Prevention of Acute Kidney Injury in Children Undergoing Cardiac Surgery: A Narrative Review

Selected 2022 Highlights in Congenital Cardiac Anesthesia

This article is a review of the highlights of pertinent literature of interest to the congenital cardiac anesthesiologist, and was published in 2022. After a search of the United States National Library of Medicine PubMed database, several topics emerged in which significant contributions were made in 2022. The authors of this manuscript considered the following topics noteworthy to be included in this review-intensive care unit admission after congenital cardiac catheterization interventions, antifibrinolytics in pediatric cardiac surgery, the current status of the pediatric cardiac anesthesia workforce in the United States, and kidney injury and renal protection during congenital heart surgery.

Dexmedetomidine and acute kidney injury following cardiac surgery in pediatric patients—An updated systematic review and meta-analysis

Background

Acute kidney injury (AKI) is a common postoperative complication in pediatric patients undergoing cardiac surgery and associated with poor outcomes. Dexmedetomidine has the pharmacological features of organ protection in cardiac surgery patients. The aim of this meta-analysis is to investigate the effect of dexmedetomidine infusion on the incidence of AKI after cardiac surgery in pediatric patients.

Methods

The databases of Pubmed, Embase, and Cochrane Library were searched until April 24, 2022 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RevMan 5.3 was used to perform statistical analyses.

Results

Five relevant trials with a total of 630 patients were included. The pooled result using fixed-effects model with OR demonstrated significant difference in the incidence of AKI between patients with dexmedetomidine and placebo (OR = 0.49, 95% CI: [0.33, 0.73], I² = 0%, p for effect = 0.0004). Subgroup analyses were performed based on congenital heart disease (CHD) types and dexmedetomidine intervention time. Pooled results did not demonstrate considerable difference in the incidence of AKI in pediatric patients receiving intraoperative (OR = 0.53, 95% CI: [0.29, 0.99], I² = 0%, p for effect = 0.05) or postoperative dexmedetomidine infusion (OR = 0.56, 95% CI: [0.31, 1.04], p for effect = 0.07), but a significant difference in patients receiving combination of intra- and postoperative dexmedetomidine infusion (OR = 0.27, 95% CI: [0.09, 0.77], p for effect = 0.01). Besides, there was no significant difference in duration of mechanical ventilation (SMD: –0.19, 95% CI: –0.46 to 0.08, p for effect = 0.16; SMD: –0.16, 95% CI: –0.37 to 0.06, p for effect = 0.15), length of ICU (SMD: 0.02, 95% CI: –0.41 to 0.44, p for effect = 0.93) and hospital stay (SMD: 0.2, 95% CI: –0.13 to 0.54, p for effect = 0.23), and in-hospital mortality (OR = 1.26, 95% CI: 0.33–4.84, p for effect = 0.73) after surgery according to the pooled results of the secondary outcomes.

Conclusion

Compared to placebo, dexmedetomidine could significantly reduce the postoperative incidence of AKI in pediatric patients undergoing cardiac surgery with cardiopulmonary bypass (CPB), but the considerable difference was reflected in the pediatric patients receiving combination of intra- and postoperative dexmedetomidine infusion. Besides, there was no significant difference in duration of mechanical ventilation, length of ICU and hospital stay, or in-hospital mortality after surgery.

Metabolomic profiling demonstrates evidence for kidney and urine metabolic dysregulation in a piglet model of cardiac surgery-induced acute kidney injury

Acute kidney injury (AKI) is a common cause of morbidity after congenital heart disease surgery. Progress on diagnosis and therapy remains limited, however, in part due to poor mechanistic understanding and a lack of relevant translational models. Metabolomic approaches could help identify novel mechanisms of injury and potential therapeutic targets. In the present study, we used a piglet model of cardiopulmonary bypass with deep hypothermic circulatory arrest (CPB/DHCA) and targeted metabolic profiling of kidney tissue, urine, and serum to evaluate metabolic changes specific to animals with histological acute kidney injury. CPB/DHCA animals with acute kidney injury were compared with those without acute kidney injury and mechanically ventilated controls. Acute kidney injury occurred in 10 of 20 CPB/DHCA animals 4 h after CPB/DHCA and 0 of 7 control animals. Injured kidneys showed a distinct tissue metabolic profile compared with uninjured kidneys (R² = 0.93, Q² = 0.53), with evidence of dysregulated tryptophan and purine metabolism. Nine urine metabolites differed significantly in animals with acute kidney injury with a pattern suggestive of increased aerobic glycolysis. Dysregulated metabolites in kidney tissue and urine did not overlap. CPB/DHCA strongly affected the serum metabolic profile, with only one metabolite that differed significantly with acute kidney injury (pyroglutamic acid, a marker of oxidative stress). In conclusion, based on these findings, kidney tryptophan and purine metabolism are candidates for further mechanistic and therapeutic investigation. Urine biomarkers of aerobic glycolysis could help diagnose early acute kidney injury after CPB/DHCA and warrant further evaluation. The serum metabolites measured at this early time point did not strongly differentiate based on acute kidney injury.

NEW & NOTEWORTHY This project explored the metabolic underpinnings of postoperative acute kidney injury (AKI) following pediatric cardiac surgery in a translationally relevant large animal model of cardiopulmonary bypass with deep hypothermic circulatory arrest. Here, we present novel evidence for dysregulated tryptophan catabolism and purine catabolism in kidney tissue and increased urinary glycolysis intermediates in animals who developed histological AKI. These pathways represent potential diagnostic and therapeutic targets for postoperative AKI in this high-risk population.

Effect of intraoperative theophylline use on acute kidney injury in paediatric cardiac surgery

BACKGROUND

This study aimed to examine the effects of theophylline use in preventing renal dysfunction in patients undergoing CHD surgery.

METHODS

A total of 94 patients aged 1-60 months were included in the study. Patients in the theophylline group were enrolled according to a pre-defined protocol for treatment administration, while controls were selected retrospectively from patients without theophylline treatment during the same period - who were matched according to critical baseline characteristics.

RESULTS

The incidence of acute kidney injury was similar between the two groups (p = 1.000). Higher urinary output and lower fluid balance were found intraoperatively and also postoperatively in the theophylline group (all, p < 0.050). Postoperative decrease in urinary output and estimated glomerular filtration rate were higher in the theophylline group (p < 0.050). Lower postoperative urea and creatinine levels were shown in theophylline recipients (p < 0.050). Urea levels increased significantly in the non-theophylline group during surgery (p < 0.001), and no significant change was observed in theophylline group (p = 0.136). Postoperative increase in creatinine and lactate levels was demonstrated in theophylline group (p < 0.050), and lactate levels were higher in the non-theophylline group during and after cardiopulmonary bypass (p = 0.010). Multiple linear regression analysis revealed less reduction in estimated glomerular filtration rate with higher age and in the presence of theophylline use (p < 0.050).

CONCLUSION

Although we demonstrated a similar incidence of acute kidney injury in the both groups, we revealed an important decrease in serum creatinine, urea and lactate levels, accompanied by improved estimated glomerular filtration rate, increased urine output and decreased fluid overload, with theophylline treatment, suggesting that renal functions significantly improved with the use of theophylline.

In Vitro and In Vivo Comparison of Hemoglobin and Electrolytes Following the Collection of Cell Saver Blood Washed with Either Normal Saline or Plasma-Lyte A

Cell saver blood is typically washed with normal saline (NS); however, recent studies have reported decreased red blood cell hemolysis and increased platelet function when a more physiologic washing solution, such as Plasma-Lyte A (PL-A) is used. We evaluated the in vitro and in vivo effects of NS compared to PL-A as washing solutions for cell saver blood in pediatric cardiac surgery. Cell saver blood was re-infused for up to 24 hours post-collection. Laboratory and clinical data were collected from infants receiving cell saver washed with either NS (n = 20) or PL-A (n = 21). Compositions of the cell saver blood were compared between groups at 5 in vitro time points and in vivo patient blood at 24 hours post-bypass. Although there were differences in in vitro laboratory values between groups; 24 hours post-bypass, in vivo results were similar. Our data supports 24-hour reinfusion of cell saver washed with either NS versus PL-A in pediatric cardiac surgery patients, and provides data on the differences in cell saver composition to guide future studies.

Goal-directed perfusion to reduce acute kidney injury after paediatric cardiac surgery (GDP-AKIp): study protocol for a prospective randomised controlled trial

INTRODUCTION

Cardiac surgery-associated acute kidney injury (CS-AKI) occurs in up to 40%~60% of paediatric patients and increases postoperative morbidity and mortality. A goal-directed perfusion (GDP) strategy aimed at maintaining indexed oxygen delivery (DO₂i) above the critical threshold (reported to be 260~300 mL/min/m² in adults) during cardiopulmonary bypass (CPB), is effective in reducing the incidence of CS-AKI. However, no clear standards of paediatric critical DO₂i exist. Our prior prospective cohort study exploring the critical DO₂i threshold during paediatric CPB has found the nadir DO₂i <353 mL/min/m² was an independent risk predictor of CS-AKI. Based on this background, this trial is designed to further determine whether the implementation of the GDP initiative aimed at maintaining DO₂i ≥360 mL/min/m² would reduce the rate of CS-AKI in paediatrics and improve clinical outcome.

METHODS AND ANALYSIS

This is a prospective, single-centre, randomised controlled trial. In total, 166 paediatric patients undergoing cardiac surgery will be randomly allocated to the GDP group or control group. Patients in the GDP arm will be treated with a GDP strategy during CPB aimed to maintain DO₂i at ≥360 mL/min/m² (to ensure safely above the risk DO₂i threshold we found). The perfusion strategy for patients in the control arm will be factored on body surface area and temperature. The primary outcome is the rate of postoperative CS-AKI (it is defined according to paediatric Risk, Injury, Failure, Loss of renal function and End-stage renal disease criteria). The secondary end points include: (1) the other oxygen metabolism parameters during CPB; (2) major complication and all-cause mortality (in-hospital or within 30 days postoperatively); (3) short-term clinical outcomes (ie, time to extubation, mechanical ventilation time, hospital stay).

ETHICS AND DISSEMINATION

The study has been approved by the Biomedical Research Ethics committee of West China Hospital of Sichuan University (approval number: 2019(863)). Results will be disseminated through peer-reviewed publications and conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2000029232.

Effects of intraoperative dexmedetomidine on the incidence of acute kidney injury in pediatric cardiac surgery patients: A randomized controlled trial

BACKGROUND

Perioperative dexmedetomidine use has been reported to reduce the incidence of postoperative acute kidney injury after adult cardiac surgery. However, large-scale randomized controlled trials evaluating the effect of dexmedetomidine use on acute kidney injury in pediatric patients are lacking.

AIMS

We investigated whether intraoperative dexmedetomidine could reduce the incidence of acute kidney injury in pediatric cardiac surgery patients.

METHODS

In total, 141 pediatric patients were randomly assigned to dexmedetomidine or control groups. After anesthetic induction, patients in the dexmedetomidine group were administered 1 µg/kg of dexmedetomidine over 10 minutes and an additional 0.5 µg/kg/h of dexmedetomidine during surgery. Additionally, 1 µg/kg of dexmedetomidine was infused immediately after cardiopulmonary bypass was initiated. The incidence of acute kidney injury was defined following Kidney Disease Improving Global Outcomes guidelines.

RESULTS

The final analysis included 139 patients. The incidence of acute kidney injury did not differ between dexmedetomidine and control groups (16.9% vs 23.5%; odds ratio 0.661; 95% CI 0.285 to 1.525; P = .33). Similarly, neither the incidence of abnormal postoperative estimated glomerular filtration rate values (P = .96) nor the incidence of arrhythmia, mechanical ventilation duration, length of stay in the intensive care unit, and hospitalization differed between the two groups.

CONCLUSIONS

Intraoperative dexmedetomidine did not reduce acute kidney injury incidence in pediatric cardiac surgery patients.

Impact of Different Cardiopulmonary Bypass Strategies on Renal Injury After Pediatric Heart Surgery

BACKGROUND

The purpose of this study is to compare the incidence and severity of acute kidney injury (AKI) after open heart surgery in neonates and infants for two different cardiopulmonary bypass (CPB) strategies.

METHODS

In all, 151 infants undergoing cardiac surgery were prospectively enrolled between June 2017 and June 2018 at two centers, one using conventional CPB (2.4 L · min^-1 · m^-2, 150 mL · kg^-1 · min^-1) with reduction of flow rates with moderate hypothermia and with a targeted hematocrit greater than 25% (center 1, n = 91), and the other using higher bypass flow rates (175 to 200 mL · kg^-1 · min^-1) and higher minimum hematocrit (greater than 32%) CPB (center 2, n = 60). The primary endpoint was the incidence of postoperative AKI as defined by Acute Kidney Injury Network criteria and risk factors associated with AKI.

RESULTS

Preoperative characteristics and complexity of surgery were comparable between centers. The overall incidence of early postoperative AKI was 10.6% (16 of 151), with 15.4% (14 of 91) in center 1 and 3.3% (2 of 60) in center 2 (P = .02). Mean lowest flow rates on CPB were 78 mL · kg^-1 · min^-1 vs 118 mL · kg^-1 · min^-1 and mean highest hematocrit on separation from CPB were 33% vs 43% at center 1 and 2, respectively (P < .001). Center 1 used less packed red blood cells but more fresh frozen plasma than center 2 (P = .001). By multivariate analysis, only lower flows on CPB (78 vs 96 mL · kg^-1 · min^-1, P = .043) and lower hematocrit at the end of CPB (33% vs 37%, P = .007) were associated with AKI.

CONCLUSIONS

In this contemporary comparative study, higher flow rates and higher hematocrit during cardiopulmonary bypass were associated with better preservation of renal function.

Alkaline Phosphatase Treatment of Acute Kidney Injury in an Infant Piglet Model of Cardiopulmonary Bypass with Deep Hypothermic Circulatory Arrest

Acute kidney injury (AKI) is associated with prolonged hospitalization and mortality following infant cardiac surgery, but therapeutic options are limited. Alkaline phosphatase (AP) infusion reduced AKI in phase 2 sepsis trials but has not been evaluated for cardiac surgery-induced AKI. We developed a porcine model of infant cardiopulmonary bypass (CPB) with deep hypothermic circulatory arrest (DHCA) to investigate post-CPB/DHCA AKI, measure serum/renal tissue AP activity with escalating doses of AP infusion, and provide preliminary assessment of AP infusion for prevention of AKI. Infant pigs underwent CPB with DHCA followed by survival for 4 h. Groups were treated with escalating doses of bovine intestinal AP (1, 5, or 25U/kg/hr). Anesthesia controls were mechanically ventilated for 7 h without CPB. CPB/DHCA animals demonstrated histologic and biomarker evidence of AKI as well as decreased serum and renal tissue AP compared to anesthesia controls. Only high dose AP infusion significantly increased serum or renal tissue AP activity. Preliminary efficacy evaluation demonstrated a trend towards decreased AKI in the high dose AP group. The results of this dose-finding study indicate that AP infusion at the dose of 25U/kg/hr corrects serum and tissue AP deficiency and may prevent AKI in this piglet model of infant CPB/DHCA.

Protective effect of dexmedetomidine on kidney injury of parturients with preeclampsia undergoing cesarean section: a randomized controlled study

The present study aimed to elucidate the effects of dexmedetomidine on kidney injury of parturients with preeclampsia (PE) undergoing cesarean section. Total 134 cesarean delivery women with PE were randomly divided into intervention group (IG) and control group (CG). Both groups underwent combined spinal and epidural anesthesia (CSEA), the IG was treated with 0.4 μg/(kg·min) dexmedetomidine for 10 min before surgery. The CG was treated with equivalent saline. Heart rate (HR), blood pressure, oxygen saturation (SpO₂) of the two groups were measured at different time point after administration. Level of inflammatory factors were detected by enzyme-linked immunosorbent assay (ELISA). Visual analogue score (VAS), Ramsay sedation score (RSS), and kidney injury related indexes were evaluated at different time points. The plasma-drug concentration of patients was determined by High Performance Liquid Chromatography (HPLC) method. Compared with CG, HR, PE, and diastolic blood pressure (DBP) showed lower level while SpO₂ showed higher level in IG. Furthermore, expression of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and IL-10 in IG was decreased after drug administration, the contents of β2-MG, KIM-1 and urine protein were also decreased in contrast to the CG (all P<0.05). Besides, VAS score was decreased but Ramsay score was increased in the IG (both P<0.05). The results of HPLC showed that the half life of dexmedetomidine was about 20 min and it is speculated that the drug can be quickly metabolized within 24 h. Dexmedetomidine exerted protective effects on kidney injury of parturients with PE undergoing cesarean section.

Pharmacological interventions for the prevention of acute kidney injury after pediatric cardiac surgery: a network meta-analysis

BACKGROUND

Acute kidney injury constitutes a major complication of cardiac surgery in pediatric patients. The present meta-analysis aims to accumulate current literature and assess the efficacy of pharmacological interventions in preventing postoperative renal dysfunction after congenital heart surgery.

METHODS

Literature search was conducted using Medline (1966-2018), Scopus (2004-2018), Cochrane Central Register of Controlled Trials CENTRAL (1999-2018), Clinicaltrials.gov (2008-2018), and Google Scholar (2004-2018) databases. Statistical analysis was performed with Review Manager 5.3 and R 3.4.3.

RESULTS

Meta-analysis included 14 studies, with a total of 2,625 patients. AKI incidence was significantly lower in the dexmedetomidine (OR 0.49, 95% CI [0.28-0.87]) and acetaminophen (OR 0.43, 94% CI [0.28-0.67]) groups, while no difference was present in patients receiving corticosteroid (OR 1.16, 95% CI [0.69-1.95]), fenoldopam (OR 0.47, 95% CI [0.22-1.02]), or aminophylline (OR 0.98, 95% CI [0.29-3.34]). Network meta-analysis proposed that dexmedetomidine had the greatest probability (44.5%) to rank first, although significant overlap with the other treatments was observed.

CONCLUSIONS

The present meta-analysis suggests that no firm evidence exists about the protective role of pharmacological interventions in the pediatric population. Future randomized controlled trials should clarify the effectiveness of dexmedetomidine and acetaminophen and indicate the optimal protocol to be applied, to protect renal function in the perioperative setting.