Acute kidney injury after cardiac arrest

Serum lactate/creatinine ratio and acute kidney injury in cardiac arrest patients

OBJECTIVES

Serum lactate and creatinine levels upon admission in cardiac arrest (CA) patients significantly correlate with acute kidney injury (AKI) post-restoration of autonomic circulation. However, the association between serum lactate/creatinine ratio (LCR) and AKI in this population remains unclear. This study aimed to explore the relationship between LCR at admission and cardiac arrest-associated acute kidney injury (CA-AKI).

DESIGN AND METHODS

We conducted a secondary analysis of previously published data on CA patient resuscitation, categorizing them into tertiles based on LCR levels. Univariate and multivariate logistic regression models and subgroup analyses were employed to investigate the association between LCR and CA-AKI. Non-linear correlations were explored using restricted cubic splines, and a two-piece wise logistic proportional hazards model for both sides of the inflection point was constructed.

RESULTS

A total of 374 patients (72.19 % male) were included, with intensive care unit mortality, in-hospital mortality, and neurologic dysfunction rates of 51.87 %, 56.95 %, and 39.57 %, respectively. The overall CA-AKI incidence was 59.09 %. Multivariate logistic proportional hazards analysis revealed a negative association between LCR and CA-AKI incidence (adjusted odds ratio [OR] 0.85, 95 % confidence intervals [CI] = 0.78-0.93, P=0.001). Triple spline restriction analysis depicted an L-shaped correlation between baseline LCR and CA-AKI incidence. Particularly, a baseline LCR<0.051 was negatively associated with CA-AKI incidence (OR 0.494, 95 % CI=0.319-0.764, P=0.002). Beyond the LCR turning point, estimated dose-response curves remained consistent with a horizontal line.

CONCLUSIONS

Baseline LCR in CA patients exhibits an L-shaped correlation with AKI incidence following restoration of autonomic circulation. The threshold for CA-AKI is 0.051. This finding suggests that LCR may aid in identifying CA patients at high risk of AKI.

2024 RECOVER Guidelines: Monitoring. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR

OBJECTIVE

To systematically review evidence on and devise treatment recommendations for patient monitoring before, during, and following CPR in dogs and cats, and to identify critical knowledge gaps.

DESIGN

Standardized, systematic evaluation of literature pertinent to peri-CPR monitoring following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by Evidence Evaluators, and findings were reconciled by Monitoring Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk:benefit relationship, and clinical feasibility. This process was implemented using an Evidence Profile Worksheet for each question that included an introduction, consensus on science, treatment recommendations, justification for these recommendations, and important knowledge gaps. A draft of these worksheets was distributed to veterinary professionals for comment for 4 weeks prior to finalization.

SETTING

Transdisciplinary, international collaboration in university, specialty, and emergency practice.

RESULTS

Thirteen questions pertaining to hemodynamic, respiratory, and metabolic monitoring practices for identification of cardiopulmonary arrest, quality of CPR, and postcardiac arrest care were examined, and 24 treatment recommendations were formulated. Of these, 5 recommendations pertained to aspects of end-tidal CO2 (ETco2) measurement. The recommendations were founded predominantly on very low quality of evidence, with some based on expert opinion.

CONCLUSIONS

The Monitoring Domain authors continue to support initiation of chest compressions without pulse palpation. We recommend multimodal monitoring of patients at risk of cardiopulmonary arrest, at risk of re-arrest, or under general anesthesia. This report highlights the utility of ETco2 monitoring to verify correct intubation, identify return of spontaneous circulation, evaluate quality of CPR, and guide basic life support measures. Treatment recommendations further suggest intra-arrest evaluation of electrolytes (ie, potassium and calcium), as these may inform outcome-relevant interventions.

High incidence of acute kidney injury in extracorporeal resuscitation, Leading to poor prognosis

Background

Extracorporeal membrane oxygenation (ECMO) patients have a high incidence of acute kidney injury (AKI). Extracorporeal cardiopulmonary resuscitation (ECPR) patients are more likely to develop AKI than ECMO patients because of serious injury during cardiac arrest (CA).

Objectives

This study aims to assess the occurrence and outcomes of AKI in ECPR and ECMO, and to identify specific risk factors and clinical implications of AKI in ECPR.

Methods

This is a retrospective observational study from a single tertiary care hospital in Gwangju, Korea. Adults (≥18 years) who received ECMO with cardiac etiology in the emergency and inpatient departments from January 2015 to December 2021 were included. The patients (n = 169) were divided into two groups, ECPR and ECMO without CA, and the occurrence of AKI was investigated. The primary outcome of the study was in-hospital mortality, and the secondary outcomes were six-month cerebral performance category (CPC) and AKI during hospitalization.

Results

The incidence of AKI was significantly higher with ECPR (67.5 %) than with ECMO without CA (38.4 %). ECPR was statistically significant for Expire (adjusted OR (aOR) 2.45, 95 % CI 1.28-4.66) and Poor CPC (2.59, 1.32-5.09). AKI was also statistically significant for Expire (6.69, 3.37-13.29) and Poor CPC (5.45, 2.73-10.88). AKI was the determining factor for the outcomes of ECPR (p = 0.01).

Conclusions

ECPR patients are more likely to develop AKI than ECMO without CA patients. In ECPR patients, AKI leads to poor outcomes. Therefore, clinicians should be careful not to develop AKI in ECPR patients.

Construction and validation of a risk prediction model for acute kidney injury in patients after cardiac arrest

OBJECTIVE

Identifying patients at high risk for cardiac arrest-associated acute kidney injury (CA-AKI) helps in early preventive interventions. This study aimed to establish and validate a high-risk nomogram for CA-AKI.

METHODS

In this retrospective dataset, 339 patients after cardiac arrest (CA) were enrolled and randomized into a training or testing dataset. The Student's t-test, non-parametric Mann-Whitney U test, or χ2 test was used to compare differences between the two groups. Optimal predictors of CA-AKI were determined using the Least Absolute Shrinkage and Selection Operator (LASSO). A nomogram was developed to predict the early onset of CA-AKI. The performance of the nomogram was assessed using metrics such as area under the curve (AUC), calibration curves, decision curve analysis (DCA), and clinical impact curve (CIC).

RESULTS

In total, 150 patients (44.2%) were diagnosed with CA-AKI. Four independent risk predictors were identified and integrated into the nomogram: chronic kidney disease, albumin level, shock, and heart rate. Receiver operating characteristic (ROC) analyses showed that the nomogram had a good discrimination performance for CA-AKI in the training dataset 0.774 (95%CI, 0.715-0.833) and testing dataset 0.763 (95%CI, 0.670-0.856). The AUC values for the two groups were calculated and compared using the Hanley-McNeil test. No statistically significant differences were observed between the groups. The calibration curve demonstrated good agreement between the predicted outcome and actual observations. Good clinical usefulness was identified using DCA and CIC.

CONCLUSION

An easy-to-use nomogram for predicting CA-AKI was established and validated, and the prediction efficiency of the clinical model has reasonable clinical practicability.

Epidemiology and outcome predictors in 450 patients with hanging-induced cardiac arrest: a retrospective study

Background

Cardiac arrest is the most life-threatening complication of attempted suicide by hanging. However, data are scarce on its characteristics and outcome predictors.

Methods

This retrospective observational multicentre study in 31 hospitals included consecutive adults admitted after cardiac arrest induced by suicidal hanging. Factors associated with in-hospital mortality were identified by multivariate logistic regression with multiple imputations for missing data and adjusted to the temporal trends over the study period.

Results

Of 450 patients (350 men, median age, 43 [34-52] years), 305 (68%) had a psychiatric history, and 31 (6.9%) attempted hanging while hospitalized. The median time from unhanging to cardiopulmonary resuscitation was 0 [0-5] min, and the median time to return of spontaneous circulation (ROSC) was 20 [10-30] min. Seventy-nine (18%) patients survived to hospital discharge. Three variables were independently associated with higher in-hospital mortality: time from collapse or unhanging to ROSC>20 min (odds ratio [OR], 4.71; 95% confidence intervals [95%CIs], 2.02-10.96; p = 0.0004); glycaemia >1.4 g/L at admission (OR, 6.38; 95%CI, 2.60-15.66; p < 0.0001); and lactate >3.5 mmol/L at admission (OR, 6.08; 95%CI, 1.71-21.06; p = 0.005). A Glasgow Coma Scale (GCS) score of >5 at admission was associated with lower in-hospital mortality (OR, 0.009; 95%CI, 0.02-0.37; p = 0.0009).

Conclusion

In patients with hanging-induced cardiac arrest, time from collapse or unhanging to return of spontaneous circulation, glycaemia, arterial lactate, and coma depth at admission were independently associated with survival to hospital discharge. Knowledge of these risk factors may help guide treatment decisions in these patients at high risk of hospital mortality.

Predictors of acute kidney injury in patients after extracorporeal cardiopulmonary resuscitation

OBJECTIVES

Extracorporeal cardiopulmonary resuscitation (eCPR) is increasingly used due to its beneficial outcomes and results compared with conventional CPR. Data after eCPR for acute kidney injury (AKI) are lacking. We sought to investigate factors predicting AKI in patients who underwent eCPR.

METHODS

From January 2016 until December 2020, patients who underwent eCPR at our institution were retrospectively analyzed and divided into two groups: patients who developed AKI (n = 60) and patients who did not develop AKI (n = 35) and analyzed for outcome parameters.

RESULTS

Overall, 63% of patients suffered AKI after eCPR and 45% of patients who developed AKI needed subsequent dialysis. Patients who developed AKI showed higher values of creatinine (1.1 mg/dL vs 1.5 mg/dL, p ⩽ 0.01), urea (34 mg/dL vs 42 mg/dL, p = 0.04), CK (creatine kinase) (923 U/L vs 1707 U/L, p = 0.07) on admission, and CK after 24 hours of ECMO support (1705 U/L vs 4430 U/L, p = 0.01). ECMO explantation was significantly more often performed in patients who suffered AKI (24% vs 48%, p = 0.01). In-hospital mortality (86% vs 70%; p = 0.07) did not differ significantly.

CONCLUSION

Patients after eCPR are at high risk for AKI, comparable to those after conventional CPR. Baseline urea levels predict the development of AKI during the hospital stay.

Potential Antioxidant Multitherapy against Complications Occurring in Sepsis

Septic shock currently represents one of the main causes of mortality in critical patient units with an increase in its incidence in recent years, and it is also associated with a high burden of morbidity in surviving patients. Within the pathogenesis of sepsis, oxidative stress plays an important role. The excessive formation of reactive oxygen species (ROS) leads to mitochondrial damage and vasomotor dysfunction that characterizes those patients who fall into septic shock. Currently, despite numerous studies carried out in patients with septic shock of different causes, effective therapies have not yet been developed to reduce the morbidity and mortality associated with this pathology. Despite the contribution of ROS in the pathophysiology of sepsis and septic shock, most studies performed in humans, with antioxidant monotherapies, have not resulted in promising data. Nevertheless, some interventions with compounds such as ascorbate, N-acetylcysteine, and selenium would have a positive effect in reducing the morbidity and mortality associated with this pathology. However, more studies are required to demonstrate the efficacy of these therapies. Taking into account the multifactorial features of the pathophysiology of sepsis, we put forward the hypothesis that a supplementation based on the association of more than one antioxidant compound should result in a synergistic or additive effect, thus improving the beneficial effects of each of them alone, potentially serving as a pharmacological adjunct resource to standard therapy to reduce sepsis complications. Therefore, in this review, it is proposed that the use of combined antioxidant therapies could lead to a better clinical outcome of patients with sepsis or septic shock, given the relevance of oxidative stress in the pathogenesis of this multi-organ dysfunction.

The conundrum of the complex relationship between acute kidney injury and cardiac arrhythmias

Acute kidney injury (AKI) is defined by a rapid increase in serum creatinine levels, reduced urine output, or both. Death may occur in 16%-49% of patients admitted to an intensive care unit with severe AKI. Complex arrhythmias are a potentially serious complication in AKI patients with pre-existing or AKI-induced heart damage and myocardial dysfunction, fluid overload, and especially electrolyte and acid-base disorders representing the pathogenetic mechanisms of arrhythmogenesis. Cardiac arrhythmias, in turn, increase the risk of poor renal outcomes, including AKI. Arrhythmic risk in AKI patients receiving kidney replacement treatment may be reduced by modifying dialysis/replacement fluid composition. The most common arrhythmia observed in AKI patients is atrial fibrillation. Severe hyperkalemia, sometimes combined with hypocalcemia, causes severe bradyarrhythmias in this clinical setting. Although the likelihood of life-threatening ventricular arrhythmias is reportedly low, the combination of cardiac ischemia and specific electrolyte or acid-base abnormalities may increase this risk, particularly in AKI patients who require kidney replacement treatment. The purpose of this review is to summarize the available epidemiological, pathophysiological, and prognostic evidence aiming to clarify the complex relationships between AKI and cardiac arrhythmias.

Renal Injuries after Cardiac Arrest: A Morphological Ultrastructural Study

BACKGROUND

This study aims to investigate the probable lesions and injuries induced in the renal tissue after a cardiac arrest. The renal ischemia-reperfusion model in cardiac arrest describes the effects of ischemia in the kidneys, alongside a whole-body ischemia-reperfusion injury. This protocol excludes ischemic conditions caused by surgical vascular manipulation, venous injury or venous congestion.

METHODS

For the experimental study, 24 swine were subjected to cardiac arrest. Seven minutes later, the cardiopulmonary resuscitation technique was performed for 5 min. Afterwards, advanced life support was provided. The resuscitated swine consisted one group and the non-resuscitated the other. Tissue samples were obtained from both groups for light and electron microscopy evaluation.

RESULTS

Tissue lesions were observed in the tubules, parallel to destruction of the microvilli, reduction in the basal membrane invaginations, enlarged mitochondria, cellular vacuolization, cellular apoptosis and disorganization. In addition, fusion of the podocytes, destruction of the Bowman's capsule parietal epithelium and abnormal peripheral urinary space was observed. The damage appeared more extensive in the non-resuscitated swine group.

CONCLUSIONS

Acute kidney injury is not the leading cause of death after cardiac arrest. However, evidence suggests that the kidney damage after a cardiac arrest should be highly considered in the prognosis of the patients' health outcome.

Postresuscitation care and prognostication after cardiac arrest-Does sex matter?

Background

There are conflicting results concerning sex-specific differences in the post-cardiac arrest period. We investigated the sex distribution of patients after successful cardiopulmonary resuscitation (CPR), differences in treatment, complications, outcome and sex-specific performance of biomarkers for prognostication of neurological outcome.

Methods

Prospective observational study including cardiac-arrest (CA) patients treated with mild therapeutic hypothermia (MTH) at 33 °C for 24 h or normothermia. We investigated common complications including pneumonia and acute kidney injury (AKI) and neuron-specific enolase, secretoneurin and tau protein as biomarkers of neurological outcome, which was assessed with the cerebral performance categories score at hospital discharge.

Results

Out of 134 patients 26% were female. Women were significantly older (73 years, interquartile range (IQR) 56–79 years vs. 62 years, IQR 53–70 years; p = 0.038), whereas men showed a significantly higher rate of pneumonia (29% vs. 6%; p = 0.004) and a trend towards higher rates of AKI (62% vs. 45%; p = 0.091). Frequency of MTH treatment was not significantly different (48% vs. 31%; p = 0.081). Female sex was not associated with neurological outcome in multivariable analysis (p = 0.524). There was no significant interaction of sex with prognostication of neurological outcome at 24, 48 and 72 h after CPR. At the respective time intervals p_interaction for neuron-specific enolase was 0.524, 0.221 and 0.519, for secretoneurin 0.893, 0.573 and 0.545 and for tau protein 0.270, 0.635, and 0.110.

Conclusion

The proportion of female patients was low. Women presented with higher age but had fewer complications during the post-CA period. Female sex was not associated with better neurological outcome. The performance of biomarkers is not affected by sex.

Supplementary Information

The online version of this article (10.1007/s00508-022-02026-x) contains supplementary material, which is available to authorized users.

The influence of timing of coronary angiography on acute kidney injury in out-of-hospital cardiac arrest patients: a retrospective cohort study

BACKGROUND

Acute kidney injury (AKI) is a frequent complication in cardiac arrest survivors and associated with adverse outcome. It remains unclear whether the incidence of AKI increases after the post-cardiac arrest contrast administration for coronary angiography and whether this depends on timing of angiography. Aim of this study was to investigate whether early angiography is associated with increased development of AKI compared to deferred angiography in out-of-hospital cardiac arrest (OHCA) survivors.

METHODS

In this retrospective multicenter cohort study, we investigated whether early angiography (within 2 h) after OHCA was non-inferior to deferred angiography regarding the development of AKI. We used an absolute difference of 5% as the non-inferiority margin. Primary non-inferiority analysis was done by calculating the risk difference with its 90% confidence interval (CI) using a generalized linear model for a binary outcome. As a sensitivity analysis, we repeated the primary analysis using propensity score matching. A multivariable model was built to identify predictors of acute kidney injury.

RESULTS

A total of 2375 patients were included from 2009 until 2018, of which 1148 patients were treated with early coronary angiography and 1227 patients with delayed or no angiography. In the early angiography group 18.5% of patients developed AKI after OHCA and 24.1% in the deferred angiography group. Risk difference was - 3.7% with 90% CI ranging from - 6.7 to - 0.7%, indicating non-inferiority of early angiography. The sensitivity analysis using propensity score matching showed accordant results, but no longer non-inferiority of early angiography. The factors time to return of spontaneous circulation (odds ratio [OR] 1.12, 95% CI 1.06-1.19, p < 0.001), the (not) use of angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (OR 0.20, 95% CI 0.04-0.91, p = 0.04) and baseline creatinine (OR 1.05, 95% CI 1.03-1.07, p < 0.001) were found to be independently associated with the development of AKI.

CONCLUSIONS

Although AKI occurred in approximately 20% of OHCA patients, we found that early angiography was not associated with a higher AKI incidence than a deferred angiography strategy. The present results implicate that it is safe to perform early coronary angiography with respect to the risk of developing AKI after OHCA.

Accumulated Epinephrine Dose is Associated With Acute Kidney Injury Following Resuscitation in Adult Cardiac Arrest Patients

The goal of this study was to investigate the association between total epinephrine dosage during resuscitation and acute kidney injury after return of spontaneous circulation in patients with cardiac arrest. We performed a secondary analysis of previously published data on the resuscitation of cardiac arrest patients. Bivariate, multivariate logistic regression, and subgroup analyses were conducted to investigate the association between total epinephrine dosage during resuscitation and acute kidney injury after return of spontaneous circulation. A total of 312 eligible patients were included. The mean age of the patients was 60.8 ± 15.2 years. More than half of the patients were male (73.4%) and had an out-of-hospital cardiac arrest (61.9%). During resuscitation, 125, 81, and 106 patients received ≤2, 3 - 4, and ≥5 mg epinephrine, respectively. After return of spontaneous circulation, there were 165 patients (52.9%) and 147 patients (47.1%) with and without acute kidney injury, respectively. Both bivariate and multivariate analysis showed a statistically significant association between total epinephrine dosage and acute kidney injury. The subgroup analysis showed that the strength of the association between epinephrine dosage and acute kidney injury varied by location of cardiac arrest. Further multivariate regression analysis found that the association between epinephrine dosage and acute kidney injury was only observed in patients with in-hospital cardiac arrest after adjusting for multiple confounding factors. Compared with in-hospital cardiac arrest patients who received ≤2 mg of epinephrine, patients with 3–4 mg of epinephrine or ≥5 mg of epinephrine had adjusted odds ratios of 4.2 (95% confidence interval 1.0–18.4) and 11.3 (95% confidence interval 2.0–63.0), respectively, to develop acute kidney injury. Therefore, we concluded that a higher epinephrine dosage during resuscitation was associated with an increased incidence of acute kidney injury after return of spontaneous circulation in adult patients with in-hospital cardiac arrest.

Nouvelles approches diagnostiques de l’insuffisance rénale aiguë

L’insuffisance rénale, véritable problème de santé publique, concernerait plus de 82 000 personnes en France. On estime que 5 à 10 % de la population française souffriraient d’une maladie rénale pouvant conduire à une insuffisance rénale avec un taux de mortalité de plus de 10 % par an. À l’inverse de la maladie rénale chronique irréversible, l’insuffisance rénale aiguë est considérée comme un dysfonctionnement transitoire et réversible. Au-delà de l’intérêt de la prévention, le diagnostic précoce de l’insuffisance rénale aiguë permettrait de mettre en place des thérapeutiques adaptées et ciblées afin d’éviter l’évolution vers des lésions rénales irréversibles. Cependant, il demeure un véritable challenge pour le praticien puisque l’on présume que près de 10 % de la population française présenteraient des lésions rénales asymptomatiques. Bien que la définition de l’insuffisance rénale aiguë ait été simplifiée durant ces dernières années, il existe de nombreuses limites. En parallèle, des progrès majeurs ont été réalisés notamment en termes de diagnostic. L’objectif de cette mise au point est de faire un rappel sur l’évolution de l’insuffisance rénale aiguë, les définitions actuelles et de présenter les nouvelles approches diagnostiques en cours de développement.

Innovations and Emerging Therapies to Combat Renal Cell Damage: NAD+ As a Drug Target

Significance: Acute kidney injury (AKI) is a common and life-threatening complication in hospitalized and critically ill patients. It is defined by an abrupt deterioration in renal function, clinically manifested by increased serum creatinine levels, decreased urine output, or both. To execute all its functions, namely excretion of waste products, fluid/electrolyte balance, and hormone synthesis, the kidney requires incredible amounts of energy in the form of adenosine triphosphate. Recent Advances: Adequate mitochondrial functioning and nicotinamide adenine dinucleotide (NAD+) homeostasis are essential to meet these high energetic demands. NAD+ is a ubiquitous essential coenzyme to many cellular functions. NAD+ as an electron acceptor mediates metabolic pathways such as oxidative phosphorylation (OXPHOS) and glycolysis, serves as a cosubstrate of aging molecules (i.e., sirtuins), participates in DNA repair mechanisms, and mediates mitochondrial biogenesis. Critical Issues: In many forms of AKI and chronic kidney disease, renal function deterioration has been associated with mitochondrial dysfunction and NAD+ depletion. Based on this, therapies aiming to restore mitochondrial function and increase NAD+ availability have gained special attention in the last two decades. Future Directions: Experimental and clinical studies have shown that by restoring mitochondrial homeostasis and increasing renal tubulo-epithelial cells, NAD+ availability, AKI incidence, and chronic long-term complications are significantly decreased. This review covers some general epidemiological and pathophysiological concepts; describes the role of mitochondrial homeostasis and NAD+ metabolism; and analyzes the underlying rationale and role of NAD+ aiming therapies as promising preventive and therapeutic strategies for AKI. Antioxid. Redox Signal. 35, 1449-1466.

Acute kidney injury and cardiac arrest in the modern era: an updated systematic review and meta-analysis

Objective: Acute kidney injury (AKI) is associated with higher morbidity and mortality in cardiac arrest (CA). There are limited contemporary data on the incidence and outcomes of AKI in CA.Methods: We comprehensively searched the databases of MEDLINE, EMBASE, PUBMED, and the Cochrane from inception to November 2020. Observational studies that reported the incidence of AKI in CA survivors were included. Data from each study were combined using the random effects to calculate pooled incidence and risk ratios with 95% confidence intervals (CIs). The primary outcome was short-term mortality and secondary outcomes included long-term mortality, incidence of AKI, and use of renal replacement therapy (RRT). Subgroup and meta-regression analyses were performed to explore heterogeneity.Main results: A total of 25 observational studies comprising 8,165 patients were included. The incidence of AKI in CA survivors was 40.3% (range 32.9-47.8%). In stage 3 AKI, one-fourth of patients required RRT. AKI was associated with an increased risk of both short-term (OR 2.27 [95% CI 1.74-2.96]; p < 0.001) and long-term mortality (OR 1.51 [95% CI 1.93-3.25]; p < 0.001). Meta-regression and subgroup analyses did not suggest any effect of hypothermia on incidence of AKI.Conclusion: AKI complicates the care of 40% of CA survivors and is associated with significantly increased short- and long-term mortality.

Cardiogenic shock and acute kidney injury: the rule rather than the exception

Cardiogenic shock (CS) is a life-threatening condition of poor end-organ perfusion, caused by any cardiovascular disease resulting in a severe depression of cardiac output. Despite recent advances in replacement therapies, the outcome of CS is still poor, and its management depends more on empirical decisions rather than on evidence-based strategies. By its side, acute kidney injury (AKI) is a frequent complication of CS, resulting in the onset of a cardiorenal syndrome. The combination of CS with AKI depicts a worse clinical scenario and holds a worse prognosis. Many factors can lead to acute renal impairment in the setting of CS, either for natural disease progression or for iatrogenic causes. This review aims at collecting the current evidence-based acknowledgments in epidemiology, pathophysiology, clinical features, diagnosis, and management of CS with AKI. We also attempted to highlight the major gaps in evidence as well as to point out possible strategies to improve the outcome.

Association between acute kidney injury and mortality after successful cardiopulmonary resuscitation: a retrospective observational study

BACKGROUND AND OBJECTIVES

Acute Kidney Injury (AKI) affect mortality and morbidity in critically ill patients. There have been few studies examining the prevalence of AKI and mortality after successful cardiopulmonary resuscitation. In the present study, we investigated the association between AKI and mortality in post-cardiac arrest patients admitted to the Intensive Care Unit (ICU).

METHODS

Our retrospective analysis included 109 patients, admitted to the ICU following successful cardiopulmonary resuscitation between 2014 and 2016. We compared two scoring systems to estimate mortality.

RESULTS AND DISCUSSION

AKI were diagnosed in 46.7% (n = 51) of the patients based on the RIFLE criteria and 66.1% (n = 72) using the KDIGO. Mortality rate was significantly higher among patients with AKI diagnosed according to the RIFLE criteria (p = 0.012) and those with AKI diagnosed using KDIGO criteria (p = 0.003). Receiver Operating Characteristic (ROC) analysis showed that both scoring systems were able to successfully detect mortality (Area under the ROC curve = 0.693 for RIFLE and 0.731 for KDIGO).

CONCLUSION

AKI increases mortality and morbidity rates after cardiac arrest. Although more renal injury and mortality were detected with KDIGO, the sensitivity and specificity of both scoring systems were similar in predicting mortality in patients with Return of Spontaneous Circulation (ROSC).

Veno-arterial CO2 difference and respiratory quotient after cardiac arrest: An observational cohort study

PURPOSE

To characterize venous-arterial CO₂ difference (ΔpCO₂) and the respiratory quotient (RQ) in post cardiac arrest patients and evaluate the association between these parameters and patient outcome.

MATERIALS AND METHODS

Data were obtained retrospectively from post cardiac arrest patients admitted between 2007 and 2016 to a medical intensive care unit. Comatose, adult patients in whom arterial and venous blood gas analyses were concomitantly performed in the first 24 h were included. Patients were grouped according to the time-point of sampling; 0-6, 6-12 and 12-24 h after admission.

RESULTS

308 patients were included; 174 (56%) died before ICU discharge and 212 (69%) had an unfavorable neurologic outcome. RQ was associated with ICU mortality (OR:1.09 (95%CI: 1.04-1.14; p < 0.01)), although not with neurological outcome. ΔpCO₂ was negatively associated with both ICU mortality (OR: 0.92 (95%CI: 0.86-0.99; p = 0.02)) and poor neurologic outcome (adjusted OR: 0.93 (95%CI: 0.87-0.99; p = 0.02)). ΔpCO₂ predicted an elevated RQ; a ΔpCO₂ above 8.5 mmHg identified a high RQ with reasonable sensitivity and specificity.

CONCLUSIONS

RQ was associated with ICU mortality and ΔpCO₂ identified elevated RQ in the early phase after cardiac arrest. However, ΔpCO₂ were negatively associated with both ICU mortality and neurologic outcome.

Incidence, Predictors, and Prognosis of Acute Kidney Injury Among Cardiac Arrest Survivors

BACKGROUND

Acute kidney injury (AKI) is common among cardiac arrest survivors. However, the outcomes and predictors are not well studied.

METHODS

This is a cohort study of cardiac arrest patients enrolled from January 2012 to December 2016 who were able to survive for 24 hours post-cardiopulmonary resuscitation. Patients with anuria, chronic kidney disease (stage 5), and end-stage renal disease were excluded. Acute kidney injury (stage 1) or higher was defined using Kidney Disease: Improving Global Outcomes classification. Multivariable adjusted regression models were used to compute hazard ratio (HR) for association of AKI with risk of mortality and odds ratio (OR) with risk of poor neurological outcomes after adjusting for demographics, comorbidities, and medical therapy. Multivariable logistic regression model was used to compute OR for association of various predictors with AKI.

RESULTS

Of 842 cardiac arrest survivors, 588 (69.8%) developed AKI. Among AKI patients, 69.4% died compared with 52.0% among non-AKI patients. In multivariable adjusted Cox proportional hazard model, development of AKI post-cardiac arrest was significantly associated with mortality (HR: 1.35; 95% confidence interval [CI]: 1.07-1.71, P = .01) and poor neurological outcomes defined as cerebral performance category >2 (OR: 2.27; 95% CI: 1.45-3.57, P < .001) and modified Rankin scale >3 (OR: 2.22; 95% CI: 1.43-3.45, P < .001). Postdischarge dialysis was also associated with increased risk of mortality (HR: 2.57; 95% CI: 1.57-4.23, P < .001). Use of vasopressors was strongly associated with development of AKI and continued need for postdischarge dialysis.

CONCLUSIONS

Acute kidney injury was associated with increased risk of mortality and poor neurological outcomes. There is need for further studies to prevent AKI in cardiac arrest survivors.

The influence of prolonged temperature management on acute kidney injury after out-of-hospital cardiac arrest: A post hoc analysis of the TTH48 trial

BACKGROUND

Acute kidney injury (AKI) is common after cardiac arrest and targeted temperature management (TTM). The impact of different lengths of cooling on the development of AKI has not been well studied. In this study of patients included in a randomised controlled trial of TTM at 33 °C for 24 versus 48 h after cardiac arrest (TTH48 trial), we examined the influence of prolonged TTM on AKI and the incidence and factors associated with the development of AKI. We also examined the impact of AKI on survival.

METHODS

This study was a sub-study of the TTH48 trial, which included patients cooled to 33 ± 1 °C after out-of-hospital cardiac arrest for 24 versus 48 h. AKI was classified according to the KDIGO AKI criteria based on serum creatinine and urine output collected until ICU discharge for a maximum of seven days. Survival was followed for up to six months. The association of admission factors on AKI was analysed with multivariate analysis and the association of AKI on mortality was analysed with Cox regression using the time to AKI as a time-dependent covariate.

RESULTS

Of the 349 patients included in the study, 159 (45.5%) developed AKI. There was no significant difference in the incidence, severity or time to AKI between the 24- and 48-h groups. Serum creatinine values had significantly different trajectories for the two groups with a sharp rise occurring during rewarming. Age, time to return of spontaneous circulation, serum creatinine at admission and body mass index were independent predictors of AKI. Patients with AKI had a higher mortality than patients without AKI (hospital mortality 36.5% vs 12.5%, p < 0.001), but only AKI stages 2 and 3 were independently associated with mortality.

CONCLUSIONS

We did not find any association between prolonged TTM at 33 °C and the risk of AKI during the first seven days in the ICU. AKI is prevalent after cardiac arrest and TTM and occurs in almost half of all ICU admitted patients and more commonly in the elderly, with an increasing BMI and longer arrest duration. AKI after cardiac arrest is an independent predictor of time to death.

Edaravone Ameliorates Renal Warm Ischemia-Reperfusion Injury by Downregulating Endoplasmic Reticulum Stress in a Rat Resuscitation Model

Background

This study was conducted to explore whether the effect of edaravone (5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol3-one, EDR) can ameliorate renal warm ischemia-reperfusion injury (IRI) by modulating endoplasmic reticulum stress (ERS) and its downstream effector after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in a rat model.

Methods

The rats (n=10) experienced anaesthesia and intubation followed by no CA inducement were defined as the Sham group. Transoesophageal alternating current stimulation was employed to establish 8 min of CA followed by conventional CPR for a resuscitation model. The rats with successful restoration of spontaneous circulation (ROSC) randomly received EDR (3 mg/kg, EDR group, n=10) or equal volume normal saline solution (the NS group, n=10). At 24 hr after ROSC, serum creatinine (SCR), blood urea nitrogen (BUN) levels, and cystatin-C (Cys-C) levels were determined and the protein level of glucose-regulated protein (GRP78), C/EBP homologous protein (CHOP), extracellular signal-regulated kinase (ERK), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), Bax/Bcl-2, and caspase-3 were detected by Western blot method.

Results

At 24 hrs after ROSC, SCR, BUN and Cys-C were obviously increased and the proteins expression, including GRP78, CHOP and p-ERK1/2, cleaved-caspase 3 Bax/Bcl-2 ratio, were significantly upregulated in the NS group compared with the Sham group (p<0.05). The remarkable improvement of these adverse outcomes was observed in the EDR group (p<0.05).

Conclusion

In conclusion, we found that EDR ameliorates renal warm IRI by downregulating ERS and its downstream effectors in a rat AKI model evoked by CA/CPR. These data may provide evidence for future therapeutic benefits of EDR against AKI induced by CA/CPR.

The incidence of acute kidney injury following cardiac arrest and cardiopulmonary resuscitation in a rat model

OBJECTIVE

In the current study, we investigated the incidence of acute kidney injury (AKI) induced by cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) and whether such an AKI can recover spontaneously in rats.

METHODS

We used transesophageal alternating current stimulation to establish 7 min of CA rat model followed by conventional CPR. The experimental rats were randomly divided into three groups (n = 20 per group) according to the different time points after restoration spontaneous circulation (ROSC): the ROSC 24 h, ROSC 48 h, and ROSC 72 h group. The diagnosis of rat AKI refers to the 2012 KDIGO adult AKI diagnostic criteria. The severity of AKI quantified by the serum creatinine (SCR), blood urea nitrogen (BUN) levels and histological features of renal tissue.

RESULTS

The incidence rates of AKI in ROSC 24 h, ROSC 48 h, and ROSC 72 h group were 65%, 45%, and 42.9%. Moreover, the values of SCR and BUN were highest at ROSC 24 h, and then gradually decreased with the time of ROSC. The histological changes of the renal tissues such as glomerular collapse, renal tubular cell swelling, and inflammatory cell infiltration had also observed.

CONCLUSION

The incidence of AKI in rats was high after suffering from CA and CPR, but renal function improved with the prolongation of ROSC time, indicating the ability of the kidney to self-repair.

Perioperative urinary heat shock protein 72 as an early marker of acute kidney injury in dogs

OBJECTIVE

Acute kidney injury (AKI) may be a complication in dogs undergoing surgery. Urinary heat shock protein 72 (uHSP72) is a sensitive biomarker of canine AKI. To assess the occurrence of perioperative AKI, based on uHSP72 compared with serum creatinine (sCr), and whether its occurrence is associated with the American Society of Anesthesiology physical status (ASA status).

STUDY DESIGN

Clinical prospective study.

ANIMALS

A total of 80 client-owned and shelter dogs.

METHODS

Dogs scheduled for elective or emergency surgery were assigned ASA status (ASA I-IV). Preoperative and 24 hour postoperative serum and urine samples were collected. sCr, uHSP72 and urinary creatinine (uCr) were measured.

RESULTS

Postoperative uHSP72/uCr concentration [median (range)] of all dogs undergoing surgery [2.40 (0.14-252) ng mg^-1] was significantly increased compared with preoperative uHSP72/uCr [1.30 (0.11-142) ng mg^-1] concentration (p < 0.001). Conversely, postoperative sCr concentration of all dogs [0.88 (0.3-1.6) mg dL^-1] significantly decreased compared with preoperative sCr concentration [0.8 (0.2-5.0) mg dL^-1; p = 0.001]. Median uHSP72/uCr concentration differed both preoperatively (p = 0.007) and postoperatively (p = 0.019) among the ASA status groups. Increased uHSP/uCr was measured in 20 dogs preoperatively and 33 dogs postoperatively, whereas only five dogs fulfilled the criteria of AKI based on sCr.

CONCLUSIONS

The occurrence of increased uHSP72/uCr perioperatively suggests that the proportion of dogs with AKI is considerably higher than perceived.

CLINICAL RELEVANCE

Dogs undergoing surgery should be closely monitored for AKI before and after anesthesia, using currently available markers (e.g., sCr) and more sensitive markers.

Effect of estimated glomerular filtration rate (eGFR) on incidence of out-of-hospital cardiac arrests: A case-control study

OBJECTIVES

Serum creatinine levels in the post-resuscitative state have been associated with poor prognosis for out-of-hospital cardiac arrest (OHCA). Several studies have focused on kidney dysfunction in the general population, and the results suggested that serum creatinine level elevation or reduction of the estimated glomerular filtration rate (eGFR) are associated with increased risk of death and cardiovascular events. However, it is uncertain whether the serum creatinine levels or eGFR of OHCA patients are related to the incidence of OHCA. The aim of this study was to determine the association between eGFR and the incidence of OHCA.

METHODS

This study was a case-control study performed using the Cardiac Arrest Pursuit Trial with Unique Registration and Epidemiologic Surveillance (CAPTURES) project dataset and the Korea National Health and Nutrition Examination Survey (KNHANES) dataset. Cases were defined as emergency medical service-treated adult OHCA patients with presumed cardiac etiology collected from the CAPTURES dataset. Four controls from the KNHANES dataset were matched to one case based on age, gender, and county. Multivariable conditional logistic regression analysis was conducted to evaluate the effect of eGFR on the incidence of OHCA.

RESULTS

A total of 1211 matched case-control pairs were included in the study analysis. We classified eGFR into 6 categories (≥90, 60-89, 45-59, 30-44, 15-29, and <15 mL/min/1.73 m²) according to the chronic kidney disease stage. Subjects with an eGFR ≥90 mL/min/1.73 m² were used as the reference group. In both the unadjusted and adjusted models, lower eGFR was significantly associated with OHCA incidence. The odds ratio (OR) for OHCA incidence increased sharply as the eGFR declined; the adjusted OR (95% CI) for OHCA incidence was 4.09 (2.81-5.95) with an eGFR of 60-89 mL/min/1.73 m², 36.59 (22.24-60.21) with an eGFR of 45-59 mL/min/1.73 m², 55.26(29.66-102.94) with an eGFR of 30-44 mL/min/1.73 m², 89.65 (37.25-215.79) with an eGFR of 15-29 mL/min/1.73 m², and 241.87 (73.49-796.01) with an eGFR of less than 15 mL/min/1.73 m².

CONCLUSION

In this study, we observed an association between reduced eGFR and the risk of OHCA incidence in a large, community-based population. Future prospective studies are needed to better understand how reduced renal function is associated with OHCA occurrence as well as the impact of intensive risk management and intervention of renal function on OHCA incidence.

Increased compensatory kidney workload results in cellular damage in a short time porcine model of mixed acidemia - Is acidemia a 'first hit' in acute kidney injury?

Acute kidney injury (AKI) corrupts the outcome of about 50% of all critically ill patients. We investigated the possible contribution of the pathology acidemia on the development of AKI. Pigs were exposed to acidemia, acidemia plus hypoxemia or a normal acid-base balance in an experimental setup, which included mechanical ventilation and renal replacement therapy to facilitate biotrauma caused by extracorporeal therapies. Interestingly, extensive histomorphological changes like a tubular loss of cell barriers occurred in the kidneys after just 5 hours exposure to acidemia. The additional exposure to hypoxemia aggravated these findings. These ‘early’ microscopic pathologies opposed intra vitam data of kidney function. They did not mirror cellular or systemic patterns of proinflammatory molecules (like TNF-α or IL 18) nor were they detectable by new, sensitive markers of AKI like Neutrophil gelatinase-associated lipocalin. Instead, the data suggest that the increased renal proton excretion during acidemia could be an ‘early’ first hit in the multifactorial pathogenesis of AKI.

Acute kidney injury from sepsis: current concepts, epidemiology, pathophysiology, prevention and treatment

Sepsis-associated acute kidney injury (S-AKI) is a frequent complication of the critically ill patient and is associated with unacceptable morbidity and mortality. Prevention of S-AKI is difficult because by the time patients seek medical attention, most have already developed acute kidney injury. Thus, early recognition is crucial to provide supportive treatment and limit further insults. Current diagnostic criteria for acute kidney injury has limited early detection; however, novel biomarkers of kidney stress and damage have been recently validated for risk prediction and early diagnosis of acute kidney injury in the setting of sepsis. Recent evidence shows that microvascular dysfunction, inflammation, and metabolic reprogramming are 3 fundamental mechanisms that may play a role in the development of S-AKI. However, more mechanistic studies are needed to better understand the convoluted pathophysiology of S-AKI and to translate these findings into potential treatment strategies and add to the promising pharmacologic approaches being developed and tested in clinical trials.

Renal function after out-of-hospital cardiac arrest; the influence of temperature management and coronary angiography, a post hoc study of the target temperature management trial

Background

To elucidate the incidence of acute kidney injury (AKI) after out-of-hospital cardiac arrest (OHCA) and to examine the impact of target temperature management (TTM) and early coronary angiography on renal function.

Methods

Post hoc analysis of the TTM trial, a multinational randomised controlled trial comparing target temperature of 33 °C versus 36 °C in patients with return of spontaneous circulation after OHCA. The impact of TTM and early angiography (within 6 h of OHCA) versus late or no angiography on the development of AKI during the 7-day period after OHCA was analysed. AKI was defined according to modified KDIGO criteria in patients surviving beyond day 2 after OHCA.

Results

Following exclusions, 853 of 939 patients enrolled in the main trial were analysed. Unadjusted analysis showed that significantly more patients in the 33 °C group had AKI compared to the 36 °C group [211/431 (49%) versus 170/422 (40%) p = 0.01], with a worse severity (p = 0.018). After multivariable adjustment, the difference was not significant (odds ratio 0.75, 95% confidence interval 0.54–1.06, p = 0.10].

Five hundred seventeen patients underwent early coronary angiography. Although the unadjusted analysis showed less AKI and less severe AKI in patients who underwent early angiography compared to patients with late or no angiography, in adjusted analyses, early angiography was not an independent risk factor for AKI (odds ratio 0.73, 95% confidence interval 0.50–1.05, p = 0.09).

Conclusions

In OHCA survivors, TTM at 33 °C compared to management at 36 °C did not show different rates of AKI and early angiography was not associated with an increased risk of AKI.

Trial registration

NCT01020916. Registered on www.ClinicalTrials.gov 26 November 2009 (main trial).

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2390-0) contains supplementary material, which is available to authorized users.

Cardiac arrhythmias after renal I/R depend on IL-1β

AIMS

Cardiac arrhythmias are one of the most important remote complications after kidney injury. Renal ischemia reperfusion (I/R) is a major cause of acute renal injury predisposing to several remote dysfunctions, including cardiac electrical disturbance. Since IL-1β production dependent on NLRP3 represents a link between tissue malfunctioning and cardiac arrhythmias, here we tested the hypothesis that longer ventricular repolarization and arrhythmias after renal I/R depend on this innate immunity sensor.

METHODS AND RESULTS

Nlrp3^-/- and Casp1^-/- mice reacted to renal I/R with no increase in plasma IL-1β, different from WT (wild-type) I/R. A prolonged QJ interval and an increased susceptibility to ventricular arrhythmias were found after I/R compared to Sham controls in wild-type mice at 15 days post-perfusion, but not in Nlrp3^-/- or CASP1^-/- I/R, indicating that the absence of NLRP3 or CASP1 totally prevented longer QJ interval after renal I/R. In contrast with WT mice, we found no renal atrophy and no renal dysfunction in Nlrp3^-/- and Casp1^-/- mice after renal I/R. Depletion of macrophages in vivo after I/R and a day before IL-1β peak (at 7 days post-perfusion) totally prevented prolongation of QJ interval, suggesting that macrophages might participate as sensors of tissue injury. Moreover, treatment of I/R-WT mice with IL-1r antagonist (IL-1ra) from 8 to 15 days post perfusion did not interfere with renal function, but reversed QJ prolongation, prevented the increase in susceptibility to ventricular arrhythmias and rescued a close to normal duration and amplitude of calcium transient.

CONCLUSION

Taken together, these results corroborate the hypothesis that IL-1β is produced after sensing renal injury through NRLP3-CASP1, and IL-1β on its turn triggers longer ventricular repolarization and increase susceptibility to cardiac arrhythmias. Still, they offer a therapeutic approach to treat cardiac arrhythmias that arise after renal I/R.

In-Hospital Survival and Neurological Recovery Among Patients Requiring Renal Replacement Therapy in Post-Cardiac Arrest Period

Objectives

Acute kidney injury (AKI) is common after cardiac arrest (CA). Few data exist on survival and neurological outcomes measured at hospital discharge of patients with severe AKI requiring renal replacement therapy (RRT) within the first 72 hours (i.e., duration of post-CA syndrome).

Methods

Single-center, prospective, observation cohort of patients with in- or out-of-hospital CA who survived to intensive care unit admission and were considered for targeted temperature management between 2010 and 2016 were reviewed. After excluding preexisting RRT history, patients with new RRT requirements within the first 72 hours after CA were included. Primary outcome of survival and secondary outcome of good neurological recovery defined as cerebral performance category score of 1 to 2, were compared between patients with and without RRT. Within 24 hours of initiating RRT, illness severity, as measured by Sequential Organ Failure Assessment score, Acute Physiology and Chronic Health Evaluation–II, and Charlson Comorbidity Index, was compared between survivors and nonsurvivors.

Results

Of 524 patients, 65 (12.4%) had new RRT requirements within 72 hours. Survival rates and good neurological recovery at discharge were comparable between RRT and non-RRT groups (19 of 65 [29%] vs. 162 of 459 [35%], P = 0.3, and 8 of 19 [42%] vs. 73 of 162 [45%], respectively). Sixty-three percent (12 of 19) of survivors requiring RRT did not need dialysis on discharge. Among patients requiring RRT, prognostic factors, including illness severity scores and indications for RRT, did not differ between survivors and nonsurvivors.

Conclusions

Patients with severe AKI requiring RRT during the post-CA syndrome period were not associated with any significant reduction in survival or poor neurological recovery, compared with those without RRT. Among those requiring RRT, none of the known prognostic factors predicted survival.

Markers of cardiogenic shock predict persistent acute kidney injury after out of hospital cardiac arrest

OBJECTIVE

Ischemia and reperfusion injury (IRI) in cardiac arrest patients after return to spontaneous circulation causes dysfunctions in multiple organs. Kidney injury is generally transient but in some patients persists and contributes both to mortality and increased resource utilisation. Ongoing shock may compound renal injury from IRI, resulting in persistent dysfunction. We tested whether cardiac dysfunction was associated with the development of persistent acute kidney injury (PAKI) in the first 72 h after cardiac arrest.

METHODS

We performed an observational retrospective study from January 2013 to April 2017. We included consecutive patients treated after out-of-hospital cardiac arrest at a single academic medical center with renal function measured and immediately and for 48 h post arrest. We also recorded each patient's pre arrest baseline creatinine, demographic and clinical characteristics. Our primary outcome of interest was PAKI, defined as acute kidney injury (AKI) on at least 2 measurements 24 h apart. We compared demographics and outcomes between patients with PAKI and those without, and used logistic regression to identify independent predictors of PAKI.

RESULTS

Of 98 consecutive patients, we excluded 24 for missing data. AKI was present in 75% of subjects on arrival. PAKI developed in 35% of patients. PAKI patients had a longer hospital length of stay (median 21 vs 11 days) and lower hospital survival (47% vs 71%). Serum lactate levels, dosage of adrenaline during resuscitation and days of dobutamine infusion strongly predicted PAKI.

CONCLUSIONS

Among patient who survive cardiac arrest, acute AKI is common and PAKI occurs in more than one third. PAKI is associated both with survival and with length of stay at the hospital. High doses of adrenaline, high serial serum lactate levels, and dose of dobutamine predict PAKI. Evaluation of the trajectory of renal function over the first few days after resuscitation can provide prognostic information about patient recovery.

Acute kidney injury and mild therapeutic hypothermia in patients after cardiopulmonary resuscitation - a post hoc analysis of a prospective observational trial

Background

The aim of this study was to investigate the influence of mild therapeutic hypothermia (MTH) on the incidence of and recovery from acute kidney injury (AKI).

Methods

Patients who had undergone successful cardiopulmonary resuscitation (CPR) were included. Serum creatinine and cystatin C were measured at baseline, daily up to 5 days and at ICU discharge. AKI was defined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria. MTH was applied for 24 h targeting a temperature of 33 °C. Neurological outcome was assessed with the Cerebral Performance Categories score at hospital discharge.

Results

126 patients were included in the study; 73 patients (58%) developed AKI. Patients treated with MTH had a significantly lower incidence of AKI as compared to normothermia (NT) (44 vs. 69%; p = 0.004). Patients with less favourable neurological outcomes had a significantly higher rate of AKI, although when treated with MTH the occurrence of AKI was reduced (50 vs. 80%; p = 0.017). Furthermore, MTH treatment was accompanied by significantly lower creatinine levels on day 0–1 and at ICU discharge (day 0: 1.12 (0.90–1.29) vs. 1.29 (1.00–1.52) mg/dl; p = 0.016) and lower cystatin C levels on day 0–3 and at ICU discharge (day 0: 0.88 (0.77–1.10) vs. 1.29 (1.06–2.16) mg/l; p < 0.001).

Conclusions

Mild therapeutic hypothermia seems to have a protective effect against the development of AKI and on renal recovery. This may be less pronounced in patients with a favourable neurological outcome.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2061-6) contains supplementary material, which is available to authorized users.

TIMP-2/IGFBP7 predicts acute kidney injury in out-of-hospital cardiac arrest survivors

Background

Acute kidney injury (AKI) is a common complication after cardiopulmonary resuscitation (CPR) and predicts in-hospital mortality. To which extent post-resuscitation disease or the initial event of cardiac arrest and the duration of insufficient cardiac output triggers AKI is challenging to discriminate. Knowledge on molecular mediators of AKI is scarce. Early identification of patients at high risk of AKI is hampered by the low sensitivity of the established tests in clinical routine practice. The present study aimed to determine the diagnostic utility of the novel urine biomarkers tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) for the early recognition of AKI in patients with non-traumatic shock.

Methods

The performance of [TIMP-2]·[IGFBP7] was prospectively analysed in 48 patients with shock following out-of-hospital cardiac arrest (OHCA). All patients were treated with target temperature management (TTM) for 24 h. Urinary [TIMP-2]·[IGFBP7] samples were collected at 3 and 24 h after determination of OHCA.

Results

Patients (n = 31 (65%)) developed AKI after an average of 26 ± 12 h. Patients who developed AKI had significantly higher [TIMP-2]·[IGFBP7] compared to individuals that did not develop AKI (1.52 ± 0.13 vs. 0.13 ± 0.14; p < 0.05) as early as 3 h after determination of OHCA,. For urine [TIMP-2]*[IGFBP7], the area under the curve (AUC) for the development of AKI was 0.97 (CI 0.90–1.00) at 3 h after OHCA. The optimal [TIMP-2]·[IGFBP7] cut-off value for the prediction of AKI was 0.24. The sensitivity was 96.8% and specificity was 94.1%.

Conclusions

Urinary [TIMP-2]•[IGFBP7] reliably predicts AKI in high-risk patients only 3 h after determination of OHCA with a cut-off at 0.24. This novel test may help to identify patients at high risk of AKI to enrol into clinical studies to further elucidate the pathophysiology of AKI and devise targeted interventions in the future.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2042-9) contains supplementary material, which is available to authorized users.

Hypothermia and kidney: a focus on ischaemia-reperfusion injury

Cellular damage after reperfusion of ischaemic tissue is defined as ischaemia–reperfusion injury (IRI). Hypothermia is able to decrease oxygen consumption, preventing a rapid loss of mitochondrial activity. However, even though cooling can help to decrease the deleterious effects of ischaemia, the consequences are not exclusively beneficial, such that hypothermic storage is a compromise between benefits and harm. The present review details the relationship between renal IRI and hypothermia, describing the pathophysiology of IRI and hypothermic protection through experimental evidence. Although experimental models of renal IRI are a valuable tool for understanding the pathophysiology of renal ischaemia–reperfusion, the clinical transfer of experimental results has several limitations, particularly because of anatomical and physiological differences. In this review limitations of animal models but also hypothermia as a strategy to protect the kidney from IRI are discussed. We also attempt to describe three clinical scenarios where hypothermia is used in clinical settings of IRI: transplantation, deceased donors and post-cardiac arrest.

Association of plasma neutrophil gelatinase-associated lipocalin with acute kidney injury and clinical outcome in cardiac arrest survivors depends on the time of measurement

PURPOSE

The optimal timing for measurement of neutrophil gelatinase-associated lipocalin (NGAL) level to predict acute kidney injury (AKI) and prognosis in cardiac arrest (CA) survivors has not been elucidated. We aimed to compare the diagnostic and prognostic performance of NGAL levels after return of spontaneous circulation (ROSC) and at 48 h after CA.

METHODS

We included 231 adult cardiac arrest survivors who underwent targeted temperature management between May 2013 and December 2016. The primary outcome was stage 2 and 3 AKI (high stage AKI), and the secondary outcomes were in-hospital mortality and neurologic outcome. Sixty-one (26.4%) developed high stage AKI, 50 (21.6%) died, and 152 (65.8%) had a poor neurologic outcome.

RESULTS

NGAL level at 48 h (0.876; 95% confidence interval [CI], 0.826-0.916) had a higher area under receiver operating characteristic curve than NGAL level after ROSC (0.694; 95% CI, 0.631-0.753). Both NGAL levels were independently associated with high stage AKI. NGAL level at 48 h (1.001; 95% CI, 1.000-1.002) remained a significant predictor for in-hospital mortality, while neither of the NGAL levels were independently associated with neurologic outcome.

CONCLUSIONS

NGAL at 48 h after CA seems to be a robust predictor for high stage AKI and in-hospital mortality.

Recent advances in the pathogenetic mechanisms of sepsis-associated acute kidney injury

Sepsis is a serious medical condition that can lead to multi-organ failure and shock, and it is associated with increased mortality. Acute kidney injury (AKI) is a frequent complication of sepsis in critically ill patients, and often requires renal replacement therapy. The pathophysiology of AKI in sepsis has not yet been fully defined. In the past, classic theories were mainly focused on systemic hemodynamic derangements, underscoring the key role of whole kidney hypoperfusion due to reduced renal blood flow. However, a growing body of experimental and clinical evidence now shows that, at least in the early phase of sepsis-associated AKI, renal blood flow is normal, or even increased. This could suggest a dissociation between renal blood flow and kidney function. In addition, the scant data available from kidney biopsies in human studies do not support diffuse acute tubular necrosis as the predominant lesion. Instead, increasing importance is now attributed to kidney damage resulting from a complex interaction between immunologic mechanisms, inflammatory cascade activation, and deranged coagulation pathways, leading to microvascular dysfunction, endothelial damage, leukocyte/platelet activation with the formation of micro-thrombi, epithelial tubular cell injury and dysfunction. Moreover, the same processes, through maladaptive responses leading to fibrosis acting from the very beginning, may set the stage for progression to chronic kidney disease in survivors from sepsis-associated AKI episodes. The aim of this narrative review is to summarize and discuss the latest evidence on the pathophysiological mechanisms involved in septic AKI, based on the most recent data from the literature.

Plasma Neutrophil Gelatinase-Associated Lipocalin Measured Immediately After Restoration of Spontaneous Circulation Predicts Acute Kidney Injury in Cardiac Arrest Survivors Who Underwent Therapeutic Hypothermia

Early diagnosis of acute kidney injury (AKI) after cardiac arrest (CA) is challenging. We aimed to identify the diagnostic and prognostic performance of neutrophil gelatinase-associated lipocalin (NGAL) for AKI and its clinical outcomes. A retrospective observational study, involving adult comatose CA survivors treated with therapeutic hypothermia between May 2013 and December 2016, was conducted. AKI was classified according to the guidelines of Kidney Disease Improving Global Outcomes. NGAL levels were measured after return of spontaneous circulation (ROSC). The primary outcome was development of AKI within 7 days after CA, and the secondary outcome was inhospital mortality. The study included 279 patients, of which 111 (39.8%) developed AKI and 61 (21.9%) died. Thirty-seven (33.3%) of patients in the AKI group had stage 3 AKI, and 45 (40.5%) patients received renal replacement therapy. The area under the curve of NGAL levels for diagnosing AKI was 0.725 (95% confidence interval [CI] 0.668-0.776), and NGAL levels were independently associated with the development of AKI (odds ratio [OR] 1.004; 95% CI 1.002-1.006). Nonsurvivors had significantly higher NGAL levels (221.0 ng/mL [154.0-355.5] vs. 148.5 ng/mL [97.0-232.9]; p < 0.001). The development of AKI was independently associated with mortality (OR 4.926; 95% CI 2.353-10.311); however, NGAL level was not associated with mortality (OR 1.000; 95% CI 0.999-1.001). Plasma NGAL level measured after ROSC can be an early predictor for the development of AKI after CA. The presence of AKI was associated with increased inhospital mortality.

Risk factors of prognosis after acute kidney injury in hospitalized patients

The risk factors, especially laboratory indicators, of prognosis after acute kidney injury (AKI) remain unclear. We conducted a retrospective survey of Chinese People's Liberation Army General Hospital from January 1, 2012 to December 31, 2012 according to the AKI diagnosis standard issued by Kidney Disease Improving Global Outcomes. The epidemiological features and factors influencing hospital mortality and renal function recovery were evaluated through logistic regression analysis. Among 77 662 cases of hospitalized patients, 1387 suffered from AKI. The incidence rate and mortality of AKI were 1.79% and 14.56%, respectively. Multivariate logistic regression analysis revealed that high AKI stage, age greater than 80 years, neoplastic disease, low cardiac output, increased white blood cell count, and decreased platelet count and serum albumin levels were the risk factors affecting the mortality of AKI patients. Conversely, body mass index between 28 and 34.9 was a protective factor. Increased AKI stage, tumor disease, post-cardiopulmonary resuscitation, and RRT were the risk factors of renal function recovery upon discharge. In addition to traditional risk factors, white blood cell count, platelet count, albumin, and BMI were the predictors of the mortality of AKI patients. No laboratory indicators were found to be the risk factors of renal function recovery in AKI patients.

The influence of targeted temperature management on the pharmacokinetics of drugs administered during and after cardiac arrest: a systematic review

OBJECTIVE

Pharmacokinetic parameters of drugs are widely investigated under normothermic conditions and normal hemodynamic parameters. The European Resuscitation Council recommends the use of targeted temperature management (TTM) with a target temperature of 34 °C in cardiac arrest (CA) patients. The aim of this literature review is to investigate the influence of CA combined with TTM on the pharmacokinetics of drugs. Results of preclinical and clinical studies are compared with each other. Only the most important drugs, administered during CA in emergency setting, were studied.

METHODS

A literature search was conducted within PubMed and Google Scholar. The search terms included 'therapeutic hypothermia', 'TTM', 'drug metabolism', 'pharmacokinetics during hypothermia', 'cardiac arrest/etiology'. In Pubmed, MeSH-terms were also included: 'myocardial infarction/therapy', 'heart arrest/complications' and 'hypothermia'. To search for preclinical studies: the search terms 'pigs' and 'swine' were used. After the primary shift of relevant findings, further articles were found through references of these (snowballing method), as well as through related articles as suggested by the databases.

RESULTS

Due to the reduced cardiac output during TTM, most of the distribution volume ([Formula: see text]) of drugs included in this literature study is decreased. Only the [Formula: see text] of chlorzoxazone in CA rats and midazolam in non-CA patients are significantly increased during respectively deep and mild hypothermia. The renal, hepatic and biliary clearance of drugs administered during CA/TTM/hypothermia are decreased.

DISCUSSION

The combination of a decreased [Formula: see text] and a decrease in the metabolization/excretion of drugs during CA/TTM result in higher plasma concentrations compared to the plasma concentrations during CA without TTM.

Physiological aspects of Toll-like receptor 4 activation in sepsis-induced acute kidney injury

Sepsis‐induced acute kidney injury (SI‐AKI) is common and associated with high mortality. Survivors are at increased risk of chronic kidney disease. The precise mechanism underlying SI‐AKI is unknown, and no curative treatment exists. Toll‐like receptor 4 (TLR4) activates the innate immune system in response to exogenous microbial products. The result is an inflammatory reaction aimed at clearing a potential infection. However, the consequence may also be organ dysfunction as the immune response can cause collateral damage to host tissue. The purpose of this review is to describe the basis for how ligand binding to TLR4 has the potential to cause renal dysfunction and the mechanisms by which this may take place in gram‐negative sepsis. In addition, we highlight areas for future research that can further our knowledge of the pathogenesis of SI‐AKI in relation to TLR4 activation. TLR4 is expressed in the kidney. Activation of TLR4 causes cytokine and chemokine release as well as renal leucocyte infiltration. It also results in endothelial and tubular dysfunction in addition to altered renal metabolism and circulation. From a physiological standpoint, inhibiting TLR4 in large animal experimental SI‐AKI significantly improves renal function. Thus, current evidence indicates that TLR4 has the ability to mediate SI‐AKI by a number of mechanisms. The strong experimental evidence supporting a role of TLR4 in the pathogenesis of SI‐AKI in combination with the availability of pharmacological tools to target TLR4 warrants future human studies.

Neurology of cardiopulmonary resuscitation

This chapter aims to provide an up-to-date review of the science and clinical practice pertaining to neurologic injury after successful cardiopulmonary resuscitation. The past two decades have seen a major shift in the science and practice of cardiopulmonary resuscitation, with a major emphasis on postresuscitation neurologic care. This chapter provides a nuanced and thoughtful historic and bench-to-bedside overview of the neurologic aspects of cardiopulmonary resuscitation. A particular emphasis is made on the anatomy and pathophysiology of hypoxic-ischemic encephalopathy, up-to-date management of survivors of cardiopulmonary resuscitation, and a careful discussion on neurologic outcome prediction. Guidance to practice evidence-based clinical care when able and thoughtful, pragmatic suggestions for care where evidence is lacking are also provided. This chapter serves as both a useful clinical guide and an updated, thorough, and state-of-the-art reference on the topic for advanced students and experienced practitioners in the field.

The impact of extracerebral organ failure on outcome of patients after cardiac arrest: an observational study from the ICON database

Background

We used data from a large international database to assess the incidence and impact of extracerebral organ dysfunction on prognosis of patients admitted after cardiac arrest (CA).

Methods

This was a sub-analysis of the Intensive Care Over Nations (ICON) database, which contains data from all adult patients admitted to one of 730 participating intensive care units (ICUs) in 84 countries from 8–18 May 2012, except admissions for routine postoperative surveillance. For this analysis, patients admitted after CA (defined as those with “post-anoxic coma” or “cardiac arrest” as the reason for ICU admission) were included. Data were collected daily in the ICU for a maximum of 28 days; patients were followed up for outcome data until death, hospital discharge, or a maximum of 60 days in-hospital. Favorable neurological outcome was defined as alive at hospital discharge with a last available neurological Sequential Organ Failure Assessment (SOFA) subscore of 0–2.

Results

Among the 469 patients admitted after CA, 250 (53 %) had had out-of-hospital CA; 210 (45 %) patients died in the ICU and 357 (76 %) had an unfavorable neurological outcome. Non-survivors had a higher incidence of renal (43 vs. 16 %), cardiovascular (56 vs. 45 %), and respiratory (62 vs. 48 %) failure on admission and during the ICU stay than survivors (all p < 0.05). Similar results were found for patients with unfavorable vs. favorable neurological outcomes. In multivariable analysis, independent predictors of ICU mortality were renal failure on admission, high admission Simplified Acute Physiology Score (SAPS) II, high maximum serum lactate levels within the first 24 h after ICU admission, and development of sepsis. Independent predictors of unfavorable neurological outcome were mechanical ventilation on admission, high admission SAPS II score, and neurological dysfunction on admission.

Conclusions

In this multicenter cohort, extracerebral organ dysfunction was common in CA patients. Renal failure on admission was the only extracerebral organ dysfunction independently associated with higher ICU mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1528-6) contains supplementary material, which is available to authorized users.

Effect of Erythropoietin on Postresuscitation Renal Function in a Swine Model of Ventricular Fibrillation

Purpose. To investigate the effect of EPO administration on postresuscitation renal function. Methods. Twenty-four female Landrace/Large-White piglets aged 10–15 weeks with average weight of 19 ± 2 kg were randomly assigned to 2 different groups of 12 subjects each. After the end of an 8-minute ventricular fibrillation, the control group (Group C) received saline as placebo, whereas the EPO group (Group E) received EPO 5000 U/kg. The animals were resuscitated according to the 2010 European Resuscitation Council Guidelines for Resuscitation. Results. Five animals (41.67%) from Group C and 11 animals (91.67%) from Group E achieved ROSC (p = 0.027). Eight animals (66.67%, 5 surviving and 3 nonsurviving) from Group C suffered severe kidney damage or AKI compared to animals from Group E, in which none of the swine had evidence of severe kidney damage or AKI (p = 0.001). There was a statistically significant difference in all tested biochemical markers between the two groups, as well as a positive correlation of creatinine with NGAL, L-FABP, and IL-18 (summed mean values' p = 0.049, 0.01, and 0.004, resp.). Conclusions. Administration of EPO protected swine from postresuscitation acute kidney injury.

Analgesia, sedation, and neuromuscular blockade during targeted temperature management after cardiac arrest

The approach to sedation, analgesia, and neuromuscular blockade during targeted temperature management (TTM) remains largely unstudied, forcing clinicians to adapt previous research from other patient environments. During TTM, very little data guide drug selection, doses, and specific therapeutic goals. Sedation should be deep enough to prevent awareness during neuromuscular blockade, but titration is complex as metabolism and clearance are delayed for almost all drugs during hypothermia. Deeper sedation is associated with prolonged intensive care unit (ICU) and ventilator therapy, increased delirium and infection, and delayed wakening which can confound early critical neurological assessments, potentially resulting in erroneous prognostication and inappropriate withdrawal of life support. We review the potential therapeutic goals for sedation, analgesia, and neuromuscular blockade during TTM; the adverse events associated with that treatment; data suggesting that TTM and organ dysfunction impair drug metabolism; and controversies and potential benefits of specific monitoring. We also highlight the areas needing better research to guide our therapy.