Circulating endotoxin and cytokines after cardiopulmonary bypass: differential correlation with duration of bypass and systemic inflammatory response/multiple organ dysfunction syndromes

Whole Blood Reactivity to Viral and Bacterial Pathogens after Non-Emergent Cardiac Surgery during the Acute and Convalescence Periods Demonstrates a Distinctive Profile of Cytokines Production Compared to the Preoperative Baseline in Cohort of 108 Patients, Suggesting Immunological Reprogramming during the 28 Days Traditionally Recognized as the Post-Surgical Recovery Period

The release of danger signals from tissues in response to trauma during cardiac surgery creates conditions to reprogram the immune system to subsequent challenges posed by pathogens in the postoperative period. To demonstrate this, we tested immunoreactivity before surgery as the baseline (tbaseline), followed by subsequent challenges during the acute phase (t24h), convalescence (t7d), and long-term recovery (t3m). For 108 patients undergoing elective heart surgery, whole blood was stimulated with lipopolysaccharide (LPS), Influenza A virus subtype N2 (H3N2), or the Flublok™ vaccine to represent common pathogenic challenges. Leukocytosis, platelet count, and serum C-reactive protein (CRP) were used to measure non-specific inflammation. Cytokines were measured after 18 h of stimulation to reflect activation of the various cell types (activated neutrophils-IL-8; activated T cells-IL-2, IFNγ, activated monocyte (MO)-TNFα, IL-6, and deactivated or atypically activated MO and/or T cells-M-CSF, IL-10). IL-2 and IL-10 were increased at t7d, while TNFα was suppressed at t24h when LPS was utilized. Interestingly, M-CSF and IL-6 production was elevated at seven days in response to all stimuli compared to baseline. While some non-specific markers of inflammation (white cell count, IL-6, and IL-8) returned to presurgical levels at t3m, CRP and platelet counts remained elevated. We showed that surgical stimulus reprograms leukocyte response to LPS with only partial restoration of non-specific markers of inflammation.

Biomarker-based risk model to predict persistent multiple organ dysfunctions after congenital heart surgery: a prospective observational cohort study

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is an important cause of post-operative morbidity and mortality for children undergoing cardiac surgery requiring cardiopulmonary bypass (CPB). Dysregulated inflammation is widely regarded as a key contributor to bypass-related MODS pathobiology, with considerable overlap of pathways associated with septic shock. The pediatric sepsis biomarker risk model (PERSEVERE) is comprised of seven protein biomarkers of inflammation and reliably predicts baseline risk of mortality and organ dysfunction among critically ill children with septic shock. We aimed to determine if PERSEVERE biomarkers and clinical data could be combined to derive a new model to assess the risk of persistent CPB-related MODS in the early post-operative period.

METHODS

This study included 306 patients < 18 years old admitted to a pediatric cardiac ICU after surgery requiring cardiopulmonary bypass (CPB) for congenital heart disease. Persistent MODS, defined as dysfunction of two or more organ systems on postoperative day 5, was the primary outcome. PERSEVERE biomarkers were collected 4 and 12 h after CPB. Classification and regression tree methodology were used to derive a model to assess the risk of persistent MODS.

RESULTS

The optimal model containing interleukin-8 (IL-8), chemokine ligand 3 (CCL3), and age as predictor variables had an area under the receiver operating characteristic curve (AUROC) of 0.86 (0.81-0.91) for differentiating those with or without persistent MODS and a negative predictive value of 99% (95-100). Ten-fold cross-validation of the model yielded a corrected AUROC of 0.75 (0.68-0.84).

CONCLUSIONS

We present a novel risk prediction model to assess the risk for development of multiple organ dysfunction after pediatric cardiac surgery requiring CPB. Pending prospective validation, our model may facilitate identification of a high-risk cohort to direct interventions and studies aimed at improving outcomes via mitigation of post-operative organ dysfunction.

Cell saver blood transfusions may be associated with a decrease in inflammation and improved outcome measures in pediatric cardiac surgery patients

OBJECTIVE

Cardiopulmonary bypass (CPB) is a requisite for correction of congenital heart disease by open-heart surgery and induces a systemic inflammatory response that can lead to complications such as acute lung injury and acute kidney injury. In addition, blood transfusions are commonly required for this type of surgery, and they may further exacerbate this inflammatory response and increase morbidity and mortality. We hypothesized that, in contrast to red blood cells, intraoperative cell saver (CS) blood transfusions attenuate the post-CPB proinflammatory cytokine response.

METHODS

Serum cytokine concentrations of IL-10, IL-1RA, IL-6, IL-8, and TNF-α were measured at four time points (preoperatively and postoperatively on postoperative days 0, 1, and 2).

RESULTS

Anti-inflammatory IL-10 levels were significantly lower in the CS group on POD 0 than in the control group (mean 1083.2 pg/mL vs 2080.2 pg/mL, 95%CI 357.4-1636.6, p = .0026). Of the clinical parameters measured, mean BUN and creatinine levels on POD 2 were significantly lower in the CS group (13.79 vs 21.88, p = .004 and 0.45 vs 0.55, p = .055, respectively). In addition, the duration of milrinone use decreased by 80% in the CS group (0.20, 95%CI 0.04, 0.94; p = .048), the median time to extubation in hours was significantly lower in the CS group (3.5 vs 6.5; 95%CI -38.00, -0.50; p = .026), and hospital length of stay was decreased by 60% in the CS group (p = .003).

CONCLUSIONS

CS transfusions in children may lower postoperative anti-inflammatory IL-10 levels, possibly due to an overall decrease in proinflammatory state, and may be associated with improvements in renal and pulmonary functions.

Effect of Cyclosporine on Cytokine Production in Elective Coronary Artery Bypass Grafting: A Sub-Analysis of the CiPRICS (Cyclosporine to Protect Renal Function in Cardiac Surgery) Study

OBJECTIVES

The augmented inflammatory response to cardiac surgery is a recognized cause of postoperative acute kidney injury. The present study aimed to investigate the effects of preoperative cyclosporine treatment on cytokine production and delineate factors associated with postoperative kidney impairment.

DESIGN

A randomized, double-blind, placebo-controlled, single-center study.

SETTING

At a tertiary care, university hospital.

PARTICIPANTS

Patients eligible for elective coronary artery bypass grafting surgery; 67 patients were enrolled.

INTERVENTIONS

Patients were randomized to receive 2.5 mg/kg cyclosporine or placebo before surgery. Cytokine levels were measured after the induction of anesthesia and 4 hours after the end of cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Tissue-aggressive (interleukin [IL]-1β, macrophage inflammatory protein [MIP]-1β, granulocyte colony-stimulating factor [G-CSF], IL-6, IL-8, IL-17, MCP-1), as well tissue-lenient (IL-4) cytokines, were significantly elevated in response to surgery. Changes in cytokine levels were not affected by cyclosporine pretreatment.

CONCLUSIONS

Elective coronary artery bypass grafting surgery with cardiopulmonary bypass triggers cytokine activation. This activation was not impacted by preoperative cyclosporine treatment.

Effect of 6% Hydroxyethyl Starch 130/0.4 on Inflammatory Response and Pulmonary Function in Patients Having Cardiac Surgery: A Randomized Clinical Trial

BACKGROUND

Cardiac surgery with cardiopulmonary bypass induces a profound inflammatory response that, when severe, can lead to multiorgan system dysfunction. Preliminary data suggest that administration of hydroxyethyl starch (HES) solutions may mitigate an inflammatory response and improve pulmonary function. Our goal was to examine the effect of 6% HES 130/0.4 versus 5% human albumin given for intravascular plasma volume replacement on the perioperative inflammatory response and pulmonary function in patients undergoing cardiac surgery.

METHODS

This was a subinvestigation of a blinded, parallel-group, randomized clinical trial of patients undergoing elective aortic valve replacement surgery at the Cleveland Clinic main campus, titled "Effect of 6% Hydroxyethyl Starch 130/0.4 on Kidney and Haemostatic Function in Cardiac Surgical Patients." Of 141 patients who were randomized to receive either 6% HES 130/0.4 or 5% human albumin for intraoperative plasma volume replacement, 135 patients were included in the data analysis (HES n = 66, albumin n = 69). We assessed the cardiopulmonary bypass-induced inflammatory response end points by comparing the 2 groups' serum concentrations of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and macrophage migration inhibitory factor (MIF), measured at baseline and at 1 and 24 hours after surgery. We also compared the 2 groups' postoperative pulmonary function end points, including the ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (Pao2:Fio2 ratio), dynamic lung compliance, oxygenation index (OI), and ventilation index (VI) at baseline, within 1 hour of arrival to the intensive care unit, and before tracheal extubation. The differences in the postoperative levels of inflammatory response and pulmonary function between the HES and albumin groups were assessed individually in linear mixed models.

RESULTS

Serum concentrations of the inflammatory markers (TNF-α, IL-6, MIF) were not significantly different (P ≥ .05) between patients who received 6% HES 130/0.4 or 5% albumin, and there was no significant heterogeneity of the estimated treatment effect over time (P ≥ .15). The results of pulmonary function parameters (Pao2:Fio2 ratio, dynamic compliance, OI, VI) were not significantly different (P ≥ .05) between groups, and there was no significant heterogeneity of the estimated treatment effect over time (P ≥ .15).

CONCLUSIONS

Our investigation found no significant difference in the concentrations of inflammatory markers and measures of pulmonary function between cardiac surgical patients who received 6% HES 130/0.4 versus 5% albumin.

Ex vivo immune profiling in patient blood enables quantification of innate immune effector functions

The assessment of a patient's immune function is critical in many clinical situations. In complex clinical immune dysfunction like sepsis, which results from a loss of immune homeostasis due to microbial infection, a plethora of pro- and anti-inflammatory stimuli may occur consecutively or simultaneously. Thus, any immunomodulatory therapy would require in-depth knowledge of an individual patient's immune status at a given time. Whereas lab-based immune profiling often relies solely on quantification of cell numbers, we used an ex vivo whole-blood infection model in combination with biomathematical modeling to quantify functional parameters of innate immune cells in blood from patients undergoing cardiac surgery. These patients experience a well-characterized inflammatory insult, which results in mitigation of the pathogen-specific response patterns towards Staphylococcus aureus and Candida albicans that are characteristic of healthy people and our patients at baseline. This not only interferes with the elimination of these pathogens from blood, but also selectively augments the escape of C. albicans from phagocytosis. In summary, our model could serve as a valuable functional immune assay for recording and evaluating innate responses to infection.

Passive Peritoneal Drainage Impact on Fluid Balance and Inflammatory Mediators: A Randomized Pilot Study

BACKGROUND

Infants after cardiopulmonary bypass are exposed to increasing inflammatory mediator release and are at risk of developing fluid overload. The aim of this pilot study was to evaluate the impact of passive peritoneal drainage on achieving negative fluid balance and its ability to dispose of inflammatory cytokines.

METHODS

From September 2014 to November 2016, infants undergoing STAT category 3, 4, and 5 operations were randomized to receive or not receive intraoperative prophylactic peritoneal drain. We analyzed time to negative fluid balance and perioperative variables for each group. Pro- and anti-inflammatory cytokines were measured from serum and peritoneal fluid in the passive peritoneal drainage group and serum in the control group postoperatively.

RESULTS

Infants were randomized to prophylactic passive peritoneal drain group (n = 13) and control (n = 12). The groups were not significantly different in pre- and postoperative peak lactate levels, postoperative length of stay, and mortality. Peritoneal drain patients reached time to negative fluid balance at a median of 1.42 days (interquartile range [IQR]: 1.00-2.91), whereas the control at 3.08 (IQR: 1.67-3.88; P = .043). Peritoneal drain patients had lower diuretic index at 72 hours, median of 2.86 (IQR: 1.21-4.94) versus 6.27 (IQR: 4.75-11.11; P = .006). Consistently, tumor necrosis factor-α, interleukin (IL)-4, IL-6, IL-8, IL-10, and interferon-γ were present at higher levels in peritoneal fluid than serum at 24 and 72 hours. However, serum cytokine levels in peritoneal drain and control group, at 24 and 72 hours postoperatively, did not differ significantly.

CONCLUSIONS

The prophylactic passive peritoneal drain patients reached negative fluid balance earlier and used less diuretic in early postoperative period. The serum cytokine levels did not differ significantly between groups at 24 and 72 hours postoperatively. However, there was no significant difference in mortality and postoperative length of stay.

Effects of cardiopulmonary bypass on the development of lymphopenia and sepsis after cardiac surgery in children with congenital cardiopathy

The objective of the present study was to investigate whether lymphopenia occurring after heart surgery with cardiopulmonary bypass (CPB) is related to apoptosis and or sepsis in children. The design was a prospective cohort study in a third level care hospital in Mexico City. In total, 68 children (31 girls and 37 boys) with congenital cardiopathy who needed corrective cardiac surgery with or without CPB were included. The samples were obtained from central blood before, immediately after and 24 h after surgery. Complete blood counts and lymphocyte apoptosis were analyzed. Systemic inflammatory response syndrome (SIRS), sepsis and the type of microorganism were recorded. A total of 53 patients received CPB and 15 did not. Lymphocyte count decreased after surgery in both groups (P<0.001). However, neutrophil count increased markedly in both groups. Apoptosis of B (CD19⁺) lymphocytes was higher in the non-CPB group (14, 2 and 21% before, immediately after and 24 h after surgery, respectively) than the CPB group (0, 2 and 3%, respectively), but apoptosis of cytotoxic T lymphocytes (CD8⁺) was higher in the CPB group (5, 4 and 3% before, immediately after and 24 h after surgery, respectively) than in the non-CPB group (2, 3 and 2%, respectively). However, the extent of apoptosis of T and B lymphocytes after surgery did not differ between groups. The CPB group had more complications than the non-CPB group [38 (71.7%) vs. 9 (60.0%)]. In conclusion, the decrease in lymphocyte count may be related to apoptosis of cytotoxic T lymphocytes in children receiving cardiac surgery with CPB and to apoptosis of B lymphocytes in those not receiving CPB. The decreased lymphocyte counts in both groups suggested that CPB is not the main cause of this decrease. Children who received CPB during surgery had more complications, such as sepsis and cardiogenic shock than did those who did not receive CPB.

Study Protocol for a Pilot, Open-Label, Prospective, and Observational Study to Evaluate the Pharmacokinetics of Drugs Administered to Patients during Extracorporeal Circulation; Potential of In Vivo Cytochrome P450 Phenotyping to Optimise Pharmacotherapy

Pharmacokinetic alterations of medications administered during surgeries involving cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) have been reported. The impact of CPB on the cytochrome P450 (CYP) enzymes’ activity is the key factor. The metabolic rates of caffeine, dextromethorphan, midazolam, omeprazole, and Losartan to the CYP-specific metabolites are validated measures of in vivo CYP 1A2, 2D6, 3A4, 2C19, and 2C9 activities, respectively. The study aim is to assess the activities of major CYPs in patients on extracorporeal circulation (EC). This is a pilot, prospective, open-label, observational study in patients undergoing surgery using EC and patients undergoing laparoscopic cholecystectomy as a control group. CYP activities will be measured on the day, and 1–2 days pre-surgery/3–4 days post-surgery (cardiac surgery and Laparoscopic cholecystectomy) and 1–2 days after starting ECMO, 1–2 weeks after starting ECMO, and 1–2 days after discontinuation from ECMO. Aforementioned CYP substrates will be administered to the patient and blood samples will be collected at 0, 1, 2, 4, and 6 h post-dose. Major CYP enzymes’ activities will be compared in each participant on the day, and before/after surgery. The CYP activities will be compared in three study groups to investigate the impact of CYPs on EC.

Serum levels of interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α, renal function biochemical parameters and clinical outcomes in pediatric cardiopulmonary bypass surgery

BACKGROUND

Cardiopulmonary bypass causes detrimental effects on remote organs due to inflammatory response. One of these organs is kidney that is frequently affected by cardiac surgery. Acute kidney injury is a post-cardiopulmonary bypass complication, which may result in increased post-operative morbidity and mortality. Post-cardiopulmonary bypass inflammatory response may contribute to remote organ dysfunction. In the present study, we investigated the relation between cytokines including interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α, and renal function tests such as creatinine and blood urea nitrogen (BUN).

METHODS

In total, 91 patients between the ages of 4 and 60 months were enrolled for elective cardiac surgery with cardiopulmonary bypass after informed consent. Data regarding renal function tests and clinical outcomes were carefully recorded until 24 hours after admission to intensive care unit and analyzed.

RESULTS

Our findings support that there is a direct correlation between cytokines including interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α and cardiopulmonary bypass time, duration of operation, and intensive care unit stay. Longer cardiopulmonary bypass time was associated with higher interleukin-8 at cross-clamp removal and 24 hours post- intensive care unit as well as higher interleukin-10 at declamp time. Higher interleukin-6 at declamp time was directly correlated with higher post-operative BUN. Interleukin-8 level after anesthesia induction was directly correlated with intensive care unit stay duration. Higher blood interleukin-6 and tumor necrosis factor-α levels following 24 hours of admission to intensive care unit were associated with longer mechanical ventilation time.

CONCLUSION

Higher circulatory pro-inflammatory cytokine level is associated with adverse outcomes such as increased intensive care unit stay and longer mechanical ventilation time in pediatric patients. It is also correlated with unfavorable biochemical parameter of renal function, BUN. Findings hint that proper control of the inflammatory response is vital for the control of unfavorable clinical and pathological outcomes.

Vitamin C to Improve Organ Dysfunction in Cardiac Surgery Patients-Review and Pragmatic Approach

The pleiotropic biochemical and antioxidant functions of vitamin C have sparked recent interest in its application in intensive care. Vitamin C protects important organ systems (cardiovascular, neurologic and renal systems) during inflammation and oxidative stress. It also influences coagulation and inflammation; its application might prevent organ damage. The current evidence of vitamin C's effect on pathophysiological reactions during various acute stress events (such as sepsis, shock, trauma, burn and ischemia-reperfusion injury) questions whether the application of vitamin C might be especially beneficial for cardiac surgery patients who are routinely exposed to ischemia/reperfusion and subsequent inflammation, systematically affecting different organ systems. This review covers current knowledge about the role of vitamin C in cardiac surgery patients with focus on its influence on organ dysfunctions. The relationships between vitamin C and clinical health outcomes are reviewed with special emphasis on its application in cardiac surgery. Additionally, this review pragmatically discusses evidence on the administration of vitamin C in every day clinical practice, tackling the issues of safety, monitoring, dosage, and appropriate application strategy.

Current Evidence about Nutrition Support in Cardiac Surgery Patients-What Do We Know?

Nutrition support is increasingly recognized as a clinically relevant aspect of the intensive care treatment of cardiac surgery patients. However, evidence from adequate large-scale studies evaluating its clinical significance for patients&rsquo; mid- to long-term outcome remains sparse. Considering nutrition support as a key component in the perioperative treatment of these critically ill patients led us to review and discuss our understanding of the metabolic response to the inflammatory burst induced by cardiac surgery. In addition, we discuss how to identify patients who may benefit from nutrition therapy, when to start nutritional interventions, present evidence about the use of enteral and parenteral nutrition and the potential role of pharmaconutrition in cardiac surgery patients. Although the clinical setting of cardiac surgery provides advantages due to its scheduled insult and predictable inflammatory response, researchers and clinicians face lack of evidence and several limitations in the clinical routine, which are critically considered and discussed in this paper.

Effect of cardiopulmonary bypass on cytochrome P450 enzyme activity: implications for pharmacotherapy

For patients undergoing cardiopulmonary bypass (CPB) during cardiac surgery, there are well-documented changes in the pharmacokinetics (PK) of commonly administered drugs. Although multiple factors potentially underpin these changes, there has been scant research attention on the impact of CPB to alter the activities of cytochrome P450 (CYP) isoenzymes. PK changes during cardiac surgery with CPB have the potential to adversely affect the safety and efficacy of pharmacotherapy and increase the risk of drug-drug interactions. Clinically significant changes in drug PK during CPB are likely to be prominent for drugs where CYP metabolism is a major clearance (CL) mechanism. However, clinical data from patients undergoing CPB surgery in support of this hypothesis are lacking, leaving a significant knowledge gap. In this review, we address the effects of CPB on the release of pro-inflammatory cytokines, in surgeries with and without CPB, both pre and post initiation of surgery. We reviewed literature to explore the relationship between the release of pro-inflammatory cytokines, and the expression and activities of CYP enzymes. Through this approach, we provide new insight on the effects of CPB on the PK of drugs administered to patients in the clinical setting. Future research to address this knowledge gap will have considerable impact to assist clinicians with optimizing pharmacotherapy in this patient population.

Effects of gelatine and medium molecular weight starch as priming fluid in cardiopulmonary bypass - a randomised controlled trial

Perioperative volume replacement after cardiopulmonary bypass is complicated by post-bypass systemic inflammatory process. The aim of this study was to assess the effects of using two different colloid solutions as priming fluids in cardiopulmonary bypass. The study's primary end point was to measure the amount of fluid replacement needed during and post-cardiopulmonary bypass; blood loss, change in blood profile and intraocular pressure were secondary end points, used as measures of plasma oncotic pressures. Patients undergoing coronary artery bypass grafting were recruited. Both patients and surgeons were blinded to receive either Gelofusine® or Voluven® as priming fluids. At fixed intervals during cardiopulmonary bypass, the patients had their intraocular pressures measured. Intra and postoperative fluid replacement was in the form of 4.5% human albumin and the amount was recorded for each subject. The result did not show any significant differences in the amount of fluid needed to be replaced, in blood loss or in blood profile between the two groups. However, it showed an increase in intraocular pressure in both groups once cardiopulmonary bypass commenced. The average intraocular pressure was higher in the Gelofusine ® group compared to the Voluven® group. The significant increase in intraocular pressure measurements in the Gelofusine® group compared to the Voluven® group support the hypothesis that Voluven maintains the plasma oncotic pressure better and reduces fluid shift. Perfusion (2007) 22, 57—62.

WITHDRAWN: Prophylactic steroids for pediatric open heart surgery

The Cochrane Heart Group withdrew this review as the current author team are unable to progress to the final review stage. This title has been taken over by a new author team who are producing a review, starting with a new protocol (Corticosteroids in paediatric heart surgery).

The editorial group responsible for this previously published document have withdrawn it from publication.

A cardiopulmonary bypass with deep hypothermic circulatory arrest rat model for the investigation of the systemic inflammation response and induced organ damage

Background

Cardiopulmonary bypass (CPB) is a commonly used technique in cardiac surgery. CPB is however associated with a strong induction of systemic inflammatory response syndrome (SIRS) which in conjunction with ischemia and reperfusion may lead to multiple organ failure.

The aim of the study was to establish and characterize a CPB rat model incorporating deep hypothermic circulatory arrest with a specific focus on the extent of the inflammatory reactions and organ damage as a groundwork for novel therapeutics against SIRS and I/R induced organ injury.

Materials and methods

Male Wistar rats (n = 6) were cannulated for CPB, connected to a heart-lung-machine (HLM) and cooled to a temperature of 16°C before they underwent 45 minutes of deep hypothermic circulatory arrest with global ischaemia. Arrest was followed by rewarming and 60 minutes of reperfusion. Haemodynamic and vital parameters were recorded throughout the CPB procedure. Only animals displaying sinus rhythm throughout reperfusion were utilized for analysis. Rats were euthanized and tissue samples were harvested. Blood gas analysis was performed and blood samples were taken. Induction of organ damage was examined by analysis of protein levels and phosphorylation status of kinases and stress proteins. Results were compared to animals (n = 6) which did not undergo CPB.

Results

CPB induced leucocytosis and an increase of interleukin-6 and TNF-α plasma values indicating an inflammatory response. Markers of tissue damage and dysfunction, such as troponin T, creatinine and AST were elevated. Phosphorylation of STAT3 was induced in all examined organs. Activation of MAPK and induction of heat shock proteins occurred in an organ-specific manner with most pronounced effects in heart, lungs and kidneys.

Conclusions

The presented CPB rat model shows the induction of SIRS and activation of specific signalling cascades. SIRS seems not to be provoked during DHCA and is elicited mainly during reperfusion. This model might be suitable to test the efficacy of therapeutics applied in major heart surgery with and without DHCA.

Safety and utility of passive peritoneal drainage following Fontan palliation

OBJECTIVE

Placement of peritoneal drainage catheters intra-operatively has been shown to help prevent fluid overload in children recovering from surgery for two-ventricle heart disease. We aimed to determine whether this practice is also helpful in children recovering from Fontan palliation.

MATERIAL AND METHODS

A retrospective review was performed on children with single-ventricle anatomy undergoing Fontan palliation at our institution from 2007 to 2011. Variables in those with peritoneal drainage were compared with those without using t-tests, Mann-Whitney U-tests, chi-square tests, or analysis of variance for repeated measures as appropriate. Data were represented as mean with standard deviation unless otherwise noted.

RESULTS

A total of 43 children were reviewed, 21 (49%) with peritoneal drainage catheters. No complications from catheter placement occurred. The groups did not differ with regard to cardiopulmonary bypass duration, dominant ventricle, pre-operative haemodynamic data, fenestration use, and initial intensive care unit ventilation index. Central venous pressures, vasoactive medication use, and diuretic use during the first 48 hours were also not statistically different. At 48 hours, the median fluid balance was -9 (interquartile range : -50, +20) in those with peritoneal drainage and +77 cc/kg (interquartile range : +22, +96) in those without (p < 0.001), yet median duration of mechanical ventilation was 40 hours (range: 19-326) in those with peritoneal drainage and 23 hours (range: 9-92) in those without, p = 0.01.

CONCLUSION

Patients with peritoneal drainage recovering from Fontan palliation achieved negative fluid balance as compared with those without peritoneal drainage, although this difference was associated with a longer duration of mechanical ventilation.

Postoperative complications and association with outcomes in pediatric cardiac surgery

OBJECTIVE

Our primary aim was to study postoperative complications in pediatric cardiac surgery patients and their association with cardiopulmonary bypass (CPB) use. The secondary aim was to evaluate the association of postoperative complications with established outcome measures.

METHODS

A single-institution retrospective observational study was undertaken of consecutive pediatric cardiac surgery patients during a 1-year period. Five cardiac and 15 extracardiac complications were studied. CPB use, CPB parameters, demographics, and Risk Adjusted Classification for Congenital Heart Surgery (RACHS-1) levels were evaluated as risk factors for complications. Outcomes, including mechanical ventilation duration, pediatric cardiac intensive care unit stay, hospital stay, and mortality were studied.

RESULTS

A total of 325 patients were studied: 271 with CPB and 54 without CPB. Of the 325 patients, 141 (43%) had ≥1 complication (95% confidence interval, 38%-49%). Of the 325 patients, 82 (25%) developed cardiac and 120 (37%) developed extracardiac complications. The evidence from logistic regression analysis was insufficient to suggest a relationship between CPB support and the incidence of cardiac or extracardiac complications after adjusting for age, gender, previous sternotomy, and RACHS-1 levels. For patients receiving CPB, longer CPB times, higher RACHS-1 levels, and a lower temperature with CPB were associated with a greater number of cardiac complications (P < .01). Longer CPB times and higher RACHS-1 levels were associated with a greater number of extracardiac complications (P = .006). Postoperative complications were significantly associated with an increased mechanical ventilation duration, pediatric cardiac intensive care unit stay, and hospital stay and mortality (P < .01).

CONCLUSIONS

Postoperative complications occurred in 43% of pediatric cardiac surgeries performed both with and without CPB. The complications were associated with longer mechanical ventilation and pediatric cardiac intensive care unit and hospital stays, and increased mortality.

Dynamic changes in HMGB1 levels correlate with inflammatory responses during cardiopulmonary bypass

High mobility group box 1 (HMGB1), which is released by activated immune cells and necrotic cells, has properties similar to those of pro-inflammatory cytokines. Cardiopulmonary bypass (CPB) induces systemic inflammation and aortic cross-clamping induces myocardial ischemia. This study was conducted to observe the dynamic changes of HMGB1 and tumor necrosis factor (TNF)-α levels during CPB and to analyze their clinical significance. A total of 78 cases of American Society of Anesthesiologists (ASA) grade II-IV undergoing elective valve replacement under CPB were included in this study. Blood and urine samples were collected after anesthesia prior to surgery (T1), before aortic cross-clamping (T2), after CPB (T3) and on the first day after surgery (T4), as well as the second (T5) and third (T6) day after surgery for determination of the levels of HMGB1, TNF-α, alanine aminotransferase (ALT), creatinine (Cr), blood urea nitrogen (BUN), N-acetyl-β-D-glucosamidase (NAG) and β2-microglobulin (β2-MG). Results revealed that: i) the serum levels of HMGB1 elevated as early as T1, increased until reaching a peak at T3, then decreased to a lower level at T4; ii) the serum level of TNF-α was low at T1, gradually increased in a similar manner to HMGB1, then decreased following CPB and reached the lowest point at T5; and iii) the levels of HMGB1 were positively correlated with serum TNF-α and serum ALT at T3. In conclusion, HMGB1 levels may be used as an indicator of inflammation and may be a novel target for controlling inflammation during CPB. The optimal treatment time is T3 (after CPB).

Three short perioperative infusions of n-3 PUFAs reduce systemic inflammation induced by cardiopulmonary bypass surgery: a randomized controlled trial

BACKGROUND

Fish oil (FO) has antiinflammatory effects, which might reduce systemic inflammation induced by a cardiopulmonary bypass (CPB).

OBJECTIVE

We tested whether perioperative infusions of FO modify the cell membrane composition, inflammatory responses, and clinical course of patients undergoing elective coronary artery bypass surgery.

DESIGN

A prospective randomized controlled trial was conducted in cardiac surgery patients who received 3 infusions of 0.2 g/kg FO emulsion or saline (control) 12 and 2 h before and immediately after surgery. Blood samples (7 time points) and an atrial biopsy (during surgery) were obtained to assess the membrane incorporation of PUFAs. Hemodynamic data, catecholamine requirements, and core temperatures were recorded at 10-min intervals; blood triglycerides, nonesterified fatty acids, glucose, lactate, inflammatory cytokines, and carboxyhemoglobin concentrations were measured at selected time points.

RESULTS

Twenty-eight patients, with a mean ± SD age of 65.5 ± 9.9 y, were enrolled with no baseline differences between groups. Significant increases in platelet EPA (+0.86%; P = 0.0001) and DHA (+0.87%; P = 0.019) were observed after FO consumption compared with at baseline. Atrial tissue EPA concentrations were higher after FO than after control treatments (+0.5%; P < 0.0001). FO did not significantly alter core temperature but decreased the postoperative rise in IL-6 (P = 0.018). Plasma triglycerides increased transiently after each FO infusion. Plasma concentrations of glucose, lactate, and blood carboxyhemoglobin were lower in the FO than in the control group on the day after surgery. Arrhythmia incidence was low with no significant difference between groups. No adverse effect of FO was detected.

CONCLUSIONS

Perioperative FO infusions significantly increased PUFA concentrations in platelet and atrial tissue membranes within 12 h of the first FO administration and decreased biological and clinical signs of inflammation. These results suggest that perioperative FO may be beneficial in elective cardiac surgery with CPB.

Insufflation of hydrogen gas restrains the inflammatory response of cardiopulmonary bypass in a rat model

Systemic inflammatory responses in patients receiving cardiac surgery with the use of the cardiopulmonary bypass (CPB) significantly contribute to CPB-associated morbidity and mortality. We hypothesized that insufflated hydrogen gas (H₂) would provide systemic anti-inflammatory and anti-apoptotic effects during CPB, therefore reducing proinflammatory cytokine levels. In this study, we examined the protective effect of H₂ on a rat CPB model. Rats were divided into three groups: the sham operation (SHAM) group, received sternotomy only; the CPB group, which was initiated and maintained for 60 min; and the CPB + H₂ group in which H₂ was given via an oxygenator during CPB for 60 min. We collected blood samples before, 20 min, and 60 min after the initiation of CPB. We measured the serum cytokine levels of (tumor necrosis factor-α, interleukin-6, and interleukin-10) and biochemical markers (lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase). We also measured the wet-to-dry weight (W/D) ratio of the left lung 60 min after the initiation of CPB. In the CPB group, the cytokine and biochemical marker levels significantly increased 20 min after the CPB initiation and further increased 60 min after the CPB initiation as compared with the SHAM group. In the CPB + H₂ group, however, such increases were significantly suppressed at 60 min after the CPB initiation. Although the W/D ratio in the CPB group significantly increased as compared with that in the SHAM group, such an increase was also suppressed significantly in the CPB + H₂ group. We suggest that H₂ insufflation is a possible new potential therapy for counteracting CPB-induced systemic inflammation.

Comparison of the effects of pulsatile cardiopulmonary bypass, non-pulsatile cardiopulmonary bypass and off-pump coronary artery bypass grafting on the respiratory system and serum carbonyl

BACKGROUND

We aimed to investigate the effects of off-pump coronary artery bypass grafting (CABG), pulsatile cardiopulmonary bypass (CPB), and non-pulsatile CPB techniques on oxidative stress and the respiratory system in the current study.

MATERIALS AND METHODS

The patients were allocated into three different groups according to perfusion techniques, as follows: off-pump CABG group (n=10); pulsatile CPB (n=11); and non-pulsatile CPB group (n=11). Serum carbonyl level was measured and a pulmonary function test was performed preoperatively and postoperatively.

RESULTS

The postoperative increase in the carbonyl level was significantly lower in the off-pump CABG group compared to the other two groups, while there was no significant difference between the pulsatile and non-pulsatile CPB groups with respect to carbonyl levels. Arterial partial pressure of oxygen, forced expiratory volume in one second, and forced vital capacity were significantly higher in the off-pump CABG group compared to other two groups in the postoperative period.

CONCLUSION

We found that off-pump CABG had less negative effects on oxidative stress and the respiratory system compared to pulsatile CPB and non-pulsatile CPB techniques. Additionally, there was no significant difference between pulsatile and non-pulsatile CPB.

Passive peritoneal drainage improves fluid balance after surgery for congenital heart disease

OBJECTIVE

In some centers, passive peritoneal drainage (PD) is implemented following surgery for congenital heart disease. The utility of this practice has yet to be studied. We hypothesized that passive PD can promote negative fluid balance without compromising intravascular volume.

METHODS

A retrospective review of infants who underwent repair of complete atrioventricular septal defect (AVSD) between 6/2006 and 8/2010 was completed. Data are represented as mean ± standard deviation.

RESULTS

Thirty-six infants underwent AVSD repair, 18 of whom had PD catheters placed without complication. Infants with passive PD had longer duration of cardiopulmonary bypass (211 ± 59 vs 137 ± 41 min, P < 0.001) and aortic cross-clamp (148 ± 29 vs 102 ± 21 min, P < 0.001); had higher Aristotle complexity score (12.6 ± 3 vs 10.7 ± 2, P = 0.03) and ventilatory support immediately after surgery (ventilation index score 19.5 ± 6.5 vs 14.3 ± 2.5, P = 0.004); and received greater fluid administration (225 ± 6 3 vs 168 ± 45 ml kg(-1), P = 0.002) in the first 48 postoperative hours. Despite these differences, infants with passive PD achieved negative fluid balance more rapidly (12 ± 10 vs 27.3 ± 13 h, P < 0.0001) and to a greater extent (-73 + 55 vs +2.6 + 39 mL kg(-1) at 48 h, P = 0.002). Moreover, postoperative hemodynamics, urine output, creatinine clearance, blood urea nitrogen, peak lactate, and duration of mechanical ventilation were similar between groups.

CONCLUSIONS

Passive PD is safe and promotes negative fluid balance after repair of complete AVSD without adversely affecting intravascular volume.

Safe time limits of aortic cross-clamping and cardiopulmonary bypass in adult cardiac surgery

OBJECTIVES

We evaluated the impact of aortic cross-clamping time (XCT) and cardiopulmonary bypass time (CPBT) on the immediate and late outcome after adult cardiac surgery and attempted to identify their safe time limits.

METHODS

This study includes 3280 patients who underwent adult cardiac surgery of various complexities. Myocardial protection was achieved with tepid continuous antegrade/retrograde blood cardioplegia.

RESULTS

Receiver operating characteristics (ROC) curve analysis showed that XCT (area under the curve, AUC: 0.66), CPBT (AUC: 0.73) and CPBT with unclamped aorta (AUC: 0.77) were significantly associated with 30-day postoperative mortality. XCT of increasing 30-minute intervals (Odds Ratio (OR) 1.21, 95%C.I. 1.01-1.52) and CPBT of increasing 30-minute intervals (OR 1.47, 95%C.I. 1.27-1.71) were independent predictors of 30-day mortality. The best cutoff value for XCT was 150 min (30-day death: 1.8% vs. 12.2%, adjusted OR 3.07, 95%C.I. 1.48-6.39, accuracy 91.5%) and for CPBT 240 min (30-day death: 1.9% vs. 31.5%, adjusted OR 8.78, 95%C.I. 4.64-16.61, accuracy 96.0%). These parameters were significantly associated also with postoperative morbidity, particularly with postoperative stroke.

CONCLUSIONS

XCT and CPBT are predictors of immediate postoperative morbidity and mortality. In our experience, cardiac procedures with CPBT<240 min and XCT<150 min were associated with a rather low risk of immediate postoperative adverse events independently of the complexity of surgery patient's operative risk.

Endothelin-A receptor inhibition after cardiopulmonary bypass: cytokines and receptor activation

BACKGROUND

Basic studies have suggested that cross-talk exists between the endothelin-A receptor (ET-AR) and tumor necrosis factor signaling pathway. This study tested the hypothesis that administration of an ET-AR antagonist at the separation from cardiopulmonary bypass would alter the tumor necrosis factor activation in the early postoperative period.

METHODS

Patients (n = 44) were randomly allocated to receive bolus infusion of vehicle, 0.1, 0.5, 1, or 2 mg/kg of the ET-AR antagonist (sitaxsentan), at the separation from cardiopulmonary bypass (n = 9, 9, 9, 9, and 8, respectively). Plasma levels of tumor necrosis factor-alpha and soluble tumor necrosis factor receptor 1 and 2 were measured.

RESULTS

Compared with the vehicle group at 24 hours, plasma levels of tumor necrosis factor-alpha and tumor necrosis factor receptor 2 (indicative of receptor activation) were reduced in the 1 mg/kg ET-AR antagonist group (by approximately 13 pg/mL and approximately 0.5 ng/mL, respectively; p < 0.05). Plasma tumor necrosis factor receptor I levels also decreased (by approximately 1 ng/mL) after infusion of the higher doses of the ET-AR antagonist and remained lower (by approximately 3 ng/mL) at 24 hours after infusion (p < 0.05). In addition, a dose effect was observed between the ET-AR antagonist and these indices of tumor necrosis factor activation (p < 0.01).

CONCLUSIONS

This study demonstrated a mechanistic relationship between the ET-AR and tumor necrosis factor receptor activation in the post-cardiac surgery period. Thus, in addition to the potential cardiovascular effects, a selective ET-AR antagonist can modify other biological processes relevant to the post-cardiac surgery setting.

Very early extubation after open-heart surgery in children does not influence cardiac function

The objective of our study was to evaluate hemodynamic effects and the cardiac function after very early extubation within the first 6 hours after open-heart surgery in children. During a 12-month period, we performed a retrospective study of 50 children (ages 3 months to 7 years) admitted to the pediatric intensive care unit immediately after minor cardiac surgery. All children were extubated within the first 6 hours after their arrival. Arterial blood and central venous pressure were monitored, and arterial blood gas analysis was performed. Cardiac index, stroke volume index, systemic vascular resistance index, and extravascular lung water index were measured by thermodilution. Early extubation of children after minor open-heart surgery with cardiopulmonary bypass is safe and does not affect cardiac functions. A slight decrease of arterial oxygen tension not resulting in respiratory or metabolic acidosis or reintubation was noted. Very early extubation in children after open-heart surgery does not promote cardiodepressive effects. It is a safe procedure that helps to reduce the unnecessary and prolonged mechanical ventilation of children after cardiopulmonary bypass surgery.

Hypertonic-hyperoncotic solutions improve cardiac function in children after open-heart surgery

OBJECTIVES

Hypertonic-hyperoncotic solutions are used for the improvement of micro- and macrocirculation in various types of shock. In pediatric intensive care medicine, controlled, randomized studies with hypertonic-hyperoncotic solutions are lacking. Hypertonic-hyperoncotic solutions may improve cardiac function in children. The primary objective of this controlled, randomized, blinded study was to evaluate the hemodynamic effects and safety of hypertonic-hyperoncotic solution infusions in children shortly after open-heart surgery for congenital cardiac disease. The secondary objective was to determine whether the administration of hypertonic-hyperoncotic solutions could be a potential and effective therapeutic option for preventing a probable capillary leakage syndrome that frequently occurs in children after open-heart surgery.

METHODS

The children were randomly assigned to 2 groups of 25. The hypertonic-hyperoncotic solution group received Poly-(O-2)-hydroxyethyl-starch 60.0 g, with molecular weight of 200 kDa, Na+ 1232 mmol/L and osmolality of 2464 mOsmol/L (7.2% sodium chloride with 6% hydroxyethyl-starch 200 kDa). The isotonic saline solution group received isotonic saline solution (0.9% sodium chloride). Atrial and ventricular septal defects were corrected using a homograft patch. Monitoring consisted of an arterial, a central venous, and a thermodilution catheter (PULSIOCATH). Cardiac index, extravascular lung water index, stroke volume index, mean arterial blood pressure, and systemic vascular resistance index were measured (Pulse Contour Cardiac Output technique). Immediately after surgery, patients were loaded either with hypertonic-hyperoncotic solution or with isotonic saline solution (4 mL/kg). Blood samples (sodium concentration, osmolality, thrombocyte count, fibrinogen, and arterial blood gases) were drawn directly before; immediately after; 15 minutes after; and, 1, 4, 12, and 24 hours after the end of volume loading. Hemodynamic parameters were registered at the same time. The total amount of dobutamine required was documented, as well as the 24- and 48-hour fluid balances.

RESULTS

In the hypertonic-hyperoncotic solution group, cardiac index was 3.6 +/- 0.26 L/min per m2 before volume administration and increased to 5.96 +/- 0.27 after the administration of the study solution (64%). Fifteen and 60 minutes after administration, the cardiac index remained significantly elevated (5.55 +/- 0.29 L/min per m2 and 4.65 +/- 0.18 L/min per m2, respectively) and returned to preadministration values after 4 hours. In the isotonic saline solution group, the cardiac index did not change during the entire observation period (3.39 +/- 0.21 before and 3.65 +/- 0.23 L/min per m2 after isotonic saline solution). The systemic vascular resistance index decreased in the hypertonic-hyperoncotic solution group after administration from 1396 +/- 112 to 868 +/- 63 dyn/sec per cm(-5)/m2. The decrease of systemic vascular resistance index in the hypertonic-hyperoncotic solution group was transiently significant within 60 minutes after administration but stayed lower than before volume load (999 +/- 70 dyn/sec per cm-(5)/m2). In the isotonic saline solution group, we found no statistically relevant change in systemic vascular resistance index. Stroke volume index significantly increased after hypertonic-hyperoncotic solution infusion (53.9 +/- 3.0 mL/m2 directly after, 48.8 +/- 2.46 mL/m2 15 minutes after, and 41.4 +/- 2.2 mL/m2 60 minutes after) when compared with stroke volume index before administration (32.4 +/- 2.6 mL/m2). In the hypertonic-hyperoncotic solution group, an increase in mean arterial blood pressure remained transiently significant within 60 minutes after administration when compared with the isotonic saline solution group, in which the mean arterial blood pressure remained unchanged. Both central venous pressure and heart rate were unchanged during the whole time of observation in both groups. In the hypertonic-hyperoncotic solution group, extravascular lung water index decreased from 10.6 +/- 1.2 to 5.6 +/- 1.2 mL/kg and remained significantly decreased 15 minutes after (6.5 +/- 1.2 mL/kg) when compared with before volume administration. In the isotonic saline solution group, extravascular lung water index increased from 12.3 +/- 1.1 mL/kg to 18.1 +/- 1.7 mL/kg directly after administration and remained elevated for 60 minutes after volume loading (15.6 +/- 1.5 mL/kg). In all patients, no hypoxia (Pa(O2)<60 mm Hg) or hypercapnia (Pa(CO2) >60 mm Hg) was observed. Arterial blood gas analysis showed pH and base excess within physiologic range, and this did not change throughout the whole period of observation. After infusion of hypertonic-hyperoncotic solution, sodium concentration increased from 139.2 +/- 0.7 to 147.5 +/- 0.7 mmol/L. The maximum sodium concentration was 153 mmol/L, measured immediately after hypertonic-hyperoncotic solution in 1 patient. The total amount of fluid infused was similar in both groups. The postoperative need for infused dobutamine in the patients in the hypertonic-hyperoncotic solution group was decreased compared with the isotonic saline solution group (46.9 +/- 8.8 microg/kg vs 308.2 +/- 46.6 microg/kg). No patient presented with severe bleeding. Short- and long-term cardiac and neurologic outcome was not reduced and all patients left the hospital in a clinically sufficient state.

DISCUSSION

This study demonstrates a profound increase of cardiac index after the administration of hypertonic-hyperoncotic solution in children after uncomplicated open-heart surgery, suggesting a positive inotropic effect. The total amount of catecholamine was lower, assuming that hypertonic-hyperoncotic solution reduces the need for positive inotropic support. The observed positive cardiac effect of hypertonic-hyperoncotic solution may even be intensified by the decreased afterload (decreased systemic vascular resistance index). According to the Frank-Starling relation, an effective tool in the treatment of low cardiac output are an elevated preload while afterload is diminished. Therefore, we postulate that hypertonic-hyperoncotic solution may be helpful in preventing or attenuating low cardiac output failure in childhood. Capillary leakage syndrome also is a frequent problem after cardiopulmonary bypass. For quantification of edema formation, extravascular lung water index measurement is a useful tool. Using this approach, we provided evidence that the infusion of hypertonic-hyperoncotic solution is transiently able to reduce extravascular lung water index. This reduction was transient but might prevent the triggering of a clinically relevant capillary leakage syndrome. This is in line with in vitro studies demonstrating that hypertonic-hyperoncotic solution improves microcirculation by reducing vascular permeability. The single administration of hypertonic-hyperoncotic solution infusion was safe, and no adverse effects, such as hemostatic disturbances, were observed.

CONCLUSIONS

A single infusion of hypertonic-hyperoncotic saline solution after cardiac surgery is safe despite the hypertonicity and the colloid component of the hypertonic-hyperoncotic saline solution. In children after cardiopulmonary bypass surgery, the administration of hypertonic-hyperoncotic saline solution increased cardiac index by elevating stroke volume index in combination with a lowered systemic vascular resistance index. Extravascular lung water index transiently decreased, suggesting that hypertonic-hyperoncotic saline solution effectively counteracts the capillary leakage that often occurs after cardiac surgery in children. Additional investigations might elucidate whether the temporary effects of hypertonic-hyperoncotic saline solution are beneficial in the treatment of severe capillary leakage after complicated cardiac surgery. It has to be shown that hypertonic-hyperoncotic saline solution is a long-lasting, effective treatment strategy for low cardiac output failure in children that is caused by sepsis, multiorgan failure, and endothelial edema. We have provided evidence to pediatric intensive care clinicians that the single administration of hypertonic-hyperoncotic saline solution might be a useful and safe treatment in the amelioration of contractility, inotropy, and the possible treatment of early-onset capillary leakage.

Perioperative serum interleukins in neonates with hypoplastic left-heart syndrome and transposition of the great arteries

OBJECTIVE

The primary study objective was to examine the impact of diagnosis on the inflammatory response in neonates with congenital heart disease undergoing cardiac surgery. The secondary objective was to study the impact of the inflammatory response on postoperative outcome in these neonates.

DESIGN

Observational study.

SETTING

Tertiary care children's hospital heart center.

PATIENTS

Neonates with hypoplastic left-heart syndrome (HLHS) undergoing stage I repair and patients with transposition of the great arteries (TGA) undergoing arterial switch operation.

MEASUREMENTS AND MAIN RESULTS

There were 24 neonates with HLHS and 21 neonates with TGA. Serum samples to measure interleukin (IL)-6 and -10 were obtained before and after CPB at 1, 3, 6, and 24 hours postoperatively. Time to extubation, intensive care unit (ICU) length of stay, and peritoneal fluid drainage were compared between the groups. Serum IL-6 and IL-10 concentrations increased after CPB when compared to the preoperative concentration. Preoperative concentrations of IL-6 were significantly elevated in the HLHS group (HLHS: 32 [21.1, 69.6] pg/mL v TGA: 7.2 [3.6, 22.5] pg/mL [median, 25th, and 75th percentile], p = 0.003) and remained elevated immediately after CPB, and at 3 and 6 hours postoperatively. The IL-10 to IL-6 ratio was lower in the HLHS group preoperatively and immediately after CPB. ICU length of stay was significantly longer in the HLHS group (TGA 4 [3-6] days v HLHS 6 [5-8] days, p = 0.031). Mortality in the HLHS group (4/24) was associated with significantly higher IL-6 postoperatively (IL-6 immediately postoperatively: HLHS survivors 59.9 [34.3, 65.7] pg/mL v nonsurvivors 98.7 [94.4, 104.5] pg/mL, p < 0.011).

CONCLUSIONS

All neonates with TGA or HLHS have a significant inflammatory response after CPB. Neonates with HLHS have evidence of an activated inflammatory response before CPB, which remains significant in the postoperative period. Accelerated interleukin expression and an abnormal cytokine balance correlate with longer time to extubation, longer ICU length of stay, and increased peritoneal fluid volume.

Endotoxin: The uninvited guest

In the laboratory environment where biomaterials are synthesized and their biocompatibility assessed, we find that endotoxin contamination is hard to avoid and must not be ignored. In those relatively few cases where endotoxin was known to be present, it has been clearly shown that endotoxin can significantly affect the biological response observed and hence confound any effect of the material. This short review explains what endotoxin is, how to test for it and remove it and what its effect on the biological response to biomaterials is. We advocate routine testing of endotoxin on biomaterials and of reagents used in experimental evaluation of biomaterials and this should be the responsibility of every scientist to ensure the validity of any biomaterial study.

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.

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.

Surgical trauma affects the proinflammatory status after cardiac surgery to a higher degree than cardiopulmonary bypass

OBJECTIVES

Cytokines contribute to the development of the systemic inflammatory response syndrome or multiple-organ failure frequently observed after cardiopulmonary bypass-supported cardiac surgery. To quantify the contribution of bypass-induced versus trauma-induced inflammatory response after coronary artery bypass grafting, we examined plasma cytokine levels in 120 patients with coronary artery disease who were treated with or without cardiopulmonary bypass-assisted procedures.

METHODS

Patients were treated in accordance with one of the following protocols: (1) elective percutaneous coronary intervention without cardiopulmonary bypass (n = 69), (2) cardiopulmonary bypass-supported percutaneous coronary intervention (cardiopulmonary bypass-percutaneous coronary intervention; n = 10), and (3) cardiopulmonary bypass-supported coronary artery bypass grafting (cardiopulmonary bypass-coronary artery bypass grafting; n = 41). Cytokine levels (picograms/milliliter) were measured by enzyme-linked immunosorbent assay from plasma samples obtained at various time points.

RESULTS

Interleukin-6 was measured in blood samples from all 3 patient populations. The maximum interleukin-6 level was 13.6 +/- 22.3 pg/mL in the percutaneous coronary intervention group, 170.4 +/- 165.4 pg/mL in the cardiopulmonary bypass-percutaneous coronary intervention group, and 640.3 +/- 285.7 pg/mL in the cardiopulmonary bypass-coronary artery bypass grafting group. Interleukin-6 levels were significantly different, and the 95% confidence intervals did not overlap. In the cardiopulmonary bypass-percutaneous coronary intervention group, bypass duration correlated well with interleukin-6 production ( r = 0.915; P < .001), whereas these parameters did not correlate in patients who underwent cardiopulmonary bypass-coronary artery bypass grafting ( r = 0.307; P = .054).

CONCLUSIONS

These findings support the suggestion that surgical trauma and cardiopulmonary bypass contribute to the inflammatory response after cardiac surgery, although trauma may contribute to a higher degree.

Biomaterial-associated thrombosis: roles of coagulation factors, complement, platelets and leukocytes

Our failure to produce truly non-thrombogenic materials may reflect a failure to fully understand the mechanisms of biomaterial-associated thrombosis. The community has focused on minimizing coagulation or minimizing platelet adhesion and activation. We have infrequently considered the interactions between the two although we are generally familiar with these interactions. However, we have rarely considered in the context of biomaterial-associated thrombosis the other major players in blood: complement and leukocytes. Biomaterials are known agonists of complement and leukocyte activation, but this is frequently studied only in the context of inflammation. For us, thrombosis is a special case of inflammation. Here we summarize current perspectives on all four of these components in thrombosis and with biomaterials and cardiovascular devices. We also briefly highlight a few features of biomaterial-associated thrombosis that are not often considered in the biomaterials literature: The importance of tissue factor and the extrinsic coagulation system. Complement activation as a prelude to platelet activation and its role in thrombosis. The role of leukocytes in thrombin formation. The differing time scales of these contributions.

Acute fetal hypoxia: the modulating effect of infection

The fetal brain is protected from the effects of acute hypoxia by a range of haemodynamic and metabolic compensations. Hypoxia alone is therefore an unusual cause of perinatal brain injury in either preterm or term infants. More recently, materno-fetal infection has been implicated as a causative factor in cases of cerebral palsy associated with preterm and term birth. This paper explores the concept that exposure to infection, and in particular pro-inflammatory cytokines, may reduce the threshold at which hypoxia becomes neurotoxic, so making the brain much more vulnerable to even mild hypoxic insults. The hypothesis is supported by an increasing body of evidence from animal studies that also demonstrate the importance of duration between exposure to infection and subsequent hypoxia. There are a number of clinical and research implications that centre around the role of antibiotics, mode and timing of delivery, maternal cooling during labour and the role of immune-modulating drugs.

Plasma levels of interleukin-8 and expression of interleukin-8 receptors on circulating neutrophils and monocytes after cardiopulmonary bypass in children

OBJECTIVE

Cardiopulmonary bypass induces a systemic inflammatory response that causes substantial clinical morbidity. This study sought to determine cellular and humoral variables of inflammation. We hypothesized that chemokines are a major source of stimulation of neutrophils and monocytes in pediatric cardiac surgery.

METHODS

We performed an observational prospective clinical study of 20 pediatric patients before and after cardiopulmonary bypass. Plasma levels of interleukin-6, interleukin-8, myeloperoxidase, and nitric oxide were measured by immunoassays. Expression of interleukin-8 receptors (CXCR1, CXCR2) and CD14 of circulating neutrophils and monocytes was assessed by flow cytometry. Clinical evaluations included length of inotropic support and mechanical ventilation as well as oxygenation.

RESULTS

Two hours after cardiopulmonary bypass, plasma levels of interleukin-6 and interleukin-8 were strongly increased (P =.0001 and P =.0032, respectively). Interleukin-6 and interleukin-8 concentrations correlated with the length of inotropic support, as well as with the length of mechanical ventilation (r >.70, P </=.0006), and were inversely related to the ratio of arterial oxygen tension to fraction of inspired oxygen. There was a strong association between the postoperative levels of interleukin-6 and nitric oxide, as well as between interleukin-6 and CD14 expression on monocytes (r >.62, P </=.0031). The expression of CXCR2 but not CXCR1 on neutrophils and monocytes correlated negatively with the levels of interleukin-8 and myeloperoxidase.

CONCLUSIONS

After cardiopulmonary bypass, impairment of cardiovascular and respiratory function correlated with the levels of interleukin-6 and interleukin-8 as mediators of an inflammatory response. The negative correlation of CXCR2 expression with interleukin-8 and myeloperoxidase indicates that myeloid cells were stimulated by CXC chemokines with Glu-Leu-Arg (ELR) motif and thereby contributed to tissue damage, leading to impairment of cardiovascular and respiratory function.

Association of tumor necrosis factor gene polymorphisms and prolonged mechanical ventilation after coronary artery bypass surgery

OBJECTIVE

Prolonged mechanical ventilation is a common complication after coronary artery bypass graft surgery. Tumor necrosis factor alpha is an important proinflammatory mediator in the post-coronary artery bypass graft inflammatory cascade. We attempted to study the effect of polymorphisms at the -308 site in the promoter region of the tumor necrosis factor gene (TNF-308) and the +250 site within the lymphotoxin-alpha gene (LT alpha+250) on the risk of prolonged mechanical ventilation after coronary artery bypass grafting.

DESIGN

Prospective observational study.

SETTING

Tertiary care center.

PATIENTS

A total of 400 patients undergoing coronary artery bypass grafting were enrolled.

MEASUREMENTS

The primary end point was time to extubate. Secondary end points were the percentages of patients extubated at 8, 24, and 48 hrs; the length of intensive care unit and hospital stay; the need for a rehabilitation facility; and 30-day mortality. Precollected blood was used for gene analysis. Genotyping was performed by polymerase chain reaction and restriction enzyme digestion.

MAIN RESULTS

Patients with an AA genotype at the LT alpha+250 site and those without the LT alpha+250G/-308TNFG haplotype had a shorter duration of mechanical ventilation (11.5 vs. 27.8 hrs and 11.2 vs. 29.4 hrs; =.039 and.01, respectively). The risk of prolonged mechanical ventilation at 8, 24, and 48 hrs was higher for patients with a GA or GG genotype at the LT alpha+250 site and the LT alpha+250G/TNF-308G haplotype. This association between genotype and duration of mechanical ventilation was more dramatic in patients undergoing conventional coronary artery bypass grafting than in those undergoing off-pump coronary artery bypass grafting. With Bayesian analysis, clinical criteria and genotype can be used sequentially to predict the risk of prolonged mechanical ventilation.

CONCLUSIONS

The LT alpha+250 and LT alpha+250G/TNF-308G haplotypes are associated with prolonged mechanical ventilation after coronary artery bypass graft. Preoperative genetic screening may guide intraoperative management to reduce postoperative complications.

Tumor necrosis factor and clinical and metabolic courses after cardiac surgery in children

OBJECTIVE

This study was undertaken to determine the relationship between plasma tumor necrosis factor concentrations and hemodynamic and metabolic parameters during the postoperative clinical course in children undergoing cardiac surgery.

METHODS

Tumor necrosis factor levels of 10 consecutive children undergoing surgery for repair of congenital heart defects were analyzed in blood samples drawn at predetermined time points during surgery and up to 24 hours thereafter. Clinical data were collected at these times for correlation to tumor necrosis factor levels.

RESULTS

All the patients survived. Tumor necrosis factor was detected in all 10 children. Tumor necrosis factor levels declined after induction of general anesthesia (201 +/- 65 pg/mL) steadily decreasing during surgery, reaching 80 +/- 50 pg/mL at 24 hours after the operation. Tumor necrosis factor levels were found to be inversely correlated with mean blood pressure values and indicators of acidosis (bicarbonate levels and base excess, P <.03). They were not correlated with the durations of cardiopulmonary bypass and aortic crossclamping.

CONCLUSIONS

Tumor necrosis factor released into the circulation during and after pediatric cardiac surgery under cardiopulmonary bypass may be related to the hemodynamic and acid-base changes observed after cardiac surgery. Elucidation of the relationship between tumor necrosis factor and patient outcome in high-risk patients awaits further studies.