Predictive value of interleukin-6 in post-cardiac arrest patients treated with targeted temperature management at 33 °C or 36 °C

Non-Coding RNAs to Aid in Neurological Prognosis after Cardiac Arrest

Cardiovascular disease in general, and sudden cardiac death in particular, have an enormous socio-economic burden worldwide. Despite significant efforts to improve cardiopulmonary resuscitation, survival rates remain low. Moreover, patients who survive to hospital discharge have a high risk of developing severe physical or neurological symptoms. Being able to predict outcomes after resuscitation from cardiac arrest would make it possible to tailor healthcare approaches, thereby maximising efforts for those who would mostly benefit from aggressive therapy. However, the identification of patients at risk of poor recovery after cardiac arrest is still a challenging task which could be facilitated by novel biomarkers. Recent investigations have recognised the potential of non-coding RNAs to aid in outcome prediction after cardiac arrest. In this review, we summarize recent discoveries and propose a handful of novel perspectives for the use of non-coding RNAs to predict outcome after cardiac arrest, discussing their use for precision medicine.

The Role of Inflammatory Cytokines in Cardiac Arrest

Introduction:

Post-cardiac arrest syndrome (PCAS) is characterized by systemic ischemia/reperfusion injury, anoxic brain injury, and post-arrest myocardial dysfunction superimposed on a precipitating pathology. The role of inflammatory cytokines in cardiac arrest remains unclear.

Aims:

We aimed to describe, with an emphasis on clinical applications, what is known about the role of inflammatory cytokines in cardiac arrest.

Data Sources:

A PubMed literature review was performed for relevant articles. Only articles in English that studied cytokines in patients with cardiac arrest were included.

Results:

Cytokines play a crucial role in the pathogenesis of PCAS. Following cardiac arrest, the large release of circulating cytokines mediates the ischemia/reperfusion injury, brain dysfunction, and myocardial dysfunction seen. Interleukins, tumor necrosis factor, and matrix metalloproteinases all play a unique prognostic role in PCAS. High levels of inflammatory cytokines have been associated with mortality and/or poor neurologic outcomes. Interventions to modify the systemic inflammation seen in PCAS continue to be heavily studied. Currently, the only approved medical intervention for comatose patients following cardiac arrest is targeted temperature management. Medical agents, including minocycline and sodium sulfide, have demonstrated promise in animal models.

Conclusions:

The role of inflammatory cytokines for both short- and long-term outcomes is an important area for future investigation.

Venoarterial Extracorporeal Membrane Oxygenation Increased Immune Function of Spleen and Decreased Reactive Oxygen Species During Post-Resuscitation

We aimed to investigate the effect of venoarterial extracorporeal membrane oxygenation (VA-ECMO) on immune function of the spleen and reactive oxygen species (ROS) during post-resuscitation in a porcine model. After 8 min of untreated ventricular fibrillation and 6 min of basic life support, pigs were randomized into two groups: Group 1 received VA-ECMO and Group 2 received conventional cardiopulmonary resuscitation. After successful return of spontaneous circulation, the hemodynamic status was determined and blood samples were collected at 0, 1, 2, 4, and 6 h. Surviving pigs were euthanized 6 h after return of spontaneous circulation, their spleens were harvested and the T-cells were separated. Then, we investigated immune function parameters of the spleen and ROS levels. VA-ECMO increased the return of spontaneous circulation and 6 h survival rate after return of spontaneous circulation. Compared with the conventional cardiopulmonary resuscitation group, the VA-ECMO group showed increased superoxide dismutase and decreased malondialdehyde and ROS levels. Furthermore, VA-ECMO was associated with a high rate of CD4+ and CD4+/CD8+, high levels of interleukin 2, interferon γ, and interferon γ/interleukin 4, as well as high proliferation of lymphocytes. The apoptotic rate of T-cells was lower in the VA-ECMO group than it was in the conventional cardiopulmonary resuscitation group. VA-ECMO increased immune function of spleen and decreased ROS levels during post-resuscitation. Further research is expected to illustrate whether the differences in immune responses are due to ROS or some other perfusion related effect on spleen.

Interleukin-6 Levels in Cerebrospinal Fluid and Plasma in Patients with Severe Spontaneous Subarachnoid Hemorrhage

BACKGROUND

Inflammatory processes play a key role in the pathophysiology of subarachnoid hemorrhage (SAH). This study evaluated whether different temporal patterns of intrathecal and systemic inflammation could be identified in the acute phase after SAH. The intensity of the inflammation was also assessed in clinical subgroups.

METHODS

Cerebrospinal fluid (CSF) and blood samples were collected at days 1, 4, and 10 after ictus in 44 patients with severe SAH. Interleukin-6 (IL-6) was analyzed by a routine monoclonal antibody-based method. Median IL-6 values for each day were calculated. Day 4 IL-6 values were compared in dichotomized groups (age, sex, World Federation of Neurosurgical Societies [WFNS] grade, Fisher scale grade, outcome, vasospasm, central nervous system infection and systemic infections).

RESULTS

CSF IL-6 levels were significantly elevated from day 1 to days 4 and 10, whereas plasma IL-6 showed a different trend at lower levels. Median CSF IL-6 concentrations for days 1, 4, and 10 were 876.5, 3361, and 1567 ng/L, whereas plasma was 26, 27.5, and 15.9 ng/L, respectively. No significant differences in CSF concentrations were observed between the subgroups, with the most prominent one being in day 4 IL-6 in the WFNS subgroups (grades 1-3 vs. 4-5, 1158.5 vs. 5538 ng/L; P = 0.056). Patients with systemic infection had significantly higher plasma IL-6 concentrations than patients without infection (31 vs. 16.05 ng/L, respectively; P = 0.028).

CONCLUSIONS

Distinctly different inflammatory patterns could be seen intrathecally compared with the systemic circulation. In plasma, a significant difference in the intensity of the inflammation was seen in cases with systemic infection. No other subgroup showed statistically significant differences.

Methods for Defining the Neuroprotective Properties of Xenon

Xenon has features that make it an ideal general anesthetic agent; cost and scarcity mitigate xenon's widespread use in the operating room. Discovery of xenon's cytoprotective properties resulted in its application to thwart ongoing acute neurologic injury, an unmet clinical need. The discovery that xenon's neuroprotective effect interacts synergistically with targeted temperature management (TTM) led to its investigation in clinical settings, including in the management of the postcardiac arrest syndrome, in which TTM is indicated. Following successful demonstration of xenon's efficacy in combination with TTM in a preclinical model of porcine cardiac arrest, xenon plus TTM was shown to significantly decrease an imaging biomarker of brain injury for out of hospital cardiac arrest victims that had been successfully resuscitated. With the development of an efficient delivery system the stage is now set to investigate whether xenon improves survival, with good clinical outcome, for successfully resuscitated victims of a cardiac arrest.

Impact of age on cardiovascular function, inflammation, and oxidative stress in experimental asphyxial cardiac arrest

BACKGROUND

Advanced age is an independent predictor of poor outcome after cardiac arrest (CA). From experimental studies of regional ischemia-reperfusion injury, advanced age is associated with larger infarct size, reduced organ function, and augmented oxidative stress. The objective of this study was to investigate the effect of age on cardiovascular function, oxidative stress, inflammation, and endothelial activation after CA representing global ischemia-reperfusion.

METHODS

Aged (26 months) and young (5 months) rats were subjected to 8 min of asphyxia induced CA, resuscitated and observed for 360 min. Left ventricular pressure-derived cardiac function was measured at baseline and 360 min after CA. Blood samples obtained at baseline, 120 min, and 360 min after CA were analyzed for IL-1β, IL-6, IL-10, TNF-α, elastase, sE-selectin, sL-selectin, sI-CAM1, hemeoxygenase-1 (HO-1) and protein carbonyl. Tissue samples of brain, heart, kidney, and lung were analyzed for HO-1.

RESULTS

Cardiac function, evaluated by dP/dt_max and dP/dt_min , was decreased after CA in both young and aged rats, with no group differences. Mean arterial pressure increased after CA in young, but not old rats. Aged rats showed significantly higher plasma levels of elastase and sE-selectin after CA, and there was a significant different development over time between groups for IL-6 and IL-10. Young rats showed higher levels of HO-1 in plasma and renal tissue after CA.

CONCLUSION

In a rat model of asphyxial CA, advanced age is associated with an attenuated hyperdynamic blood pressure response and increased endothelial activation.

Significant Cytokine mRNA Expression Changes Immediately after Initiation of Cardiopulmonary Resuscitation

Introduction

The purpose of this study was to evaluate immediate immunological changes following cardiopulmonary resuscitation (CPR). mRNA expression levels of selected immunomodulatory cytokines in out-of-hospital cardiac arrest (OHCA) survivors were detected and correlated to clinical parameter.

Methods

OHCA survivors with sustained unconsciousness after return of spontaneous circulation (ROSC) were included. PAXgene whole blood samples were drawn immediately after initiation of CPR and subsequently after 6 h, 12 h, 24 h, 48 h, and 72 h. TNF-alpha, IL-8, IL-10, and IL-1ra mRNA levels were quantified by RT-qPCR and compared to multiple organ failure, 30-day survival, and the induction of therapeutic hypothermia (TH).

Results

25 patients (63 ± 15 years) were enrolled presenting a characteristic time-dependent cytokine profile in the early postresuscitation period. High initial TNF-alpha and IL-8 mRNA levels were followed by a significant decrease. IL-1ra mRNA levels significantly increased beginning after 6 h. Nonsurvivors showed significantly higher IL-8 mRNA levels immediately after CPR. TH induced significantly higher IL-1ra mRNA levels compared to normothermia.

Conclusion

Significant mRNA cytokine expression changes are already detectable immediately after initiation of CPR. These expressional changes are significantly different depending on 30-day survival. TH seems to attenuate proinflammatory immune reaction by a significant increase of IL-1ra mRNA levels. This trial is registered with DRKS00012940.

Inflammatory Biomarkers Interleukin-6 and C-Reactive Protein and Outcomes in Stable Coronary Heart Disease: Experiences From the STABILITY (Stabilization of Atherosclerotic Plaque by Initiation of Darapladib Therapy) Trial

BACKGROUND

Evaluation of cardiovascular prognosis in patients with stable coronary heart disease is based on clinical characteristics and biomarkers indicating dysglycemia, dyslipidemia, renal dysfunction, and possibly cardiac dysfunction. Inflammation plays a key role in atherosclerosis, but the association between inflammatory biomarkers and clinical outcomes is less studied in this population.

METHODS AND RESULTS

Overall, 15 828 patients with coronary heart disease in the STABILITY (Stabilization of Atherosclerotic Plaque by Initiation of Darapladib Therapy) trial were randomized to treatment with darapladib or placebo and observed for a median of 3.7 years. In 14 611 patients, levels of interleukin-6 (IL-6) and high-sensitivity C-reactive protein were measured in plasma samples: median levels were 2.1 (interquartile range, 1.4-3.2) ng/L and 1.3 (interquartile range, 0.6-3.1) mg/L, respectively. Associations between continuous levels or quartile groups and adjudicated outcomes were evaluated by spline graphs and Cox regression adjusted for clinical factors and cardiovascular biomarkers. IL-6 was associated with increased risk of major adverse cardiovascular events (quartile 4 versus quartile 1 hazard ratio [HR], 1.60; 95% confidence interval [CI], 1.30-1.97; P<0.0001); cardiovascular death (HR, 2.15; 95% CI, 1.53-3.04; P<0.0001); myocardial infarction (HR, 1.53; 95% CI, 1.14-2.04; P<0.05); all-cause mortality (HR, 2.11; 95% CI, 1.62-2.76; P<0.0001); and risk of hospitalization for heart failure (HR, 2.28; 95% CI, 1.34-3.89; P<0.001). Cancer death was doubled in the highest IL-6 quartile group (HR, 2.34; 95% CI, 1.20-4.53; P<0.05). High-sensitivity C-reactive protein was associated with both cardiovascular and non-cardiovascular events in the unadjusted model, but these did not remain after multivariable adjustments.

CONCLUSIONS

IL-6, an upstream inflammatory marker, was independently associated with the risk of major adverse cardiovascular events, cardiovascular and all-cause mortality, myocardial infarction, heart failure, and cancer mortality in patients with stable coronary heart disease. IL-6 might reflect a pathophysiological process involved in the development of these events.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00799903.

Early Lactate Clearance Is Associated With Improved Outcomes in Patients With Postcardiac Arrest Syndrome: A Prospective, Multicenter Observational Study (SOS-KANTO 2012 Study)

OBJECTIVES

To determine whether early lactate reduction is associated with improved survival and good neurologic outcome in patients with out-of-hospital cardiac arrest.

DESIGN

Ad hoc data analysis of a prospective, multicenter observational study.

SETTING

Out-of-hospital cardiac arrest patients at 67 emergency hospitals in Kanto, Japan between January 2012 and March 2013.

PATIENTS

Adult patients with out-of-hospital cardiac arrest admitted to the hospital after successful resuscitation were identified.

INTERVENTIONS

Blood lactate concentrations were measured at hospital admission and 6 h after hospital admission. Early lactate clearance was defined as the percent change in lactate level 6 h after a baseline measurement.

MEASUREMENTS AND MAIN RESULTS

The 543 patients (mean age, 65 ± 16 yr; 72.6% male) had a mean lactate clearance of 42.4% ± 53.7%. Overall 30-day survival and good neurologic outcome were 47.1% and 27.4%, respectively. The survival proportion increased with increasing lactate clearance (quartile 1, 29.4%; quartile 2, 42.6%; quartile 3, 51.5%; quartile 4, 65.2%; p < 0.001). Multivariate logistic regression analysis showed that lactate clearance quartile was an independent predictor of the 30-day survival and good neurologic outcome. In the Cox proportional hazards model, the frequency of mortality during 30 days was significantly higher for patients with lactate clearance in quartile 1 (hazard ratio, 3.12; 95% CI, 2.14-4.53), quartile 2 (hazard ratio, 2.13; 95% CI, 1.46-3.11), and quartile 3 (hazard ratio, 1.49; 95% CI, 1.01-2.19) than those with lactate clearance in quartile 4. Furthermore, multivariate logistic regression analysis revealed that lactate clearance was a significant predictor of good neurologic outcome at 30 days after hospital admission.

CONCLUSIONS

Effective lactate reduction over the first 6 hours of postcardiac arrest care was associated with survival and good neurologic outcome independently of the initial lactate level.

Targeted temperature management in neurological intensive care unit

Targeted temperature management (TTM) shows the most promising neuroprotective therapy against hypoxic/ischemic encephalopathy (HIE). In addition, TTM is also useful for treatment of elevated intracranial pressure (ICP). HIE and elevated ICP are common catastrophic conditions in patients admitted in Neurologic intensive care unit (ICU). The most common cause of HIE is cardiac arrest. Randomized control trials demonstrate clinical benefits of TTM in patients with post-cardiac arrest. Although clinical benefit of ICP control by TTM in some specific critical condition, for an example in traumatic brain injury, is still controversial, efficacy of ICP control by TTM is confirmed by both in vivo and in vitro studies. Several methods of TTM have been reported in the literature. TTM can apply to various clinical conditions associated with hypoxic/ischemic brain injury and elevated ICP in Neurologic ICU.

Mortality in patients resuscitated from out-of-hospital cardiac arrest based on automated blood cell count and neutrophil lymphocyte ratio at admission

INTRODUCTION

The neutrophil lymphocyte ratio(NLR) is a marker of systemic inflammation. We hypothesized that admission NLR is related to mortality and that epinephrine application during resuscitation influences NLR in patients after successful resuscitation from out of hospital cardiac arrest (OHCA).

METHODS

This retrospective cohort study is based on a registry including all OHCA patients who had a presumed cardiac cause of cardiac arrest and achieved sustained ROSC prior to admission between 2005 and 2014. Patients were categorized into three groups according to the calculated NLR at admission (NLR <6, ≥6, and 'abnormal differential' indicating no differential blood cell count on patients report due to exceedance of machine predefined parameter limits). The primary outcome measure was long-term mortality after OHCA. Cox proportional hazards models were used for multivariable analysis.

RESULTS

Out of 2273 OHCA patients during the study period a total of 1188(52%) patients were eligible for analysis, of those 274(23%) were female and mean age was 64 (25-75 IQR:52-72). Compared to a NLR<6 (n=442), adjusted hazard ratio for long-term mortality was significantly higher in patients with a NLR≥6 (n=447; 1.52 (95%CI 1.03-2.24)) and in patients with abnormal differential (n=299; 3.16 (95%CI 2.02-4.97)). Epinephrine application during resuscitation did not explain the effect of NLR on mortality.

CONCLUSION

In this large retrospective cohort study of altogether >1000 OHCA patients, hospital admission NLR<6 compared to abnormal differential or NLR≥6 was associated with mortality independently from epinephrine application.

Serum levels of interleukin-6 may predict organ dysfunction earlier than SOFA score

Aim

To investigate the clinical utility of interleukin‐6 (IL‐6), procalcitonin (PCT), and C‐reactive protein (CRP) as predictive markers in consideration of the time‐course changes in critically ill patients with organ dysfunction.

Methods

Serum levels of IL‐6, PCT, CRP, and Sequential Organ Failure Assessment (SOFA) scores were measured sequentially in 92 patients during their initial 5 days following admission to the intensive care unit. Maximum values were analyzed. Patients were assigned to a low ( ≤ 8), intermediate ( > 8 and ≤ 16), or high ( > 16 and ≤ 24) SOFA score group.

Results

There were significant differences in the maximum serum levels of IL‐6 and PCT among the three SOFA score groups (IL‐6, P < 0.0001; PCT, P = 0.0004). Specifically, comparisons between the groups revealed significant differences in IL‐6 levels (low versus intermediate, P = 0.0007; intermediate versus high, P = 0.0010). The probability of patients with the maximum value was greatest on day 1 (56.5%) for IL‐6, on day 1 (39.1%) or day 2 (38.0%) for PCT, on day 3 (39.1%) for CRP, and on day 1 (43.5%) for SOFA score. The median (interquartile range) peak day of IL‐6 was day 1 (1–2), which was significantly earlier than that of SOFA score at day 2 (1–3) (P = 0.018).

Conclusion

Serum levels of IL‐6 reflected the severity of organ dysfunction in critically ill patients most accurately compared to PCT and CRP. Interleukin‐6 elevated soonest from the insult and reached its peak earlier than SOFA score.

Predicting the outcomes for out-of-hospital cardiac arrest patients using multiple biomarkers and suspension microarray assays

Predicting the prognosis for cardiac arrest is still challenging. Combining biomarkers from diverse pathophysiological pathways may provide reliable indicators for the severity of injury and predictors of long-term outcomes. We investigated the feasibility of using a multimarker strategy with key independent biomarkers to improve the prediction of outcomes in cardiac arrest. Adult out-of-hospital cardiac arrest patients with sustained return of spontaneous circulation were prospectively enrolled in this study. Blood samples were taken at 2 and 24 hours after cardiac arrest. Suspension microarray assays were used to test 21 different biomarkers. A total of 99 patients were enrolled, 45 of whom survived to hospital discharge. We identified 11 biomarkers that, when combined with clinical variables and factors of APACHE II score and history of arrhythmia, were independent determinants for outcome of in-hospital mortality (concordance = 0.9249, standard error = 0.0779). Three biomarkers combined with APACHE II and age were independent determinants for favorable neurological outcome at hospital discharge (area under the receiver-operator characteristic curve, 0.938; 95% confidence interval, 0.854 ~ 1.0). In conclusion, a systemic multiple biomarker approach using suspension microarray assays can identify independent predictors and model the outcomes of cardiac arrest patients during the post-cardiac arrest period.