Browsing by Subject "resuscitation"
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Item Intravenous pyruvate to protect heart and brain during closed-chest resuscitation and recovery from cardiac arrest(2014-08-01) Cherry, Brandon H.; Mallet, Robert T.; Olivencia-Yurvati, Albert H.; Raven, Peter B.Cardiac arrest is a leading cause of death in the United States and Western Europe. Cardiopulmonary resuscitation (CPR) is the only means of sustaining the victim until application of defibrillatory countershocks. Although it has been over 50 years since its advent, CPR remains a work in progress. Many initially resuscitated victims later die from the damage sustained from ischemia-reperfusion, and treatments to combat the extensive ischemia-reperfusion injury sustained during cardiac arrest-resuscitation remain elusive. The major mechanism of injury underlying ischemia-reperfusion is the intense overproduction of reactive oxygen and nitrogen species (RONS) that accumulate during reperfusion and compromise normal cell function. RONS formed during resuscitation trigger lipid peroxidation, disable enzymes vital for cell metabolism and survival and, ultimately, induce cell death within affected organs. In order to prevent extensive damage to the central nervous system culminating in permanent neurocognitive disability and death, prospective treatments must possess robust antioxidant properties, traverse the blood-brain barrier between the cerebral circulation and brain parenchyma, and be non-toxic at effective doses. Pyruvate is a natural intermediary metabolite, energy-yielding substrate and antioxidant. Pyruvate neutralizes RONS, thereby dampening oxidative stress and preventing covalent oxidative modification of enzymes and lipid membranes, and generates ATP to support brain function. Pyruvate readily traverses the blood-brain barrier and is non-toxic over a wide range of doses, including those previously demonstrated to protect the heart during cardiopulmonary bypass and the brain during stroke, thereby supporting oxygen and fuel delivery to the recovering brain. Moreover, pyruvate has been shown to promote cardiac electromechanical and metabolic recovery following cardiac arrest and open-chest CPR. This study tested whether infusion of pyruvate during, CPR and early recovery can decrease the biomarkers of oxidative stress after cardiac arrest. Isoflurane-anesthetized pigs were subjected to 6 min electrically-induced, untreated ventricular fibrillation, followed by 4 min closed-chest CPR, defibrillation and either 1 or 4 h recovery. Beginning at 5.5 min arrest, either sodium pyruvate or NaCl control were infused iv for the duration of CPR and for the first 60 min after recovery of spontaneous circulation (ROSC). Arterial blood was sampled pre-arrest and at 5, 15, 30, 60, 120, 180, and 240 min ROSC for analyses of blood gases and plasma constituents. At either 1 h (i.e. end of treatment infusion) or 4 h ROSC, a craniotomy was performed, the pig was euthanized, the brain was removed, and biopsies from hippocampus and cerebellum were snap-frozen in liquid nitrogen for biochemical analysis. The first phase of this project tested the hypothesis that intravenous administration of sodium pyruvate during precordial compressions and the first 60 min ROSC restores hemodynamic, metabolic, and electrolyte homeostasis in a closed chest porcine model of cardiac arrest. Resuscitation with pyruvate sharply decreased the incidence of lethal pulseless electrical activity (PEA) following defibrillatory countershocks, and lowered the dosage of vasoconstrictor phenylephrine required to maintain systemic arterial pressure. Pyruvate also enhanced glucose clearance, elevated arterial bicarbonate, and raised arterial pH. The second phase of this project tested the hypothesis that pyruvate prevents the decrease in activity of the brain’s antioxidant enzymes following cardiac arrest and hyperoxic (100% O2). Activities of glutathione peroxidase and glutathione reductase were decreased at 60 min ROSC vs. sham in both the hippocampus and cerebellum. Pyruvate partially preserved glutathione peroxidase activity at 1 h ROSC, but by 4 h, after 3 h of pyruvate clearance from the circulation, the enzyme’s activity fell to the same extent as in NaCl-infused pigs. Interestingly, the glutathione peroxidase/reductase activity fell sharply in non-arrested sham pigs between the time points corresponding to 1 and 4 h ROSC, suggesting that hyperoxia resulting from ventilation with 100% produced sufficient oxidative stress to inactivate the enzymes. Similarly, lactate dehydrogenase activity fell between 1 and 4 h ROSC in hippocampus and especially cerebellum. In sham pigs, lactate dehydrogenase activity decreased from the time points corresponding to 1 and 4 h ROSC, and pyruvate had no effect on lactate dehydrogenase in either region of the brain. Thus, cardiac arrest and hyperoxic ventilation disabled a critical antioxidant system in two ischemia-sensitive brain regions. Pyruvate afforded partial protection of these enzymes which waned after pyruvate cleared from the circulation. We conclude that 1) Pyruvate infusion during cardiac arrest, CPR and early recovery promotes conversion from ventricular fibrillation to a productive sinus rhythm instead of lethal PEA; 2) Pyruvate hastened glucose clearance, a prognostic measure used clinically; 3) Pyruvate elevated the arterial bicarbonate concentration and raised arterial pH, which combats the acidemia normally observed following ROSC; 4) Cardiac arrest-resuscitation and hyperoxic ventilation disabled the glutathione peroxidase-reductase system, a critical component of the brain’s antioxidant defenses, in hippocampus and cerebellum; and 5) Pyruvate delayed oxidative inactivation of glutathione peroxidase in the cerebellum, but this effect subsided as pyruvate elevated. These investigations demonstrate the therapeutic effects and limitations of pyruvate as a resuscitative treatment to hasten electrocardiographic and metabolic recovery post cardiac arrest.Item Pyruvate Protection of Myocardium and Brain Following Cardiopulmonary Arrest and Resuscitation(2006-12-01) Sharma, Arti B.; Robert T. Mallet; Neeraj Agarwal; James L. CaffreySharma, Arti Bashu, Pyruvate Protection of Myocardium and Brain Following Cardiopulmonary Arrest and Resuscitation. Doctor of Philosophy (Molecular Physiology), December 2006; 167 pp; 29 figures; bibliography, 206 titles. Approximately 350,000 people experience cardiac arrest in the United States each year, and merely 4-33% of the victims survive to hospital discharge. Cardiac and neurological injuries following resuscitation are the main factors responsible for mortality. Neurodeficit and cognitive dysfunction following recovery from cardiac arrest may persist for us to two years and greatly compromise quality of life in survivors. Loss of effective circulating blood volume during cardiac arrest results in ischemia, energy depletion, ionic imbalance, calcium overload, acidosis and oxidant mediated cytotoxicity. The burst of reactive oxygen species upon reperfusion imposes an oxidant burden resulting in modification of cellular components such as membrane phospholipids and proteins, and the initiation of inflammatory and cell death cascades. This injury is most pronounced in organs with high metabolic demands such as the heart and brain. Therapies aimed at reducing metabolic impairments such as energy depletion and oxidative stress may mitigate post-resuscitation complications, improve survival and enhance quality of life. Pyruvate, a natural metabolite of the glycolytic pathway, has been shown to enhance post-ischemic energy and antioxidant reserves, and effects improvements in calcium homeostasis and metabolic acidosis. The main purpose of this investigation was to evaluate pyruvate as a corrective metabolic intervention during cardiopulmonary resuscitation and examine its cardio- and neuroprotective effects following recovery from cardiopulmonary arrest. To address these objectives as a canine model of 5 min cardiopulmonary arrest, open chest cardiac compressions (OCCC) and resuscitation was developed. In the first study intravenous sodium pyruvate or control NaCl was administered during the first 30 min of resuscitation and its effects on cardiac function and metabolites examined through the first 3 h following return of spontaneous circulation. Cardiac arrest resulted in a severe collapse of myocardial phosphocreatine phosphorylation potential and antioxidant redox state. Pyruvate treatment substantially enhanced recovery of energy and antioxidant reserves during early reperfusion. Pyruvate also enhanced contractile performance and carotid blood flow at 15-25 min return of spontaneous circulation (ROSC), and better maintained cardiac function at 3 h ROSC. Thus a latent effect of temporary metabolic correction by intravenous pyruvate therapy during early resuscitation was manifest as improved cardiac function, 3 h after the acute insult. Oxidative stress during resuscitation can modify membrane lipids and proteins. Inactivation of myocardial enzymes may exacerbate ischemic derangements of myocardial metabolism. To study the impact of cardiac arrest on left ventricular enzymes, beagles were subjected to cardiac arrest and myocardial enzyme activities were measured in snap-frozen left ventricle. Severe depletion of glutathione (GSH) antioxidant redox state occurred during cardiac arrest, which recovered partially following cardiac massage and then completely during early ROSC. Concomitant with oxidant stress, activities of phosphofructokinase, citrate synthase, aconitase, malate dehydrogenase, creatine kinase, glucose 6-phosphate dehydrogenase and glutathione reductase fell sharply during arrest, and recovered gradually after resuscitation and ROSC, in parallel with GSH redox state. We then tested whether oxidative stress is responsible for the loss of enzyme activity during cardiac arrest. Metabolic (pyruvate) or pharmacological (N-acetylcysteine) antioxidants were infused iv for 30 min immediately before cardiac arrest. Antioxidant pretreatments augmented phosphofructokinase, aconitase and malate dehydrogenase activities before arrest, and enhanced these activities, as well as citrate synthase and glucose 6-phosphate dehydrogenase, during arrest. Cardiac arrest thus reversibly inactivates several important myocardial metabolic enzymes, while protection of these enzymes by antioxidants implicates oxidative stress as a principal mechanism of enzyme inactivation. The third part of this investigation was directed towards addressing the question whether metabolic correction with pyruvate therapy during ROSC, would extend protection and enhance neurological recovery over an extended period of 3 days following cardiac arrest-resuscitation. Neurological evaluation in the days following recovery from cardiac arrest revealed considerable impairment of function. Activation of matrix metalloproteinases and increased myeloperoxidase activity were also detected in frozen brain tissue. Loss of viable neuronal structure and cell death as indicted by histological evidence and TUNEL were detected 3 days following arrest. Treatment with pyruvate for the first hour of reperfusion prevented neurological deficit on days 1 and 2 of recovery, partially mitigated the inflammatory response and prevented neuronal loss. By preventing early metabolic disturbances during resuscitation and immediate reperfusion, intravenous pyruvate therapy protected the heart and brain from dysfunction and injury. The following figure summarizes these major findings. [see dissertation] Figure: Pyruvate mediated metabolic protection following cardiopulmonary arrest-resuscitation.Item Pyruvate-Enriched Ringer's Solution Protects Hindlimb and Myocardial Tissue During Hemorrhagic Shock and Hindlimb Ischemia(2011-07-22) Gurji, Hunaid Adam; Mallet, Robert T.; Olivencia-Yurvati, Albert; Raven, Peter B.Gurji, HA. Pyruvate-Enriched Ringer’s Solution Protects Hindlimb and Myocardial Tissue During Hemorrhagic Shock and Hindlimb Ischemia. Doctor of Philosophy (Integrative Physiology), July 22, 2011, 111 pp, 1 table, 23 figures, 209 references, 142 titles. Copious blood loss is the leading cause of death in military combat. Extreme exsanguination following traumatic injury causes hypotension which may culminate in hemorrhagic shock, multiple open organ failure, and death. Currently, the only available strategy to treat hemorrhage is to apply tourniquets and administer resuscitative fluids. Although necessary to limit blood loss, protracted tourniquet application imposes ischemia on distal tissues. Revascularization of the injured limb reintroduces oxygenated blood into the ischemic zone, forming toxic reactive oxygen species. These highly reactive compounds can inactivate key metabolic enzymes, hamper ATP production, and cause end organ dysfunction. Fluid resuscitation provides crucial hemodynamic support, and affords an opportunity to treat the deleterious effects of hemorrhagic shock and ischemia-reperfusion. In order to mitigate the harmful effects of hemorrhagic shock and ischemia-reperfusion of tourniqueted extremities, a fluid resuscitant should contain agents capable of suppressing the formation of reactive oxygen and nitrogen species, thus protecting cellular metabolic function; stabilizing tissue energetics; and safeguarding end organic function. Pyruvate, an endogenous energy substrate, possesses strong antioxidative properties. This study tested whether substituting pyruvate for lactate in a Ringer’s solution would be effective at mitigating reactive oxygen species formation, protect key ATP-generating and ATP-shuttling enzymes from inactivation, bolster skeletal and cardiac muscle phosphorylation potentials, and stabilize cardiac electrical function in goats subjected to hemorrhagic shock and hindlimb ischemia-reperfusion. Isoflurane-anesthetize goats were subjected to a controlled hemorrhaged to reduce the mean arterial pressure to c. 50 mmHg. After reaching this target pressure, hindlimb ischemia (HLI) was imposed for a total of 90 min by femoral artery crossclamp and tourniquet application around the hindlimb. After 30 min of hindlimb ischemia, pyruvate- (PR) or lactate- enriched (LR) Ringer’s solution was infused intravenously (10mL/min) for 90 min. Time control (TC) goats were neither hemorrhaged nor subjected to hindlimb ischemia. At the conclusion of- and 3.5 h after- fluid resuscitation, the left ventricle and the right gastrocnemius were biopsied and flash-frozen for biochemical analysis of metabolites, enzymes, and markers of oxidative stress. In addition, custom-written software was developed to analyze QT interval variability- a marker of electrical instability- from the lead II electrocardiogram. The first phase of this project tested the hypothesis that resuscitation with PR vs. LR effectively protects cardiac metabolism and preserves cardiac electrical performance during hemorrhagic shock and hindlimb ischemia. Resuscitation with PR effectively suppressed the formation of myocardial tissue 8-isoprostane vs. goats resuscitated with LR during the acute and subacute phases of the protocol. In addition, myocardial creatine kinase (CK) activity fell after LR administration vs. TC; however, PR preserved CK activity better than LR during fluid resuscitation and 4 h after hindlimb ischemia reperfusion. PR administration augmented myocardial phosphocreatine phosphorylation potential during fluid administration and 3.5 h later to values significantly higher than those in LR-resuscitated goats. Pro-arrhythmic QTc variability was markedly increased in LR vs. PR and TC during both phases of the protocol. The second phase of this project tested the hypothesis that resuscitation with PR preserves tissue energetics in the reperfused gastrocnemius during hemorrhagic shock and hindlimb ischemia. Resuscitation with PR vs. LR effectively protected the gastrocnemius from oxidative stress in both protocols, as evidenced by the suppression of 8-isoprostane formation. PR prevented CK and aconitase inactivation vs. LR during the acute phase of reperfusion, and this enzyme protection persisted at least 3.5 h after completing fluid resuscitation. Additionally, PR augmented muscle phosphocreatine phosphorylation potential vs. TC and LR during the acute phase of reperfusion, and, like CK and aconitase activities, this augmented energy state persisted 3.5 h after the end of fluid resuscitation. We conclude that 1) Pyruvate Ringer’s resuscitation during hemorrhagic shock and hindlimb ischemia provides antioxidative protection in skeletal and cardiac muscle during fluid resuscitation; 2) Pyruvate-fortified fluid resuscitation prevents inactivation of enzymes involved in production and shuttling of ATP; 3) PR augments cardiac and muscle phosphorylation potentials during fluid resuscitation; and 4) Resuscitation with PR effectively protects cardiac electrical rhythm in the face of hemorrhagic shock and hindlimb ischemia. These investigations demonstrate the powerful antioxidative protection imposed by pyruvate, its positive effects on muscle and cardiac metabolism and energy state and its role in stabilizing cardiac electrical function during hemorrhagic shock and hindlimb ischemia.Item Sex Differences in Oxidative Stress and Inflammation Responses During and After Simulated Hemorrhage(2020-05) Barnes, Haley J.; Rickards, Caroline A.; Hodge, Lisa M.; Mallet, Robert T.; Goulopoulou, StylianiHemorrhage (i.e., massive blood loss) induces an oxidative stress and inflammatory response that can persist even following hemostasis and resuscitation. Premenopausal females exhibit a survival advantage following hemorrhage compared to young males. In this study, we hypothesized that young males would elicit a greater oxidative stress and inflammatory response compared to young females, both during and after a simulated hemorrhage via lower body negative pressure (LBNP). Young, healthy human subjects (10F; 10M) participated in a stepwise-LBNP protocol to presyncope. Venous blood samples were collected at baseline, presyncope, and 1-h into recovery (i.e., following "resuscitation"). The oxidative stress response was assessed via circulating F2-isoprostanes (F2-IsoP) using gas chromatography-negative ion chemical ionization-mass spectrometry. The inflammatory response was assessed via circulating tissue necrosis factor-α (TNF-α), C-Reactive Protein (CRP), thymus and activation-regulated chemokine (TARC), and interleukin (IL)-5, IL-6, IL-7, and IL-10, using a MSD® Multiplex assay. LBNP tolerance time was similar between male and female subjects (Males, 1592±124 s vs. Females, 1437 ± 113 s; P = 0.37). There was no effect of time or sex on the absolute or relative change in F2-IsoP during or after LBNP (P ≥ 0.12). However, male subjects exhibited a greater pro-and anti-inflammatory response during and after LBNP compared to female subjects (Notable markers at 1-h recovery compared to baseline, IL-6: Males, 101.4 ± 138.9% vs. Females, 12.3 ± 34.0%, P = 0.06; IL-10: Males, 71.1 ± 133.3% vs. Females, -2.2 ± 11.8%; P = 0.06). These data suggest that there may be a potential sex difference in the inflammatory response to simulated hemorrhage.