Asphyxia-induced Cardiac Arrest Research Articles

Abstract 198: Protective Effects of Exosomes Derived From Remote Ischemic Adaptation on Neurological Function After Cardiac Arrest in Rats

Objective: To assess the therapeutic effects and underlying mechanisms of exogenous exosomes derived from RIC in improving post-resuscitation neurologic dysfunction in a rat model of CA. Methods: Exogenous exosomes were isolated from the plasma of healthy adult male Sprague-Dawley rats that underwent RIC.36 adult male SD rats were randomly assigned to three groups: 1) Sham, 2) Control, or 3) Exosome. The control and exosome groups underwent 7 minutes of asphyxia-induced cardiac arrest. Five minutes after the ROSC, either exosome (1х10 10 Particles) or placebo (normal saline) were administered via intravenous infusion. Neurological outcomes were assessed using the neuropsychological deficit score (NDS), open field test, Y maze, and Morris Water Maze. Levels of plasma hyaluronic acid (HA) and syndecan-1 (Sdc-1) were measured to evaluate the degree of endothelium glycocalyx degradation. Results: Compared with Sham group, the Control group showed significant neurological dysfunction after ROSC. Compared to the control group, the exosome group exhibited significantly better performance in the open field, Y maze experiments and Morris water maze ( p < 0.05). Compared with the Sham group, the plasma levels of HA and Sdc-1 in the Control group were significantly increased 24 hours after ROSC (P<0.05), while the plasma levels of HA and Sdc-1 in the Exosome group were significantly lower than those in the Control group(P<0.05). Conclusions: Exosomes derived from RIC have been shown to be effective in improving neurological dysfunction following cardiac arrest. The reduction of endothelium glycocalyx degradation may be involved in the underlying mechanism.

Comparison of hemodynamic effects of chest compression delivered via machine or human in asphyxiated piglets

BackgroundHigh-quality chest compressions (CC) are an important factor of neonatal resuscitation. Mechanical CC devices may provide superior CC delivery and improve resuscitation outcomes. We aimed to compare the hemodynamic effects of CC delivered by machine and human using a neonatal piglet model.MethodsTwelve asphyxiated piglets were randomized to receive CC during resuscitation using an automated mechanical CC device (“machine”) or the two-thumb encircling technique (“human”). CC was superimposed with sustained inflations.ResultsTwelve newborn piglets (age 0–3 days, weight 2.12 ± 0.17 kg) were included in the study. Machine-delivered CC resulted in an increase in stroke volume, and minimum and maximum rate of left ventricle pressure change (dp/dtmin and dp/dtmax) compared to human-delivered CC.ConclusionsDuring machine-delivered CC, stroke volume and left ventricular contractility were significantly improved. Mechanical CC devices may provide improved cardiopulmonary resuscitation outcomes in neonatal cardiac arrest induced by asphyxia.ImpactMachine chest compression leads to changes in hemodynamic parameters during resuscitation of asphyxiated neonatal piglets, namely greater stroke volume and left ventricular contractility, compared with standard two-thumb compression technique. Mechanical chest compression devices may provide improved cardiopulmonary resuscitation outcomes in neonatal and pediatric asphyxia-induced cardiac arrest.

EXTRACORPOREAL CARDIOPULMONARY RESUSCITATION WITH THERAPEUTIC HYPOTHERMIA MITIGATES KIDNEY INJURY AFTER CARDIAC ARREST IN RATS.

Many patients with cardiac arrest (CA) experience severe kidney injury after the return of spontaneous circulation. This study aimed to compare the renal protective effect of conventional cardiopulmonary resuscitation (CCPR), extracorporeal cardiopulmonary resuscitation (ECPR), and ECPR with therapeutic hypothermia (ECPR+T) in a CA rat model. Twenty-four adult male Sprague-Dawley rats were randomly and equally allocated into the sham, CCPR, ECPR, and ECPR+T groups. The sham group underwent basic surgical procedures without asphyxia-induced CA. The other three groups were treated with asphyxiation to establish the CA model. Subsequently, they were rescued using three different therapeutic methods. The end points were 1 h after return of spontaneous circulation or death. Renal injury was evaluated by histopathology. Oxidative stress, endoplasmic reticulum stress, necroptosis, inflammatory, and apoptosis-related genes, and proteins were detected using western blotting, ELISA, and assay kit. Compared with CCPR, ECPR and ECPR+T alleviated oxidative stress by upregulating nuclear factor erythroid 2-related factor 2, superoxide dismutase, glutathione and downregulating heme oxygenase-1, and malondialdehyde. Expression of endoplasmic reticulum stress-related proteins, glucose-regulated protein 78, and CCAAT/enhancer-binding protein homologous protein was lower in ECPR and ECPR+T groups than that in the CCPR group, along with levels of TNF-α, IL-6, and IL-β, and necroptosis proteins (receptor-interacting serine/threonine kinases 1 and 3). Furthermore, the ECPR and ECPR+T groups had significantly increased B-cell lymphoma 2 and decreased B-cell lymphoma 2-associated X levels compared with the CCPR group. Extracorporeal cardiopulmonary resuscitation and ECPR+T alleviate kidney damage after CA in rats compared with CCPR. Furthermore, ECPR+T had a better renal protective effect.

Insight into the mechanisms of therapeutic hypothermia for asphyxia cardiac arrest using a comprehensive approach of GC-MS/MS and UPLC-Q-TOF-MS/MS based on serum metabolomics

Cardiac arrest (CA) is a severe worldwide health problem. Therapeutic hypothermia is widely used to reduce the cardiac injury and improve the neurological outcomes after CA. However, a few studies have reported the changes of serum metabolic characteristics after CA. The healthy male New Zealand Rabbits successfully resuscitated from 10-min asphyxia-induced CA were divided randomly into the normothermia (NT) group and mild therapeutic hypothermia (HT) group. The sham group underwent sham-operation. Survival was recorded and neurological deficit score (NDS) was assessed. The serum non-targeted metabolomics were detected using ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) and gas chromatography tandem mass spectrometry (GC-MS/MS) at 15 min, 3 h, 6 h and 24 h after return of spontaneous circulation (ROSC). Our study showed that the heart rate (HR) significantly slowed down during 0.5–6 h post ROSC, consistent with the decreasing trend of body temperature in the HT group. Compared with the NT group, the levels of Lac and PCO2 at 24 h post ROSC were lower, while a significant increase in PO2 level at 24 h post ROSC was observed in the HT group. The survival rate of the HT group was significantly higher than that of the NT group, and NDS scores were remarkably increased at 24 h post ROSC in the NT group. Significant differences in metabolic profiles at 15 min, 3 h, 6 h and 24 h post ROSC were observed among the Sham, NT and HT groups. The differential metabolites detected by UPLC-Q-TOF-MS/MS and GC-MS/MS were screened for further study between every two groups (NT vs sham, HT vs sham and HT vs NT) at 15 min, 3 h, 6 h and 24 h post ROSC. Phenylalanine metabolism, alanine, aspartate and glutamate metabolism and tricarboxylic acid (TCA) cycle were enriched in NT vs sham, HT vs sham and HT vs NT respectively. Our study demonstrated that therapeutic hypothermia improves the survival and neurological outcomes in rabbit model of cardiac arrest, and firstly represents the dynamic metabolic changes in the hypothermia therapy for CA by comprehensive UPLC-Q-TOF-MS/MS- and GC-MS/MS-based metabolomics.

Rat model of asphyxia-induced cardiac arrest and resuscitation.

Neurologic injury after cardiopulmonary resuscitation is the main cause of the low survival rate and poor quality of life among patients who have experienced cardiac arrest. In the United States, as the American Heart Association reported, emergency medical services respond to more than 347,000 adults and more than 7,000 children with out-of-hospital cardiac arrest each year. In-hospital cardiac arrest is estimated to occur in 9.7 per 1,000 adult cardiac arrests and 2.7 pediatric events per 1,000 hospitalizations. Yet the pathophysiological mechanisms of this injury remain unclear. Experimental animal models are valuable for exploring the etiologies and mechanisms of diseases and their interventions. In this review, we summarize how to establish a standardized rat model of asphyxia-induced cardiac arrest. There are four key focal areas: (1) selection of animal species; (2) factors to consider during modeling; (3) intervention management after return of spontaneous circulation; and (4) evaluation of neurologic function. The aim was to simplify a complex animal model, toward clarifying cardiac arrest pathophysiological processes. It also aimed to help standardize model establishment, toward facilitating experiment homogenization, convenient interexperimental comparisons, and translation of experimental results to clinical application.

Abstract 02: Intravenous Oxygen Microparticles as Resuscitative Fluid Improves Outcomes in a Swine Model of Asphyxial Cardiac Arrest

Introduction: Asphyxia-induced cardiac arrest (ACA) can lead to organ damage and death within minutes, with a reported survival rate of 25-38%. It is the leading cause of in-hospital cardiac arrest in children and elderly and the second in adults. The direct injection of oxygen as a rescue therapy for ACA is not yet possible. Methods: We manufactured immediate-release intravenous oxygen (IVO 2 ) microparticles with a shell composed of biocompatible dextran polymers formed by nanoprecipitation. Following intravenous injection, the hydrophobic shell transitions from a crystalline state to a rapidly dissolving, fluid shell based on pH (A). IVO 2 was manufactured following Good Manufacturing Practice control over particle size, chemical purity, and sterility. Following instrumentation, Yorkshire swine (n=10 control, n=6 IVO 2 ) underwent complete asphyxia by endotracheal tube occlusion for 12 minutes (B). ACLS was performed whenever SBP<40 mmHg. At minute 6, 8 and 10 of asphyxia, IVO 2 or placebo (20 mL/kg fluid phase) was administered. Animals were then survived for 4 days in an ICU environment, followed by brain MRI and neurohistology. Results: Animals receiving IVO 2 exhibited increased arterial oxygen saturation during asphyxia (p<0.05, C), with less CPR time (p<0.001, D) and higher ROSC (p=0.011, E). Three out of 6 IVO 2 animals vs 0/3 surviving controls were successfully extubated (p=0.035). IVO 2 treatment was associated with increased survival (p=0.037, F) with improved swine neurologic deficit scores (p<0.05, G). MRI (H) and pathology (I) demonstrated devastating hypoxic-ischemic injury in all surviving controls, endpoints that were significantly improved with IVO 2 . No significant adverse effects were noted in hematologic, coagulation, hepatic, or renal function due to IVO 2 . Conclusion: Treatment of ACA with IVO 2 may diminish critical oxygen deficit, resulting in improved survival and neurological outcomes.

Abstract 04: Chest Compressions Superimposed With Sustained Inflations Compared to Continuous Chest Compressions with Asynchronized Ventilation During Cardiopulmonary Resuscitation in Asphyxiated Pediatric Piglets - A Randomized Controlled Animal Study

Introduction: Respiratory arrest is the leading cause of pediatric cardiac arrest. Pediatric CRP guidelines therefore focus on respiratory support during CPR, but the optimal approach to oxygen delivery and coronary perfusion during pediatric CPR is not known. Animal studies reported that chest compressions superimposed with constant high distending pressure, or sustained inflation (CC+SI), significantly reduces time to return of spontaneous circulation (ROSC) compared to 3:1 chest compression:ventilation in neonatal piglets or chest compressions with asynchronous ventilation (CCaV) in pediatric piglets. During CC+SI, both cardiovascular and respiratory parameters were improved, which resulted in the faster time to ROSC. Hypothesis: In the current study, we hypothesized that CC+SI, compared to CCaV, would reduce time to ROSC in pediatric piglets with asphyxia-induced cardiac arrest. Methods: Twenty-eight pediatric piglets (21-24 days old, 7.5-9.2 kg) were anesthetized, intubated, instrumented, and exposed to 30 min normocapnic hypoxia followed by asphyxia. Piglets were then randomized to, and received, either CC+SI or CCaV for resuscitation (n=14 per group). Resuscitative efforts were continued until ROSC was achieved, or up to a maximum of 10 min. Hemodynamic parameters were monitored throughout the experiment and up to 30 min post-ROSC. Results and Conclusions: Overall, the mean (SD) time to ROSC was 208 (190) sec with CC+SI and 388 (258) sec with CCaV (p=0.045) (Table 1). There was a 100% increase in the number of piglets achieving ROSC with CC+SI compared to CCaV (CC+SI n=12 versus CCaV n=6, p=0.046). Median minute ventilation in the CC+SI group was 2,315 mL/min compared with 354 mL/min in the CCaV group (p=0.0001). Both systolic and diastolic blood pressure were higher in the CC+SI group, compared to the CCaV group throughout resuscitation. In summary, CC+SI improved time to ROSC and increased the number of piglets achieving ROSC. There was significantly higher minute ventilation with CC+SI, compared to CCaV, and both systolic and diastolic blood pressure were higher throughout resuscitation with CC+SI compared to CCaV. Studies in pediatric patients using CC+SI are warranted.

Abstract 165: 21% Or 100% Oxygen During Cardiopulmonary Resuscitation in Asphyxiated Pediatric Piglets - A Randomized Controlled Animal Study

Background: Current pediatric resuscitation guidelines recommend 100% oxygen (O 2 ) during cardiopulmonary resuscitation (CPR), however the most effective O 2 concentration for pediatric patients remains unknown. Aim: To determine if 21%O 2 during CPR with either chest compression (CC) during sustained inflation (SI) (CC+SI) or continuous chest compression with asynchronized ventilation (CCaV) will reduce time to return of spontaneous circulation (ROSC) compared to 100%O 2 in pediatric piglets with asphyxia-induced cardiac arrest. Methods: Piglets (20-23 days of age, weighing 6.2-10.2 kg) were anesthetized, intubated, instrumented, and exposed to asphyxia. Cardiac arrest was defined as mean arterial blood pressure <25 mmHg with bradycardia. After cardiac arrest, piglets were randomized to CC+SI or CCaV with either 21% or 100%O 2 or sham. Heart rate, arterial blood pressure, carotid blood flow, and respiratory parameters were continuously recorded. Results: There were no differences in baseline parameters or the duration and degree of asphyxiation. Median (interquartile range) time to ROSC was 107 (90-440) and 140 (105-200) sec with CC+SI 21% and 100%O 2 and 600 (50-600) and 600 (95-600)sec with CCaV 21% and 100%O 2 (p=0.27). Overall, 6 (86%) and 6 (86%) with CC+SI 21% and 100%O 2 and 3 (43%) and 3 (43%) achieved ROSC with CCaV 21% and 100%O 2 (p=0.13). Conclusions: In pediatric piglets resuscitated with 21% oxygen compared to 100% oxygen, using either CCaV or CC+SI had similar time to ROSC and survival. CPR using CC+SI had shorter time to ROSC and higher survival compared to CCaV. Clinical studies comparing 21% with 100%O 2 during pediatric CPR are warranted.

A Randomized, Controlled Animal Study: 21% or 100% Oxygen during Cardiopulmonary Resuscitation in Asphyxiated Infant Piglets.

During pediatric cardiopulmonary resuscitation (CPR), resuscitation guidelines recommend 100% oxygen (O2); however, the most effective O2 concentration for infants unknown. We aimed to determine if 21% O2 during CPR with either chest compression (CC) during sustained inflation (SI) (CC + SI) or continuous chest compression with asynchronized ventilation (CCaV) will reduce time to return of spontaneous circulation (ROSC) compared to 100% O2 in infant piglets with asphyxia-induced cardiac arrest. Piglets (20-23 days of age, weighing 6.2-10.2 kg) were anesthetized, intubated, instrumented, and exposed to asphyxia. Cardiac arrest was defined as mean arterial blood pressure < 25 mmHg with bradycardia. After cardiac arrest, piglets were randomized to CC + SI or CCaV with either 21% or 100% O2 or the sham. Heart rate, arterial blood pressure, carotid blood flow, and respiratory parameters were continuously recorded. Baseline parameters, duration, and degree of asphyxiation were not different. Median (interquartile range) time to ROSC was 107 (90-440) and 140 (105-200) s with CC + SI 21% and 100% O2, and 600 (50-600) and 600 (95-600) s with CCaV 21% and 100% O2 (p = 0.27). Overall, six (86%) and six (86%) piglets with CC + SI 21% and 100% O2, and three (43%) and three (43%) piglets achieved ROSC with CCaV 21% and 100% O2 (p = 0.13). In infant piglets resuscitated with CC + SI, time to ROSC reduced and survival improved compared to CCaV. The use of 21% O2 had similar time to ROSC, short-term survival, and hemodynamic recovery compared to 100% oxygen. Clinical studies comparing 21% with 100% O2 during infant CPR are warranted.

Inhibition of Nitrosative Stress Attenuates Myocardial Injury and Improves Outcomes after Cardiac Arrest and Resuscitation.

Nitrosative stress is widely involved in cell injury via inducing the nitration modification of a variety of proteins. This study aimed to investigate whether inhibition of nitrosative stress attenuated myocardial injury and improved outcomes in a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Adult male Wistar rats were subjected to asphyxia-induced cardiac arrest and subsequently resuscitation. One minute after return of spontaneous circulation (ROSC), rats were randomized and administered the nitrosative stress inhibitor, FeTMPyP (1 or 3 mg/kg), or normal saline as a placebo. 3-Nitrotyrosine (3-NT), mean arterial pressure (MAP), heart rate (HR), mortality, electrocardiogram (ECG), left ventricular ejection fraction (EF) and fractional shortening (FS), and levels of myocardial apoptosis were evaluated. The concentrations of lactate, creatine kinase MB isoenzyme (CK-MB), and angiotensin II (Ang II), were measured in blood samples. 3-NT level was significantly increased in the heart after ROSC. Administration of FeTMPyP (1 or 3 mg/kg) attenuated the increase of 3-NT in the myocardium. Inhibition of nitrosative stress improved survival and attenuated CA/CPR-induced reperfusion injury by maintaining the stability of MAP and HR, and reducing the accumulation of lactic acid. Post-cardiac arrest rats had higher serum CK-MB and Ang II than healthy rats, while EF and FS were lower in healthy rats. Inhibition of nitrosative stress not only alleviated ischemic heart injury but also reduced the occurrence of CA/CPR-induced of arrhythmias. Moreover, nitrosative stress mediated the upregulation of Cleaved caspase-3 and downregulation Bcl-2, which was abolished by FeTMPyP. Inhibition of nitrosative stress is a novel molecular target to alleviate myocardial injury and improve outcomes in a rat model of CA/CPR.

Hydrogen therapy after resuscitation improves myocardial injury involving inhibition of autophagy in an asphyxial rat model of cardiac arrest

Hydrogen (H2) therapy is a therapeutic strategy using molecular H2. Due to its ability to regulate cell homeostasis, H2 therapy has exhibited marked therapeutic effects on a number of oxidative stress-associated diseases. The present study investigated the effectiveness of H2 therapy in protecting against myocardial injury in a rat model of asphyxial cardiac arrest and cardiopulmonary resuscitation. Rats underwent 10-min asphyxia-induced cardiac arrest (CA) and cardiopulmonary resuscitation (CPR), and were randomly divided into control and H2 therapy groups. After resuscitation, the H2 therapy group was administered room air mixed with 2% H2 gas for respiration. During CA/CPR, the arterial pressure and heart rate were measured every minute. Survival rate, cardiac function, myocardial injury biomarkers creatine kinase-MB and cardiac troponin-T, and histopathological changes were evaluated to determine the protective effects of H2 therapy in CA/CPR. Immunohistochemistry and western blot analysis were used to determine the expression levels of autophagy-associated proteins. In vitro, H9C2 cells were subjected to hypoxia/reoxygenation and H2-rich medium was used in H2 treatment groups. Western blotting and immunofluorescence were used to observe the expression levels of autophagy-associated proteins. Moreover, an adenovirus-monomeric red fluorescent protein-green fluorescent protein-LC3 construct was used to explore the dynamics of autophagy in the H9C2 cells. The results showed that H2 therapy significantly improved post-resuscitation survival and cardiac function. H2 therapy also improved mitochondrial mass and decreased autophagosome numbers in cardiomyocytes after resuscitation. The treatment inhibited autophagy activation, with lower expression levels of autophagy-associated proteins and decreased autophagosome formation in vivo and vitro. In conclusion, H2 gas inhalation after return of spontaneous circulation improved cardiac function via the inhibition of autophagy.

Omecamtiv mecarbil treatment improves post-resuscitation cardiac function and neurological outcome in a rat model.

BackgroundMyocardial dysfunction is a major cause of poor outcomes in the post-cardiac arrest period. Omecamtiv mecarbil (OM) is a selective small molecule activator of cardiac myosin that prolongs myocardial systole and increases stroke volume without apparent effects on myocardial oxygen demand. OM administration is safe and improves cardiac function in patients with acute heart failure. Whether OM improves post-resuscitation myocardial dysfunction remains unclear. This study investigated the effect of OM treatment on post-resuscitation myocardial dysfunction and outcomes.Methods and resultsAdult male rats were resuscitated after 9.5 min of asphyxia-induced cardiac arrest. OM and normal saline was continuously intravenously infused after return of spontaneous circulation (ROSC) at 0.25 mg/kg/h for 4 h in the experimental group and control group, respectively (n = 20 in each group). Hemodynamic parameters were measured hourly and monitored for 4 h after cardiac arrest. Recovery of neurological function was evaluated by neurological functioning scores (0–12; favorable: 11–12) for rats 72 h after cardiac arrest. OM treatment prolonged left ventricular ejection time and improved post-resuscitation cardiac output. Post-resuscitation heart rate and left ventricular systolic function (dp/dt40) were not different between groups. Kaplan-Meier analysis showed non-statistically higher 72-h survival in the OM group (72.2% [13/18] and 58.8% [10/17], p = 0.386). The OM group had a higher chance of having favorable neurological outcomes in surviving rats 72 h after cardiac arrest (84.6% [11/13] vs. 40% [4/10], p = 0.026). The percentage of damaged neurons was lower in the OM group in a histology study at 72 h after cardiac arrest (55.5±2.3% vs. 76.2±10.2%, p = 0.004).ConclusionsOM treatment improved post-resuscitation myocardial dysfunction and neurological outcome in an animal model. These findings support further pre-clinical studies to improve outcomes in post-cardiac arrest care.

Changes of Key Rate-Limiting Enzyme Activity in Glucose Metabolism After Cardiopulmonary Resuscitation.

To investigate the activity of key rate-limiting enzymes of glucose metabolism after restoration of spontaneous circulation (ROSC), to explore the potential pathophysiological mechanism of impaired myocardial energy metabolism after cardiopulmonary resuscitation (CPR). Twenty-one male Sprague-Dawley rats were randomized into three experimental groups assigned in accordance with different observation times after ROSC: Sham, instrumented rats without induced cardiac arrest or resuscitation; post-resuscitation (PR2 h); PR24 h. In these groups, CPR, including precordial compressions and synchronized mechanical ventilation, was initiated 6 min after asphyxia-induced cardiac arrest. Hearts were harvested after ROSC and samples were used to detect high-energy phosphate and glucose metabolic enzyme activity. Compared with sham, the contents of phosphocreatine and adenosine triphosphate reduced in the PR2 h group, while remained unchanged in the PR24 h group. Activities of hexokinase and pyruvate kinase did not change after ROSC. Phosphofructokinase activity decreased only in the PR24 h group. Activities of pyruvate dehydrogenase and citrate synthase fell in PR2 h group and recovered in the PR24 h group. However, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase activities fell in the PR2 h group, but did not recover in the PR24 h group. Lowered key rate-limiting enzymes activity in glucose metabolism resulted in impairment of energy production in the early stage of ROSC, but partially recovered in 24 h. This process has a role in the mechanism of impaired myocardial energy metabolism after CPR. This investigation might shed light on new strategies to treat post resuscitation myocardial dysfunction.

Levosimendan in rats decreases acute kidney injury after cardiopulmonary resuscitation by improving mitochondrial dysfunction.

BackgroundAcute kidney injury (AKI), the most common complication after cardiac resuscitation, is highly prevalent and harmful. There is increasing evidence that levosimendan can improve cardiac output, increase renal blood flow, and prevent AKI. As a novel calcium sensitizer, levosimendan may exert its protective effect via mitochondria.MethodsRat models of asphyxia-induced cardiac arrest and cardiopulmonary resuscitation (CPR) were set up. Thirty healthy adult male SD rats were randomly divided into CPR group (CPR group, n=10), levosimendan-treated group (levo group, n=10), and sham-operated group (sham group, n=10). Twelve hours after CPR, serum renal function indicators were measured, the kidney injury and mitochondrial morphological changes were observed. Oxygen uptake of the mitochondria, mitochondrial adenosine triphosphate (ATP) and mitochondrial free Ca2+ concentration were measured. Oxidative stress-related indicator levels in rat kidney tissues were further detected to analyze the differences in apoptosis rates among these three groups. Mitochondrial optic atrophy 1 (Opa1), dynamin-related protein 1 (Drp1), and apoptosis-related proteins were detected using Western blotting.ResultsCompared with the sham group, the CPR group had a significant increase in renal tissue damage. PAS staining and HE stains confirmed that CPR led to renal histopathological damage and destruction of the mitochondrial structure. Levosimendan improved the histopathological and ultrastructural damages of kidneys. Further analysis revealed that mitochondrial ATP content, NADH dehydrogenase, succinate dehydrogenase/cytochrome C oxidase, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (CSH-Px) decreased. Free Ca2+ concentration and malondialdehyde (MDA) significantly increased (all P<0.05) in the kidney tissues of rats in the CPR group. However, mitochondrial ATP content, NADH dehydrogenase, succinate dehydrogenase/cytochrome C oxidase, SOD, CAT, and CSH-Px increased, whereas free Ca2+ concentration and MDA decreased (all P<0.05) in the levo group. The apoptosis rate increased in the CPR group. There were significantly increased levels of Drp1 protein levels, and significantly decreased Opa1 expression (all P<0.05). However, the levo group showed the opposite effects (all P<0.05).ConclusionsLevosimendan can alleviate AKI following CPR, which may be achieved by improving mitochondrial dysfunction and suppressing the mitochondrial apoptosis pathway.

Dexmedetomidine post-conditioning attenuates cerebral ischemia following asphyxia cardiac arrest through down-regulation of apoptosis and neuroinflammation in rats

BackgroundNeuroprotection strategies after cardiac arrest (CA)/cardiopulmonary resuscitation (CPR) remain key areas of basic and clinical research. This study was designed to investigate the neuroprotective effects of dexmedetomidine following resuscitation and potential mechanisms.MethodsAnesthetized rats underwent 6-min asphyxia-based cardiac arrest and resuscitation, after which the experimental group received a single intravenous dose of dexmedetomidine (25 μg/kg). Neurological outcomes and ataxia were assessed after the return of spontaneous circulation. The serum levels and brain expression of inflammation markers was examined, and apoptotic cells were quantified by TUNEL staining.ResultsNeuroprotection was enhanced by dexmedetomidine post-conditioning after the return of spontaneous circulation. This enhancement was characterized by the promotion of neurological function scores and coordination. In addition, dexmedetomidine post-conditioning attenuated the serum levels of the pro-inflammatory cytokine tumor necrosis factor (TNF)-α at 2 h, as well as interleukin IL-1β at 2, 24, and 48 h. TUNEL staining showed that the number of apoptotic cells in the dexmedetomidine post-conditioning group was significantly reduced compared with the control group. Further western blot analysis indicated that dexmedetomidine markedly reduced the levels of caspase-3 and nuclear factor-kappa B (NF-κB) in the brain.ConclusionsDexmedetomidine post-conditioning had a neuroprotective effect against cerebral injury following asphyxia-induced cardiac arrest. The mechanism was associated with the downregulation of apoptosis and neuroinflammation.

The effect of high-dose intramuscular epinephrine on the recovery of spontaneous circulation in an asphyxia\u2010induced cardiac arrest rat model

BackgroundObtaining vascular access can be challenging during resuscitation following cardiac arrest, and it is particularly difficult and time-consuming in paediatric patients. We aimed to compare the efficacy of high-dose intramuscular (IM) versus intravascular (IV) epinephrine administration with regard to the return of spontaneous circulation (ROSC) in an asphyxia-induced cardiac arrest rat model.Methods Forty-five male Sprague-Dawley rats were used for these experiments. Cardiac arrest was induced by asphyxia, and defined as a decline in mean arterial pressure (MAP) to 20 mmHg. After asphyxia-induced cardiac arrest, the rats were randomly allocated into one of 3 groups (control saline group, IV epinephrine group, and IM epinephrine group). After 540 s of cardiac arrest, cardiopulmonary resuscitation was performed, and IV saline (0.01 cc/kg), IV (0.01 mg/kg, 1:100,000) epinephrine or IM (0.05 mg/kg, 1:100,000) epinephrine was administered. ROSC was defined as the achievement of an MAP above 40 mmHg for more than 1 minute. Rates of ROSC, haemodynamics, and arterial blood gas analysis were serially observed.ResultsThe ROSC rate (61.5%) of the IM epinephrine group was less than that in the IV epinephrine group (100%) but was higher than that of the control saline group (15.4%) (log-rank test). There were no differences in MAP between the two groups, but HR in the IM epinephrine group (beta coefficient = 1.02) decreased to a lesser extent than that in the IV epinephrine group with time.ConclusionsIM epinephrine induced better ROSC rates compared to the control saline group in asphyxia-induced cardiac arrest, but not compared to IV epinephrine. The IM route of epinephrine administration may be a promising option in an asphyxia-induced cardiac arrest.

Abstract 155: Identification of Decreased Plasma Lysophosphatidylcholine Using Phospholipidomics in Cardiac Arrest: A Novel Therapeutic Application

Introduction: Cardiac arrest (CA) is a significant public health burden with few effective therapies available. Plasma phospholipids are important for proper organ function. We hypothesized that alterations in plasma phospholipids may play an important role in the pathophysiology of CA and normalizing these alterations may be a novel therapeutic application for the treatment of CA. Objective: The aim of this study was to test the phospholipid therapy as a novel therapeutic approach in CA. Methods and Results: We performed phospholipidomics on plasma samples from CA patients and controls from North Shore University Hospital to identify plasma phospholipids that correlate with injury severity. We then confirmed the finding using our rat model of 10 and 14 min of asphyxia-induced CA. Finally, we tested the effect of administering LPC using the same model. From the phospholipids analyzed, lysophosphatidylcholine (LPC) levels were found to be the most significantly decreased in CA patients, which was also associated with survival of patients. The same trend was observed in the rat model where rats after 14 min CA had significantly lower plasma LPC levels than rats after 10 min CA. We also found that LPC levels began to decrease continuously following resuscitation, but not during the ischemic phase of CA. Finally, we found that LPC administration substantially increased rat survival compared to the control group. Rats who survived in the LPC-treated group displayed significantly improved brain function and the neuroprotective effect of LPC is supported by improved brain histology. We also found LPC treatment increased plasma IL-10 levels and decreased IL-6 levels post-CA. Conclusion: Plasma LPC levels inversely correlated with survival and LPC treatment significantly improved brain function and rat survival. This data indicates that the decrease of plasma LPC is a major mechanism responsible for brain damage demonstrating the potential of LPC as a novel therapeutic in CA.

Supplement of Lipid Emulsion to Epinephrine Improves Resuscitation Outcomes of Asphyxia-Induced Cardiac Arrest in Aged Rats.

ObjectiveThe goal of the study was to investigate the efficacy of lipid supplement to epinephrine-based therapy in resuscitation of asphyxia-induced cardiac arrest in aged rats.MethodsThe study included two parts: in experiment A, rats underwent asphyxial cardiac arrest and cardiopulmonary resuscitation, randomized to receive epinephrine and normal saline (control group, n=22), epinephrine and intralipid 20% (long-chain triglycerides (LCT) group, n=22) or epinephrine and lipovenoes 20% (LCT/medium-chain triglcerides (MCT) group, n=22). Return of spontaneous circulation, recurrence of asystole after resuscitation, hemodynamic metrics, arterial blood gas values, neurological assessment score and indexes of pulmonary transudation were recorded. In experiment B, rats using the same model and resuscitation protocol were randomly divided into 21 groups: Control 0, Control 20, Control 40, Control 60, Control 80, Control 100, Control 120, LCT 0, LCT 20, LCT 40, LCT 60, LCT 80, LCT 100, LCT 120, LCT/MCT 0, LCT/MCT 20, LCT/MCT 40, LCT/MCT 60, LCT/MCT 80, LCT/MCT 100 and LCT 120 (n=10, the subscripts represent respective endpoint of observation in minutes). Myocardial bioenergetics were determined.ResultsIn experiment A, the LCT and LCT/MCT groups had a shorter time to return of spontaneous circulation (ROSC) (P=0.001and P<0.001, respectively) and higher survival rate (P=0.033 and P=0.014, respectively) compared with the Control group. The LCT/MCT group had higher MAP (P<0.001 and P=0.001, respectively), HR (P<0.001 and P=0.004, respectively) and RPP (P<0.001 and P<0.001, respectively) compared with the Control and LCT groups, respectively. In experiment B, the LCT/MCT group had a higher energy charge compared with the control group at 20 (P<0.001) and 40 (P<0.001) minutes. The LCT group had higher energy charge compared with the Control group at 40 (P<0.001) and 60 (P<0.001) minutes.ConclusionThe supplement of lipid emulsion to epinephrine improves resuscitation outcomes of asphyxia-induced cardiac arrest than epinephrine alone in our in vivo model of aged rat. LCT/MCT emulsion may be superior to LCT emulsion in epinephrine-based resuscitation.

Sustained inflation with 21% versus 100% oxygen during cardiopulmonary resuscitation of asphyxiated newborn piglets - A randomized controlled animal study

BackgroundCurrent neonatal resuscitation guidelines recommend using 100% oxygen during chest compressions (CC), however the most effective oxygen concentration during cardiopulmonary resuscitation remains controversial. AimIn term newborn piglets with asphyxia-induced cardiac arrest does 21% oxygen compared to 100% oxygen during resuscitation using CC during sustained inflation (SI; CC + SI) will have a reduced time to return of spontaneous circulation (ROSC). Intervention and measurementsTwenty-two mixed breed piglets (1–3 days old, 1.7–2.4 kg), were obtained on the day of the experiment and anesthetized, intubated, instrumented, and exposed to 30-min normocapnic hypoxia followed by asphyxia. Piglets were resuscitated using CC + SI and randomized to 21% oxygen (n = 8) or 100% oxygen (n = 8). Heart rate, arterial blood pressure, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment. Main resultsBaseline parameters were similar between 21% and 100% oxygen groups. There was no difference in asphyxiation (duration and degree) between groups. Time to ROSC was similar between 21% and 100% oxygen groups: median (interquartile range - IQR) 80 (70−190)sec vs. 90 (70−324)sec, (p = 0.56). There was no significant difference in the rate of ROSC between 21% and 100% oxygen groups: 7/8 (88%) vs. 5/8 (63%), (p = 0.569). All piglets that achieved ROSC survived to four hours post-resuscitation. Hemodynamics and regional perfusion were not significantly different between groups. ConclusionsIn term newborn piglets resuscitated by CC + SI, the use of 21% oxygen resulted in a similar time to ROSC, short-term survival, and hemodynamic recovery compared to 100% oxygen.

Inhibition of mast cell tryptase attenuates neuroinflammation via PAR-2/p38/NF\u03baB pathway following asphyxial cardiac arrest in rats

BackgroundCardiac arrest survivors suffer from neurological dysfunction including cognitive impairment. Cerebral mast cells, the key regulators of neuroinflammation contribute to neuroinflammation-associated cognitive dysfunction. Mast cell tryptase was demonstrated to have a proinflammatory effect on microglia via the activation of microglial protease-activated receptor-2 (PAR-2). This study investigated the potential anti-neuroinflammatory effect of mast cell tryptase inhibition and the underlying mechanism of PAR-2/p-p38/NFκB signaling following asphyxia-induced cardiac arrest in rats.MethodsAdult male Sprague-Dawley rats resuscitated from 10 min of asphyxia-induced cardiac arrest were randomized to four separate experiments including time-course, short-term outcomes, long-term outcomes and mechanism studies. The effect of mast cell tryptase inhibition on asphyxial cardiac arrest outcomes was examined after intranasal administration of selective mast cell tryptase inhibitor (APC366; 50 μg/rat or 150 μg/rat). AC55541 (selective PAR-2 activator; 30 μg/rat) and SB203580 (selective p38 inhibitor; 300 μg/rat) were used for intervention. Short-term neurocognitive functions were evaluated using the neurological deficit score, number of seizures, adhesive tape removal test, and T-maze test, while long-term cognitive functions were evaluated using the Morris water maze test. Hippocampal neuronal degeneration was evaluated by Fluoro-Jade C staining.ResultsMast cell tryptase and PAR-2 were dramatically increased in the brain following asphyxia-induced cardiac arrest. The inhibition of mast cell tryptase by APC366 improved both short- and long-term neurological outcomes in resuscitated rats. Such behavioral benefits were associated with reduced expressions of PAR-2, p-p38, NFκB, TNF-α, and IL-6 in the brain as well as less hippocampal neuronal degeneration. The anti-neuroinflammatory effect of APC366 was abolished by AC55541, which when used alone, indeed further exacerbated neuroinflammation, hippocampal neuronal degeneration, and neurologic deficits following cardiac arrest. The deleterious effects aggregated by AC55541 were minimized by p38 inhibitor.ConclusionsThe inhibition of mast cell tryptase attenuated neuroinflammation, led to less hippocampal neuronal death and improved neurological deficits following cardiac arrest. This effect was at least partly mediated via inhibiting the PAR-2/p-p38/NFκB signaling pathway. Thus, mast cell tryptase might be a novel therapeutic target in the management of neurological impairment following cardiac arrest.