Clinical efficacy of heparin-bonded bypass circuits related to cytokine responses in children

Nuclear Cell-Free DNA Predicts Adverse Events After Pediatric Cardiothoracic Surgery

BACKGROUND

Preoperative risk stratification in cardiac surgery includes patient and procedure factors that are used in clinical decision-making. Despite these tools, unidentified factors contribute to variation in outcomes. Identification of latent physiologic risk factors may strengthen predictive models. Nuclear cell-free DNA (ncfDNA) increases with tissue injury and drops to baseline levels rapidly. The goal of this investigation is to measure and to observe ncfDNA kinetics in children undergoing heart operations with cardiopulmonary bypass (CPB), linking biomarkers, organ dysfunction, and outcomes.

METHODS

This is a prospective observational study of 116 children <18 years and >3 kg undergoing operations with CPB. Plasma ncfDNA samples were collected and processed in a stepwise manner at predefined perioperative time points. The primary outcome measure was occurrence of postoperative cardiac arrest or extracorporeal membrane oxygenation.

RESULTS

Data were available in 116 patients (median age, 0.9 years [range, 0-17.4 years]; median weight, 7.8 kg [range, 3.2-98 kg]). The primary outcome was met in 6 of 116 (5.2%). Risk of primary outcome was 2% with ncfDNA <20 ng/mL and 33% with ncfDNA >20 ng/mL (odds ratio, 25; CI, 3.96-158; P = .001). Elevated ncfDNA was associated with fewer hospital-free days (P < .01).

CONCLUSIONS

This study analyzes ncfDNA kinetics in children undergoing operations with CPB for congenital heart disease. Elevated preoperative ncfDNA is strongly associated with postoperative arrest and extracorporeal membrane oxygenation. Further studies are needed to validate this technology as a tool to predict morbidity in children after cardiac surgical procedures.

Study protocol and statistical analysis plan for the Early Peritoneal Dialysis in Infants after Cardiac Surgery (EPICS) trial

Background: Peritoneal dialysis (PD) is a commonly used therapy after infant cardiac surgery. It is unclear whether early PD commenced soon after admission to an intensive care unit (ICU) after cardiac surgery results in better outcomes. Objective: To describe the study protocol and statistical analysis plan for the Early Peritoneal Dialysis in Infants after Cardiac Surgery (EPICS) trial. Design, setting, participants and intervention: The EPICS trial is an open, randomised, two-group, single-centre clinical study of infants ≤ 180 days of age who had cardiac surgery (in Risk-Adjusted Classification for Congenital Heart Surgery version 1 categories 3-6) with cardiopulmonary bypass. Participants will be randomly assigned 1:1 to early PD (treatment group) or no early PD (control group). Those assigned to the treatment group will begin receiving PD soon after ICU admission and continue receiving it for 24 hours. Those in the control group will not receive PD during the first 24 hours. Main outcome measures: The primary outcome is a composite measure consisting of one or more of death, cardiac arrest, emergency chest reopening, and requirement for extracorporeal membrane oxygenation (ECMO) within 90 days. The main secondary outcomes are duration of mechanical ventilation, ICU length of stay, hospital length of stay, vasoactive-inotropic score at 24 hours, and cumulative per cent fluid balance by end of Day 2. At Day 90, events such as mortality, requirement for ECMO, cardiac arrest, chest reopening, volume of packed red blood cell transfusion, postoperative infection, readmission to ICU, renal injury and brain injury will be assessed. Conclusions: The EPICS trial aims to evaluate the role of early PD after infant cardiac surgery in lowering the rate of a composite major outcome. In addition, it will test the effect of early PD on duration of mechanical ventilation, and on ICU and hospital length of stay. Trial registration: ACTRN12617001614381.

Early Peritoneal Dialysis and Major Adverse Events After Pediatric Cardiac Surgery: A Propensity Score Analysis

OBJECTIVES

Early peritoneal dialysis may have a role in modulating the inflammatory response after cardiopulmonary bypass. This study sought to test the effect of early peritoneal dialysis on major adverse events after pediatric cardiac surgery involving cardiopulmonary bypass.

DESIGN

In this observational study, the outcomes in infants post cardiac surgery who received early peritoneal dialysis (within 6 hr of completing cardiopulmonary bypass) were compared with those who received late peritoneal dialysis. The primary outcome was a composite of one or more of cardiac arrest, emergency chest reopening, requirement for extracorporeal membrane oxygenation, or death. Secondary outcomes included duration of mechanical ventilation, length of intensive care, and hospital stay. A propensity score methodology utilizing inverse probability of treatment weighting was used to minimize selection bias due to timing of peritoneal dialysis.

SETTING

Cardiac ICU, The Royal Children's Hospital, Melbourne, VIC, Australia.

PATIENTS

From 2012 to 2015, infants who were commenced on peritoneal dialysis after cardiac surgery were included.

MEASUREMENTS AND MAIN RESULTS

Among 239 eligible infants, 56 (23%) were commenced on early peritoneal dialysis and 183 (77%) on late peritoneal dialysis. At 90 days, early peritoneal dialysis as compared with late peritoneal dialysis was associated with a decreased risk of primary outcome (relative risk, 0.16; 95% CI, 0.05-0.47; p < 0.001 and absolute risk difference, -18.1%; 95% CI, -25.1 to -11.1; p < 0.001). Early peritoneal dialysis was also associated with a decrease in duration of mechanical ventilation and intensive care stay. Among infants with a cardiopulmonary bypass greater than 150 minutes, early peritoneal dialysis was also associated with a survival advantage (relative risk, 0.14; 95% CI, 0.03-0.84; p = 0.03 and absolute risk difference, -7.8; 95% CI, -13.6 to -2; p = 0.008).

CONCLUSIONS

Early peritoneal dialysis in infants post cardiac surgery is associated with a decrease in the rate of major adverse events. The role of early peritoneal dialysis warrants the conduct of randomized trials both in high and low-to-middle income countries; any beneficial effects if confirmed have the potential to strongly influence outcomes for children born with congenital heart disease.

Strategies for blood conservation in pediatric cardiac surgery

Cardiac surgery accounts for the majority of blood transfusions in a hospital. Blood transfusion has been associated with complications and major adverse events after cardiac surgery. Compared to adults it is more difficult to avoid blood transfusion in children after cardiac surgery. This article takes into account the challenges and emphasizes on the various strategies that could be implemented, to conserve blood during pediatric cardiac surgery.

Serum TNF-α levels in children with congenital heart disease undergoing cardiopulmonary bypass: A cohort study in China and a meta-analysis of the published literature

OBJECTIVE

To investigate the changes in tumor necrosis factor alpha (TNF-α) serum levels after cardiopulmonary bypass (CPB) in children with congenital heart disease (CHD), followed by a meta-analysis to analyze the clinical value of TNF-α in CPB.

METHODS

Our cohort study enrolled 67 CHD children, assigned into off-pump group (n=32) and CPB group (n=35). The TNF-α serum levels in two groups were detected by ELISA before the operation (T1), at the end of the operation (0 hour, T2), and after 24 hours of the operation (T3). For meta-analysis, literature search was conducted to identify published case-control articles about the changes of TNF-α serum levels with CPB of CHD.

RESULTS

The TNF-α levels in CPB group were lower than that in the off-pump group at T3 (P=.006). TNF-α level at T3 was significantly lower than that at T1 and T2 (all P<.05). Meta-analysis results further confirmed that the TNF-α levels of CHD children were dramatically decreased at T3 as compared to that at T1 and T2 (both P<.001).

CONCLUSION

The TNF-α serum levels showed a transient and dramatic decline after 24 hours of CPB, and it may act as an important biological indicator for monitoring the efficacy of CPB in CHD children.

Cardiopulmonary Bypass-Induced Inflammatory Response: Pathophysiology and Treatment

OBJECTIVES

The objectives of this review are to discuss the pathophysiology of the pro-inflammatory response to the cardiopulmonary bypass circuit, the impact of ischemia reperfusion injury on post-operative organ function, the compensatory anti-inflammatory response and the evidence for immune-modulatory strategies and their impact on outcomes.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSION

Innovations such as the development of more biocompatible surfaces and miniaturized circuits, as well as the increasing expertise of surgeons, anesthesiologists and perfusionists has transformed cardiac surgery and the use of cardiopulmonary bypass into a relatively routine procedure with favorable outcomes. Despite these refinements, the attendant inflammatory response to bypass, ischemia reperfusion injury and the compensatory anti-inflammatory response contribute to post-operative morbidity and mortality. Additional studies are needed to further delineate the impact of immunomodulatory strategies on outcomes.

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.

Immunologic and Infectious Diseases in Pediatric Cardiac Critical Care: Proceedings of the 10th International Pediatric Cardiac Intensive Care Society Conference

Since the inception of the Pediatric Cardiac Intensive Care Society (PCICS) in 2003, remarkable advances in the care of children with critical cardiac disease have been developed. Specialized surgical approaches, anesthesiology practices, and intensive care management have all contributed to improved outcomes. However, significant morbidity often results from immunologic or infectious disease in the perioperative period or during a medical intensive care unit admission. The immunologic or infectious illness may lead to fever, which requires the attention and resources of the cardiac intensivist. Frequently, cardiopulmonary bypass leads to an inflammatory state that may present hemodynamic challenges or complicate postoperative care. However, inflammation unchecked by a compensatory anti-inflammatory response may also contribute to the development of capillary leak and lead to a complicated intensive care unit course. Any patient admitted to the intensive care unit is at risk for a hospital acquired infection, and no patients are at greater risk than the child treated with mechanical circulatory support. In summary, the prevention, diagnosis, and management of immunologic and infectious diseases in the pediatric cardiac intensive care unit is of paramount importance for the clinician. This review from the tenth PCICS International Conference will summarize the current knowledge in this important aspect of our field.

Anti-Inflammatory Effects of Heparin and Its Derivatives: A Systematic Review

Background. Heparin, used clinically as an anticoagulant, also has anti-inflammatory properties. The purpose of this systematic review was to provide a comprehensive review regarding the efficacy and safety of heparin and its derivatives as anti-inflammatory agents. Methods. We searched the following databases up to March 2012: Pub Med, Scopus, Web of Science, Ovid, Elsevier, and Google Scholar using combination of Mesh terms. Randomized Clinical Trials (RCTs) and trials with quasi-experimental design in clinical setting published in English were included. Quality assessments of RCTs were performed using Jadad score and Consolidated Standards of Reporting Trials (CONSORT) checklist. Results. A total of 280 relevant studies were reviewed and 57 studies met the inclusion criteria. Among them 48 studies were RCTs. About 65% of articles had score of 3 and higher according to Jadad score. Twelve studies had a quality score > 40% according to CONSORT items. Asthma (n = 7), inflammatory bowel disease (n = 5), cardiopulmonary bypass (n = 8), and cataract surgery (n = 6) were the most studied disease condition. Forty studies use unfractionated heparin (UFH) for intervention; the remaining studies use low molecular weight heparin (LMWH). Conclusion. Despite the conflicting results, heparin seems to be a safe and effective anti-inflammatory agent; although it is shown that heparin can decrease the level of inflammatory biomarkers and improves patient conditions, still more data from larger rigorously designed studies are needed to support use of heparin as an anti-inflammatory agent in clinical setting. However, because of the association between inflammation, atherogenesis, thrombogenesis, and cell proliferation, heparin and related compounds with pleiotropic effects may have greater therapeutic efficacy than compounds acting against a single target.

Oxygenator Is the Main Responsible for Leukocyte Activation in Experimental Model of Extracorporeal Circulation: A Cautionary Tale

In order to assess mechanisms underlying inflammatory activation during extracorporeal circulation (ECC), several small animal models of ECC have been proposed recently. The majority of them are based on home-made, nonstandardized, and hardly reproducible oxygenators. The present study has generated fundamental information on the role of oxygenator of ECC in activating inflammatory signaling pathways on leukocytes, leading to systemic inflammatory response, and organ dysfunction. The present results suggest that experimental animal models of ECC used in translational research on inflammatory response should be based on standardized, reproducible oxygenators with clinical characteristics.

Bone tissue engineering: current strategies and techniques--part I: Scaffolds

Bone repair and regeneration is a dynamic process that involves a complex interplay between the (1) ground substance, (2) cells, and (3) milieu. While each constituent is integral to the final product, it is often helpful to consider each component individually. Therefore, we created a two-part review to examine scaffolds and cells' roles in bone tissue engineering. In Part I, we review the myriad of materials use for in vivo bone engineering. In Part II, we discuss the variety cell types (e.g., osteocytes, osteoblasts, osteoclasts, chondrocytes, mesenchymal stem cells, and vasculogenic cells) that are seeded upon or recruited to these scaffolds. In Part III, we discuss the optimization of the microenvironment. The biochemical processes and sequence of events that guide matrix production, cellular activation, and ossification are vital to developing successful bone tissue engineering strategies and are thus succinctly reviewed herein.

Investigation of inflammatory response at blood–poly (2-methoxyethyl acrylate) (PMEA) interface in vivo via scanning tunneling microscope

The effects of an amphiphilic polymer coating of poly(2-methoxyethyl acrylate) (PMEA) on immunoglobulin adsorption and leukocyte adhesion were investigated. Forty patients were operated on using noncoated and PMEA-coated oxygenator fibers; leukocyte counts adhered onto the noncoated and coated fibers. It appears that the adsorbed immunoglobulin on noncoated fiber surfaces plays a role in leukocyte adhesion and complement activation by an alternative pathway, while the PMEA coating reduced the complement activation on the oxygenator hollow fibers. The biomaterial and blood interaction at the interface could potentially be used as an indicator for predicting the artificial devices long-term clinical performance.

Pulmonary function in children after surgical and percutaneous closure of atrial septal defect

This study aimed to study differences in lung function after surgical and percutaneous atrial septal defect (ASD) closure. Several studies have demonstrated abnormalities of pulmonary function in adults and children with ASD. These abnormalities persist even a few years after correction. This study compared pulmonary function between patients who underwent ASD closure by surgery and those who had closure by device. This is the ideal pediatric population for studying changes in lung function caused by cardiopulmonary bypass or sternotomy. The 46 patients in this study were treated by percutaneous closure (group 1) or surgical closure (group 2) of ASD and then scheduled for pulmonary function testing an average of 5.8 years after ASD closure. The mean values of functional residual capacity, total lung capacity, and residual volume did not differ between the two groups. The surgical group showed a significant decrease in expiratory reserve volume (p < 0.04) and forced vital capacity (p < 0.03). Expiratory flow at 25, 50, and 75% of forced vital capacity did not differ between the two groups but was on the lower limit of normal in both groups. Percutaneous closure of ASD can minimize the side effects of surgical closure on lung function. Longitudinal lung function follow-up assessment after cardiac surgery is warranted to detect and measure restrictive abnormalities in this type of congenital heart disease and others.

Anti-inflammatory modalities: their current use in pediatric cardiac surgery in the United Kingdom and Ireland

OBJECTIVE

To determine the use of anti-inflammatory therapies in infants and children undergoing cardiac surgery in the United Kingdom and Ireland.

DESIGN

Questionnaire survey.

SUBJECTS

All centers that undertake pediatric cardiac surgery in the United Kingdom and Ireland.

RESULTS

All centers use at least one anti-inflammatory therapy, with 46% of centers using more than one. Both modified ultrafiltration (80%) and steroids (80%) are widely used as anti-inflammatory strategies. Among centers that use steroids, dose, preparation, and timing of steroid administered was highly variable. Heparin-bonded circuits and aprotinin are infrequently used as anti-inflammatory techniques.

CONCLUSION

Although anti-inflammatory interventions are believed to contribute to improved patient outcome following cardiopulmonary bypass, this survey has shown that there are still widespread variations in practice. Rather than reflecting poor clinical practice, we believe this reflects a lack of good evidence supporting clinical benefit.

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.

Prolonged Extracorporeal Membrane Oxygenation Support for Acute Respiratory Distress Syndrome

When all conventional treatments for respiratory failure in patients with acute respiratory distress syndrome (ARDS) have failed, extracorporeal membrane oxygenation (ECMO) can provide a chance of survival in these desperately ill patients. A 49-year-old male patient developed septic shock and progressive ARDS after liver abscess drainage. Venovenous ECMO was given due to refractory respiratory failure on postoperative day 6. Initially, two heparin-binding hollow-fiber microporous membrane oxygenators in parallel were used in the ECMO circuit. Twenty-two oxygenators were changed in the first 22 days of ECMO support because of plasma leak in the oxygenators. Each oxygenator had an average life of 48 hours. Thereafter, a single silicone membrane oxygenator was used in the ECMO circuit, which did not require change during the remaining 596 hours of ECMO. The patient's tidal volume was only 90 mL in the nadir and less than 300 mL for 26 days during the ECMO course. The patient required ECMO support for 48 days and survived despite complications, including septic shock, ARDS, acute renal failure, drug-induced leukopenia, and multiple internal bleeding. This patient received an unusually long duration of ECMO support. However, he survived, recovered well, and was in New York Heart Association functional class I-II, with a forced expiratory volume in 1 second of 81% of the predicted level 18 months later. In conclusion, ECMO can provide a chance of survival for patients with refractory ARDS. The reversibility of lung function is possible in ARDS patients regardless of the severity of lung dysfunction at the time of treatment.

Steroid use before pediatric cardiac operations using cardiopulmonary bypass: an international survey of 36 centers

OBJECTIVE

Steroid administration before pediatric cardiac operations using cardiopulmonary bypass has been shown to modulate the inflammatory response and reduce myocardial injury. We hypothesized that current steroid administration practices among pediatric cardiac surgical centers are highly variable.

DESIGN

Questionnaire survey.

SETTING

Pediatric intensive care units.

SUBJECTS

All members of the Pediatric Cardiac Intensive Care Society.

INTERVENTIONS

A self-administered survey was sent to >130 members and 70 institutions participating in the Pediatric Cardiac Intensive Care Society.

MEASUREMENTS AND MAIN RESULTS

Thirty-six questionnaires were returned: 14 international and 22 domestic centers. Cumulatively, these centers treat >11,000 pediatric cardiac patients per year. Ninety-seven percent (35 of 36) of these centers report the use of steroids before cardiopulmonary bypass, yet only 40% (14 of 35) administer steroids with every case. Of the 21 centers that selectively use steroids, 12 do so only for neonates, five administer steroids based on surgeon preference, and four administer steroids for cases anticipated to involve bypass time >2 hrs or deep hypothermic circulatory arrest. Of the 35 centers using steroids, 11 deliver a single dose in the circuit prime, 18 administer a single dose to the patient, and six give multiple doses. The timing of the steroid dose to the patient is variable; 12 centers administer a dose on induction of anesthesia; six centers administer the dose 2-12 hrs before operation. Regimens in the six centers using multiple doses of steroids before cardiopulmonary bypass are as follows: administration at induction and in the prime (two centers); 12 hrs preoperatively and at induction (one center); prime, induction, and 6 hrs preoperatively (one center); prime and midnight preoperatively (one center); and prime plus 2 and 8 hrs preoperatively (one center). Eight centers continue steroid administration following bypass.

CONCLUSION

Although nearly all centers surveyed administer steroids before cardiopulmonary bypass, the type, dosing, route, and timing of administration are highly variable. The inconsistencies in these data and the pediatric literature would support the undertaking of a large, multiple-center clinical trial to evaluate the risks and benefits of steroid administration before pediatric cardiopulmonary bypass.

An analysis of oxygen consumption and oxygen delivery in euthermic infants after cardiopulmonary bypass with modified ultrafiltration

BACKGROUND

The balance between systemic oxygen consumption (VO2) and delivery (DO2) is impaired after cardiopulmonary bypass (CPB) and is related to systemic inflammatory response syndrome. We sought to assess VO2 and DO2 and their relationship with proinflammatory cytokines after CPB with the use of modified ultrafiltration (MUF) in infants.

METHODS

Sixteen infants, aged 1-11.5 months (median, 6.3 months), undergoing hypothermic CPB with MUF were studied during the first 12 hours after arrival in the intensive care unit (ICU). The central temperature was maintained at 36.8-37.1 degrees C using external cooling or warming. VO2 was continuously measured using respiratory mass spectrometry. Arterial blood samples for the tumor necrosis factor (TNF), interleukin-6 (IL-6), and interleukin-8 (IL-8) were taken and DO2 was calculated using the Fick principle on arrival at the ICU, and 2, 4, 8, and 12 hours postoperatively. Cytokines were additionally measured after induction of anesthesia and at the end of MUF.

RESULTS

VO2 significantly decreased by 18.8% during the study period. DO2 was depressed throughout this period and reached a nadir at 8 hours (357.1 +/- 136.2 ml x min(-1) x m(-2)). The decrease in cytokines was accompanied with the decrease in VO2 despite varied relationships between the levels of each of the cytokines and VO2 measurements.

CONCLUSIONS

Our data indicate an unusual continuous decrease in VO2 during the first 12 hours after CPB in infants. Control of body temperature to maintain euthermia in addition to the use of MUF may be beneficial to the balance between VO2 and DO2 in the early postoperative period.

Clinical benefits of continuous leukocyte filtration during cardiopulmonary bypass in patients undergoing valvular repair or replacement

Valve operations in the form of repair or replacement make up a significant population of patients undergoing surgical procedures in the USA annually with the use of cardiopulmonary bypass. These patients experience a wide range of complications that are considered to be mediated by activation of complement and leukocytes. The extracorporeal perfusion circuit consists of multiple synthetic artificial surfaces. The biocompatibility of the blood contact surfaces is a variable that predisposes patients to an increased risk of complement mediation and activation. This can result in an inflammatory process, causing leukocytes to proliferate and sequester in the major organ systems. The purpose of this study was to determine whether filtration of activated leukocytes improved clinical outcomes following surgical intervention for valve repair or replacement. In this paper, we report a retrospective matched cohort study of 700 patients who underwent valve procedures from June 1999 to December 2002. The control group (CG) consisted of patients who had a conventional arterial line filter. In the study group (SG), patients had a conventional arterial line filter and a leukocyte arterial line filter (Pall Medical, NY). In the SG, blood diverted to the cardioplegia system was also leukocyte depleted to enhance myocardial preservation by adapting this device to the outflow port on the filter. Patient characteristics were similar for the SG and the CG, including 228 males and 122 females, mean age (62.4 versus 64.2 years), cardiopulmonary bypass time (127+/-64 versus 116+/-53 min), and aortic crossclamp time (84+/-23 versus 81+/-23 min). Our results demonstrate that the SG achieved statistically significant reduction in the time to extubation (p =0.03) and the number of patients with prolonged intubation in excess of 24 hours (p <0.04), in addition to improved postoperative oxygenation (p=0.01), and decreased length of hospital stay (p =0.03). We believe that leukocyte filters are clinically beneficial, as demonstrated by the results presented in this study.

Different Proinflammatory Cytokine Serum Pattern in Neonate Patients Undergoing Open Heart Surgery. Relevance of IL-8

The purpose of this work was to investigate the clinical significance of serum levels of proinflammatory cytokines in pediatric patients undergoing cardiopulmonary bypass. We divided the patients in two groups: 8 neonates, and 19 non-newborn children. IL-1beta, IL-6, IL-8, and TNF serum levels were quantified before sternotomy, at admission to the PICU (30 min postoperatively), 24 h after the onset of surgery and 3 days after the operation. Surgical cardiac stress elicits significant increments of IL-6, IL-8 and TNF serum concentrations in both neonates and non-neonates, regardless of their preoperative clinical condition. However, in newborns the magnitude of the proinflammatory cytokine increments was, in particular with IL-8, remarkably greater than in older children. Moreover, neonate and non-neonate patients showed clearly disparate patterns of serum concentrations over time of both IL-8 and TNF. There was a marked relationship between IL-8 levels and postoperative morbidity, evaluated by pulmonary dysfunction, days on inotropic support and days of PICU stay in both neonates and non-neonates patients. In contrast, we found no relationship between serum levels of IL-6 and TNF and postoperative clinical data. Newborn and non-newborn patients undergoing cardiopulmonary bypass exhibit dissimilar patterns of proinflammatory cytokines. IL-8 might be implicated in the multiorganic dysfunction related to cardiopulmonary bypass in pediatric patients.

Phosphorylcholine or heparin coating for pediatric extracorporeal circulation causes similar biologic effects in neonates and infants

OBJECTIVE

Cardiac surgery for complex congenital malformations with use of extracorporeal circulation predisposes to an excessive systemic inflammatory response and a consecutive capillary leak syndrome. In a prospective randomized study the influence of 2 oxygenators especially designed for pediatric use on inflammatory markers and clinical outcome was investigated.

METHODS

Forty neonates and infants (body surface area, <0.36 m(2)) undergoing cardiac surgery with extracorporeal circulation were randomized into one of 3 groups: in the first group (n = 14) the Medtronic Minimax Oxygenator and in the second group (n = 12) the Dideco Lilliput 1 Oxygenator, both with a 750-mL priming volume, were used. In the third group the Dideco Lilliput 1 Oxygenator was filled with a reduced priming volume of 450 mL. Parameters of interest for evaluation of a systemic inflammatory response after extracorporeal circulation were interleukin 6, tumor necrosis factor alpha, neutrophil elastase, complement C3, and free hemoglobin. In addition, erythrocyte, leukocyte, and thrombocyte counts and hemoglobin and C-reactive protein values were determined at different measurement points before, during, and after the operation.

RESULTS

In all 3 groups peak values for tumor necrosis factor alpha were observed during the operation, whereas interleukin 6, elastase, and free hemoglobin values peaked in the first 4 hours. The highest values for leukocytes and C-reactive protein were obtained between 24 and 72 hours after the operation. Erythrocyte and thrombocyte counts, as well as hemoglobin values, were lowest at extracorporeal circulation onset, normalizing under substitution in the first 4 hours after the operation. By using the Lilliput/750 oxygenator, higher interleukin 6 values 1 and 4 hours after the operation and higher tumor necrosis factor alpha values during and 1 hour after the operation could be observed compared with results with the Minimax and Lilliput/450 oxygenators. In spite of our randomization protocol, patients in the Lilliput/750 group were significantly smaller and younger than those in the Minimax group. However, the statistical analysis showed no correlation between age and interleukin 6 or tumor necrosis factor alpha values, but it did show a correlation between younger age and the occurrence of capillary leak syndrome. Accordingly, the number of children with clinically complicated course (capillary leak, longer duration of catecholamine therapy, and ventilation) was higher in the Lilliput/750 group than in the Minimax group.

CONCLUSION

By using an adequate priming volume, the systemic inflammatory response is similar after use of the Dideco Lilliput 1 Oxygenator and the Medtronic Minimax Oxygenator. Tip-to-tip surface coating of the extracorporeal circulation with either heparin or phosphorylcholine seems to have similar biologic effects in neonates and infants undergoing cardiac surgery.

Influence of two different perfusion systems on inflammatory response in pediatric heart surgery

BACKGROUND

This study tests the hypothesis that a cardiopulmonary bypass system that combines complete heparin-coating, a centrifugal pump, and a closed circuit in comparison with a conventional system (uncoated system, roller pump, and hard shell venous reservoir) attenuates the inflammatory response in pediatric heart surgery.

METHODS

In a prospective randomized controlled clinical study 40 consecutive children weighing 10 kg or less were included and divided into two groups. Concentrations of complement proteins (C3a, sC5b-9, C4d, and Bb), granulocyte degranulation products (polymorphonuclear [PMN] elastase), and proinflammatory cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6, and IL-8) were measured.

RESULTS

C3a and sC5b-9 concentrations were lower (C3a, p < 0.001; sC5b-9, p = 0.01) in the combined (heparin-coated/centrifugal pump/closed reservoir) group, the peak values being 58% and 37% of conventional group values. The Bb- and C4d-fragment values indicated activation of the complement system through the alternative pathway in both groups. PMN elastase concentrations were lower (p = 0.02) in the combined group, the peak values being 43% of conventional group values. There were no significant intergroup differences regarding TNF-alpha, IL-6, or IL-8 concentrations.

CONCLUSIONS

The use of a fully heparin-coated system, a centrifugal pump, and a closed circuit during CPB in children (10 kg or less) leads to a lower degree of complement activation and PMN elastase release compared with a conventional system.

Heparin-bonded cardiopulmonary bypass circuits reduce cognitive dysfunction

OBJECTIVE

To determine the incidence of cerebral dysfunction in cardiac surgical patients exposed to heparin-bonded cardiopulmonary bypass (HB-CPB) versus nonheparin-bonded cardiopulmonary bypass (NH-CPB) circuits through neuropsychometric testing and to correlate these findings with markers of the systemic inflammatory response to CPB.

DESIGN

Prospective, randomized, blinded clinical trial.

SETTING

University hospital.

PARTICIPANTS

Sixty-one patients undergoing elective cardiac surgery.

INTERVENTIONS

A cohort of 61 patients scheduled for elective coronary artery bypass graft surgery were prospectively randomized to receive either HB-CPB or NH-CPB circuits during surgery. Patients were evaluated for cerebral injury using a battery of neuropsychometric tests at the following 3 time points: (1) before surgery as a baseline examination, (2) postoperative day 5, and (3) postoperative week 6. Blood samples were drawn to measure inflammatory markers at the following time points: (1) preincision, after induction of anesthesia, (2) 15 minutes after onset of CPB, (3) 30 minutes after CPB, (4) 6 hours postoperatively, and (5) 24 hours postoperatively.

MEASUREMENTS AND MAIN RESULTS

Neuropsychometric performance was evaluated by group-rate and event-rate analyses. By group-rate analysis, patients undergoing surgery with HB-CPB performed significantly better at 5 days after surgery on 2 neuropsychometric tests (trails A [p < 0.01] and finger tapping with the dominant hand [p < 0.01]) and at 6 weeks after surgery on one neuropsychometric test (trails A [p < 0.01]). By event-rate analysis, at 5 days, patients undergoing surgery with HB-CPB circuits had less cognitive dysfunction (p < 0.05) compared with patients undergoing surgery with NH-CPB circuits. Serum samples were analyzed to evaluate markers of complement activation (C3a), proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6), and coagulation (thrombin-antithrombin complex [TAT]) using the quantitative sandwich enzyme immunoassay technique. Although there were no significant differences in cytokine activation in either group, C3a was significantly higher in the NH-CPB group intraoperatively at 1 hour after CPB (p < 0.05), and TAT was higher in the HB-CPB group at 24 hours after surgery (p < 0.05).

CONCLUSIONS

Patients undergoing cardiac surgery with CPB have less postoperative cognitive dysfunction during CPB when HB-CPB circuits are employed. Although there was a relationship, this finding did not correlate with decreased complement activation intraoperatively and activation of coagulation postoperatively.

Clinical variables and pro-inflammatory activation in paediatric heart surgery

OBJECTIVES

The first aim was to analyse the role of preoperative characteristics and perioperative variables in predicting the inflammatory response during and early after operations for congenital heart malformations of moderate to severe complexity. The second aim was to correlate complement and cytokine activation during the same period with clinical variables reflecting the postoperative course.

METHODS

Prospective descriptive clinical study that involved 22 consecutive children (1-28 months). Five children had Down's syndrome. Concentrations of C3a, C5b-9 and IL-6 were measured.

RESULTS

C3a, C5b-9 and IL-6 increased significantly during the study period (ANOVA: C3a, p = 0.001; C5b-9, p = 0; IL-6, p = 0). C3a correlated with preoperative haemoglobin (r = 0.71, p = 0.0002) and CPB time (r = 0.72, p=0.0005). C5b-9 correlated with CPB time (r= 0.58, p=0.004). IL-6 related to presence of Down's syndrome (p=0.0001) and correlated with preoperative haemoglobin (r=0.55, p=0.02), preoperative weight deviation (r = -0.52, p = 0.03) and time in the ventilator (r = 0.68, p = 0.002).

CONCLUSIONS

Preoperative and perioperative characteristics predict the inflammatory response during open heart surgery in infants and small children. IL-6 response is related to the postoperative course.

The systemic inflammatory response after cardiac surgery with cardiopulmonary bypass in children

Paediatric cardiac surgery often requires cardiopulmonary bypass (CPB) during the surgical intervention. CPB is known to elicit a systemic inflammatory response with activation of the complement and coagulation systems, stimulation of cytokine production, cellular entrapment in organs, neutrophil activation with degranulation, platelet activation, and endothelial dysfunction. These changes are associated with a risk of postoperative organ dysfunction and increased morbidity and mortality in the postoperative period. Clinical studies have concentrated on measurement of inflammatory markers and mediators in peripheral blood, where the systemic inflammatory response in the paediatric cardiac patient seems to be different from the adult case. Looking at the organ level, experimental studies have the advantage of providing information contributing to a better understanding of the pathological events that may lead to the deteriorated organ function. This review focuses on the systemic inflammatory response after cardiac surgery with CPB in children and experimental CPB models.

Metabolic changes after cardiac surgery

The metabolic changes that occur after cardiac surgery result from a complex interaction between the effects of surgery and extracorporeal circulation per se, the inflammatory response to surgical trauma and extracorporeal circulation, perioperative use of hypothermia, the cardiovascular and neuroendocrine responses characteristic to cardiac surgery, and the drugs and blood products used to support circulation during and after operation. These changes include among others increased oxygen consumption and energy expenditure and increased secretion of insulin, growth hormone, adrenocorticotrophic hormone, cortisol, epinephrine and norepinephrine. Other changes include decreased total-Trijodthyronine levels, hyperglycemia, hyperlactatemia, increased glutamate, aspartate and free fatty acid concentrations, hypokalemia, an increased production of inflammatory cytokines and increased consumption of complement and adhesion molecules. There is evidence that better control of metabolic abnormalities improves the patients' outcome.