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Highlights • COVID-19 pandemic has changed the risk-benefit balance for cardiopulmonary resuscitation [CPR]. • Amongst many aerosol producing procedures performed on patients, CPR is a highly aerosol-generating procedure. • Available literature is inadequate to direct clinicians towards keeping low or high threshold for performing CPR in COVID-19 patient.

Introduction: Previous studies have demonstrated that ferroptosis, a newly defined iron-dependent cell death, mediates ischemia/reperfusion induced cardiomyopathy. However, it is unclear whether ferroptosis plays a role in post-resuscitation myocardial dysfunction (PRMD). This study investigated the effects of UAMC-3203, a novel analog of ferroptosis specific inhibitors, on myocardial function after cardiopulmonary resuscitation (CPR). Hypothesis: Administration of UAMC-3203 during CPR alleviates PRMD in a rat model of cardiac arrest (CA) and CPR. Methods: 18 male Sprague-Dawley rats weighing between 450-550g were randomized into 3 groups: 1) Sham, 2) Control, and 3) UAMC-3203 (5mg/kg, IP at start of precordial compression). Ventricular fibrillation (VF) was induced and continued for 6min. CPR was then initiated for 8min, after which defibrillation was attempted. Ejection fraction (EF), cardiac output (CO) and myocardial performance index (MPI) were measured by echocardiography at baseline, 15min, 1h, 3h and 6h respectively after return of spontaneous circulation (ROSC). Results: A significant reduction in cardiac function was observed after resuscitation. At 15 minutes after ROSC, ultrasound showed no difference in cardiac function between UAMC and control. However, at 1, 3, and 6 h after ROSC, UAMC significantly improved myocardial function (p Conclusion: A ferroptosis-specific inhibitor, UAMC-3203, alleviated PRMD significantly in a rat of model of CA and CPR. Further study is needed to determine the benefit of this agent in larger animals and potential safety in humans before it can be tested in clinical resuscitation.

Introduction: Massive systemic inflammation is a primary cause of myocardial dysfunction following cardiac arrest (CA) and resuscitation (CPR). We investigated the effects of ω-3 polyunsaturated fatty acids (ω-3 PUFA) on systemic inflammation and myocardial function after CA and CPR. Hypothesis: Administration of ω-3 PUFA at the start of CPR will alleviate post CPR inflammation and improve cardiac function in a rat model of CA and CPR. Methods: 18 male Sprague-Dawley rats weighing between 450g-550g were randomized into three groups: Sham, Control, and ω-3 PUFA. Ventricular fibrillation (VF) was induced and untreated for 6 min. 4J defibrillation was attempted after 8 min of CPR. Saline placebo or ω-3 PUFA (5mL/kg) was infused at the start of CPR and continued for 4h. Ejection fraction (EF), cardiac output (CO) and myocardial performance index (MPI) were measured by echocardiography at baseline, 1, 3 and 6h after return of spontaneous circulation (ROSC). Inflammatory cytokines (IL-6 and TNF-α) and cardiac biomarker (cTnI) levels in plasma were detected at baseline and 6 hrs after ROSC. Results: A decrease in EF and CO and an increase in MPI occurred after resuscitation. Significant improvement was noted in ω-3 PUFA compared to control animals (p Conclusion: Administration of ω-3 PUFA attenuates post-resuscitation systemic inflammation and improves myocardial function in a rat model of CA and CPR.

Introduction: Mitochondrial dysfunction from global ischemic-reperfusion (I/R) injury is a major contributor to post-resuscitation myocardial dysfunction. Polyethylene Glycol-20k (PEG-20k) shortens the no-flow phenomenon and improves microcirculation while MCC950 selectively inhibits activation of the NLRP3-inflammasome ensuing pyroptosis. We evaluated the effect of combined therapy with PEG-20k and MCC950 on myocardial mitochondrial function as measured by electron transport chain complex respiration in a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Methods: 30 Sprague-Dawley rats weighing between 450-550 g were randomized into five groups (n=6): (1) sham (S); (2) control (C); (3) PEG-20k (P); (4) MCC950 (M); (5) combined (P&M). Ventricular fibrillation (VF) was electrically induced and untreated for 6min, followed by 8min CPR. Resuscitation was attempted with a 4J defibrillation. 2mL P was infused over 2 min at the beginning of CPR, while M (10mg/kg) was administered intraperitoneal (IP) immediately after return of spontaneous circulation (ROSC). At ROSC 6hr, 100mg of heart was harvested, transferred directly into ice-cold K medium (1mL), and homogenized to obtain a 10% homogenate. Homogenates (50μL) were transferred to calibrated Oxygraph-2 chambers. Mitochondrial function was measured using high resolution respirometry. Oxygen flux was corrected and expressed by tissue wet weight, pmol/(min*mg). Data were analyzed by one-way analysis of variance (one-way ANOVA) followed by Tukey’s post hoc test for comparisons between multiple groups. Results: Complex I respiration in C was compromised at ROSC 6hr compared to S (564.0±160.0 vs 2729.5±339.5, p Conclusion: Combined Therapy with PEG-20k and MCC950 preserves post-resuscitation myocardial mitochondrial function in a rat model of CA and CPR.

Introduction: Artesunate (ART) possesses anti-inflammatory activity, which can mitigate the systemic inflammatory response in poor outcomes of cardiac arrest (CA). We investigated the effects of ART on myocardial and cerebral function, duration of survival, and inflammation in a rat model of CA and cardiopulmonary resuscitation (CPR). Hypothesis: ART reduces the severity of post resuscitation myocardial and cerebral dysfunction by alleviating inflammation in a rat model of CA and CPR. Methods: 30 male Sprague-Dawley rats weighing between 450g-550g were randomized into 3 groups: Sham (S), Control (C), and Artesunate (A). C and A were divided into subgroups: survival and non-survival (n=6). Ventricular fibrillation (VF) was induced and untreated for 6 min. A 4J defibrillation was attempted after 8 min of CPR. Phosphate buffer (1ml/kg, pH 7.9-8.1) or ART (2.4mg/kg), was administered at return of spontaneous circulation (ROSC). Myocardial function was measured at baseline and every hour for 4h post ROSC. Plasma levels of IL-6, TNF-α and cTnI were detected at baseline and 4h after ROSC. Survival animals were observed for an additional 72h. Neurologic deficit scores were recorded daily. Results: ART reduced the severity of post-resuscitation myocardial dysfunction compared to C. It attenuated IL-6, TNF-α and cTnI plasma levels 4h after ROSC (p Conclusion: ART reduces the severity of post-resuscitation myocardial and cerebral dysfunction, improves survival rate and attenuates inflammation in a rat of model of CA and CPR.

Introduction: Neurologic and myocardial dysfunction after successful resuscitation is prominent and mitochondrial dysfunction is predicted to be a key determinant of poor outcomes. Mitochondria contribute a critical role as effectors and targets of reperfusion injury. However, the onset and severity of mitochondrial dysfunction during cardiac arrest (CA) is not fully understood. The present study was done to explore whether changes in cerebral and myocardial mitochondria differ after cardiac arrest and cardiopulmonary resuscitation (CPR). Hypothesis: Mitochondrial injury is more severe in the brain compared to the heart during and following cardiac arrest and CPR. Methods: Sprague-Dawley rats weighing between 450 - 550 g were randomized into 4 groups (n=6): 1) sham (surgery, no ventricular fibrillation (VF) or CPR), 2) VF (VF 8 mins, no CPR); 3) VF and CPR (VF 8 mins and CPR 8 mins, no defibrillation); ROSC 1 h (VF 8 mins, CPR 8 mins, defibrillation, and observe 1 h after ROSC). VF was induced through a guide wire advanced from the right jugular vein into the right ventricle. Brain and heart mitochondria were extracted by differential centrifugation and used to measure oxidative phosphorylation and calcium retention capacity (CRC). Results: Compared with sham, brain mitochondrial CRC in VF, VF+CPR and ROSC 1 h were decreased (110±11 vs. 70±13, 62±24, 50±6 nmol Ca 2+ /mg protein, p2+ /mg protein). Brain mitochondrial oxidative phosphorylation with complex I substrate glutamate in VF, VF+CPR and ROSC 1 h were all decreased compared to sham (127 + 8 vs 92±17, 84±12, and 92±15, p Conclusions: Mitochondria in the brain are more sensitive to injury during CA and CPR compared to heart mitochondria. With markedly decreased CRC, mitochondria are likely to contribute to cerebral reperfusion injury during CPR and ROSC. Preservation of cerebral mitochondrial activity and mitochondrial function during cardiac arrest may improve post-resuscitation neurological function.

Introduction: Epinephrine is the primary drug given during cardiopulmonary resuscitation (CPR), when given early, to reverse cardiac arrest (CA) by stimulation of α-adrenergic receptors in vascular smooth muscle. This increases coronary perfusion pressure (CPP) and increases rate of return of spontaneous circulation (ROSC). However, the use of epinephrine is not associated with a significant difference in long-term survival or favorable neurologic outcome when given late after arrest onset. In the present study, we compared the effects of aortic injection of polyethylene glycol-20k (PEG-20k) vs. epinephrine during CPR on CPP and postresuscitation myocardial and cerebral function in a rat model of CA. Hypothesis: Aortic injection of PEG-20k during CPR will increase CPP to the same extent as epinephrine without adversely affecting post-resuscitation myocardial and cerebral function. Methods: Twenty four male Sprague-Dawley rats weighing between 450-550 g were randomized into four groups: 1) PEG-20k 2) epinephrine 3) saline placebo 4) saline-intra-aorta (IA). Eight minutes of CPR was initiated after 6 minutes of untreated ventricular fibrillation. PEG-20k IA (10% est. total blood volume [1.8ml]), saline IA, saline IV or epinephrine IV (20ug/kg) was given after 4 minutes of CPR by continuous infusion over 3 minutes. CPP was recorded continuously and resuscitation was attempted with 4 Joule defibrillation. Myocardial function was measured at baseline, 2, 4, and 6 hours after ROSC by echocardiography and neurologic deficit scores (NDS) were recorded at 24, 48, and 72 hours after ROSC. Results: In both saline groups, CPP did not change. However, aortic injection of PEG-20k increased CPP significantly to the same extent as epinephrine (Fig 1). Post-resuscitation ejection fraction was significantly greater in PEG-20k compared to epinephrine (64 + 1 vs 45 + 3, p+ 50 vs 450 + 50, p

Introduction: NLRP3 inflammasome mediated pyroptosis has been demonstrated to increase myocardial and cerebral ischemia/reperfusion injury. MCC950 is a newly developed highly selective inhibitor of the NLRP3 inflammasome. Hypothesis: MCC950 administered following resuscitation will reduce the severity of post-resuscitation myocardial and cerebral dysfunction and improve duration of survival in a rat model of CPR. Methods: 15 male Sprague-Dawley rats weighting between 450-550 g were randomized into three groups: 1) MCC950 2) Control 3) Sham. Ventricular fibrillation (VF) was induced and untreated for 6 min. CPR was then initiated and continued for 8 min. Resuscitation was attempted with a 4 J defibrillation. Either MCC950 (10mg/kg) or vehicle was administered intraperitoneal (IP) in line with cardiac injury animal studies immediately after return of spontaneous circulation (ROSC). Sham underwent the same surgical procedure without VF and CPR. Sublingual microcirculation was measured at baseline (BL), 3, 6 and 48 hrs after ROSC. Ejection fraction (EF) was measured at BL, 1, 3, 6 and 48 hrs after ROSC. Neurologic Deficit Score (NDS) was recorded at 48 hrs after resuscitation. Results: Post-resuscitation ejection fraction and perfused sublingual vessel density were greater in MCC950 compared to control (p Conclusion: Administration of MCC950 following ROSC mitigates post-resuscitation myocardial and cerebral dysfunction, improves sublingual microcirculation and duration of survival in a rat model of CPR.

Introduction: Gasdermin D (GSDMD), a previously unknown protein, serves as a key effector in pyroptosis and its inhibition has protective effects during cerebral ischemia and reperfusion. Necrosulfonamide (NSA) specifically blocks the mixed lineage kinase domain-like pseudo kinase (MLKL), which directly binds to GSDMD preventing pyroptotic cell death and interleukin-1 (IL-1) release. In this study, we investigated the effects of NSA on survival and neurological function after cardiac arrest and resuscitation. Hypothesis: Administration of NSA following cardiopulmonary resuscitation (CPR) will improve survival and neurological function in a rat model of cardiac arrest. Methods: Twelve male Sprague-Dawley rats weighting between 450-550g were utilized. Ventricular fibrillation was induced and untreated for 6 min followed by defibrillation after 8 min of CPR. Animals were then randomized into two groups: NSA and control. NSA (10mg/kg) or vehicle was administered 5 minutes after restoration of spontaneous circulation (ROSC) by intraperitoneal injection. Duration of survival and neurological deficit scores were recorded at 24, 48, and 72 hours after ROSC. Results: All animals were resuscitated successfully. Duration of survival was significantly longer in the NSA group compared to control (p Conclusion: Administration of NSA after ROSC improves post-resuscitation survival and neurological function in a rat model of cardiac arrest.

Introduction: Cerebral ischemia-reperfusion injury produces inflammation and cerebral microcirculatory dysfunction after cardiopulmonary resuscitation (CPR). Melatonin (N-acetyl-5-methoxytryptamine) has both anti-inflammatory and anti-oxidative properties. In this study, we investigated the effects of melatonin on inflammation and cerebral microcirculation after cardiopulmonary resuscitation in a rat model of cardiac arrest. Hypothesis: Melatonin decreases the systemic inflammatory response after cardiopulmonary resuscitation and will preserve cerebral microcirculation in a rat model of cardiac arrest. Method: Eighteen male Sprague Dawley rats weighing between 450-550 g were randomized into three groups: 1) sham: no ventricular fibrillation (VF) and CPR; 2) CPR control: untreated VF for 6 min followed by 8 min CPR; 3) CPR+melatonin: untreated VF for 6 min followed by 8 min CPR. Melatonin (10 mg/kg) was administered intraperitoneal (IP) in line with hypoxia-ischemia animal studies after return of spontaneous circulation (ROSC). Serum TNF- α, IL-1 β and cerebral microcirculation were measured at baseline and 6 h following ROSC. Result: Serum TNF-α and IL-1β were significantly lower in the CPR+melatonin group at 6h after ROSC compared to CPR controls ( p p Conclusion: In a rat model of cardiac arrest, melatonin reduced systemic inflammation and preserved cerebral microcirculation following resuscitation.

Introduction: JZL184 is a synthetic monoacylglycerol lipase inhibitor that reduces brain edema, infarct size and alleviates inflammation following cerebral ischemia in experimental studies. In this study, we compared its cerebral protective effects with therapeutic hypothermia following cardiopulmonary resuscitation (CPR) in a rat model. Hypothesis: JZL184 will have similar neuroprotective effects to therapeutic hypothermia after cardiac arrest (CA) by reducing brain and blood brain barrier (BBB) injury and preserving cerebral microcirculation following CPR. Methods: Thirty six male Sprague-Dawley rats weighing between 450-550 g were randomized: 1) control 2) hypothermia 3) JZL184. Ventricular fibrillation was induced and untreated for 6 min for all rats. Resuscitation was attempted with a 4 Joule defibrillation after 8 min of CPR. Immediately following resuscitation, either hypothermia (33+0.5 o C) or JZL184 (16 mg/k, IP) was administered. Cerebral microcirculation, S-100β, NSE and Evan’s Blue (EB) concentrations were analyzed at 6hrs after resuscitation. Results: NSE and S-100β levels were higher in control compared to hypothermia and JZL18 at 6hr post ROSC (p < 0.001) (Fig. 1). Compared with control, there was a significant decrease in brain permeability to EB in Hypothermia and JZL184 after 6hr post ROSC (p Conclusions: JZL184 administered following resuscitation reduced brain and BBB injury and preserved cerebral microcirculation at 6 hr post arrest to the same extent as hypothermia in a rat model of cardiac arrest.

INTRODUCTION: Mitochondrial injury post-cardiac arrest has been described in pre-clinical settings but the extent to which this injury occurs in humans remains largely unknown. We hypothesized that increased levels of mitochondrial biomarkers would be associated with mortality and neurological morbidity in post-cardiac arrest subjects.METHODS: We performed a prospective multicenter study of post-cardiac arrest subjects. Inclusion criteria were comatose adults who suffered an out-of-hospital cardiac arrest. Mitochondrial biomarkers were measured at 0, 12, 24, 36 and 48h after return of spontaneous circulation as well as in healthy controls.RESULTS: Out of 111 subjects enrolled, 102 had evaluable samples at 0h. Cardiac arrest subjects had higher baseline cytochrome c levels compared to controls (2.18ng/mL [0.74, 7.74] vs. 0.16ng/mL [0.03, 0.91], pCONCLUSIONS: Cytochrome c was increased in post- cardiac arrest subjects compared to controls, and in post-cardiac arrest non-survivors compared to survivors. Nuclear DNA and cell free DNA was increased in plasma of post-cardiac arrest subjects. There were no differences in mitochondrial DNA, nuclear DNA, or cell free DNA between survivors and non-survivors. Mitochondrial injury markers showed mixed results in the post-cardiac arrest period. Future research needs to investigate these differences.

OBJECTIVE: Rate of lactate change is associated with in-hospital mortality in post-cardiac arrest patients. This association has not been validated in a prospective multicenter study. The objective of the current study was to determine the association between percent lactate change and outcomes in post-cardiac arrest patients.DESIGN: Four-center prospective observational study conducted from June 2011 to March 2012.SETTING: The National Post-Arrest Research Consortium is a clinical research network conducting research in post-cardiac arrest care. The network consists of four urban tertiary care teaching hospitals.PATIENTS: Inclusion criteria consisted of adult out-of-hospital non-traumatic cardiac arrest patients who were comatose after return of spontaneous circulation.INTERVENTIONS: None.MEASUREMENTS AND MAIN RESULTS: The primary outcome was survival to hospital discharge, and secondary outcome was good neurologic outcome. We compared the absolute lactate levels and the differences in the percent lactate change over 24 hours between survivors and nonsurvivors and between subjects with good and bad neurologic outcomes. One hundred patients were analyzed. The median age was 63 years (interquartile range, 50-75) and 40% were female. Ninety-seven percent received therapeutic hypothermia, and overall survival was 46%. Survivors and patients with good neurologic outcome had lower lactate levels at 0, 12, and 24 hours (p< 0.01). In adjusted models, percent lactate decrease at 12 hours was greater in survivors (odds ratio, 2.2; 95% CI, 1.1-6.2) and in those with good neurologic outcome (odds ratio, 2.2; 95% CI, 1.1-4.4).CONCLUSION: Lower lactate levels at 0, 12, and 24 hours and greater percent decrease in lactate over the first 12 hours post cardiac arrest are associated with survival and good neurologic outcome.