Does pharmacotherapy influence the inflammatory responses during cardiopulmonary bypass in children?

High-sensitive troponinT, interleukin-8, and interleukin-6 link with post-surgery risk in infant heart surgery

BACKGROUND

This study focuses on biomarkers in infants after open heart surgery, and examines the association of high-sensitive troponin T (hs-cTnT), interleukin-6 (IL-6), and interleukin-8 (IL-8) with postoperative acute kidney injury (AKI), ventilatory support time and need of vasoactive drugs.

METHODS

Secondary exploratory study from a double-blinded clinical randomized trial (Mile-1) on 70 infants undergoing open heart surgery with cardiopulmonary bypass (CPB). In this sub-study, the entire study population was examined without considering the study drugs. The biomarkers' peak concentration (highest concentration at 2 or 6 h post-CPB) were used for statistical analyses.

RESULTS

Peak IL-8, hs-cTnT, and IL-6 occurred at 2 h post-CPB for 96%, 79%, and 63% of the patients, respectively. The odds ratio of developing AKI2-3 for IL-6 > 293 pg/mL was 23.4 (95% CI 5.3;104.0), for IL-8 > 100 pg/mL it was 11.5 (3.0;44.2), and for hs-cTnT >5597 pg/mL it was 6.1 (1.5; 24.5). In more than two third of the patients with the highest peak concentrations of IL-8, IL-6, and hs-cTnT, there was a need for ventilatory support for >24 h and use of vasoactive drugs at 24 h post-CPB, while in less than one third of the patients with the lowest peak concentrations of IL-8 and hs-cTnT such requirements were observed.

CONCLUSIONS

The peak biomarker concentrations and CPB-time strongly predicted AKI2-3, with IL-6 and IL-8 emerging as strongest predictors. Furthermore, our findings suggest that measuring hs-cTnT and IL-8 just 2 h post-CPB-weaning may assist in identifying infants suitable for early extubation and highlight those at risk of prolonged ventilation.

The influence of cardiopulmonary bypass on pediatric pharmacokinetics

INTRODUCTION

Every year thousands of children undergo surgery for congenital heart disease. Cardiac surgery requires the use of cardiopulmonary bypass, which can have unexpected consequences for pharmacokinetic parameters.

AREAS COVERED

We describe the pathophysiological properties of cardiopulmonary bypass that may influence pharmacokinetic parameters, with a focus on literature published in the last 10 years. We performed a PubMed database search with the keywords 'Cardiopulmonary bypass' AND 'Pediatric' AND 'Pharmacokinetics'. We searched related articles on PubMed and checked the references of articles for relevant studies.

EXPERT OPINION

Interest in the influence of cardiopulmonary bypass on pharmacokinetics has increased over the last 10 years, especially due to the use of population pharmacokinetic modeling. Unfortunately, study design usually limits the amount of information that can be obtained with sufficient power and the best way to model cardiopulmonary bypass is yet unknown. More information is needed on the pathophysiology of pediatric heart disease and cardiopulmonary bypass. Once adequately validated, PK models should be integrated in the patient electronic database integrating covariates and biomarkers influencing PK, making it possible to predict real-time drug concentrations and guide further clinical management for the individual patient at the bedside.

Methylprednisolone in Pediatric Cardiac Surgery: Is There Enough Evidence?

Corticosteroids have been used to decrease the inflammatory response to cardiac surgery and cardiopulmonary bypass in children for decades. Sparse information is present concerning the pharmacokinetics and pharmacodynamics of corticosteroids in the context of pediatric cardiac surgery. There is large interindividual variability in plasma concentrations, with indications for a larger volume of distribution in neonates compared to other age groups. There is ample evidence that perioperative use of MP leads to a decrease in pro-inflammatory mediators and an increase in anti-inflammatory mediators, with no difference in effect between doses of 2 and 30 mg/kg. No differences in inflammatory mediators have been shown between different times of administration relative to the start of surgery in various studies. MP has been shown to have a beneficial effect in certain subgroups of patients but is also associated with side effects. In lower risk categories, the balance between risk and benefit may be shifted toward risk. There is limited information on short- to medium-term outcome (mortality, low cardiac output syndrome, duration of mechanical ventilation, length of stay in the intensive care unit or the hospital), mostly from underpowered studies. No information on long-term outcome, such as neurodevelopmental outcome, is available. MP may provide a small benefit that is easily abolished by patient characteristics, surgical techniques, and perfusion management. The lack of evidence leads to large differences in practice between and within countries, and even within hospitals, so there is a need for adequately powered randomized studies.

Methylprednisolone Plasma Concentrations During Cardiac Surgery With Cardiopulmonary Bypass in Pediatric Patients

Introduction: To our knowledge, methylprednisolone pharmacokinetics and plasma concentrations have not been comprehensively investigated in children with congenital heart disease undergoing cardiac surgery with cardiopulmonary bypass. It is unknown whether there is a significant influence of cardiopulmonary bypass on the plasma concentrations of methylprednisolone and whether this may be an explanation for the limited reported efficacy of steroid administration in cardiac surgery with cardiopulmonary bypass.

Methods: The study was registered in the Dutch Trial Register (NTR3579; https://www.trialregister.nl/trial/3428). Methylprednisolone 30 mg/kg was administered as an intravenous bolus after induction of anesthesia. Methylprednisolone concentration was measured with liquid chromatography tandem mass spectrometry and analyzed using linear mixed-effects modeling.

Results: Thirty-nine patients were included in the study, of which three were excluded. There was an acute decrease in observed methylprednisolone plasma concentration on initiation of cardiopulmonary bypass (median = 26.8%, range = 13.9–48.14%, p < 0.001). We found a lower intercept (p = 0.02), as well as a less steep slope of the model predicted methylprednisolone concentration vs. time curve for neonates (p = 0.048). A lower intercept (p = 0.01) and a less steep slope (p = 0.0024) if the volume of cell saver blood processed was larger than 91 ml/kg were also found.

Discussion: We report similar methylprednisolone plasma concentrations as earlier studies performed in children undergoing cardiopulmonary bypass, and we confirmed the large interindividual variability in achieved methylprednisolone plasma concentrations with weight-based methylprednisolone administration. A larger volume of distribution and a lower clearance of methylprednisolone for neonates were suggested. The half-life of methylprednisolone in our study was calculated to be longer than 6 h for neonates, 4.7 h for infants, 3.6 h for preschool children and 4.7 h for school children. The possible influence of treatment of pulmonary hypertension with sildenafil and temperature needs to be investigated further.

Variation of perioperative plasma mitochondrial DNA correlate with peak inflammatory cytokines caused by cardiac surgery with cardiopulmonary bypass

Backgroud

Cardiac surgery with cardiopulmonary bypass (CPB) may cause inflammatory responses, which can deteriorate the outcomes. Inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-6,–8 and -10, can act as both the effector and the predictor for post-operative inflammatory responses. Plasma mitochondrial DNA (mtDNA) was found as a pro-inflammatory agent recently, which was released when cells were insulted.

Methods

In the present study, we included 38 patients undergoing coronary artery bypass graft (CABG) to analyze their perioperative plasma mtDNA and levels of inflammatory cytokines. Blood samples were collected before aortic cross-clamping (T1), at the end of CPB (T2), 6 h post-CPB (T3), 12 h post-CPB (T4), and 24 h post-CPB (T5). Rt-PCR and specific ELISA kits were used to quantify the plasma mtDNA and inflammatory cytokines, respectively. Bivariate correlations analysis was used to check the correlations between plasma mtDNA and inflammatory cytokines respectively.

Results

Results shown that plasma mtDNA elevated significantly at T2 and peaked at T4. Furthermore, plasma TNF-α, IL-6 and IL-8 levels significantly increased at T2 and peaked at T3 while IL-10 elevated and peaked at T2. Bivariate correlations analysis showed that the peak plasma mtDNA were positively correlated with the peak TNF-α (r = 0.677, P < 0.001), the peak IL-6 (r = 0.706, P < 0.001), the peak IL-8 (r = 0.584, P < 0.001) and the peak IL-10 (r = 0.565, P < 0.001).

Conclusion

We found that plasma mtDNA might play a key role in CPB-induced post-operative inflammatory responses.