (91 in the elderly group and 93 in the control group) received regular follow-up visit with the median duration of 38 months [interquartile range (IQR), 27-56 months]. There were not any significant differences between the two matched groups regarding overall survival and recurrent IMR-free survival (stratified log-rank P=0.185 and stratified log-rank P=0.453, respectively). The elderly group as compared to the control group did not affect midterm mortality via cox proportional hazard regression (propensity score adjusted hazard ratio, 1.143; 95% confidence interval, 0.761-1.943; P=0.285).

Conclusions

Patients over 70 years of age with moderate chronic IMR undergoing combined CABG and mitral valve repair may receive favorable in-hospital and midterm clinical outcomes.

Discovery and development of plasma kallikrein inhibitors for multiple diseases

Plasma kallikrein (PKal) belongs to the family of trypsin-like serine proteases. The expression of PKal is associated with multiple physiological systems or pathways such as coagulation pathway, platelet aggregation process, kallikrein-kinin system, renin-angiotensin system and complement pathway. On the basis of PKal's multiple physiological functions, it has been considered as a potential target for several diseases including hereditary angioedema, microvascular complications of diabetes mellitus and cerebrovascular disease. Up to now, many PKal inhibitors have been identified and a few of them have reached clinical trials or market. This review summarizes the development of small molecule and peptide PKal inhibitors having different scaffolds and discusses their structure-activity relationship and selectivity. We hope this review facilitates a comprehensive understanding of the types of PKal inhibitors developed to tackle different manifestations of PKal-associated diseases.

The Functional Immune Response of Patients on Extracorporeal Life Support

Extracorporeal life support (ECLS) is a widely used lifesaving technology. Whether ECLS results in immune dysregulation is unclear. This study's aim was to examine whether ECLS affected innate immune response. All patients placed on ECLS were eligible. Blood was obtained before, during, and after ECLS. Function of the innate immune system was measured by ex vivo lipopolysaccharide (LPS)-induced tumor necrosis factor-α (TNF-α) and plasma cytokine levels (interleukin [IL]-6, IL-8, IL-10, and TNF-α). Immunoparalysis was defined as ex vivo TNF-α levels less than 200 pg/ml. Nineteen patients were enrolled with twelve <18 years old. Median ECLS duration was 10 days (range: 3-108); nine patients died. After stratifying the cohort by the presence of immunoparalysis before ECLS, those immunoparalyzed showed increased response to LPS on days 1 and 3 (p = 0.016). Those without pre-ECLS immunoparalysis showed a transient decrease in response on day 3 (p = 0.008). Plasma IL-10 levels were elevated in those with pre-ECLS immunoparalysis and dropped significantly by day 1 (p = 0.031). The number treated with steroids was similar in the two groups. In conclusion, patients with immunoparalysis before ECLS showed a gradual increase in immune function during ECLS, whereas those without immunoparalysis had a transient decrease in responsiveness on day 3.

Extracorporeal life support during and after bilateral sequential lung transplantation in patients with pulmonary artery hypertension

The use of extracorporeal membrane oxygenator instead of standard cardiopulmonary bypass during lung transplantation is debatable. Moreover, recently, the concept of prolonged postoperative extracorporeal membrane oxygenator (ECMO) support has been introduced in many transplant centers to prevent primary graft dysfunction (PGD) and improve early and long-term results. The objective of this study was to review the results of our extracorporeal life support strategy during and after bilateral sequential lung transplantation (BSLT) for pulmonary artery hypertension. We review retrospectively our experience in BSLT for pulmonary artery hypertension between January 2010 and August 2018. A total of 38 patients were identified. Nine patients were transplanted using cardiopulmonary bypass (CPB), in eight cases CPB was followed by a prolonged ECMO (pECMO) support, 14 patients were transplanted on central ECMO support, and seven patients were transplanted with central ECMO support followed by a pECMO assistance. The effects of different support strategies were evaluated, in particular in-hospital morbidity, mortality, incidence of PGD, and long-term follow-up. The use of CPB was associated with poor postoperative results and worse long-term survival compared with ECMO-supported patients. Predictive preoperative factors for the need of intraoperative CPB instead of ECMO were identified. The pECMO strategy had a favorable effect to mitigate postoperative morbidity and mortality, not only in intraoperative ECMO-supported patients, but even in CPB-supported cases. In our experience, ECMO may be considered as the first choice circulatory support for lung transplantation. Sometimes, in very complex cases, CBP is still necessary. The pECMO strategy is very effective to reduce incidence of PGD even in CPB-supported patients.

Vasoplegic syndrome following cardiothoracic surgery-review of pathophysiology and update of treatment options

Vasoplegic syndrome is a common occurrence following cardiothoracic surgery and is characterized as a high-output shock state with poor systemic vascular resistance. The pathophysiology is complex and includes dysregulation of vasodilatory and vasoconstrictive properties of smooth vascular muscle cells. Specific bypass machine and patient factors play key roles in occurrence. Research into treatment of this syndrome is limited and extrapolated primarily from that pertaining to septic shock, but is evolving with the expanded use of catecholamine-sparing agents. Recent reports demonstrate potential benefit in novel treatment options, but large clinical trials are needed to confirm.

Louis J, Hammel J, Overman D, Blasiole B, Scott JP, Benscoter AL, Karamlou T, Ravekes WJ, Ofori-Amanfo G, Buckley JR, Zyblewski SC, McConnell P, Anderson BR, Santana-Acosta D, Eghtesady P, Bleiweis M, Swartz M, Butts RJ, Husain SA, Lambert L, Amula V, Eckhauser R, Griffiths E, Williams R, Witte M, Minich L. Rationale and design of the STeroids to REduce Systemic inflammation after infant heart Surgery (STRESS) trial

For decades, physicians have administered corticosteroids in the perioperative period to infants undergoing heart surgery with cardiopulmonary bypass (CPB) to reduce the postoperative systemic inflammatory response to CPB. Some question this practice because steroid efficacy has not been conclusively demonstrated and because some studies indicate that steroids could have harmful effects. STRESS is a randomized, placebo-controlled, double-blind, multicenter trial designed to evaluate safety and efficacy of perioperative steroids in infants (age < 1 year) undergoing heart surgery with CPB. Participants (planned enrollment = 1,200) are randomized 1:1 to methylprednisolone (30 mg/kg) administered into the CPB pump prime versus placebo. The trial is nested within the existing infrastructure of the Society of Thoracic Surgeons Congenital Heart Surgery Database. The primary outcome is a global rank score of mortality, major morbidities, and hospital length of stay with components ranked commensurate with their clinical severity. Secondary outcomes include several measures of major postoperative morbidity, postoperative hospital length of stay, and steroid-related safety outcomes including prevalence of hyperglycemia and postoperative infectious complications. STRESS will be one of the largest trials ever conducted in children with heart disease and will answer a decades-old question related to safety and efficacy of perioperative steroids in infants undergoing heart surgery with CPB. The pragmatic "trial within a registry" design may provide a mechanism for conducting low-cost, high-efficiency trials in a heretofore-understudied patient population.

Serum Albumin-Peptide Conjugates for Simultaneous Heparin Binding and Detection

Heparin is a polysaccharide-based anticoagulant agent, which is widely used in surgery and blood transfusion. However, overdosage of heparin may cause severe side effects such as bleeding and low blood platelet count. Currently, there is only one clinically licensed antidote for heparin: protamine sulfate, which is known to provoke adverse effects. In this work, we present a stable and biocompatible alternative for protamine sulfate that is based on serum albumin, which is conjugated with a variable number of heparin-binding peptides. The heparin-binding efficiency of the conjugates was evaluated with methylene blue displacement assay, dynamic light scattering, and anti-Xa assay. We found that multivalency of the peptides played a key role in the observed heparin-binding affinity and complex formation. The conjugates had low cytotoxicity and low hemolytic activity, indicating excellent biocompatibility. Furthermore, a sensitive DNA competition assay for heparin detection was developed. The detection limit of heparin was 0.1 IU/mL, which is well below its therapeutic range (0.2-0.4 IU/mL). Such biomolecule-based systems are urgently needed for next-generation biocompatible materials capable of simultaneous heparin binding and sensing.

Severe systemic inflammatory response syndrome in patients following Total aortic arch replacement with deep hypothermic circulatory arrest

Background

This cohort study aims to retrospectively investigate the incidence of severe systemic inflammatory response syndrome (sSIRS) in patients following total aortic arch replacement (TAR) under deep hypothermic circulatory arrest (DHCA) with selective cerebral perfusion and its effect on clinical outcomes.

Methods

All patients who underwent TAR with DHCA were consecutively enrolled from January 2013 until December 2015 at our institute. sSIRS was diagnosed between 12 and 48 h postoperatively if patients met all four criteria of the SIRS definition.

Results

Of the 522 patients undergoing TAR with DHCA, 31.4% developed sSIRS. Patients aged under 60 yr were characterized by a higher prevalence of sSIRS (OR = 2.93; 95% CI 2.01–4.28; P <0.001). Higher baseline serum creatinine (OR = 1.61; 95% CI 1.18–2.20; P = 0.003), concomitant coronary disease (OR = 2.00; 95% CI 1.15–3.48; P = 0.015) and extended cardiopulmonary time (OR = 1.63; 95% CI 1.23–2.18; P = 0.001) independently contributed to a greater likelihood of postoperative sSIRS onset, while the preferred administration of ulinastatin (OR = 0.69; 95% CI 0.51–0.93; P = 0.015) and dexmedetomidine (OR = 0.36; 95% CI 0.23–0.56; P < 0.001) attenuated it. Patients with sSIRS had a greater risk of developing postoperative major adverse complications compared with the no sSIRS group [56.7%(93/164) vs 26.8% (96/358), P < 0.001]. sSIRS was found to be a significant risk factor for major adverse complications (OR, 4.52; 95% CI, 3.40–6.01; P < 0.001). A significant difference was revealed in in-hospital death following TAR between the sSIRS group and the no-sSIRS group [4.88% (8/164) vs 1.12% (4/358), P = 0.019]. The Kaplan-Meier curve indicated that the time to discharge from the intensive care unit was significantly prolonged in the sSIRS group compared with patients without it (log-rank p < 0.001).

Conclusions

sSIRS occurs commonly in patients following TAR with DHCA. There is an inverse association between age and sSIRS onset, whereby age over 60 yr can lower the risk of it. sSIRS development can increase the likelihood of major postoperative major adverse events.

Tissue oxygen saturation changes and postoperative complications in cardiac surgery: a prospective observational study

Background

Cardiac surgery with extracorporeal circulation (ECC) can induce microvascular dysfunction and tissue hypoperfusion. We hypothesized that the alterations in near-infrared spectroscopy (NIRS)-derived parameters would be associated with post-operative complications in cardiac surgery patients.

Methods

Prospective observational study performed at two University Hospitals. Ninety patients undergoing cardiac surgery with ECC were enrolled. The NIRS sensor was applied on the thenar eminence. A vascular occlusion test (VOT, 3-min ischemia) was performed at baseline (t0), at Intensive Care Unit (ICU) admission (t1), 3 (t2) and 6 (t3) hours later. Baseline tissue oxygen saturation (StO₂), oxygen extraction rate and microvascular reactivity indices were calculated.

Results

In the first hours after cardiac surgery, StO₂ tended to increase (86% [80–89] at T3 versus 82% [79–86] at T0, p = ns), while both tissue oxygen extraction and microvascular reactivity tended to decrease, as indicated by increasing occlusion slope (− 8.1%/min [− 11.2 to − 7] at T3 versus − 11.2%/min [− 13.9 to − 7.9] at T0, p = ns) and decreasing recovery slope (1.9%/sec [1.1–2.9] at T3 versus 3.1%/sec [2.3–3.9] at T0, p = ns). No substantial differences were found in NIRS-derived variables and their changes over time between patients with complications and those without complications.

Conclusions

Peripheral tissue oxygen extraction and microvascular reactivity were reduced during the first hours after cardiac surgery. NIRS-derived parameters were not able to predict complications in this population of cardiac surgery patients.

Electroacupuncture Pretreatment Attenuates Inflammatory Lung Injury After Cardiopulmonary Bypass by Suppressing NLRP3 Inflammasome Activation in Rats

Cardiopulmonary bypass (CPB) can induce inflammatory lung injury, which is a common complication during cardiac surgery. Nod-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome-induced inflammation plays a crucial role in lung injury after CPB. Previous studies have shown that electroacupuncture (EA) has potential anti-inflammatory activity. However, the role of EA in CPB is poorly understood. The aim of this study was to determine whether EA was associated with CPB-induced inflammatory lung injury. In the present study, rats were treated with EA for 5 days before CPB. Two hours after CPB, the lung tissue, serum, and bronchoalveolar lavage fluid (BALF) were prepared for assessment. Our results showed that the expression of NLRP3 in the lung tissue increased significantly after CPB. The EA pretreatment suppressed NLRP3 inflammasome activation, reduced lung edema, and inhibited IL-1β release into the serum and BALF after CPB. Our findings suggest that EA pretreatment attenuates inflammatory lung injury after CPB by suppressing NLRP3 inflammasome activation.

Impact of Cardiopulmonary Bypass Time on Postoperative Duration of Mechanical Ventilation in Patients Undergoing Cardiovascular Surgeries: A Systemic Review and Regression of Metadata

The objective of this study was to detect if cardiopulmonary bypass time duration has any impact on the duration of postoperative mechanical ventilation (MV). The study design was a systematic review and regression analysis of pooled data from previously published studies. All available data are from prospective, retrospective, cross-sectional, and observational studies. Participants included only patient/human studies. There were no interventions. PubMed and Cochrane libraries were searched by utilizing different combinations of keywords: cardiopulmonary bypass and mechanical ventilation. Inclusion criteria were: (1) English articles, (2) studies with an adult population that underwent cardiac surgeries using cardiopulmonary bypass (CPB), (3) studies where the duration of CPB is provided as well as the duration of mechanical ventilation. A regression analysis was performed on the metadata.

For the hours of MV, eight studies with 13 data sets (as some studies provide data in subgroups) were included for a total number of 989 subjects. The duration of CPB ranged from 55 to 173.5 minutes for these operations. Postoperative MV hours ranged from nine to 408 hours. Stepwise multiple regression analysis found that cardiopulmonary bypass time (CPBT), age, diabetes, male gender, and ejection fraction correlated with prolonged mechanical ventilation; CPBT was the most strongly correlated variable. Cardiopulmonary bypass time appears to affect clinical outcomes adversely and is associated with prolonged MV. Avoiding CPB or limiting it to a minimum may decrease the days of MV required.

Effect of low-dose dexamethasone on extra vascular lung water in patients following on-pump elective primary coronary artery bypass graft surgery

Background

The primary objective was to compare the effect of a low-dose dexamethasone as against a saline placebo on extravascular lung water index (EVLWI) in patients undergoing elective primary coronary artery bypass surgery. The secondary endpoints were to assess the effect of dexamethasone on other volumetric parameters (pulmonary vascular permeability index, global end diastolic volume index, and intrathoracic blood volume index), Vasoactive Inotrope Scores, hemodynamic parameters and serum osmolality in both groups.

Settings and Design

Prospective observational study performed at a single tertiary cardiac care center.

Materials and Methods

Twenty patients were randomized to receive either dexamethasone (steroid group, n = 10) or placebo (nonsteroid group, n = 10) twice before the institution of cardiopulmonary bypass (CPB). EVLWI and other volumetric parameters were obtained with the help of VolumeView™ Combo Kit connected to EV 1000 clinical platform at predetermined intervals. Hemodynamic parameters, vasoactive-inotropic Scores, hematocrit values were recorded at the predetermined time intervals. Baseline and 1^st postoperative day serum osmolality values were also obtained.

Results

The two groups were evenly matched in terms of demographic and CPB data. Intra- and inter-group comparison of the baseline EVLWI including other volumetric and hemodynamic parameters with those recorded at subsequent intervals revealed no statistical difference and was similar. Generalized estimating equation model was obtained to compare the changes between the groups over the entire study period which showed that on an average the changes between the steroid and nonsteroid group in terms of all volumetric parameters were not statistically significant.

Conclusions

There were no beneficial effects of low-dose dexamethasone on EVLWI or other volumetric parameters in patients subjected to on-pump primary coronary bypass surgery. Hemodynamic parameters were also not affected. Probably, the advanced hemodynamic monitoring aided in optimal fluid management in the nonsteroidal group impacting EVLW accumulation.

The Future Directions of Research in Cardiac Anesthesiology

This article provides an overview of knowledge gaps that need to be addressed in cardiac anesthesia, including mitigating the inflammatory effects of cardiopulmonary bypass, defining myocardial infarction after cardiac surgery, improving perioperative neurologic outcomes, and the optimal management of patients undergoing valve replacement. In addition, emerging approaches to research conduct are discussed, including the use of new analytical techniques like machine learning, pragmatic trials, and adaptive designs.

Prevention of Cardiac Surgery-Associated Acute Kidney Injury: A Review of Current Strategies

Acute kidney injury is a common and often severe postoperative complication after cardiac surgery, and is associated with poor short-term and long-term outcomes. Numerous randomized controlled trials have been conducted to investigate various strategies for prevention of cardiac surgery-associated acute kidney injury. Unfortunately, most trials that have been conducted to date have been negative. However, encouraging results have been demonstrated with preoperative administration of corticosteroids, leukocyte filtration, and administration of inhaled nitric oxide intraoperatively, and implementation of a Kidney Disease: Improving Global Outcomes bundle of care approach postoperatively. These findings require validation in large, multicenter trials.

Amphiphilic multi-charged cyclodextrins and vitamin K co-assembly as a synergistic coagulant

Balancing and neutralizing heparin dosing after surgeries and hemodialysis treatment is of great importance in medical and clinical fields. In this study, a series of new amphiphilic multi-charged cyclodextrins (AMCD)s as anti-heparin coagulants were designed and synthesized. The AMCD assembly was capable of selective heparin binding through multivalent bonding and showed a better neutralizing effect towards both unfractionated heparin and low molecular weight heparin than protamine in plasma. Meanwhile, an AMCD and vitamin K (VK) co-assembly was prepared to realize heparin-responsive VK release and provide a novel VK deficiency treatment for hemodialysis patients. This AMCD-VK co-assembly for heparin neutralization & vitamin K supplementation synergistic coagulation represents a promising candidate as a clinical anti-heparin coagulant.

Anticoagulation in Neonatal ECMO: An Enigma Despite a Lot of Effort!

Extracorporeal membrane oxygenation (ECMO) is a valuable modality used to support neonates, children, and adults with cardiorespiratory failure refractory to conventional therapy. It requires use of anticoagulation to prevent clotting in the extracorporeal circuit. Balancing bleeding from excessive anticoagulation with thrombotic risk remains a difficult aspect of ECMO care. Despite many advances in ECMO technology, better understanding of the coagulation cascade and new monitoring schemes to adjust anticoagulation, bleeding and thrombosis remain the most frequent complications in ECMO and are associated with morbidity and mortality. In neonates, ECMO is also complicated by the immature hemostatic system, laboratory testing norms which are not specific for neonates, lack of uniformity in management, and paucity of high-quality evidence to determine best practices. Traditional anticoagulation focuses on the use of unfractionated heparin. Direct thrombin inhibitors are also used but have not been well-studied in the neonatal ECMO population. Anticoagulation monitoring is complex and currently available assays do not take into account thrombin generation or platelet contribution to clot formation. Global assays may add valuable information to guide therapy. This review provides an overview of hemostatic alterations, anticoagulation, monitoring and management, novel anticoagulant use, and circuit modifications for neonatal ECMO. Future considerations are also presented.

Patient Blood Management in Pediatric Cardiac Surgery: A Review

Efforts to reduce blood product transfusions and adopt blood conservation strategies for infants and children undergoing cardiac surgical procedures are ongoing. Children typically receive red blood cell and coagulant blood products perioperatively for many reasons, including developmental alterations of their hemostatic system, and hemodilution and hypothermia with cardiopulmonary bypass that incites inflammation and coagulopathy and requires systemic anticoagulation. The complexity of their surgical procedures, complex cardiopulmonary interactions, and risk for inadequate oxygen delivery and postoperative bleeding further contribute to blood product utilization in this vulnerable population. Despite these challenges, safe conservative blood management practices spanning the pre-, intra-, and postoperative periods are being developed and are associated with reduced blood product transfusions. This review summarizes the available evidence regarding anemia management and blood transfusion practices in the perioperative care of these critically ill children. The evidence suggests that adoption of a comprehensive blood management approach decreases blood transfusions, but the impact on clinical outcomes is less well studied and represents an area that deserves further investigation.

High-Dose Vitamin B12 in Vasodilatory Shock: A Narrative Review

Vasodilatory shock, as observed in postoperative states and sepsis, is hallmarked by low systemic vascular resistance and low blood pressure compensated by increased cardiac output. Gasotransmitters, such as nitric oxide and hydrogen sulfide, are implicated in the development and perpetuation of vasodilatory shock. Established therapies do not target these physiologic drivers of vasodilation. Due to their nontoxic and pleotropic effects, micronutrients are being used as rescue therapy in postoperative vasoplegia and septic shock. Here, we outline the pathophysiology of vasodilatory shock, describe the rationale for vitamin B12 (hydroxocobalamin) in vasodilatory shock, and identify literature evaluating its use in vasoplegic states.

Monitoring and optimization of the microcirculation during CPB

In this review the impact of cardiopulmonary bypass (CPB) on the microcirculation is discussed. The impact of conventional non-pulsatile perfusion is contrasted with the microcirculatory impact of pulsatile CPB which is associated with better preservation of microcirculatory function. Evidence that alterations in microcirculatory function that persist following cardiac surgery are associated with adverse clinical outcomes is reviewed. Recent studies using novel techniques employing near infrared reflectance spectroscopy (NIRS) and sublingual microscopy to explore alterations in microcirculatory function during CPB are reviewed and the implications of these observations for studies investigating minimally invasive extracorporeal circulation (MiECC) are discussed.

Clinical Effects of Perioperative Selective Decontamination of the Digestive Tract (SDD) in Cardiac Surgery: A Propensity Score Matched Cohort Analysis

OBJECTIVES

To determine the clinical effects of perioperative endotoxin reduction in the gut lumen in patients undergoing cardiac surgery with cardiopulmonary bypass.

DESIGN

Retrospective cohort analysis with propensity score matching according to treatment group.

SETTING

Tertiary center for cardiopulmonary diseases and intensive care medicine.

PARTICIPANTS

Included were patients who underwent cardiac surgery with cardiopulmonary bypass between 2008 and 2017. Excluded were readmitted patients.

INTERVENTIONS

Endotoxin reduction in the gut lumen by ingestion of oral tobramycin 80 mg and polymyxin B 100 mg 4 times daily (TP) as part of selective digestive tract decontamination, which contains amphotericin B 500 mg as well.

MEASUREMENTS AND MAIN RESULTS

A total of 6,394 patients were included, of whom 2,044 patients were in the intervention group. A total of 835 patients received both pre- and postoperative TP (Pre+/Post+), and 1,165 patients received TP only postoperatively (Pre-/Post+). The control group, not treated with TP at any moment, consisted of 4,350 patients (Pre-/Post-). After matching, 652 Pre+/Post+ patients were compared with an equal number of controls (Pre-/Post-). Pre+/Post+ group did not do better for any clinical outcome. A total of 682 Pre+/Post+ patients matched with an equal number of Pre-/Post+ patients. The latter group had a 0.3 points higher mean Sequential Organ Failure Assessment score and in the regression analysis a significantly higher intensive care unit mortality but not hospital mortality. A significant reduction in length of stay and length of mechanical ventilation for the Pre+/Post+ group was shown compared with Pre-/Post+, but these differences can be explained by unbalanced differences in the severity of illness.

CONCLUSION

Cardiosurgical patients who receive tobramycin and polymyxin orally preoperatively to reduce the gut endotoxin level do not expose convincing and relevant beneficial effects on clinical outcomes in this retrospective propensity score matching cohort study.