Bradykinin and histamine generation with generalized enhancement of microvascular permeability in neonates, infants, and children undergoing cardiopulmonary bypass surgery

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Elevated nuclear and mitochondrial cell-free deoxyribonucleic acid measurements are associated with death after infant cardiac surgery

OBJECTIVES

Mortality rates following pediatric cardiac surgery with cardiopulmonary bypass have declined over decades, but have plateaued in recent years. This is in part attributable to persistent issues with postoperative global inflammation and myocardial dysfunction, commonly manifested by systemic inflammatory response syndrome and low cardiac output syndrome, respectively. Quantified cell-free DNA (cfDNA), of nuclear or mitochondrial origin, has emerged as a biomarker for both inflammation and myocardial injury. Recent data suggest that nuclear cfDNA (ncfDNA) may quantify inflammation, whereas mitochondrial cfDNA (mcfDNA) may correlate with the degree of myocardial injury. We hypothesize that threshold levels of ncfDNA and mcfDNA can be established that are sensitive and specific for postoperative mortality mediated through independent pathways, and that association will be enhanced with combined analysis.

METHODS

Prospective observational study of infants younger than age 1 year undergoing planned surgery with cardiopulmonary bypass. The study received institutional review board approval. Samples were drawn before skin incision, immediately after completion of cardiopulmonary bypass, and subsequently at predetermined intervals postoperatively. Association of early postoperative ncfDNA and mcfDNA levels with mortality were assessed by logistic regression with cut-points chosen by receiving operating characteristic curve exploration.

RESULTS

Data were available in 59 patients. Median age and weight were 122 days (interquartile range, 63-154 days) and 4.9 kg (interquartile range, 3.9-6.2 kg). Median STAT category was 3 (interquartile range, 1-4). The primary outcome of death was met in 3 out of 59 (5%). Combined analysis of ncfDNA and mcfDNA levels at 12 hours after the initiation of cardiopulmonary bypass with death at a threshold of 50 ng/mL ncfDNA and 17 copies/μL mcfDNA yielded 100% sensitivity and negative predictive value. The specificity (91%) and positive predictive value (38%) increased through combined analysis compared with univariate analysis. Combined analysis exhibited high specificity (93%) and negative predictive value (78%) for prolonged (>30 postoperative days) hospitalization.

CONCLUSIONS

Combined analysis of early postoperative ncfDNA and mcfDNA can stratify risk of mortality and prolonged hospitalization following infant cardiac surgery. Evaluation of both ncfDNA and mcfDNA to identify states of generalized inflammation and myocardial injury may allow for targeted interventions and improved outcomes.

Effect of Intraoperative Dexamethasone on Major Complications and Mortality Among Infants Undergoing Cardiac Surgery: The DECISION Randomized Clinical Trial

IMPORTANCE

Corticosteroids are widely used in pediatric cardiac surgery to blunt systemic inflammatory response and to reduce complications; nevertheless, their clinical efficacy is uncertain.

OBJECTIVE

To determine whether intraoperative administration of dexamethasone is more effective than placebo for reducing major complications and mortality during pediatric cardiac surgery.

DESIGN, SETTING, AND PARTICIPANTS

The Intraoperative Dexamethasone in Pediatric Cardiac Surgery was an investigator-initiated, double-blind, multicenter randomized trial that involved 4 centers in China, Brazil, and Russia. A total of 394 infants younger than 12 months, undergoing cardiac surgery with cardiopulmonary bypass were enrolled from December 2015 to October 2018, with follow-up completed in November 2018.

INTERVENTIONS

The dexamethasone group (n = 194) received 1 mg/kg of dexamethasone; the control group (n = 200) received an equivolume of 0.9% sodium chloride intravenously after anesthesia induction.

MAIN OUTCOMES AND MEASURES

The primary end point was a composite of death, nonfatal myocardial infarction, need for extracorporeal membrane oxygenation, need for cardiopulmonary resuscitation, acute kidney injury, prolonged mechanical ventilation, or neurological complications within 30 days after surgery. There were 17 secondary end points, including the individual components of the primary end point, and duration of mechanical ventilation, inotropic index, intensive care unit stay, readmission to intensive care unit, and length of hospitalization.

RESULTS

All of the 394 patients randomized (median age, 6 months; 47.2% boys) completed the trial. The primary end point occurred in 74 patients (38.1%) in the dexamethasone group vs 91 patients (45.5%) in the control group (absolute risk reduction, 7.4%; 95% CI, -0.8% to 15.3%; hazard ratio, 0.82; 95% CI, 0.60 to 1.10; P = .20). Of the 17 prespecified secondary end points, none showed a statistically significant difference between groups. Infections occurred in 4 patients (2.0%) in the dexamethasone group vs 3 patients (1.5%) in the control group.

CONCLUSIONS AND RELEVANCE

Among infants younger than 12 months undergoing cardiac surgery with cardiopulmonary bypass, intraoperative administration of dexamethasone, compared with placebo, did not significantly reduce major complications and mortality at 30 days. However, the study may have been underpowered to detect a clinically important difference.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02615262.

Lower-Dose, Intravenous Chlorothiazide Is an Effective Adjunct Diuretic to Furosemide Following Pediatric Cardiac Surgery

OBJECTIVES

Postoperative fluid overload is ubiquitous in neonates and infants following operative intervention for congenital heart defects; ineffective diuresis is associated with poor outcomes. Diuresis with furosemide is widely used, yet there is often resistance at higher doses. In theory, furosemide resistance may be overcome with chlorothiazide; however, its efficacy is unclear, especially in lower doses and in this population. We hypothesized the addition of lower-dose, intravenous chlorothiazide following surgery in patients on high-dose furosemide would induce meaningful diuresis with minimal side effects.

METHODS

This was a retrospective, cohort study. Postoperative infants younger than 6 months, receiving high-dose furosemide, and given lower-dose chlorothiazide (1-2 mg/kg every 6-12 hours) were identified. Diuretic doses, urine output, fluid balance, vasoactive-inotropic scores, total fluid intake, and electrolyte levels were recorded.

RESULTS

There were 73 patients included. The addition of lower-dose chlorothiazide was associated with a significant increase in urine output (3.8 ± 0.18 vs 5.6 ± 0.27 mL/kg/hr, p < 0.001), more negative fluid balance (16.1 ± 4.2 vs -25.0 ± 6.3 mL/kg/day, p < 0.001), and marginal changes in electrolytes. Multivariate analysis was performed, demonstrating that increased urine output and more negative fluid balance were independently associated with addition of chlorothiazide. Subgroup analysis of 21 patients without a change in furosemide dose demonstrated the addition of chlorothiazide significantly increased urine output (p = 0.03) and reduced fluid balance (p < 0.01), further validating the adjunct effects of chlorothiazide.

CONCLUSION

Lower-dose, intravenous chlorothiazide is an effective adjunct treatment in postoperative neonates and infants younger than 6 months following cardiothoracic surgery.

Sevoflurane Relieves Lung Function Deterioration After Cardiopulmonary Bypass

OBJECTIVE

To investigate sevoflurane's potential to alleviate the detrimental pulmonary changes after cardiopulmonary bypass (CPB).

DESIGN

Prospective, randomized clinical investigation.

SETTING

University hospital.

PARTICIPANTS

One hundred ninety patients undergoing elective cardiac surgery.

INTERVENTIONS

Ninety-nine patients under intravenous anesthesia were administered 1 minimal alveolar concentration of sevoflurane for 5 minutes after being weaned from CPB (group SEV); intravenous anesthesia was maintained in the other 91 patients (group CTRL).

MEASUREMENTS AND MAIN RESULTS

Measurements were performed with open chest: before CPB, after CPB, and after intervention. The lungs' mechanical impedance and capnogram traces were recorded, arterial and central venous blood samples were analyzed, and lung compliance was documented. Airway resistance, tissue damping, and elastance were obtained from the impedance spectra. The capnogram phase III slope was determined using linear regression. The partial pressure of oxygen in the arterial blood/fraction of inspired oxygen ratio and shunt fraction were calculated from blood gas parameters. After CPB, sevoflurane induced bronchodilation, reflected in marked drops in airway resistance and smaller improvements in lung tissue viscoelasticity indicated by decreases in tissue damping and elastance. These changes were reflected in a decreased capnogram phase III slope and shunt fraction and increased partial pressure of oxygen in the arterial blood/fraction of inspired oxygen ratio and lung compliance. The more severe deteriorations that occurred after CPB, the greater improvements by sevoflurane were observed.

CONCLUSIONS

Sevoflurane can alleviate CPB-induced bronchoconstriction, compromised lung tissue mechanics, and enhanced intrapulmonary shunt. This benefit has particular importance in patients with severe CPB-induced lung function deterioration.

Cardiopulmonary bypass and edema: physiology and pathophysiology

Edema is a common morbidity following cardiopulmonary bypass (CPB) and can result in injury to many organs, including the heart, lungs, and brain. Generalized edema is also common and can lead to increased post-operative hospital stay and other morbidities. Pediatric patients are more susceptible to post-CPB edema and the consequences are more severe for this population. Hemodilution and systemic inflammatory responses are two suspected causes of CPB-related edema; however, the mechanisms involved are far from understood. Also, the common strategies to improve edema have not been completely successful and there is a need for new strategies at maintaining a fluid balance of patients as close to physiological as possible, especially for pediatric patients. An integrative approach to understanding edema is necessary as the forces involved in fluid homeostasis are dynamic and interdependent. Therefore, this review will focus on the physiology of fluid homeostasis and the pathologies of fluid shifts during CPB which lead to general edema as well as tissue-specific edema.

Extravascular lung water measurement using transpulmonary thermodilution in children

OBJECTIVE

Measurement of extravascular lung water (EVLW) may be useful in the treatment of critically ill children and can be performed at the bedside using the transpulmonary thermodilution technique (TPTD). There are currently no data to verify the accuracy of these measurements in (small) children. We compared the results of TPTD measurement with the clinical gold standard transpulmonary double indicator dilution (TPDD) measurement in young children.

DESIGN

Prospective clinical study in children.

SETTING

Catheterization laboratory of a university hospital.

PATIENTS AND METHODS

Twelve children (<2 yrs or <12 kg) under general anesthesia.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Measurements were performed using injections of ice-cold indicator (saline or dye) through a central venous catheter. Mean cardiac index was 3.91 L/min/m, mean intrathoracic blood volume index (ITBVITPDD) was 614.9 mL/m, and mean extravascular lung water index (EVLWITPDD) was 11.7 mL/kg. The correlation coefficient between EVLWITPDD and EVLWITPTD is 0.96 (95% confidence interval: 0.87-0.99; p < 0.0001). Bland-Altman analysis for EVLW measurements showed a mean bias of 2.34 mL/kg (18.13%) and limits of agreement +/-2.97 mL/kg (19.78%). The difference between measurements via the right atrium compared with the femoral vein was 2.8% for cardiac output, 8.2% for global end-diastolic volume, and 0.1% for EVLW.

CONCLUSION

Clinical measurement of EVLW in young children can be performed using the TPTD with the injection catheter inserted in the femoral vein. Further studies are needed to clarify the clinical value of these measurements.

Reducing risk in infant cardiopulmonary bypass: the use of a miniaturized circuit and a crystalloid prime improves cardiopulmonary function and increases cerebral blood flow

Advances in perfusion strategies have played an important role in improving outcomes following repair of complex congenital heart defects. The influence of cooling strategy, temperature, duration of circulatory arrest, and specific method of cerebral perfusion on neurologic morbidity have been extensively characterized. Similarly, the ability of pharmacologic agents to modulate the post-cardiopulmonary bypass (CPB) inflammatory response has been previously elucidated in both the laboratory and clinical arena. However, modification of the circuit and priming components have received comparably less attention. We recently showed that employment of a miniaturized circuit and a bloodless prime reduce inflammation and have salutary effects on cardiopulmonary function following hypothermic low-flow perfusion (HLF), and that this circuit may also improve cerebral protection following both deep hypothermic circulatory arrest and HLF. The current report, therefore, reviews current strategies utilized to minimize post-CPB inflammation and highlights the empirical evidence from our laboratory demonstrating the beneficial role of a miniaturized extracorporeal circuit in this context.

Visualisation of tissue kallikrein, kininogen and kinin receptors in human skin following trauma and in dermal diseases

During dermal injury and inflammation the serine proteases kallikreins cleave endogenous, multifunctional substrates (kininogens) to form bradykinin and kallidin. The actions of kinins are mediated by preferential binding to constitutively expressed kinin-B2 receptors or inducible kinin-B1 receptors. A feature of the kinin-B1 receptors is that they show low levels of expression, but are distinctly upregulated following tissue injury and inflammation. Because recent evidence suggested that kinin-B1 receptors may perform a protective role during inflammation, we investigated the specific occurrence of the kallikrein-kinin components in skin biopsies obtained from normal skin, patients undergoing surgery, basalioma, lichenificated atopic eczema, and psoriasis. The tissue was immunolabeled in order to determine the localisation of tissue pro-kallikrein, kallikrein, kininogen and kinin receptors. The kinin components were visualised in normal, diseased and traumatised skin, except that no labelling was observed for kininogen in normal skin. Of the five types of tissue examined, upregulation of kinin-B1 receptors was observed only in skin biopsies obtained following surgery. In essence, the expression of kinin-B1 receptors did not appear to be enhanced in the other biopsies. Within the multiple steps of the inflammatory cascade in wound healing, our results suggest an important regulatory role for kinin-B1 receptors during the first phase of inflammation following injury.