Effect of modified ultrafiltration on the inflammatory response in paediatric open-heart surgery: a prospective, randomized study

Novel inflammatory mediator profile observed during pediatric heart surgery with cardiopulmonary bypass and continuous ultrafiltration

BACKGROUND

Cardiopulmonary bypass (CPB) is associated with systemic inflammation, featuring increased levels of circulating pro-inflammatory cytokines. Intra-operative ultrafiltration extracts fluid and inflammatory factors potentially dampening inflammation-related organ dysfunction and enhancing post-operative recovery. This study aimed to define the impact of continuous subzero-balance ultrafiltration (SBUF) on circulating levels of major inflammatory mediators.

METHODS

Twenty pediatric patients undergoing cardiac surgery, CPB and SBUF were prospectively enrolled. Blood samples were collected prior to CPB initiation (Pre-CPB Plasma) and immediately before weaning off CPB (End-CPB Plasma). Ultrafiltrate effluent samples were also collected at the End-CPB time-point (End-CPB Effluent). The concentrations of thirty-nine inflammatory factors were assessed and sieving coefficients were calculated.

RESULTS

A profound increase in inflammatory cytokines and activated complement products were noted in plasma following CBP. Twenty-two inflammatory mediators were detected in the ultrafiltrate effluent. Novel mediators removed by ultrafiltration included cytokines IL1-Ra, IL-2, IL-12, IL-17A, IL-33, TRAIL, GM-CSF, ET-1, and the chemokines CCL2, CCL3, CCL4, CXCL1, CXCL2 and CXCL10. Mediator extraction by SBUF was significantly associated with molecular mass < 66 kDa (Chi² statistic = 18.8, Chi² with Yates' correction = 16.0, p < 0.0001). There was a moderate negative linear correlation between molecular mass and sieving coefficient (Spearman R = - 0.45 and p = 0.02). Notably, the anti-inflammatory cytokine IL-10 was not efficiently extracted by SBUF.

CONCLUSIONS

CPB is associated with a burden of circulating inflammatory mediators, and SBUF selectively extracts twenty of these pro-inflammatory factors while preserving the key anti-inflammatory regulator IL-10. Ultrafiltration could potentially function as an immunomodulatory therapy during pediatric cardiac surgery. Trial registration ClinicalTrials.gov, NCT05154864. Registered retrospectively on December 13, 2021. https://clinicaltrials.gov/ct2/show/record/NCT05154864 .

Monocyte Adhesion and Transmigration Through Endothelium Following Cardiopulmonary Bypass Shearing is Mediated by IL-8 Signaling

Background

The use of cardiopulmonary bypass (CPB) can induce sterile systemic inflammation that contributes to morbidity and mortality, especially in children. Patients have been found to have increased expression of cytokines and transmigration of leukocytes during and after CPB. Previous work has demonstrated that the supraphysiologic shear stresses present during CPB are sufficient to induce proinflammatory behavior in non-adherent monocytes. The interactions between shear stimulated monocytes and vascular endothelial cells have not been well studied and have important translational implications.

Methods

To test the hypothesis that non-physiological shear stress experienced by monocytes during CPB affects the integrity and function of the endothelial monolayer via IL-8 signaling pathway, we have used an in vitro CPB model to study the interaction between THP-1 monocyte-like cells and human neonatal dermal microvascular endothelial cells (HNDMVECs). THP-1 cells were sheared in polyvinyl chloride (PVC) tubing at 2.1 Pa, twice of physiological shear stress, for 2 hours. Interactions between THP-1 cells and HNDMVECs were characterized after coculture.

Results

We found that sheared THP-1 cells adhered to and transmigrated through the HNDMVEC monolayer more readily than static controls. When co-culturing, sheared THP-1 cells also disrupted in the VE-cadherin and led to reorganization of cytoskeletal F-actin of HNDMVECs. Treating HNDMVECs with IL-8 resulted in upregulation of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) while also increasing the adherence of non-sheared THP-1 cells. Preincubating HNDMVECs with Reparixin, an inhibitor of CXCR2/IL-8 receptor inhibited sheared THP-1 cell adhesion to the HNDMVECs.

Conclusions

These results suggested that IL-8 not only increases the endothelium permeability during monocyte migration, but also affects the initial adhesion of monocytes in a CPB setup. This study revealed a novel mechanism of post-CPB inflammation and will contribute to the development of targeted therapeutics to prevent and repair the damage to neonatal patients.

Highlights

Shear stress in a CPB-like environment promoted the adhesion and transmigration of monocytes to and through endothelial monolayer.

Treating endothelial monolayer with sheared monocytes led to disruption of VE-cadherin and reorganization of F-actin.

Interaction between sheared monocytes resulted in a significant increase of IL-8 release.

Inhibiting IL-8 receptor prevented sheared monocyte adhesion, while IL-8 promoted naive monocyte adhesion.

Identification of Inflammatory Gene in the Congenital Heart Surgery Patients following Cardiopulmonary Bypass via the Way of WGCNA and Machine Learning Algorithms

Performing cardiopulmonary bypass (CPB) to reduce ischemic injury during surgery is a common approach to cardiac surgery. However, this procedure can lead to systemic inflammation and multiorgan dysfunction. Therefore, elucidating the molecular mechanisms of CPB-induced inflammatory cytokine release is essential as a critical first step in identifying new targets for therapeutic intervention. The GSE143780 dataset which is mRNA sequencing from total circulating leukocytes of the neonatorum was downloaded from the Gene Expression Omnibus (GEO) database. A total of 21 key module genes were obtained by analyzing the intersection of differentially expressed gene (DEG) and gene coexpression network analysis (WGCNA), and then, 4 genes (TRAF3IP2-AS1, PPARGC1B, CD4, and PDLIM5) were further confirmed after the least absolute shrinkage and selection operator (LASSO) and support vector machine recursive feature elimination (SVM-RFE) screening and were used as hub genes for CPB-induced inflammatory cytokine release in patients with congenital heart defects. The enrichment analysis revealed 21 key module genes mainly related to the functions of developmental cell growth, regulation of monocyte differentiation, regulation of myeloid leukocyte differentiation, ERK1 and ERK2 cascade, volume-sensitive anion channel activity, and estrogen receptor binding. The result of gene set enrichment analysis (GSEA) showed that the hub genes were related to different physiological functions of cells. The ceRNA network established for hub genes includes 3 hub genes (PPARGC1B, CD4, and PDLIM5), 55 lncRNAs, and 34 miRNAs. In addition, 4 hub genes have 215 potential therapeutic agents. Finally, expression validation of the four hub genes revealed that they were all significantly low expressed in the surgical samples than before.

The microbiome’s relationship with congenital heart disease: more than a gut feeling

Patients with congenital heart disease (CHD) are at risk for developing intestinal dysbiosis and intestinal epithelial barrier dysfunction due to abnormal gut perfusion or hypoxemia in the context of low cardiac output or cyanosis. Intestinal dysbiosis may contribute to systemic inflammation thereby worsening clinical outcomes in this patient population. Despite significant advances in the management and survival of patients with CHD, morbidity remains significant and questions have arisen as to the role of the microbiome in the inflammatory process. Intestinal dysbiosis and barrier dysfunction experienced in this patient population are increasingly implicated in critical illness. This review highlights possible CHD-microbiome interactions, illustrates underlying signaling mechanisms, and discusses future directions and therapeutic translation of the basic research.

Shear stress associated with cardiopulmonary bypass induces expression of inflammatory cytokines and necroptosis in monocytes

Cardiopulmonary bypass (CPB) is required during most cardiac surgeries. CBP drives systemic inflammation and multiorgan dysfunction that is especially severe in neonatal patients. Limited understanding of molecular mechanisms underlying CPB-associated inflammation presents a significant barrier to improve clinical outcomes. To better understand these clinical issues, we performed mRNA sequencing on total circulating leukocytes from neonatal patients undergoing CPB. Our data identify myeloid cells, particularly monocytes, as the major cell type driving transcriptional responses to CPB. Furthermore, IL-8 and TNF-α were inflammatory cytokines robustly upregulated in leukocytes from both patients and piglets exposed to CPB. To delineate the molecular mechanism, we exposed THP-1 human monocytic cells to CPB-like conditions, including artificial surfaces, high shear stress, and cooling/rewarming. Shear stress was found to drive cytokine upregulation via calcium-dependent signaling pathways. We also observed that a subpopulation of THP-1 cells died via TNF-α-mediated necroptosis, which we hypothesize contributes to post-CPB inflammation. Our study identifies a shear stress-modulated molecular mechanism that drives systemic inflammation in pediatric CPB patients. These are also the first data to our knowledge to demonstrate that shear stress causes necroptosis. Finally, we observe that calcium and TNF-α signaling are potentially novel targets to ameliorate post-CPB inflammation.

Surgical repair for canine tricuspid valve dysplasia: Technique and case report

Tricuspid valve dysplasia (TVD) is a congenital malformation of the right atrioventricular valve characterized by restricted leaflet motion, annular dilation, and tricuspid regurgitation (TR). Severe cases typically exhibit progressive right-sided congestive heart failure, affecting the quality of life and survival. This article describes a technique for surgical repair of TVD and a case report with long-term follow-up. A 1.5-year-old intact male Labrador retriever with severe TR underwent surgical repair for TVD. Valve repair was performed under cardiopulmonary bypass and consisted of neochord mobilization of the valve leaflets and partial band annuloplasty. Transthoracic echocardiogram performed 5 days after surgery showed mild TR, a 93% decrease in anatomic regurgitant orifice area, and decreased right chamber dimensions. Forty-eight months after repair, the patient was free of clinical signs, did not have a heart murmur, and was receiving no cardiac medications. Based on this case, surgical repair of TVD is feasible with long-term durability, and the outcome suggests that the described technique may be a viable treatment option for patients with severe TVD.

Ultrafiltration in Pediatric Cardiac Surgery Review

Introduction:

The use of cardiopulmonary bypass in pediatric cardiac surgery is associated with significant inflammation, fluid overload, and end-organ dysfunction yielding morbidity and mortality. For decades, various intraoperative ultrafiltration techniques such as conventional ultrafiltration, modified ultrafiltration (MUF), zero-balance ultrafiltration (ZBUF), and combination techniques (ZBUF-MUF) have been used to mitigate these toxicities and promote improved postoperative outcomes. However, there is currently no consensus on the ultrafiltration technique or strategy that yields the most benefit for infants and children undergoing open heart surgery.

Methods:

A librarian-conducted PubMed literature search from 1990 to 2018 yielded 90 clinical studies or publications on the various forms of ultrafiltration and the impact on physiologic markers and clinical outcomes. All publications were reviewed, summarized, and conclusions synthesized. The data sets were not combined for systematic or meta-analysis due to significant heterogeneity in study protocols and patient populations.

Results:

Modified ultrafiltration significantly promotes improved myocardial function, reduction in fluid overload, and reduced bleeding and transfusion complications. Furthermore, ZBUF has shown a consistent reduction in inflammatory cytokines and improved pulmonary function and compliance. There is conflicting evidence that MUF, ZBUF, and ZBUF-MUF culminate in reduced ventilation time and intensive care unit stay.

Conclusion:

Various modes of ultrafiltration have been shown to be associated with improved physiologic function or clinical outcomes in pediatric cardiac surgery. There are some inconsistent trial results that can be explained by heterogeneity in ultrafiltration, clinical staff preferences, and institution protocols. Ultrafiltration has some essential benefit as it is ubiquitously used at pediatric heart centers; however, the optimal protocol could be yet identified.

Does modified ultrafiltration reduce the systemic inflammatory response to cardiac surgery with cardiopulmonary bypass?

Cardiopulmonary bypass (CPB) is associated with an accumulation of total body water and a systemic inflammatory response syndrome (SIRS), which, in turn, is associated with organ dysfunction and postoperative morbidity. It has been suggested that modified ultrafiltration (MUF) may be capable of reducing SIRS and improving clinical outcome by filtering out the inflammatory mediators generated during CPB. This paper reviews the data regarding the use of MUF in paediatric and adult settings. Specifically, three issues will be considered: 1) Does MUF improve clinical outcome? 2) Does MUF reduce the systemic inflammatory response to cardiac surgery with CPB? 3) Is MUF more effective than conventional ultrafiltration in improving clinical outcome?

The effect of combined conventional and modified ultrafiltration on mechanical ventilation and hemodynamic changes in congenital heart surgery

Background:

Cardiopulmonary bypass is associated with increased fluid accumulation around the heart which influences pulmonary and cardiac diastolic function. The aim of this study was to compare the effects of modified ultrafiltration (MUF) versus conventional ultrafiltration (CUF) on duration of mechanical ventilation and hemodynamic status in children undergoing congenital heart surgery.

Materials and Methods:

A randomized clinical trial was conducted on 46 pediatric patients undergoing cardiopulmonary bypass throughout their congenital heart surgery. Arteriovenous MUF plus CUF was performed in 23 patients (intervention group) and sole CUF was performed for other 23 patients (control group). In MUF group, arterial cannula was linked to the filter inlet through the arterial line, and for 10 min, 10 ml/kg/min of blood was filtered and returned via cardioplegia line to the right atrium. Different parameters including hemodynamic variables, length of mechanical ventilation, Intensive Care Unit (ICU) stay, and inotrope requirement were compared between the two groups.

Results:

At immediate post-MUF phase, there was a statistically significant increase in the mean arterial pressure, systolic blood pressure, and diastolic blood pressure (P < 0.05) only in the study group. Furthermore, there was a significant difference in time of mechanical ventilation (P = 0.004) and ICU stay (P = 0.007) between the two groups. Inotropes including milrinone (P = 0.04), epinephrine (P = 0.001), and dobutamine (P = 0.002) were used significantly less frequently for patients in the intervention than the control group.

Conclusion:

Administration of MUF following surgery improves hemodynamic status of patients and also significantly decreases the duration of mechanical ventilation and inotrope requirement within 48 h after surgery.

Effects of zero-balanced ultrafiltration on procalcitonin and respiratory function after cardiopulmonary bypass

The abnormal conditions to which blood is subjected during cardiopulmonary bypass (CPB) trigger an activation of the inflammatory response and cause pulmonary dysfunction. It has been suggested that high-volume, zero-balanced ultrafiltration (ZBUF) facilitates clearance of inflammatory mediators and improves post-operative pulmonary function. Procalcitonin, a newly discovered inflammatory mediator, has been found to be increased after CPB and has been proven to be an appropriate parameter for predicting pulmonary dysfunction secondary to CPB. The aim of this study was to investigate the effects of zero-balanced ultrafiltration (ZBUF) on procalcitonin (PCT) and respiratory function of infants with Tetralogy of Fallot (TOF) after CPB. Twenty infants with TOF undergoing open-heart total surgical correction were randomly assigned to two groups. The trial group was given ZBUF (50 ml/kg) and conventional ultrafiltration (CUF), while the control group was given CUF only. Plasma PCT and pulmonary function were monitored and compared between the two groups before the operation (T1), before rewarming (T2), at the end of the operation (T3), and at 12 h, 24 h and 48 h after the operation (T4-T6). PCT was decreased in the trial group between 12 h and 48 h post-operatively, but the differences did not reach statistical significance. The trial group's pulmonary compliance was higher at 12 h post-operatively ( p < 0.05). Oxygenation index was increased in the trial group at the end of the operation and 12 h post-operatively ( p > 0.05). Intubation time was shorter in the trial group ( P < 0.01). A positive correlation was found between peak PCT concentration and intubation time. ZBUF appeared to improve ventilation and shorten intubation time. The improved respiratory function may be due to the lower plasma PCT. Perfusion (2007) 22, 339—343.

Cerebral injury during paediatric heart surgery: perfusion issues

Suboptimal neurodevelopmental outcome is common in children who have congenital heart disease. Its aetiology is often multifactorial. This review focuses on the role of cardiopulmonary bypass. Hypothermia is the mainstay of cerebral protection. Low flow and regional low flow are preferred to deep hypothermic circulatory arrest in many situations. Cooling and rewarming, aortopulmonary collaterals, pH, air emboli, the systemic inflammatory response, haematocrit, oxygenation, glucose and ultrafiltration can influence neurodevelopmental outcome. Although no pharmacological agents have been shown to have a beneficial effect on neurodevelopmental outcome in clinical practice in children, animal work on the use of steroids several hours before surgery is encouraging.

Impact of Modified Ultrafiltration on Morbidity after Pediatric Cardiac Surgery

Cardiopulmonary bypass is a double-edged sword. Without it, corrective cardiac surgery would not be possible in the majority of children with congenital heart disease. However, much of the perioperative morbidity that occurs after cardiac surgery can be attributed to a large extent to pathophysiologic processes engendered by extracorporeal circulation. One of the challenges that has confronted pediatric cardiac surgeons has been to minimize the consequences of cardiopulmonary bypass. Ultrafiltration is a strategy that has been used for many years in an effort to attenuate the effects of hemodilution that occur when small children undergo surgery with cardiopulmonary bypass. Over the past several years, a modified technique of ultrafiltration, commonly known as modified ultrafiltration, has been used with increasing enthusiasm. Multiple studies have been undertaken to assess the effects of modified ultrafiltration on organ function and postoperative morbidity following repair of congenital heart defects. This review attempts to evaluate current available scientific evidence on the impact of modified ultrafiltration on organ function and morbidity after pediatric cardiac surgery.

Modified ultrafiltration during cardiopulmonary bypass and postoperative course of pediatric cardiac surgery

Context:

The use of cardiopulmonary bypass (CPB) provokes the inflammatory responses associated with ischemic/reperfusion injury, hemodilution and other agents. Exposure of blood cells to the bypass circuit surface starts a systemic inflammatory reaction that may causes post-CPB organ dysfunction, particularly in lungs, heart and brain.

Evidence Acquisition:

We investigated in the MEDLINE, PUBMED, and EMBASE databases and Google scholar for every available article in peer reviewed journals between 1987 and 2013, for related subjects to CPB with conventional or modified ultrafiltration (MUF) in pediatrics cardiac surgery patients.

Results:

MUF following separation from extracorporeal circulation (ECC) provides well known advantages in children with improvements in the hemodynamic, pulmonary, coagulation and other organs functions. Decrease in blood transfusion, reduction of total body water, and blood loss after surgery, are additional benefits of MUF.

Conclusions:

Consequently, MUF has been associated with attenuation of morbidity after pediatric cardiac surgery. In this review, we tried to evaluate the current evidence about MUF on the organ performance and its effect on post-CPB morbidity in pediatric patients.

Potential biomarkers for predicting outcomes in CABG cardiothoracic surgeries

The variations in recovery time, complications, and survival among cardiac patients who have undergone coronary artery bypass graft (CABG) procedures are vast. Many formulas and theories are used to predict clinical outcome and recovery time, and current prognostic predictions are based on medical and family history, lifestyle, co-morbidities, and performance status. The identification of biomarkers that provide concrete evidence supporting clinical outcome has greatly affected the field of medicine, helping clinicians in many medicine sub-specialties to forecast clinical course. Recent studies have discovered biomarkers that may be used as predictors of cardiac patients' status post-cardiothoracic surgery, and the applications are numerous. In this review, we assess currently available cardiac biomarkers as predictors of clinical outcome for post-operative CABG patients. Data were collected from various studies in which cardiac biomarkers were measured in pre-operative and post-operative CABG patients.

The effect of normovolemic modified ultrafiltration on inflammatory mediators, endotoxins, terminal complement complexes and clinical outcome in high-risk cardiac surgery patients

Objective:

The clinical benefit of normovolemic modified ultrafiltration (N-MUF) after cardiac surgery is still debated. As we have shown in a previous publication, there is a significant improvement in platelet function, so we were interested in whether ultrafiltration can reduce plasma levels of endotoxins, terminal complement complexes and cytokines after cardiopulmonary bypass (CPB) in adults with increased risk profiles.

Methods:

In this single-center, prospective, randomized trial, fifty high-risk patients (mean logistic EuroSCORE II: 17.5%) who underwent cardiac surgery were randomized. After CPB, Group 1 (n = 25) served as the control and in, Group 2 (n= 25), an N-MUF of 3000 ml was performed, using a BC140plus filter after weaning from CPB. Blood samples were taken after the induction of anesthesia, before CPB, before CPB weaning, 30 minutes after CPB and at 6, 24 and 48 hours postoperatively. Primary outcomes were plasma levels of lipopolysaccharide-binding protein (LBP), terminal complement complex (C5b9) and cytokines (IL-6, IL-10, IL-1beta, TNF-α). Secondary outcomes focused on differences in the clinical outcome.

Results:

A significant reduction in LBP concentration (preoperatively: 23.8±8.4 pg/ml, postoperatively: 14.2±12.9 pg/ml) and C5b9 (preoperatively: 4.18±2.6 pg/ml, postoperatively: 3.05±2.39 pg/ml) were detected 6 hours after N-MUF. In the N-MUF group, significantly lower concentrations of lactate could be detected in the early postoperative period. Furthermore, postoperative chest tube blood loss was significantly lower in the N-MUF group at 24 and 48 hours.

Conclusions:

N-MUF leads to a significant reduction of lipopolysaccharide-binding protein and terminal complement complex and was associated with reduced blood loss and postoperative lactate concentrations shortly after surgery.

The Hemobag: the modern ultrafiltration system for patients undergoing cardiopulmonary by pass

BACKGROUND

The return of extracorporeal circuit blood at the termination of cardiopulmonary bypass (CPB) is an important feature of blood conservation during cardiac surgery procedures globally. We report our initial clinical evaluation of the Hemobag system a blood-salvaging device designed for whole blood recovery of residual post-CPB volume.

METHODS

Residual whole blood is hemoconcetrated through the multipass "recovery loop" circuit separate from the CPB and collected in the Hemobag System. This allows the surgeons to continue with surgery, decannulate, and administer protamine simultaneously while the Hemobag is in use and the CPB circuit remains safely primed. We have compared 25 patients receiving the Hemobag to a control group of 25 patients treated with the cell washer that represented our previous standard of care method of circuit blood-salvaging technique.

RESULTS

The Hemobag system provided significantly higher hemoglobin, hematocrit, fibrinogen, albumin, and total protein levels in the final product reducing the amount of wasted autologous blood cells. There were no device-related complications. There were no significant differences in terms of blood utilization, chest tube drainage and clinical outcomes over the entire postoperative period among groups.

CONCLUSIONS

These results suggest that the Hemobag system is a safe and efficient method to multipass hemoconcentrate the residual diluted blood of the CPB circuit. The Hemobag has demonstrated its ability to maximize the composition of the residual CPB volume to achieve the best possible post-CPB hemoglobin, plasma protein and coagulation factors profile for the patient respect to CW.

ICU outcomes in adult cardiac surgery patients in relation to ultrafiltration type

Ultrafiltration (UF) is used to ameliorate the deleterious effects of cardiopulmonary bypass (CPB) in cardiac surgery patients. There are two different methods; conventional ultrafiltration (CUF), performed during CPB, and modified ultrafiltration (MUF), performed after CPB is finished. It has not been established which is better, and controversy remains regarding the optimal UF strategy. The objective of this study was to evaluate if MUF alone, or combined with CUF, could achieve greater fluid removal and contribute to better postoperative clinical outcomes. Also, the potential technique complications were studied. This was a prospective study which enrolled 125 consecutive adult patients receiving elective cardiac surgery with CPB. We analysed three treatment groups: MUF, CUF and both. Ultrafiltration was performed using a non-pulsatile CPB with a non-occlusive roller pump, Sarns 9000®, and a polysulfone ultrafilter, Minntech®. We studied pre- and intraoperative data and immediate postoperative clinical outcomes: total amount of drainage, transfusion needs, respiratory outcome, cardiac, renal and neurologic complications. Statistical analysis was performed using SPSS 11.0. All three groups were homogeneous and did not have differences in terms of demographic factors, previous history, risk scores, intervention and operative data. Volume of filtrate removal in the group which applied both techniques was larger than in the CUF or MUF groups alone (2569±823 vs 1679±651 vs 1398±353 ml, respectively, p=0.0001); however, despite this difference, there was no difference in the immediate postoperative fluid balances between the groups (596±1244 vs 880±1054 vs 986±1190 ml, p=0.30). Respiratory parameters and postoperative morbidity data analysed (total amount of drainage, transfusion needs, haemoglobin, acute lung injury, time with inotropes, ventricular failure, cardiogenic shock, neurologic complications and renal failure) were similar in all three groups, without statistical differences. Extubation time (10±7 vs 8.9±3 vs 9.4±7.9 hours, p=0.72) and ICU stay (56.6±72 vs 66.5±109 vs 44.2±25 hours, p=0.43) also were similar between the groups. We did not find any technique complication associated with any patient. In the present study, with adult patients receiving elective cardiac surgery, the combined ultrafiltration group had a larger fluid removal. However, neither type of ultrafiltration nor amount of filtered volume was accompanied by different postoperative ICU clinical outcomes. Ultrafiltration was considered a safe and reliable technique, with no related complications.

Factors influencing neurologic outcome after neonatal cardiopulmonary bypass: what we can and cannot control

Advances in cardiopulmonary bypass and surgical techniques have led to progress in the early repair of congenital heart defects in children. However, as increasing numbers survive their initial cardiac operation, an awareness is emerging that significant early and late neurologic morbidities continue to complicate otherwise successful operative repairs. Adverse neurologic outcomes after neonatal cardiac surgery are multifactorial and relate to both fixed and modifiable mechanisms. The purpose of this review is to (1) review mechanisms of brain injury after neonatal cardiopulmonary bypass, (2) examine risk factors, and (3) speculate on how investigations may improve our understanding of neurologic injury.

Effect of Flow Rate, Negative Pressure, and Duration of Modified Ultrafiltration on Hemodynamics and Inflammatory Mediators

The objective of this study was to evaluate the effect of flow rate, negative pressure, and duration on modified ultrafiltration (MUF). Eighty children weighing less than 10 kg with congenital heart disease were randomly divided into four groups: group C (conventional MUF); group H (high flow rate MUF); group P (high negative pressure MUF); and group L (long duration, high flow rate MUF). The changes in body weight, hematocrit, and hemodynamics were recorded. Tumor necrosis factor and interleukin-6 were measured before bypass, bypass stop, and MUF cessation. The durations of MUF in groups H and P were significantly shorter than in the other two groups; the volume filtered in group L was much greater than in the other three groups. The changes of bodyweight, heart rate, blood pressure, and hematocrit were similar in all groups. The increased extent of inflammatory mediators was a little lower in group L. Modified ultrafiltration can reverse hemodilution and improve cardiac function even with high flow rate or negative pressure. Prolonging the duration of MUF can filter out more inflammatory mediators, but the increased trend cannot be reversed in 15 minutes.

Blood purification for hypercytokinemia

Blood purification has been steadily improved in the field of critical care, supported by advances in related biomedical technologies as well as efforts to develop better operating procedures. As it has become clear that hypercytokinemia plays a key role in the pathophysiology of critical pathological conditions, use of various blood purification techniques to control hypercytokinemia has been investigated. Answers to questions concerning the optimal cytokine-removing device (dialyzer/hemofilter/adsorber) as well as operating procedures and conditions of such devices in particular clinical conditions have been obtained in the course of such investigations. The recent success in real-time monitoring of cytokine levels in clinical practice to assess the extent of cytokine network activation may improve the precision and efficacy of blood purification in the treatment of hypercytokinemia. In addition, the recently documented effects of genetic factors on hypercytokinemia suggest that the introduction of tailor-made medicine considering the differences in genetic background among individual patients may improve the efficacy of blood purification as a countermeasure to hypercytokinemia.

Interleukin-10 and its role in clinical immunoparalysis following pediatric cardiac surgery

OBJECTIVE

A systemic insult is associated with subsequent hyporesponsiveness to endotoxin (as measured by ex vivo tumor necrosis factor [TNF]-alpha production) and an increased risk of late nosocomial infection in some patients. When combined with low monocyte surface major histocompatibility complex class II expression, this state of altered host defense is now commonly referred to as immunoparalysis. This study was undertaken to delineate the relationship between observed levels of the anti-inflammatory cytokine interleukin-10, common genetic polymorphisms that influence these levels, and the occurrence and severity of endotoxin hyporesponsiveness in children following elective cardiac surgery requiring cardiopulmonary bypass.

DESIGN

A prospective observational clinical study.

SETTING

A tertiary pediatric cardiac center.

PATIENTS

Thirty-six infants and children <2 yrs of age undergoing elective cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We investigated the production of TNF-alpha, interleukin-6, interleukin-8, interleukin-1 receptor antagonist, and interleukin-10 in whole blood in response to lipopolysaccharide (Neisseria meningitides 10 ng/mL) in samples drawn before, during, and up to 48 hrs after surgery. Patients were genotyped for the -1082, -819, and -592 interleukin-10 promoter polymorphisms. Whole blood cytokine response to lipopolysaccharide was reduced postoperatively to </=50% of preoperative levels for all cytokines measured. Stimulated cytokine production was lowest in cases with the highest postoperative plasma interleukin-10 levels, which were in turn associated with the GCC haplotype. Those patients in whom the whole blood response to endotoxin was maintained (TNF-alpha >100 pg/mL) over the first 48 hrs were more likely to have an uncomplicated short stay (odds ratio 4.7, 95% confidence interval 1-22).

CONCLUSIONS

Immediately following cardiac surgery, many children become relatively refractory to lipopolysaccharide stimulation. This immunoparalysis appears to be related in part to high circulating levels of interleukin-10 and places these patients at increased risk of postoperative complications. Interleukin-10 genotype may be a risk factor for immunoparalysis.

Recent developments in the perioperative management of the paediatric cardiac patient

PURPOSE OF REVIEW

Survival of infants born with complex cardiac anomalies has dramatically improved, and the growing population of patients with congenital heart disease reaching adulthood has resulted in an increased incidence of long-term complications related to the perioperative period. This review focuses on recent advances in strategies to prevent, detect, treat, or predict early and late complications arising from open heart surgery for congenital heart disease.

RECENT FINDINGS

Aprotinine and recombinant factor VIIa may effectively reduce the risk of excessive perioperative bleeding, and the use of steroids, complement component C4A, heparin-coated circuits, and modified ultrafiltration may play a role in the control of the postoperative inflammatory response. Milrinone is becoming increasingly popular in the prevention and treatment of the reduced postoperative cardiac output, and extracorporeal life support has become a well established and successful form of support for postoperative myocardial dysfunction, even in the functionally univentricular heart. In recent years interest increased in optimizing myocardial protection using contents-differentiated and temperature-differentiated blood cardioplegia and in optimizing cerebral protection using a higher haematocrit during bypass and by using selective regional perfusion in favour of circulatory arrest.

SUMMARY

Hearts can be mended, but salvation of hearts and brains needs further rigorous attention.

Aprotinin attenuates the elevation of pulmonary vascular resistance after cardiopulmonary bypass

Pulmonary vascular resistance (PVR) is generally believed to be elevated after cardiopulmonary bypass (CPB) due to whole body inflammation. Aprotinin has an antiinflammatory action, and it was hypothesized that aprotinin would attenuate the PVR increase induced by CPB. Ten mongrel dogs were placed under moderately hypothermic CPB for 2 hr. The experimental animals were divided into a control group (n=5, group I) and an aprotinin group (n=5, group II). In group II, aprotinin was administered during pre-bypass (50,000 KIU/kg) and post-bypass (10,000 KIU/kg) periods. Additional aprotinin (50,000 KIU/kg) was mixed in CPB priming solution. PVRs at pre-bypass and post-bypass 0, 1, 2, 3 hr were calculated, and lung tissue was obtained after the experiment. Post-bypass PVRs were significantly higher than prebypass levels in all animals (n=10, p<0.001). PVR elevation in group II was less than in group I at 3 hr post-bypass (p=0.0047). Water content of the lung was lower in group II (74+/-9.4%) compared to that of group I (83+/-9.5%), but the difference did not reach significance (p=0.076). Pathological examination showed a near normal lung structure in group II, whereas various inflammatory reactions were observed in group I. We concluded that aprotinin may attenuate CPB-induced PVR elevation through its anti-inflammatory effect.

Soluble alpha2-macroglobulin receptor is increased in endotracheal aspirates from infants and children after cardiopulmonary bypass

OBJECTIVE

Cytokine dysregulation contributes to the systemic inflammatory response after cardiopulmonary bypass. Clearance of cytokine binding proteins may be important in the resolution of inflammation. Our aim was to determine whether the cytokine binding protein alpha 2 -macroglobulin and its soluble receptor were upregulated in endotracheal aspirates from infants and children undergoing cardiopulmonary bypass.

METHODS

Seventy tracheal aspirates were collected before and after cardiopulmonary bypass from 35 infants and children undergoing surgical correction of congenital heart defects. alpha 2 -Macroglobulin and the soluble alpha 2 -macroglobulin receptor were identified by Western blot. With the use of multi-analyte cytokine profiling, pro-inflammatory and anti-inflammatory cytokines were quantified, normalized to total protein, and expressed as ratios. Paired t tests and Wilcoxon signed-rank tests were performed between prebypass and postbypass samples. Correlations were examined among alpha 2 -macroglobulin, soluble alpha 2 -macroglobulin receptor, cytokine ratios, and the clinical variables of cardiopulmonary bypass, aortic crossclamp, and circulatory arrest times.

RESULTS

alpha 2 -Macroglobulin increased by 50% (mean densitometry increase 82,683 +/- 184,594, P = .012), and soluble alpha 2 -macroglobulin receptor increased by 17% (mean densitometry increase 506,148 +/- 687,037, P = .0001) after cardiopulmonary bypass. The ratio of interleukin-8/interleukin-4 increased by 136% ( P = .0001), and interleukin-8/interleukin-10 increased by 102% ( P = .001). The increase in soluble alpha 2 -macroglobulin receptor was positively correlated with the ratios of interleukin-8/interleukin-4 and interleukin-8/interleukin-10. There were no statistically significant positive correlations between the increase in alpha 2 -macroglobulin or soluble alpha 2 -macroglobulin receptor and measured clinical variables.

CONCLUSIONS

We report for the first time the upregulation of alpha 2 -macroglobulin and soluble alpha 2 -macroglobulin receptor in tracheal aspirates after cardiopulmonary bypass in infants and children. Soluble alpha 2 -macroglobulin receptor correlates with increased alpha 2 -macroglobulin and a disproportionate increase in pro-inflammatory to anti-inflammatory cytokine ratios.

New strategies to control the inflammatory response in cardiac surgery

PURPOSE OF REVIEW

To present and interpret data from recent clinical studies (July 2002-August 2003) of strategies to control the inflammatory response after cardiac surgery.

RECENT FINDINGS

Off-pump coronary artery bypass techniques, which avoid the need for extracorporeal circulation, attenuate the inflammatory response and appear to confer clinical benefit. Concerns regarding the quality of the revascularization after off-pump coronary artery bypass appear to have been allayed. At present, ventricular assist devices do not enhance the efficacy of off-pump coronary artery bypass. In patients undergoing cardiopulmonary bypass, heparin-coated circuits, hypothermic pulmonary perfusion, normoxic reperfusion after aortic unclamping, and modified ultrafiltration hold promise. Strategies to maintain perioperative haemodynamic stability, such as enoximone therapy, may be beneficial, particularly in elderly patients. Aprotinin may have important beneficial anti-inflammatory actions in higher-risk adult and paediatric patients. The therapeutic potential of corticosteroids, particularly when administered in multiple dosages is increasingly clear. Direct anti-mediator therapies that focus upon key effector molecules and pathways of the inflammatory response offer future therapeutic options.

SUMMARY

The potential for strategies that inhibit the inflammatory response to improve outcome after cardiac surgery is clear. Large-scale multicentre trials investigating the most promising strategies, including off-pump coronary artery bypass, heparin-coated circuits, and perioperative corticosteroid and aprotinin therapy, are urgently needed. These trials need to be restricted to the high-risk patient groups most likely to experience benefit. In the interim, the optimal strategy to minimize the inflammatory response to cardiac surgery will remain elusive.