Effect of perfusion temperature on the inflammatory response during pediatric cardiac surgery

Strategies to attenuate maladaptive inflammatory response associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) initiates an intense inflammatory response due to various factors: conversion from pulsatile to laminar flow, cold cardioplegia, surgical trauma, endotoxemia, ischemia-reperfusion injury, oxidative stress, hypothermia, and contact activation of cells by the extracorporeal circuit. Redundant and overlapping inflammatory cascades amplify the initial response to produce a systemic inflammatory response, heightened by coincident activation of coagulation and fibrinolytic pathways. When unchecked, this inflammatory response can become maladaptive and lead to serious postoperative complications. Concerted research efforts have been made to identify technical refinements and pharmacologic interventions that appropriately attenuate the inflammatory response and ultimately translate to improved clinical outcomes. Surface modification of the extracorporeal circuit to increase biocompatibility, miniaturized circuits with sheer resistance, filtration techniques, and minimally invasive approaches have improved clinical outcomes in specific populations. Pharmacologic adjuncts, including aprotinin, steroids, monoclonal antibodies, and free radical scavengers, show real promise. A multimodal approach incorporating technical, circuit-specific, and pharmacologic strategies will likely yield maximal clinical benefit.

Frozen elephant trunk technique for aortic arch surgery: the Bordeaux University Hospital experience with Thoraflex hybrid prosthesis

BACKGROUND

Aortic arch surgery still represents a challenge, and the frozen elephant trunk (FET) allows a one-step surgery for complex aortic diseases. The aim of the study was to analyze the results of patients undergoing FET procedure for aortic arch surgery at Bordeaux University Hospital.

METHODS

Patients undergoing FET procedure for multisegmented aortic arch pathologies were analyzed in this single-center retrospective study. Further subgroup analyses were performed according to the degree of urgency of the operation (elective versus emergent surgery) and cerebral protection technique: bilateral selective antegrade cerebral perfusion (B-SACP) versus the unilateral one (U-SACP), regardless of the degree of urgency.

RESULTS

From August 2018 to August 2022, 77 consecutive patients (64.1±9.9 years, 54 males) were enrolled: 43 (55.8%) for elective surgery and 34 (44.2%) in emergency. Technical success was 100%. 30-day mortality was 15.6% (N.=12, 7% elective vs. 26.5% emergent, P=0.043). Six (7.8%) non-disabling strokes occurred (1.9% B-SACP vs. 20% U-SACP, P=0.021). Median follow-up was 1.11 years (interquartile range, 0.62-2.07). The 1-year overall survival was 81.6±4.45%. The elective group showed a survival trend when compared to the emergency one (P=0.054). However, further examination at landmark analysis elective surgery showed a better survival trend compared to emergency surgery up to 1.78 years (P=0.034), after which significance was lost (P=0.521).

CONCLUSIONS

Thoraflex hybrid prosthesis for FET technique demonstrated feasibility and satisfactory short-term clinical outcomes, even in emergent settings. In our practice B-SACP seems to offer better protection and less neurological complications compared to U-SACP, nevertheless further analyses are warranted.

Neuroprotective strategies with circulatory arrest in open aortic surgery - A meta-analysis

Objective

Deep hypothermic circulatory arrest (DHCA) in aortic surgery is associated with morbidity and mortality despite evolving strategies. With the advent of antegrade cerebral perfusion (ACP), moderate hypothermic circulatory arrest (MHCA) was reported to have better outcomes than DHCA. There is no standardised guideline or consensus regarding the hypothermic strategies to be employed in open aortic surgery. Meta-analysis was performed comparing DHCA with MHCA + ACP in patients having aortic surgery.

Methods

A systematic review of the literature was undertaken. Any studies with DHCA versus MHCA + ACP in aortic surgeries were selected according to specific inclusion criteria and analysed to generate summative data. Statistical analysis was performed using STATS Direct. The primary outcomes were hospital mortality and post-operative stroke. Secondary outcomes were cardiopulmonary bypass time (CPB), post-operative blood transfusion, length of ICU stay, respiratory complications, renal failure and length of hospital stay. Subgroup analysis of primary outcomes for Arch surgery alone was also performed.

Results

Fifteen studies were included with a total of 5869 patients. There was significantly reduced mortality (Pooled OR = +0.64, 95% CI = +0.49 to +0.83; p = 0.0006) and stroke rate (Pooled OR = +0.62, 95% CI = +0.49 to +0.79; p < 0.001) in the MHCA group. MHCA was associated significantly with shorter CPB times, shorter duration in ICU, less pulmonary complications, and reduced rates of sepsis. There was no statistical difference between the two groups in terms of circulatory arrest times, X-Clamp times, total operation duration, transfusion requirements, renal failure and post-op hospital stay.

Conclusion

MHCA + ACP are associated with significantly better post-operative outcomes compared with DHCA for both mortality and stroke and majority of the secondary outcomes.

Normothermia versus Hypothermia during Cardiopulmonary Bypass in Cases of Repair of Atrioventricular Septal Defect

Background

Cardiopulmonary bypass (CPB) used for cardiac surgery is now uniformly carried out under normothermic conditions in adult patients; however, the temperature applied in pediatric CPB vary significantly, ranging from deep hypothermia to normothermia due to the lack of a consistent approach to CPB temperature in pediatric cardiac surgery, which is related to a lack of supportive evidence. Organs protection aim to decrease metabolic requirement and provide energy and oxygen, hypothermia has reached these goals by arresting and cooling the heart, delivering oxygen, and modifying reperfusion. Recently, a large number of studies investigated effect of hypothermia to decrease the negative impact of hypothermia. It has been suggested that the degree of hypothermia affects the inflammatory responses triggered by CPB. However, the use of normothermia during CPB had been introduced and resulted in acceptable results. We hypothesized that the use of normothermia during corrective surgery of AV septal defects improves the outcome of the CPB.

Objective

The study aimed to compare the outcome of normothermic technique and mild hypothermic technique during (CPB) in pediatric cardiac patients undergoing repair of atrioventricular (AV) septal defect and their effect on tissue perfusion, serum lactate level, duration of patient intubation, and postoperative hospital stay.

Patients and Methods

Forty patients presented for repair of AV defect aged from 1 month to 36 months were divided randomly into two equal groups (20 patients in each): Group I (Normothermic group) of body temperature more than 35°C up to 37°C and Group II (mild Hypothermic group) body temperature between (32°C-35°C). Basal data include complete blood count, electrolytes, arterial blood gases (ABGs), coagulation profile, and liver function tests were collected. Hemodynamic variables, ABG, serum lactate, and activated clotting time (ACT) measured in different time intervals related to CPB. With the termination of CPB, aortic cross-clamping time (minutes), CPB time (minutes), spontaneous regaining of the heart function, need for inotropic administration, and/or vasopressor requirements to wean the heart from CPB were reported in all patients.

Results

This study showed statistically significant lower PH and HCO3 levels and significantly higher serum lactate levels in Group II (hypothermic) than Group I (normothermic) after weaning from CPB. Furthermore, ACT level was statistically significantly higher in Group II than Group I after weaning of CPB. During postoperative period, hypothermic group showed significantly higher liver enzymes than the normothermic group. The duration of inotropes administration and duration of intubation were significantly longer in Group II than Group I.

Conclusion

Normothermia during CPB showed better global tissue perfusion than hypothermia in elective surgeries for repair of AV defects in the form of less degree of lactic acidosis, less effect on coagulation system, shorter duration of inotropic support, shorter intubation period, and shorter stay in the intensive care unit.

Hypothermic effects on gas exchange performance of membrane oxygenator and blood coagulation during cardiopulmonary bypass in pigs

INTRODUCTION

Whether hypothermic cardiopulmonary bypass could attenuate both blood coagulation and platelet activation compared to normothermic cardiopulmonary bypass remains elusive.

METHODS

Biocompatibility of a polymer-coated cardiopulmonary bypass circuit was comparatively assessed by plasma proteomics between juvenile pigs undergoing hypothermic (23°C) cardiopulmonary bypass and those undergoing normothermic (37°C) cardiopulmonary bypass (n = 6, respectively). Plasma samples were taken three times: 5 minutes after initiation of cardiopulmonary bypass (T5, before cooling), just before declamping and rewarming (Tc), and just before termination of cardiopulmonary bypass (Trw, 120 minutes). Proteomic analysis was quantitively performed by isobaric tags for relative and absolute quantification labeling. Thrombin-antithrombin complexes (TAT III) were measured by enzyme immunoassay, and vitamin K-dependent protein C (PROC), β-thromboglobulin (TG), and P-selectin were measured by enzyme-linked immunosorbent assay. Blood gas analyses evaluated oxygenator performance.

RESULTS

Hypothermic cardiopulmonary bypass had a significantly higher PaO₂ at Tc and lower PaCO₂ at Trw than normothermic cardiopulmonary bypass. Two hundred twenty-four proteins were identified with statistical criteria of both protein confidence (>95%) and false discovery rate (<5%). Six of these proteins significantly decreased at Tc than at T5 in hypothermic cardiopulmonary bypass (p = 0.02-0.04), with three related to platelet degranulation. Protein C decreased at Trw compared with T5 in normothermic cardiopulmonary bypass (p = 0.04). Thrombin-antithrombin complex had a slightly larger increase with normothermic cardiopulmonary bypass at Trw than with hypothermic cardiopulmonary bypass. β-thromboglobulin and P-selectin levels were significantly lower at Trw with hypothermic cardiopulmonary bypass than with normothermic cardiopulmonary bypass (p = 0.04).

CONCLUSION

Hypothermic cardiopulmonary bypass attenuated platelet degranulation/blood coagulation and maintained better oxygenator performance compared to normothermic cardiopulmonary bypass in juvenile pigs.

Risk factors and impact of postoperative hyperglycemia in nondiabetic patients after cardiac surgery: A prospective study

Cardiac surgery induces a significant inflammatory hypermetabolic stress response, resulting in postoperative hyperglycemia in both preoperatively diabetic and nondiabetic patients. Such postoperative hyperglycemia has been associated with adverse outcomes in surgery and postsurgical recovery. Yet, while diabetes is a known risk factor for postoperative hyperglycemia, predictors of postoperative hyperglycemia among nondiabetics in the local Southeast Asian population remain unknown.We aim to investigate the predictors and outcomes associated with hyperglycemia after cardiac surgery among nondiabetics in the local Southeast Asian population. We analyzed data from 1602 nondiabetic adult patients undergoing elective cardiac surgery, from 2008 to 2010 at the 2 main heart centers in Singapore.Nondiabetic patients who developed postoperative hyperglycemia tended to be women, older, more obese, and hypertensive. Higher body mass index (BMI), age, aortic cross-clamp time, and blood transfusion were identified as independent risk factors of postoperative hyperglycemia. Postoperative hyperglycemia was also significantly associated with postoperative cardiac arrhythmias (26.9% vs 15.0%, P < .001), acute kidney injury (30.0% vs 20.1%, P < .001), longer intensive care unit (ICU) stay (46.7 ± 104.1 vs 37.2 ± 76.6 hours, P = .044) and longer hospitalization (11.5 ± 12.2 vs 9.6 ± 8.0 days, P < .001).Our study identified aortic cross-clamp time and blood transfusion as independent risk factors of postoperative hyperglycemia after cardiac surgery in nondiabetics. Similar to other studies, higher BMI and age were independent risk factors for postoperative hyperglycemia. Postoperative hyperglycemia was also associated with adverse perioperative outcomes and should thereby be avoided by treating modifiable risk factors identified in this study including reducing blood transfusion and aortic cross-clamp time. Our findings contribute to early risk stratification of nondiabetic patients who are at increased risk of postoperative hyperglycemia.

Direct Splanchnic Perfusion Safely Avoids Deep Hypothermia

Deep hypothermia for the operative correction of congenital cardiac lesions protects hypoperfused organs, mostly because of its effect on lowering metabolic demand and oxygen requirement. Deleterious cerebral and extracranial side effects of deep hypothermia itself calls for a reexamination of the therapeutic value of hypothermia, and has led to the development of alternative perfusion strategies. Here we describe the potential advantages of milder hypothermia over deep hypothermia and our method of a practical and reproducible implementation of multisite perfusion under mild hypothermia (32°C).

Selective visceral perfusion improves renal flow and hepatic function in neonatal aortic arch repair

OBJECTIVES

The aortic arch repair in the neonatal period is a complex procedure with significant morbidity. We define a useful double-perfusion technique and its effect on the function of abdominal organs in the postoperative course.

METHODS

Nine patients with double perfusion (Group 1) were compared with 14 patients with antegrade cerebral perfusion (Group 2). The objective was to discern the incidence of postoperative acute kidney injury and impaired hepatic function, as well as tissue perfusion and myocardial function parameters. Mechanical ventilation time, postoperative length of stay and 30-day mortality were measured. We excluded patients with extracorporeal membrane oxygenation, early mortality (<72 h) and preoperative renal or hepatic insufficiency.

RESULTS

Nine (39%) patients developed postoperative acute kidney injury, with 22% (n = 2) in Group 1 and 50% (n = 7) in Group 2 (P = 0.183). A higher urine output was observed during the first 24 h for Group 1 (P = 0.032). Eleven patients developed impaired hepatic function in the immediate postoperative period: 2 (18.2%) in Group 1 and 9 (81.8%) in Group 2 (P = 0.04). The international normalized ratio (P = 0.006-0.031) and prothrombin time (P = 0.007-P = 0.016) were significantly lower in the double-perfusion group during the first 72 h. Significant difference was observed in lactate levels in the first 72 h (P = 0.001-0.009). There was no postoperative mortality in either group.

CONCLUSIONS

Selective visceral perfusion is a safe procedure that provides a better urine output, hepatic function and tissue perfusion. This technique allows for the repair of complex aortic arch anomalies in neonates without deep hypothermic circulatory arrest.

Recent innovations in perfusion and cardiopulmonary bypass for neonatal and infant cardiac surgery

The development and refinement of cardiopulmonary bypass (CPB) has made the repair of complex congenital heart defects possible in neonates and infants. In the past, the primary goal for these procedures was patient survival. Now that substantial survival rates have been achieved for even the most complex of repairs in these patients, focus has been given to the reduction of morbidity. Although a necessity for these complex neonatal and infant heart defect repairs, CPB can also be an important source of perioperative complications. Recent innovations have been developed to mitigate these risks and is the topic of this review. Specifically, we will discuss improvements in minimizing blood transfusions, CPB circuit design, monitoring, perfusion techniques, temperature management, and myocardial protection, and then conclude with a brief discussion of how further systematic improvements can be made in these areas.

Oxidation Reduction Potential (ORP) is Predictive of Complications Following Pediatric Cardiac Surgery

Oxidation reduction potential (ORP) or Redox is the ratio of activity between oxidizers and reducers. Oxidative stress (OS) can cause cellular injury and death, and is important in the regulation of immune response to injury or disease. In the present study, we investigated changes in the redox system as a function of cardiopulmonary bypass (CPB) in pediatric patients. 664 plasma samples were collected from 162 pediatric patients having cardiac surgery of various CPB times. Lower ORP values at 12 h post-CPB were associated with poor survival rate (mean ± SD 167 ± 20 vs. 138 ± 19, p = 0.005) and higher rate of thrombotic complications (153 ± 21 vs. 168 ± 20, p < 0.008). Similarly, patients who developed infections had lower ORP values at 6 h (149 ± 19 vs. 160 ± 22, p = 0.02) and 12 h (156 ± 17 vs. 168 ± 21, p = 0.004) post-CPB. Patients that developed any post-operative complication also had lower 6 h (149 ± 17 vs. 161 ± 23, p = 0.002) and 12 h (157 ± 18 vs. 170 ± 21, p = 0.0007) post-CPB ORP values. Free hemoglobin and IL-6, IL-10, and CRP were not associated with ORP levels. However, higher haptoglobin levels preoperatively were protective against decreases in ORP. Decreased ORP is a marker for poor outcome and predictive of post-operative thrombosis, infection, and other complications in critically ill pediatric cardiac surgery patients. These results suggest that redox imbalance and OS may contribute to the risk of complications and poor outcome in pediatric CBP patients. Haptoglobin may be a marker for increased resilience to OS in this population.

Neonatal Aortic Arch Reconstruction With Direct Splanchnic Perfusion Avoids Deep Hypothermia

BACKGROUND

Neonatal aortic arch reconstruction, typically performed with deep hypothermia and selective cerebral perfusion, leaves splanchnic organ protection dependent on hypothermia alone. A simplified method of direct in-field descending aortic perfusion during neonatal arch reconstruction permits the avoidance of deep hypothermia. We hypothesize that direct splanchnic perfusion at mild hypothermia provides improved or equivalent safety compared with deep hypothermia and may contribute to postoperative extracardiac organ recovery.

METHODS

Included were 138 biventricular patients aged younger than 90 days undergoing aortic arch reconstruction with cardiopulmonary bypass. Patients were grouped according to perfusion method A (selective cerebral perfusion with deep hyperthermia at 18° to 20°C) or method B (selective cerebral perfusion and splanchnic perfusion at 30° to 32°C). Patient characteristics and perioperative clinical and serologic data were analyzed. Significance was assigned for p of less than 0.05.

RESULTS

Of the 138 survivors, 63 underwent method A and 75 underwent method B. The median age at operation was 8.5 days (range, 6 to 15 days), and median weight was 3.2 kg (range, 2.8 to 3.73 kg), with no significant differences between groups. Cardiopulmonary bypass times were comparable between the two perfusion methods (p = 0.255) as were the ascending aortic cross-clamp times (p = 0.737). The postoperative glomerular filtration rate was significantly different between our groups (p = 0.028 to 0.044), with method B achieving a higher glomerular filtration rate. No significant differences were seen in ventilator time, postoperative length of stay, fractional increase of postoperative serum creatinine over preoperative serum creatinine, and postoperative lactate.

CONCLUSIONS

A simplified method of direct splanchnic perfusion during neonatal aortic arch reconstruction avoids the use of deep hypothermia and provides renal protection at least as effective as deep hypothermia.

Endothelial permeability following coronary artery bypass grafting: an observational study on the possible role of angiopoietin imbalance

BACKGROUND

Unresolved inflammation resulting in capillary leakage with endothelial barrier dysfunction is a major contributor to postoperative morbidity and mortality after coronary artery bypass graft (CABG). Angiopoietins (ANGs) are vascular growth factors, also mediating inflammation and disruption of the endothelium, thus inducing capillary leakage. We hypothesized that changes in the relative serum levels of ANG1 and ANG2 influence endothelial barrier function and perioperative morbidity after CABG.

METHODS

After approval and informed consent, serum samples (n = 28) were collected pre CABG surgery, 1, 6, and 24 h after aortic de-clamping. ANG1, ANG2, soluble ANG receptor TIE2 (sTIE2), and IL-6 serum concentrations were analyzed by ELISA. Human pulmonary microvascular endothelial cells (HPMECs) were incubated with patient serum and FITC-dextran permeability was assessed. Furthermore, ANG2 secretion of HPMECs was analyzed after incubation with IL-6-containing patient serum.

RESULTS

CABG induced an early and sustained increase of ANG2/ANG1 ratio (5-fold after 24 h compared to pre-surgery). These changes correlated with elevated serum lactate levels, fluid balance, as well as the duration of mechanical ventilation. Permeability of HPMECs significantly increased after incubation with post-surgery serum showing a marked shift of ANG2/ANG1 balance (18-fold) compared to serum with a less pronounced increase (6-fold). Furthermore, CABG resulted in increased IL-6 serum content. Pre-incubation with serum containing high levels of IL-6 amplified the ANG2 secretion by HPMECs; however, this was not influenced by blocking IL-6.

CONCLUSIONS

CABG affects the balance between ANG1 and ANG2 towards a dominance of the barrier-disruptive ANG2. Our data suggest that this ANG2/ANG1 imbalance contributes to an increased postoperative endothelial permeability, likewise being reflected by the clinical course. The results strongly suggest a biological effect of altered angiopoietin balance during cardiac surgery on endothelial permeability.

Normothermic versus hypothermic cardiopulmonary bypass in children undergoing open heart surgery (thermic-2): study protocol for a randomized controlled trial

Background

During open heart surgery, patients are connected to a heart-lung bypass machine that pumps blood around the body (“perfusion”) while the heart is stopped. Typically the blood is cooled during this procedure (“hypothermia”) and warmed to normal body temperature once the operation has been completed. The main rationale for “whole body cooling” is to protect organs such as the brain, kidneys, lungs, and heart from injury during bypass by reducing the body’s metabolic rate and decreasing oxygen consumption. However, hypothermic perfusion also has disadvantages that can contribute toward an extended postoperative hospital stay. Research in adults and small randomized controlled trials in children suggest some benefits to keeping the blood at normal body temperature throughout surgery (“normothermia”). However, the two techniques have not been extensively compared in children.

Objective

The Thermic-2 study will test the hypothesis that the whole body inflammatory response to the nonphysiological bypass and its detrimental effects on different organ functions may be attenuated by maintaining the body at 35°C-37°C (normothermic) rather than 28°C (hypothermic) during pediatric complex open heart surgery.

Methods

This is a single-center, randomized controlled trial comparing the effectiveness and acceptability of normothermic versus hypothermic bypass in 141 children with congenital heart disease undergoing open heart surgery. Children having scheduled surgery to repair a heart defect not requiring deep hypothermic circulatory arrest represent the target study population. The co-primary clinical outcomes are duration of inotropic support, intubation time, and postoperative hospital stay. Secondary outcomes are in-hospital mortality and morbidity, blood loss and transfusion requirements, pre- and post-operative echocardiographic findings, routine blood gas and blood test results, renal function, cerebral function, regional oxygen saturation of blood in the cerebral cortex, assessment of genomic expression changes in cardiac tissue biopsies, and neuropsychological development.

Results

A total of 141 patients have been successfully randomized over 2 years and 10 months and are now being followed-up for 1 year. Results will be published in 2015.

Conclusions

We believe this to be the first large pragmatic study comparing clinical outcomes during normothermic versus hypothermic bypass in complex open heart surgery in children. It is expected that this work will provide important information to improve strategies of cardiopulmonary bypass perfusion and therefore decrease the inevitable organ damage that occurs during nonphysiological body perfusion.

Trial Registration

ISRCTN Registry: ISRCTN93129502, http://www.isrctn.com/ISRCTN93129502 (Archived by WebCitation at http://www.webcitation.org/6Yf5VSyyG).

Outcome of inflammatory response after normothermia during cardiopulmonary bypass surgery in infants with isolated ventricular septal defect

Purpose

A recent study analyzing several cytokines reported that long cardiopulmonary bypass (CPB) time and long aortic cross clamp (ACC) time were accompanied by enhanced postoperative inflammation, which contrasted with the modest influence of the degree of hypothermia. In this present study, we aimed to examine the effect of CPB temperature on the clinical outcome in infants undergoing repair of isolated ventricular septal defect (VSD).

Methods

Of the 212 infants with isolated VSD who underwent open heart surgery (OHS) between January 2001 and December 2010, 43 infants were enrolled. They were classified into 2 groups: group 1, infants undergoing hypothermic CPB (26℃-28℃; n=19) and group 2, infants undergoing near-normothermic CPB (34℃-36℃; n=24).

Results

The age at the time of the OHS, and number of infants aged<3 months showed no significant differences between the groups. The CPB time and ACC time in group 1 were longer than those in group 2 (88 minutes vs. 59 minutes, P=0.002, and 54 minutes vs. 37 minutes, P=0.006 respectively). The duration of postoperative mechanical ventilation was 1.6 days in group 1 and 1.8 days in group 2. None of the infants showed postoperative neurological and developmental abnormalities. Moreover, no postoperative differences in the white blood cell count and C-reactive protein levels were noted between two groups.

Conclusion

This study revealed that hypothermic and near-normothermic CPB were associated with similar clinical outcomes and inflammatory reactions in neonates and infants treated for simple congenital heart disease.

The effect of cardiopulmonary bypass and hypothermic circulatory arrest on hepatic histology in newborn animals: an experimental study

Still little is known about the effect of cardiac surgery on neonatal hepatic tissue. We examined the effect of cardiopulmonary bypass (CPB) and the effect of deep hypothermic circulatory arrest (DHCA) on neonatal hepatic tissue. Liver biopsies of neonatal piglets were taken after CPB (n = 4), after DHCA (n = 5), and after surgery without CPB (non-CPB; n = 3). Additionally, findings were compared to those of control piglets (n = 9). The liver specimens were fixed, stained with hematoxylin and eosin, and scored regarding inflammatory reaction, hepatocellular edema, and apoptosis. Inflammation score of treated groups was higher than in control; CPB 2.5 ± 0.5, DHCA 1.6 ± 0.4, non-CPB 1.2 ± 0.6, control 0.4 ± 0.3 (P < 0.001 CPB and DHCA vs. control; P < 0.05 non-CPB vs. control). Hepatic cell edema was more evident after DHCA (score 2.0 ± 0.4 vs. 0.2 ± 0.3 in control and 0.6 ± 0.5 after CPB; P < 0.001 and P < 0.05, respectively). The highest apoptotic cell count was in the non-CPB group (22.3 ± 6.3 vs. 11.4 ± 3.6 in control and 8.9 ± 5.4 after CPB; P < 0.05). The present study showed that (i) surgical trauma induces hepatic cell apoptosis; (ii) CPB increases hepatic inflammatory reaction; and (iii) DHCA amplifies hepatic cell edema.

Establishment of a coculture model for studying inflammation after pediatric cardiopulmonary bypass: from bench to bedside

Cardiopulmonary bypass (CPB) has been known to induce an inflammatory response that is influenced by various factors. Hypothermia is supposed to reduce inflammation after CPB. We developed an in vitro coculture model for CPB and compared the effects of hypothermia on the inflammatory response in the coculture model with results from a clinical prospective randomized trial. The coculture model consisted of endothelial cells and monocytes. Cells were stimulated with tumor necrosis factor (TNF)-α and exposed to deep hypothermia (20°C) or normothermia (37°C). In the clinical trial, 20 patients undergoing CPB for ventricular septum defect receive either normothermic (37°C) or mild hypothermic (32°C) CPB. We observed a significant interleukin (IL)-6 and IL-8 release in the coculture model 2 and 24 h after the experimental start. In the clinical trial, cytokines were significantly increased directly after weaning from CPB and remained elevated until 24 h. IL-8 and IL-6 secretions were similar in the hypothermic and normothermic group of the coculture model and the patients after 24 h. These results demonstrate that the inflammatory reaction observed in our coculture model is comparable with the cytokine increase in the blood of children undergoing CPB. Our coculture model could be useful for studies on the mechanisms of CPB-induced inflammation.

Washing red blood cells and platelets transfused in cardiac surgery reduces postoperative inflammation and number of transfusions: results of a prospective, randomized, controlled clinical trial

OBJECTIVES

Children undergoing cardiac surgery with cardiopulmonary bypass are susceptible to additional inflammatory and immunogenic insults from blood transfusions. We hypothesize that washing red blood cells and platelets transfused to these patients will reduce postoperative transfusion-related immune modulation and inflammation.

DESIGN

Prospective, randomized, controlled clinical trial.

SETTING

University hospital pediatric cardiac intensive care unit.

PATIENTS

Children from birth to 17 yrs undergoing cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

Children were randomized to an unwashed or washed red blood cells and platelet transfusion protocol for their surgery and postoperative care. All blood was leuko-reduced, irradiated, and ABO identical. Plasma was obtained for laboratory analysis preoperatively, immediately, and 6 and 12 hrs after cardiopulmonary bypass. Primary outcome was the 12-hr postcardiopulmonary bypass interleukin-6-to-interleukin-10 ratio. Secondary measures were interleukin levels, C-reactive protein, and clinical outcomes.

MEASUREMENTS AND MAIN RESULTS

One hundred sixty-two subjects were studied, 81 per group. Thirty-four subjects (17 per group) did not receive any blood transfusions. Storage duration of blood products was similar between groups. Among transfused subjects, the 12-hr interleukin ratio was significantly lower in the washed group (3.8 vs. 4.8; p = .04) secondary to lower interleukin-6 levels (after cardiopulmonary bypass: 65 vs.100 pg/mL, p = .06; 6 hrs: 89 vs.152 pg/mL, p = .02; 12 hrs: 84 vs.122 pg/mL, p = .09). Postoperative C-reactive protein was lower in subjects receiving washed blood (38 vs. 43 mg/L; p = .03). There was a numerical, but not statistically significant, decrease in total blood product transfusions (203 vs. 260) and mortality (2 vs. 6 deaths) in the washed group compared to the unwashed group.

CONCLUSIONS

Washed blood transfusions in cardiac surgery reduced inflammatory biomarkers, number of transfusions, donor exposures, and were associated with a nonsignificant trend toward reduced mortality. A larger study powered to test for clinical outcomes is needed to determine whether these laboratory findings are clinically significant.

Bedside prediction rule for infections after pediatric cardiac surgery

Purpose

Infections after pediatric cardiac surgery are a common complication, occurring in up to 30% of cases. The purpose of this study was to develop a bedside prediction rule to estimate the risk of a postoperative infection.

Methods

All consecutive pediatric cardiac surgery procedures between April 2006 and May 2009 were retrospectively analyzed. The primary outcome variable was any postoperative infection, as defined by the Center of Disease Control (2008). All variables known to the clinician at the bedside at 48 h post cardiac surgery were included in the primary analysis, and multivariable logistic regression was used to construct a prediction rule.

Results

A total of 412 procedures were included, of which 102 (25%) were followed by an infection. Most infections were surgical site infections (26% of all infections) and bloodstream infections (25%). Three variables proved to be most predictive of an infection: age less than 6 months, postoperative pediatric intensive care unit (PICU) stay longer than 48 h, and open sternum for longer than 48 h. Translation into prediction rule points yielded 1, 4, and 1 point for each variable, respectively. Patients with a score of 0 had 6.6% risk of an infection, whereas those with a maximal score of 6 had a risk of 57%. The area under the receiver operating characteristic curve was 0.78 (95% confidence interval 0.72–0.83).

Conclusions

A simple bedside prediction rule designed for use at 48 h post cardiac surgery can discriminate between children at high and low risk for a subsequent infection.

Pediatric warm open heart surgery and prolonged cross-clamp time

BACKGROUND

The safety of normothermic pediatric cardiac surgery remains controversial. This study evaluated the performance of normothermic cardiopulmonary bypass (CPB) associated with intermittent warm blood cardioplegia during prolonged aortic cross-clamp time (CCT).

METHODS

This retrospective study included 234 consecutive patients weighing less than 10 kg operated under CPB from August 2006 to November 2007. Patients were divided into two groups: group 1 contained 38 patients with CCT exceeding 90 minutes, and group 2 had 196 patients with shorter CCT. Classic factors were used to analyze outcomes, and outcomes were compared with those from the Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery database.

RESULTS

Results, expressed as values for group 1 vs those for group 2, were mortality rate, 5.3% vs 2%; length of hospital stay exceeding 21 days, 5% vs 0.5%; delayed chest closure, 21% vs 2.6%; epinephrine infusion, 45% vs 11%; organ failure, 13% vs 2%; reoperation due to bleeding, 3% vs 0.5%; heart block, 3% vs 1%; time to extubation, in hours, 64 +/- 94 vs 19 +/- 48; plasma lactate concentrations after bypass, 2.6 vs 1.9 mmol/L; length of stay in intensive care, in hours, 100 +/- 105 vs 52 +/- 48.

CONCLUSIONS

Despite expected differences between the two groups, our results were within the range of values described in the literature. This led us to conclude that warm pediatric cardiac surgery with a long CCT is safe. A large, multicenter, randomized prospective study comparing normothermic and hypothermic pediatric cardiac surgery is underway.