The cytokine balance during CABG surgery with and without cardiopulmonary bypass

Postoperative 20% albumin vs standard care and acute kidney injury after high-risk cardiac surgery (ALBICS): study protocol for a randomised trial

Background

Acute kidney injury (AKI) is a common complication of cardiac surgery. Factors such as cardiopulmonary bypass, aortic cross-clamping and surgical stress may precipitate renal hypoperfusion and ischaemia, inflammation and oxidative stress are associated with development of AKI. Albumin’s pharmacological properties and widespread availability have the potential to mitigate these factors. However, the effect of albumin on cardiac surgery-associated AKI is unknown.

Objective

To evaluate the impact of postoperative 20% albumin infusion on kidney function after high-risk cardiac surgery.

Methods

We designed an open-label, multicentre, randomised controlled trial—the ALBICS study (ALBumin Infusion and acute kidney injury following Cardiac Surgery). A total of 590 patients undergoing high-risk cardiac surgery (combined procedure or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m²) will be enrolled into the study and randomly allocated to receive a postoperative 20% albumin infusion or standard care in a 1:1 ratio, stratified by centre and baseline renal function. The study fluid will be administered upon arrival in intensive care for 15 h. Patients will be followed up until 28 days after surgery or until discharge from the hospital. The primary outcome is the proportion of patients who develop AKI in both groups. Secondary outcomes to be measured are proportions of AKI stage II and III, 28-day mortality, mechanical ventilation time and length of stay in intensive care and hospital.

Conclusion

This trial aims to determine if a postoperative infusion of concentrated albumin reduces the risk of AKI following high-risk cardiac surgery.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12619001355167. Registered on 03 October 2019—retrospectively registered. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378383.

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.

Interleukin-6 and interleukin-10 as acute kidney injury biomarkers in pediatric cardiac surgery

BACKGROUND

Children undergoing cardiac surgery may exhibit a pronounced inflammatory response to cardiopulmonary bypass (CPB). Inflammation is recognized as an important pathophysiologic process leading to acute kidney injury (AKI). The aim of this study was to evaluate the association of the inflammatory cytokines interleukin (IL)-6 and IL-10 with AKI and other adverse outcomes in children after CPB surgery.

METHODS

This is a sub-study of the Translational Research Investigating Biomarker Endpoints in AKI (TRIBE-AKI) cohort, including 106 children ranging in age from 1 month to 18 years undergoing CPB. Plasma IL-6 and IL-10 concentrations were measured preoperatively and postoperatively [day 1 (within 6 h after surgery) and day 3].

RESULTS

Stage 2/3 AKI, defined by at least a doubling of the baseline serum creatinine concentration or dialysis, was diagnosed in 24 (23%) patients. The preoperative IL-6 concentration was significantly higher in patients with stage 2/3 AKI [median 2.6 pg/mL, interquartile range (IQR) 2.6 0.6-4.9 pg/mL] than in those without stage 2/3 AKI (median 0.6 pg/mL, IQR 0.6-2.2 pg/mL) (p = 0.03). After adjustment for clinical and demographic variables, the highest preoperative IL-6 tertile was associated with a sixfold increased risk for stage 2/3 AKI compared with the lowest tertile (adjusted odds ratio 6.41, 95 % confidence interval 1.16-35.35). IL-6 and IL-10 levels increased significantly after surgery, peaking postoperatively on day 1. First postoperative IL-6 and IL-10 measurements did not significantly differ between patients with stage 2/3 AKI and those without stage 2/3 AKI. The elevated IL-6 level on day 3 was associated with longer hospital stay (p = 0.0001).

CONCLUSIONS

Preoperative plasma IL-6 concentration is associated with the development of stage 2/3 AKI and may be prognostic of resource utilization.