Beneficial effects of nitric oxide on outcomes after cardiac arrest and cardiopulmonary resuscitation in hypothermia-treated mice

Clinical Effects of Nitric Oxide Added to the Oxygenator of Children on Extracorporeal Membrane Oxygenation: Pre-Post Cohort Study

Nitric oxide (NO) can be safely delivered through the sweep gas to the oxygenator of an extracorporeal membrane oxygenation (ECMO) circuit. It has theoretical benefits such as preventing platelet adhesion to surfaces, mitigating inflammatory response and protection against ischemia-reperfusion injury. In this uncontrolled before-after study of children on ECMO, the outcomes of those who received NO were compared with those who did not. Among 393 ECMO runs (from 337 patients), 192 of 393 (49%) received NO and 201 of 393 (51%) did not. The use of NO was associated with a 37% reduction in circuit change (adjusted risk ratio [aRR]: 0.63, 95% confidence interval [CI]: 0.42-0.93). The aRR (95% CI) for risk of neurologic injury was 0.72 (0.47-1.11). We observed potential heterogeneity of treatment effect for the risk of neurologic injury in children who had cardiac surgery: the risk with NO was lower in those who had cardiac surgery (aRR: 0.50, 95% CI: 0.26-0.96). There was no difference in survival between the study groups. In children managed with NO delivered through the ECMO circuit, we report a reduction in observed rate of circuit change and lower risk of neurologic injury in children who underwent cardiac surgery. Nitric oxide therapy on ECMO warrants prospective evaluation in children.

Transcriptional response to mild therapeutic hypothermia in noise-induced cochlear injury

Introduction

Prevention or treatment for acoustic injury has been met with many translational challenges, resulting in the absence of FDA-approved interventions. Localized hypothermia following noise exposure mitigates acute cochlear injury and may serve as a potential avenue for therapeutic approaches. However, the mechanisms by which hypothermia results in therapeutic improvements are poorly understood.

Methods

This study performs the transcriptomic analysis of cochleae from juvenile rats that experienced noise-induced hearing loss (NIHL) followed by hypothermia or control normothermia treatment.

Results

Differential gene expression results from RNA sequencing at 24 h post-exposure to noise suggest that NIHL alone results in increased inflammatory and immune defense responses, involving complement activation and cytokine-mediated signaling. Hypothermia treatment post-noise, in turn, may mitigate the acute inflammatory response.

Discussion

This study provides a framework for future research to optimize hypothermic intervention for ameliorating hearing loss and suggests additional pathways that could be targeted for NIHL therapeutic intervention.

Inhaled nitric oxide improves post-cardiac arrest outcomes via guanylate cyclase-1 in bone marrow-derived cells

RATIONALE

Nitric oxide (NO) exerts its biological effects primarily via activation of guanylate cyclase (GC) and production of cyclic guanosine monophosphate. Inhaled NO improves outcomes after cardiac arrest and cardiopulmonary resuscitation (CPR). However, mechanisms of the protective effects of breathing NO after cardiac arrest are incompletely understood.

OBJECTIVE

To elucidate the mechanisms of beneficial effects of inhaled NO on outcomes after cardiac arrest.

METHODS

Adult male C57BL/6J wild-type (WT) mice, GC-1 knockout mice, and chimeric WT mice with WT or GC-1 knockout bone marrow were subjected to 8 min of potassium-induced cardiac arrest to determine the role of GC-1 in bone marrow-derived cells. Mice breathed air or 40 parts per million NO for 23 h starting at 1 h after CPR.

RESULTS

Breathing NO after CPR prevented hypercoagulability, cerebral microvascular occlusion, an increase in circulating polymorphonuclear neutrophils and neutrophil-to-lymphocyte ratio, and right ventricular dysfunction in WT mice, but not in GC-1 knockout mice, after cardiac arrest. The lack of GC-1 in bone marrow-derived cells diminished the beneficial effects of NO breathing after CPR.

CONCLUSIONS

GC-dependent signaling in bone marrow-derived cells is essential for the beneficial effects of inhaled NO after cardiac arrest and CPR.

Nitric oxide: Clinical applications in critically ill patients

Inhaled nitric oxide (iNO) acts as a selective pulmonary vasodilator and it is currently approved by the FDA for the treatment of persistent pulmonary hypertension of the newborn. iNO has been demonstrated to effectively decrease pulmonary artery pressure and improve oxygenation, while decreasing extracorporeal life support use in hypoxic newborns affected by persistent pulmonary hypertension. Also, iNO seems a safe treatment with limited side effects. Despite the promising beneficial effects of NO in the preclinical literature, there is still a lack of high quality evidence for the use of iNO in clinical settings. A variety of clinical applications have been suggested in and out of the critical care environment, aiming to use iNO in respiratory failure and pulmonary hypertension of adults or as a preventative measure of hemolysis-induced vasoconstriction, ischemia/reperfusion injury and as a potential treatment of renal failure associated with cardiopulmonary bypass. In this narrative review we aim to present a comprehensive summary of the potential use of iNO in several clinical conditions with its suggested benefits, including its recent application in the scenario of the COVID-19 pandemic. Randomized controlled trials, meta-analyses, guidelines, observational studies and case-series were reported and the main findings summarized. Furthermore, we will describe the toxicity profile of NO and discuss an innovative proposed strategy to produce iNO. Overall, iNO exhibits a wide range of potential clinical benefits, that certainly warrants further efforts with randomized clinical trials to determine specific therapeutic roles of iNO.

Experience of cases with inhaled nitric oxide and therapeutic hypothermia

BACKGROUND

Neonates with hypoxic-ischemic encephalopathy (HIE) on therapeutic hypothermia (TH) therapy may show persistent pulmonary hypertension of the newborn (PPHN). In Japan, the reported mortality rate is lower than in the US, possibly due to treatment differences of newborns with moderate to severe HIE and PPHN. This study aimed to determine the feasibility and long-term outcomes of inhaled nitric oxide (iNO) and TH therapy in newborns with moderate to severe HIE and PPHN.

METHODS

This was a retrospective review of neonates with moderate to severe HIE that were treated with TH from 2008 to 2017 at a large medical center in Japan. We documented their long-term neurological prognosis, measuring their developmental and Gross Motor Function Classification System level at 18 months old.

RESULTS

A total of 37 neonates with moderate to severe HIE underwent TH therapy and six of them were started with iNO therapy for PPHN. iNO with TH was safely administered to all six newborns with moderate to severe HIE with PPHN. In two neonates TH was discontinued because of intraventricular hemorrhage (IVH) and severe hypotension. Neurological outcomes were similar in newborns who were treated with iNO and TH and those who were treated with TH alone.

CONCLUSION

These initial findings suggest that monitoring hematological and cardiovascular status is important with iNO for severe asphyxia in infants with PPHN. Safer and more feasible protocols are needed for when iNO and TH therapy are administered together.

Nitrogen Oxide-Added Extracorporeal Membrane Oxygenation for Treating Critical Acute Heart Failure after Cardiac Surgery

The aim of the study was to test the use of gaseous nitric oxide added to the extracorporeal membrane oxygenation (ECMO) system for treating critical acute heart failure after cardiac surgery.

A Sulfonyl Azide-Based Sulfide Scavenger Rescues Mice from Lethal Hydrogen Sulfide Intoxication

Exposure to hydrogen sulfide (H2S) can cause neurotoxicity and cardiopulmonary arrest. Resuscitating victims of sulfide intoxication is extremely difficult, and survivors often exhibit persistent neurological deficits. However, no specific antidote is available for sulfide intoxication. The objective of this study was to examine whether administration of a sulfonyl azide-based sulfide-specific scavenger, SS20, would rescue mice in models of H2S intoxication: ongoing exposure and post-cardiopulmonary arrest. In the ongoing exposure model, SS20 (1,250 µmol/kg) or vehicle was administered to awake CD-1 mice intraperitoneally at 10 minutes after breathing 790 ppm of H2S followed by another 30 minutes of H2S inhalation. Effects of SS20 on survival was assessed. In the post-cardiopulmonary arrest model, cardiopulmonary arrest was induced by an intraperitoneal administration of sodium sulfide nonahydrate (125 mg/kg) in anesthetized mice. After 1 minute of cardiopulmonary arrest, mice were resuscitated with intravenous administration of SS20 (250 µmol/kg) or vehicle. Effects of SS20 on survival, neurological outcomes, and plasma H2S levels were evaluated. Administration of SS20 during ongoing H2S inhalation improved 24-hour survival (6/6 [100%] in SS20 versus 1/6 [17%] in vehicle; P = 0.0043). Post-arrest administration of SS20 improved 7-day survival (4/10 [40%] in SS20 versus 0/10 [0%] in vehicle; P = 0.0038) and neurological outcomes after resuscitation. SS20 decreased plasma H2S levels to pre-arrest baseline immediately after reperfusion and shortened the time to return of spontaneous circulation and respiration. The current results suggest that SS20 is an effective antidote against lethal H2S intoxication, even when administered after cardiopulmonary arrest.

Efficacy and safety of inhaled nitric oxide in the treatment of severe/critical COVID-19 patients: A systematic review

OBJECTIVE:

Present systematic review aimed to analyze the effect of inhaled nitric oxide (iNO) in the treatment of severe COVID-19 and to compare it to standard of care (SOC), antiviral medications, and other medicines.

MATERIALS AND METHODS:

Medline (PubMed), Scopus, Embase, Ovid, Web of Science, Science Direct, Wiley Online Library, BioRxiv and MedRxiv, and Cochrane (up to April 20, 2021) were the search databases. Two reviewers (SK and CK) independently selected the electronic published literature that studied the effect of nitric oxide with SOC or control. The clinical and physiological outcomes such as prevention of progressive systemic de-oxygenation/clinical improvement, mortality, duration of mechanical ventilation, improvement in pulmonary arterial pressure, and adverse events were assessed.

RESULTS:

The 14 retrospective/protective studies randomly assigning 423 patients met the inclusion criteria. Cumulative study of the selected articles showed that iNO has a mild impact on ventilation time or ventilator-free days. iNO has increased the partial pressure of oxygen/fraction of inspired oxygen ratio of fraction of inspired oxygen in a few patients as compared to baseline. However, in most of the studies, it does not have better outcome when compared to the baseline improvement.

CONCLUSIONS:

In patients with COVID-19 with acute respiratory distress syndrome, nitric oxide is linked to a slight increase in oxygenation but has no effect on mortality.

Inhaled nitric oxide in adults with in-hospital cardiac arrest: A feasibility study

BACKGROUND

While inhaled nitric oxide (iNO) has revealed benefit in cardiac arrest in an animal model, no published data has yet demonstrated the impact of iNO in humans with cardiac arrest.

METHODS

In this pilot study, we administered iNO, along with standard post-resuscitative care, in adults with in-hospital cardiac arrest (IHCA) following achievement of return of spontaneous circulation (ROSC) at an academic tertiary medical center. Patients receiving iNO were compared to age-matched controls with IHCA receiving standard care from an institutional registry. The primary outcome was survival to discharge; secondary outcome was favorable neurologic outcome, defined by a Glasgow Outcome Score of 4 or 5. Propensity-score (PS) matching analysis was performed between patients receiving iNO versus controls.

RESULTS

Twenty adults with IHCA receiving iNO were compared to 199 controls with IHCA. Similar age, Charlson comorbidity index, and initial rhythm were noted in both groups. Patients receiving iNO had higher rates of survival to discharge compared to controls (35% vs 11%, p < 0.0001) but no difference in favorable neurologic outcome (15% vs 9%, p = 0.39) in the unmatched population. In the PS-matched analysis, patients receiving iNO had higher survival to discharge (35% vs 20%, p = 0.0344) than the control group but no difference in favorable neurologic outcome (15% vs 20%, p = 0.13) were noted between both groups.

CONCLUSIONS

In this pilot study, iNO was associated with significantly higher rates of survival to discharge but not favorable neurologic outcome among patients with IHCA compared to controls. This benefit was also observed in the PS-matched analysis. A large scale randomized controlled trial comparing standard of care supplemented with iNO to standard of care alone is warranted in patients with cardiac arrest (Funded by Stony Brook University Renaissance School of Medicine, ClinicalTrials.gov number, NCT04134078).

Luteolin as an adjuvant effectively enhances CTL anti-tumor response in B16F10 mouse model

Luteolin, a naturally found dietary flavonoid, has a wide range of beneficial biological effects, including effects against tumors and oxidants. Studies proved that luteolin can modulate immune responses. In this study, we investigated the function of luteolin as an antitumor vaccine adjuvant (to treat malignant melanoma) in vitro and in vivo. We found that Luteolin may activated the PI3K-Akt pathways in APCs (Antigen Presenting Cells), induced the activation of APCs, enhanced CTL (Cytotoxic T Lymphocyte) responses, and inhibited tolerogenic T cells. To prove the role of CD8+T cells in immune process, we sorted the CD8+T cells from the immunized mice and transferred them to the B16F10 tumor-bearing mice, the result showed that the survival rate was improved. We also observed that in the mice immunized with Luteolin as an adjuvant, the tumor growth was significantly reduced. Taken together, the result demonstrated that luteolin showed promising properties as a vaccine adjuvant for treating malignant melanoma.

Effects of hypothermia on inflammatory cytokine expression in rat liver following asphyxial cardiac arrest

Hypothermic treatment is known to protect against cardiac arrest (CA) and improve survival rate. However, few studies have evaluated the CA-induced liver damage and the effects of hypothermia on this damage. Therefore, the aim of the present study was to determine possible protective effects of hypothermia on the liver after asphyxial CA. Rats were subjected to a 5-min asphyxial CA followed by return of spontaneous circulation (ROSC). The body temperature was controlled at 37±0.5˚C (normothermia group) or 33±0.5˚C (hypothermia group) for 4 h after ROSC. Livers were examined at 6, 12 h, 1 and 2 days after ROSC. Histopathological examination was performed by H&E staining. Alterations in the expression levels of pro-inflammatory (TNF-α and interleukin IL-2) and anti-inflammatory cytokines (IL-4 and IL-13) were investigated by immunohistochemistry. Sinusoidal dilatation and vacuolization were observed after asphyxial CA by histopathological examination. However, these CA-induced structural alterations were prevented by hypothermia. In immunohistochemical examination, the expression levels of pro-inflammatory cytokines were reduced in the hypothermia group compared with those in the normothermia group while the expression levels of anti-inflammatory cytokines were increased in the hypothermia group compared with those in the normothermia group. In conclusion, hypothermic treatment for 4 h following asphyxial CA in rats inhibited the increase of pro-inflammatory cytokines and stimulated the expression of anti-inflammatory cytokines compared with the normothermic group. The results of the present study suggested that hypothermic treatment after asphyxial CA reduced liver damage via the regulation of inflammation.

A randomized and blinded trial of inhaled nitric oxide in a piglet model of pediatric cardiopulmonary resuscitation

AIM

Inhaled nitric oxide (iNO) during cardiopulmonary resuscitation (CPR) improved systemic hemodynamics and outcomes in a preclinical model of adult in-hospital cardiac arrest (IHCA) and may also have a neuroprotective role following cardiac arrest. The primary objectives of this study were to determine if iNO during CPR would improve cerebral hemodynamics and mitochondrial function in a pediatric model of lipopolysaccharide-induced shock-associated IHCA.

METHODS

After lipopolysaccharide infusion and ventricular fibrillation induction, 20 1-month-old piglets received hemodynamic-directed CPR and were randomized to blinded treatment with or without iNO (80 ppm) during and after CPR. Defibrillation attempts began at 10 min with a 20-min maximum CPR duration. Cerebral tissue from animals surviving 1-h post-arrest underwent high-resolution respirometry to evaluate the mitochondrial electron transport system and immunohistochemical analyses to assess neuropathology.

RESULTS

During CPR, the iNO group had higher mean aortic pressure (41.6 ± 2.0 vs. 36.0 ± 1.4 mmHg; p = 0.005); diastolic BP (32.4 ± 2.4 vs. 27.1 ± 1.7 mmHg; p = 0.03); cerebral perfusion pressure (25.0 ± 2.6 vs. 19.1 ± 1.8 mmHg; p = 0.02); and cerebral blood flow relative to baseline (rCBF: 243.2 ± 54.1 vs. 115.5 ± 37.2%; p = 0.02). Among the 8/10 survivors in each group, the iNO group had higher mitochondrial Complex I oxidative phosphorylation in the cerebral cortex (3.60 [3.56, 3.99] vs. 3.23 [2.44, 3.46] pmol O₂/s mg; p = 0.01) and hippocampus (4.79 [4.35, 5.18] vs. 3.17 [2.75, 4.58] pmol O₂/s mg; p = 0.02). There were no other differences in mitochondrial respiration or brain injury between groups.

CONCLUSIONS

Treatment with iNO during CPR resulted in superior systemic hemodynamics, rCBF, and cerebral mitochondrial Complex I respiration in this pediatric cardiac arrest model.

Nitric oxide and the brain. Part 2: Effects following neonatal brain injury-friend or foe?

Nitric oxide (NO) has critical roles in a wide variety of key biologic functions and has intricate transport mechanisms for delivery to key distal tissues under normal conditions. However, NO also plays important roles during disease processes, such as hypoxia-ischemia, asphyxia, neuro-inflammation, and retinopathy of prematurity. The effects of exogenous NO on the developing neonatal brain remain controversial. Inhaled NO (iNO) can be neuroprotective or toxic depending on a variety of factors, including cellular redox state, underlying disease processes, duration of treatment, and dose. This review identifies key gaps in knowledge that should prompt further investigation into the possible role of iNO as a therapeutic agent after injury to the brain. IMPACT: NO is a key signal mediator in the neonatal brain with neuroprotective and neurotoxic properties. iNO, a commonly used medication, has significant effects on the neonatal brain. Dosing, duration, and timing of administration of iNO can affect the developing brain. This review article summarizes the roles of NO in association with various disease processes that impact neonates, such as brain hypoxia-ischemia, asphyxia, retinopathy of prematurity, and neuroinflammation. The impact of this review is that it clearly describes gaps in knowledge, and makes the case for further, targeted studies in each of the identified areas.

Inhaled Gases as Therapies for Post-Cardiac Arrest Syndrome: A Narrative Review of Recent Developments

Despite recent advances in the management of post-cardiac arrest syndrome (PCAS), the survival rate, without neurologic sequelae after resuscitation, remains very low. Whole-body ischemia, followed by reperfusion after cardiac arrest (CA), contributes to PCAS, for which established pharmaceutical interventions are still lacking. It has been shown that a number of different processes can ultimately lead to neuronal injury and cell death in the pathology of PCAS, including vasoconstriction, protein modification, impaired mitochondrial respiration, cell death signaling, inflammation, and excessive oxidative stress. Recently, the pathophysiological effects of inhaled gases including nitric oxide (NO), molecular hydrogen (H₂), and xenon (Xe) have attracted much attention. Herein, we summarize recent literature on the application of NO, H₂, and Xe for treating PCAS. Recent basic and clinical research has shown that these gases have cytoprotective effects against PCAS. Nevertheless, there are likely differences in the mechanisms by which these gases modulate reperfusion injury after CA. Further preclinical and clinical studies examining the combinations of standard post-CA care and inhaled gas treatment to prevent ischemia-reperfusion injury are warranted to improve outcomes in patients who are being failed by our current therapies.

Nitric Oxide in Post-cardiac Arrest Syndrome

Sudden cardiac arrest is a leading cause of death worldwide. Although the methods of cardiopulmonary resuscitation have been improved, mortality is still unacceptably high, and many survivors suffer from lasting neurological deficits due to the post-cardiac arrest syndrome (PCAS). Pathophysiologically, generalized vascular endothelial dysfunction accompanied by platelet activation and systemic inflammation has been implicated in the pathogenesis of PCAS. Because endothelial-derived nitric oxide (NO) plays a central role in maintaining vascular homeostasis, the role of NO-dependent signaling has been a focus of the intense investigation. Recent preclinical studies showed that therapeutic interventions that increase vascular NO bioavailability may improve outcomes after cardiac arrest complicated with PCAS. In particular, NO inhalation therapy has been shown to improve neurological outcomes and survival in multiple species. Clinical studies examining the safety and efficacy of inhaled NO in patients sustaining PCAS are warranted.

Administration of inhaled noble and other gases after cardiopulmonary resuscitation: A systematic review

OBJECTIVE

Inhalation of noble and other gases after cardiac arrest (CA) might improve neurological and cardiac outcomes. This article discusses up-to-date information on this novel therapeutic intervention.

DATA SOURCES

CENTRAL, MEDLINE, online published abstracts from conference proceedings, clinical trial registry clinicaltrials.gov, and reference lists of relevant papers were systematically searched from January 1960 till March 2019.

STUDY SELECTION

Preclinical and clinical studies, irrespective of their types or described outcomes, were included.

DATA EXTRACTION

Abstract screening, study selection, and data extraction were performed by two independent authors. Due to the paucity of human trials, risk of bias assessment was not performed DATA SYNTHESIS: After screening 281 interventional studies, we included an overall of 27. Only, xenon, helium, hydrogen, and nitric oxide have been or are being studied on humans. Xenon, nitric oxide, and hydrogen show both neuroprotective and cardiotonic features, while argon and hydrogen sulfide seem neuroprotective, but not cardiotonic. Most gases have elicited neurohistological protection in preclinical studies; however, only hydrogen and hydrogen sulfide appeared to preserve CA1 sector of hippocampus, the most vulnerable area in the brain for hypoxia.

CONCLUSION

Inhalation of certain gases after CPR appears promising in mitigating neurological and cardiac damage and may become the next successful neuroprotective and cardiotonic interventions.

Nitric oxide: a new role in intensive care

Inhaled nitric oxide has been used for 30 years to improve oxygenation and decrease pulmonary vascular resistance. In the past 15 years, there has been increased understanding of the role of endogenous nitric oxide on cell surface receptors, mitochondria, and intracellular processes involving calcium and superoxide radicals. This has led to several animal and human experiments revealing a potential role for administered nitric oxide or nitric oxide donors in patients with systemic inflammatory response syndrome or ischaemia-reperfusion injury, and in patients for whom exposure of blood to artificial surfaces has occurred.

Improvement in Outcomes After Cardiac Arrest and Resuscitation by Inhibition of S-Nitrosoglutathione Reductase

BACKGROUND

The biological effects of nitric oxide are mediated via protein S-nitrosylation. Levels of S-nitrosylated protein are controlled in part by the denitrosylase, S-nitrosoglutathione reductase (GSNOR). The objective of this study was to examine whether GSNOR inhibition improves outcomes after cardiac arrest and cardiopulmonary resuscitation (CA/CPR).

METHODS

Adult wild-type C57BL/6 and GSNOR-deleted (GSNOR^-/-) mice were subjected to potassium chloride-induced CA and subsequently resuscitated. Fifteen minutes after a return of spontaneous circulation, wild-type mice were randomized to receive the GSNOR inhibitor, SPL-334.1, or normal saline as placebo. Mortality, neurological outcome, GSNOR activity, and levels of S-nitrosylated proteins were evaluated. Plasma GSNOR activity was measured in plasma samples obtained from post-CA patients, preoperative cardiac surgery patients, and healthy volunteers.

RESULTS

GSNOR activity was increased in plasma and multiple organs of mice, including brain in particular. Levels of protein S-nitrosylation were decreased in the brain 6 hours after CA/CPR. Administration of SPL-334.1 attenuated the increase in GSNOR activity in brain, heart, liver, spleen, and plasma, and restored S-nitrosylated protein levels in the brain. Inhibition of GSNOR attenuated ischemic brain injury and improved survival in wild-type mice after CA/CPR (81.8% in SPL-334.1 versus 36.4% in placebo; log rank P=0.031). Similarly, GSNOR deletion prevented the reduction in the number of S-nitrosylated proteins in the brain, mitigated brain injury, and improved neurological recovery and survival after CA/CPR. Both GSNOR inhibition and deletion attenuated CA/CPR-induced disruption of blood brain barrier. Post-CA patients had higher plasma GSNOR activity than did preoperative cardiac surgery patients or healthy volunteers ( P<0.0001). Plasma GSNOR activity was positively correlated with initial lactate levels in postarrest patients (Spearman correlation coefficient=0.48; P=0.045).

CONCLUSIONS

CA and CPR activated GSNOR and reduced the number of S-nitrosylated proteins in the brain. Pharmacological inhibition or genetic deletion of GSNOR prevented ischemic brain injury and improved survival rates by restoring S-nitrosylated protein levels in the brain after CA/CPR in mice. Our observations suggest that GSNOR is a novel biomarker of postarrest brain injury as well as a molecular target to improve outcomes after CA.

The comparison of the effects of local cooling and heating on apoptosis and pyroptosis of early-stage pressure ulcers in rats

The exploration of an effective method for preventing and treating pressure ulcers (PUs) is a hot topic in medical research. Recently, disputes about the choice of heat and cold therapies have emerged for the prevention and treatment of clinical PUs. The present study was designed to compare the effect of cool and heat therapies on pyroptosis and apoptosis of early-stage PUs in rats. Sixty SD rats of SPF grade were randomly divided into the sham group, model group, heating group, and cooling group. We established a rat model of early-stage PUs by using an ischemia-reperfusion method. At the end of the experiment, the tissue underneath the compressed region was collected for hematoxylin and eosin staining, transmission electron microscopy, immunohistochemistry, immunofluorescence staining, a TdT-mediated dUTP nick-end labeling assay, a Western blot analysis, and a mitochondrial swelling experiment. Our results suggested that the mitochondrial apoptotic pathway and pyroptosis were involved in the formation of early-stage PUs, and local heating increased the PU injury in rats, while local cooling reduced the PU injury in rats. This study showed that heat therapy might not be suitable for the clinical treatment and care of early-stage PUs, while cold therapy may be more appropriate.

Moderate brain hypothermia started before resuscitation improves survival and neurobehavioral outcomes after CA/CPR in mice

AIM OF THE STUDY

No definitive experimental or clinical evidence exists whether brain hypothermia before, rather than during or after, resuscitation can reduce hypoxic-ischemic brain injury following cardiac arrest/cardiopulmonary resuscitation (CA/CPR) and improve outcomes. We examined the effects of moderate brain hypothermia before resuscitation on survival and histopathological and neurobehavioral outcomes in a mouse model.

METHODS

Adult C57BL/6 male mice (age: 8-12 weeks) were subjected to 8-min CA followed by CPR. The animals were randomly divided into sham, normothermia (NT; brain temperature 37.5 °C), and extracranial hypothermia (HT; brain temperature 28-32 °C) groups. The hippocampal CA1 was assessed 7 day after resuscitation by histochemical staining. Neurobehavioral outcomes were evaluated by the Barnes maze (BMT), openfield (OFT), rotarod, and light/dark (LDT) tests. Cleaved caspase-3 and heat shock protein 60 (HSP70) levels were investigated by western blotting.

RESULTS

The HT group exhibited higher survival and lower CA1 neuronal injury than did the NT group. HT mice showed improved spatial memory in the BMT compared with NT mice. NT mice travelled a shorter distance in the OFT and tended to spend more time in the light compartment in the LDT than did sham and HT mice. The levels of cleaved caspase-3 and HSP70 were non-significantly higher in the NT than in the sham and HT groups.

CONCLUSIONS

Moderate brain hypothermia before resuscitation improved survival and reduced histological neuronal injury, spatial memory impairment, and anxiety-like behaviours after CA/CPR in mice.

Inhaled nitric oxide

Nitric oxide (NO) is a gas that induces relaxation of smooth muscle cells in the vasculature. Because NO reacts with oxyhaemoglobin with high affinity, the gas is rapidly scavenged by oxyhaemoglobin in red blood cells and the vasodilating effects of inhaled NO are limited to ventilated regions in the lung. NO therefore has the unique ability to induce pulmonary vasodilatation specifically in the portions of the lung with adequate ventilation, thereby improving oxygenation of blood and decreasing intrapulmonary right to left shunting. Inhaled NO is used to treat a spectrum of cardiopulmonary conditions, including pulmonary hypertension in children and adults. However, the widespread use of inhaled NO is limited by logistical and financial barriers. We have designed, developed and tested a simple and economic NO generation device, which uses pulsed electrical discharges in air to produce therapeutic levels of NO that can be used for inhalation therapy. LINKED ARTICLES: This article is part of a themed section on Nitric Oxide 20 Years from the 1998 Nobel Prize. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.2/issuetoc.

The Living Dead: Mitochondria and Metabolic Arrest

Mitochondria are not just the powerhouses of the cell; these 'end of function' organelles are crucial components of cellular physiology and influence many central metabolic and signaling pathways that support complex multicellular life. Not surprisingly, these organelles play vital roles in adaptations for extreme survival strategies including hibernation and freeze tolerance, both of which are united by requirements for a strong reduction and reprioritization of metabolic processes. To facilitate metabolic rate depression, adaptations of all aspects of mitochondrial function are required, including; energetics, physiology, abundance, gene regulation, and enzymatic controls. This review discusses these factors with a focus on the stress-specific nature of mitochondrial genes and transcriptional regulators, and processes including apoptosis and chaperone protein responses. We also analyze the regulation of glutamate dehydrogenase and pyruvate dehydrogenase, central mitochondrial enzymes involved in coordinating the shifts in metabolic fuel use associated with extreme survival strategies. Finally, an emphasis is given to the novel mitochondrial research areas of microRNAs, peptides, epigenetics, and gaseous mediators and their potential roles in facilitating hypometabolism. © 2018 IUBMB Life, 70(12):1260-1266, 2018.

The relationship between low survival and acute increase of tumor necrosis factor α expression in the lung in a rat model of asphyxial cardiac arrest

Cardiac arrest (CA) is sudden loss of heart function and abrupt stop in effective blood flow to the body. The patients who initially achieve return of spontaneous circulation (RoSC) after CA have low survival rate. It has been known that multiorgan dysfunctions after RoSC are associated with high morbidity and mortality. Most previous studies have focused on the heart and brain in RoSC after CA. Therefore, the aim of this research was to perform serological, physiological, and histopathology study in the lung and to determine whether or how pulmonary dysfunction is associated with low survival rate after CA. Experimental animals were divided into sham-operated group (n=14 at each point in time), which was not subjected to CA operation, and CA-operated group (n=14 at each point in time), which was subjected to CA. The rats in each group were sacrificed at 6 hours, 12 hours, 24 hours, and 2 days, respectively, after RoSC. Then, pathological changes of the lungs were analyzed by hematoxylin and eosin staining, Western blot and immunohistochemistry for tumor necrosis factor α (TNF-α). The survival rate after CA was decreased with time past. We found that histopathological score and TNF-α immunoreactivity were significantly increased in the lung after CA. These results indicate that inflammation triggered by ischemia-reperfusion damage after CA leads to pulmonary injury/dysfunctions and contributes to low survival rate. In addition, the finding of increase in TNF-α via inflammation in the lung after CA would be able to utilize therapeutic or diagnostic measures in the future.

Effects of inhaled nitric oxide on outcome after prolonged cardiac arrest in mild therapeutic hypothermia treated rats

Guidelines endorse targeted temperature management to reduce neurological sequelae and mortality after cardiac arrest (CA). Additional therapeutic approaches are lacking. Inhaled nitric oxide (iNO) given post systemic ischemia/reperfusion injury improves outcomes. Attenuated inflammation by iNO might be crucial in brain protection. iNO augmented mild therapeutic hypothermia (MTH) may improve outcome after CA exceeding the effect of MTH alone. Following ten minutes of CA and three minutes of cardiopulmonary resuscitation, 20 male Sprague-Dawley rats were randomized to receive MTH at 33 °C for 6hrs or MTH + 20ppm iNO for 5hrs; one group served as normothermic control. During the experiment blood was taken for biochemical evaluation. A neurological deficit score was calculated daily for seven days post CA. On day seven, brains and hearts were harvested for histological evaluation. Treatment groups showed a significant decrease in lactate levels six hours post resuscitation in comparison to controls. TNF-α release was significantly lower in MTH + iNO treated animals only at four hours post ROSC. While only the combination of MTH and iNO improved neurological function in a statistically significant manner in comparison to controls on days 4–7 after CA, there was no significant difference between groups treated with MTH and MTH + iNO.

Spontaneous hypothermia ameliorated inflammation and neurologic deficit in rat cardiac arrest models following resuscitation

Cardiac arrest (CA) is a leading cause of mortality worldwide. The majority of the associated mortalities are caused by post-CA syndrome, which includes symptoms, such as neurologic damage, myocardial dysfunction and systemic inflammation. Following CA, return of spontaneous circulation (ROSC) leads to a brain reperfusion injury, which subsequently causes adverse neurologic outcomes or mortality. Therefore, investigating the underlying mechanisms of ROSC-induced neurologic deficits and establishing potential treatments is critical to prevent and treat post-CA syndrome. In the current study, CA rat models were established by asphyxia. Following ROSC, the temperature was controlled to achieve hypothermia. The general neurologic status was assessed using the neurologic deficit scale. Changes in the concentrations of interleukin (IL)-18 and IL-1β were measured with ELISA and the dynamic change in NACHT, LRR and PYD domains-containing protein 3 inflammasome components was determined by western blot analysis and immunohistochemistry. Neuronal death and apoptosis were measured via TUNEL assays. In the CA rat models, increasing the duration of CA before cardiopulmonary resuscitation was found to aggravate the neural deficit and increase the incidence of inflammation. Following ROSC, the expression level of the inflammasome components was observed to increase in CA rat models, which was accompanied by increased secretion of IL-18 and IL-1β, indicating the promotion of inflammation. In addition, the study identified the beneficial role of spontaneous hypothermia in ameliorating the ROSC-induced inflammation and neurologic deficit in CA rat models, including the downregulation of inflammasome components and attenuating neuronal apoptosis. The present study contributes to the understanding of underlying mechanisms in CA-evoked inflammation and the subsequent neurologic damage following ROSC. A novel potential therapeutic strategy that may increase survival times and the quality of life for patients suffering from post-CA syndrome is proposed in the present study.

Intracarotid Sodium Nitroprusside on Fifth Post Ischemic Stroke Day in Middle Cerebral Artery Occlusion Rat Model

INTRODUCTION

Ischemic stroke at later stages (>4.5 hour) have very few treatment options left. In those cases Nitric Oxide (NO) may provide promising results. NO is active in signaling pathways. Sodium Nitroprusside (SNP), a NO donor was tested earlier in rat Middle Cerebral Artery Occlusion (MCAO) model in early stages (5-60 minutes) and found useful but in delayed stroke cases (60-120 minutes) found useless. This was due to local inducible Nitric Oxide Synthase Enzyme (iNOS) and superoxide (causes destructive effect) formation which was skipped.

AIM

To evaluate the effect of Intracarotid Sodium Nitroprusside (ICSNP) in MCAO rat model of ischemic stroke (I/R model) fifth post ischemic stroke day.

MATERIALS AND METHODS

A total of 24 Sprague Dawley rats, weighing 250 gm to 280 gm, at CDRI-Lucknow, India were used. Rats were divided in three groups. Group A (n=4) were taken as sham with standard procedure but without any injection on fifth day, Group B (n=8) as control with injection of saline on fifth day and Group C (n=12) received SNP at dose of 3 mcg/kg/minute given directly in internal carotid artery via External Carotid Artery (ECA) with a modified intraluminal stump technique as Ischemia/Reperfusion (I/R) in ipsilateral MCAO at intracarotid artery region as a single dose therapy on fifth day and then wound was closed. Waited for full recovery for two hours, then neurobehavioural assessment scores were noted. Thereafter, the brains were quickly removed and sliced at 2 mm intervals. Animals showing no sign of neurological deficit, were excluded from the study. Tested animals were compared with control animals for neurological deficit, percentage of infarction by 2,3,5-Triphenyl Tetrazolium Chloride (TTC) staining, nNOS expression and scores were summed up. The statistical analysis was done by Newman-Keuls test, Graph Pad prism (version.5.0) and p<0.05 was considered statistically significant.

RESULTS

ICSNP group (Group C) showed a good reduction in the cerebral infarction of 53.42% as compared to control (Group B). Group A mean change in Newman-Keuls test and Graph Pad prism (version.5.0) was showing increase of 1.44 points/6.55%, compared to Group B decrease of 0.7 points. A 60% decrease in ischemic zone noted in Group A.

CONCLUSION

The use of single dose ICSNP is beneficial (53.42%) in fifth post stroke day.

Changes in histopathology and tumor necrosis factor-α levels in the hearts of rats following asphyxial cardiac arrest

OBJECTIVE

Post cardiac arrest (CA) syndrome is associated with a low survival rate in patients who initially have return of spontaneous circulation (ROSC) after CA. The aim of this study was to examine the histopathology and inflammatory response in the heart during the post CA syndrome.

METHODS

We induced asphyxial CA in male Sprague-Dawley rats and determined the survival rate of these rats during the post resuscitation phase.

RESULTS

Survival of the rats decreased after CA: 66.7% at 6 hours, 36.7% at 1 day, and 6.7% at 2 days after ROSC following CA. The rats were sacrificed at 6 hours, 12 hours, 1 day, and 2 days after ROSC, and their heart tissues were examined. Histopathological scores increased at 12 hours post CA and afterwards, histopathological changes were not significant. In addition, levels of tumor necrosis factor-α immunoreactivity gradually increased after CA.

CONCLUSION

The survival rate of rats 2 days post CA was very low, even though histopathological and inflammatory changes in the heart were not pronounced in the early stage following CA.

Gaseous Mediators and Mitochondrial Function: The Future of Pharmacologically Induced Suspended Animation?

The role of nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S) as poisonous gases is well-established. However, they are not only endogenously produced but also, at low concentrations, exert beneficial effects, such as anti-inflammation, and cytoprotection. This knowledge initiated the ongoing debate, as to whether these molecules, also referred to as “gaseous mediators” or “gasotransmitters,” could serve as novel therapeutic agents. In this context, it is noteworthy, that all gasotransmitters specifically target the mitochondria, and that this interaction may modulate mitochondrial bioenergetics, thereby subsequently affecting metabolic function. This feature is of crucial interest for the possible induction of “suspended animation.” Suspended animation, similar to mammalian hibernation (and/or estivation), refers to an externally induced hypometabolic state, with the intention to preserve organ function in order to survive otherwise life-threatening conditions. This hypometabolic state is usually linked to therapeutic hypothermia, which, however, comes along with adverse effects (e.g., coagulopathy, impaired host defense). Therefore, inducing an on-demand hypometabolic state by directly lowering the energy metabolism would be an attractive alternative. Theoretically, gasotransmitters should reversibly interact and inhibit the mitochondrial respiratory chain during pharmacologically induced suspended animation. However, it has to be kept in mind that this effect also bears the risk of cytotoxicity resulting from the blockade of the mitochondrial respiratory chain. Therefore, this review summarizes the current knowledge of the impact of gasotransmitters on modulating mitochondrial function. Further, we will discuss their role as potential candidates in inducing a suspended animation.

Mild hypothermia pretreatment protects against liver ischemia reperfusion injury via the PI3K/AKT/FOXO3a pathway

Mild hypothermia is known to protect against ischemia and reperfusion (IR) injury. The exact mechanisms of the protection are not fully understood. Forkhead box O3 (FOXO3a) has been defined as a critical mediator in cellular processes, including oxidative stress, apoptosis, inflammation, cell death and DNA repair; however, the protection function in mild hypothermia has not been reported previously. The current study was designed to investigate the function of phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/FOXO3a pathway in pretreatment with mild hypothermia during IR injury. Additionally, PI3K/AKT/FOXO3a signaling was inhibited using Ly294002 and the effect on the protective function of mild hypothermia pretreatment was evaluated. Furthermore, the apoptotic and inflammatory response induced by the IR injury was evaluated. Liver IR injury induced a significant increase in the level of apoptosis and inflammatory responses. However, pretreatment with mild hypothermia increased phospho (p)-AKT and p-FOXO3a following IR injury, and significantly reduced apoptosis and inflammatory cytokines release. However, inhibiting p-AKT and p-FOXO3a using Ly294002 suppressed the liver protection produced by mild hypothermia. In conclusion, these findings indicated that mild hypothermia pretreatment exhibited liver protective effects against IR injury associated with suppressing inflammatory cytokine release and apoptosis via the PI3K/AKT/FOXO3a pathway.

Hypothalamic or Extrahypothalamic Modulation and Targeted Temperature Management After Brain Injury

Targeted temperature management (TTM) has been recognized to protect tissue function and positively influence neurological outcomes after brain injury. While shivering during hypothermia nullifies the beneficial effect of TTM, traditionally, antishivering drugs or paralyzing agents have been used to reduce the shivering. The hypothalamic area of the brain helps in controlling cerebral temperature and body temperature through interactions between different brain areas. Thus, modulation of different brain areas either pharmacologically or by electrical stimulation may contribute in TTM; although, very few studies have shown that TTM might be achieved by activation and inhibition of neurons in the hypothalamic region. Recent studies have investigated potential pharmacological methods of inducing hypothermia for TTM by aiming to maintain the TTM and reduce the shivering effect without using antiparalytic drugs. Better survival and neurological outcome after brain injury have been reported after pharmacologically induced TTM. This review discusses the mechanisms and modulation of the hypothalamus with other brain areas that are involved in inducing hypothermia through which TTM may be achieved and provides therapeutic strategies for TTM after brain injury.

Safety of nitric oxide added to the ECMO circuit: a pilot study in children

We describe our experience of 30 consecutive children supported with ECMO and receiving 20 ppm of nitric oxide in the oxygenator of the ECMO circuit. Administration of nitric oxide into the ECMO circuit is safe and could potentially mitigate ischaemia reperfusion injury and end-organ dysfunction of children requiring mechanical support.

Neuronal injury and tumor necrosis factor-alpha immunoreactivity in the rat hippocampus in the early period of asphyxia-induced cardiac arrest under normothermia

Low survival rate occurs in patients who initially experience a spontaneous return of circulation after cardiac arrest (CA). In this study, we induced asphyxial CA in adult male Sprague-Daley rats, maintained their body temperature at 37 ± 0.5°C, and then observed the survival rate during the post-resuscitation phase. We examined neuronal damage in the hippocampus using cresyl violet (CV) and Fluore-Jade B (F-J B) staining, and pro-inflammatory response using ionized calcium-binding adapter molecule 1 (Iba-1), glial fibrillary acidic protein (GFAP), and tumor necrosis factor-alpha (TNF-α) immunohistochemistry in the hippocampus after asphyxial CA in rats under normothermia. Our results show that the survival rate decreased gradually post-CA (about 63% at 6 hours, 37% at 1 day, and 8% at 2 days post-CA). Rats were sacrificed at these points in time post-CA, and no neuronal damage was found in the hippocampus until 1 day post-CA. However, some neurons in the stratum pyramidale of the CA region in the hippocampus were dead 2 days post-CA. Iba-1 immunoreactive microglia in the CA1 region did not change until 1 day post-CA, and they were activated (enlarged cell bodies with short and thicken processes) in all layers 2 days post-CA. Meanwhile, GFAP-immunoreactive astrocytes did not change significantly until 2 days post-CA. TNF-α immunoreactivity decreased significantly in neurons of the stratum pyramidale in the CA1 region 6 hours post-CA, decreased gradually until 1 day post-CA, and increased significantly again 2 days post-CA. These findings suggest that low survival rate of normothermic rats in the early period of asphyxia-induced CA is related to increased TNF-α immunoreactivity, but not to neuronal damage in the hippocampal CA1 region.

Mechanistic characterization of nitrite-mediated neuroprotection after experimental cardiac arrest

Nitrite acts as an ischemic reservoir of nitric oxide (NO) and a potent S-nitrosating agent which reduced histologic brain injury after rat asphyxial cardiac arrest (ACA). The mechanism(s) of nitrite-mediated neuroprotection remain to be defined. We hypothesized that nitrite-mediated brain mitochondrial S-nitrosation accounts for neuroprotection by reducing reperfusion reactive oxygen species (ROS) generation. Nitrite (4 μmol) or placebo was infused IV after normothermic (37°C) ACA in randomized, blinded fashion with evaluation of neurologic function, survival, brain mitochondrial function, and ROS. Blood and CSF nitrite were quantified using reductive chemiluminescence and S-nitrosation by biotin switch. Direct neuroprotection was verified in vitro after 1 and 4 h neuronal oxygen glucose deprivation measuring neuronal death with inhibition studies to examine mechanism. Mitochondrial ROS generation was quantified by live neuronal imaging using mitoSOX. Nitrite significantly reduced neurologic disability after ACA. ROS generation was reduced in brain mitochondria from nitrite- versus placebo-treated rats after ACA with congruent preservation of brain ascorbate and reduction of ROS in brain sections using immuno-spin trapping. ATP generation was maintained with nitrite up to 24 h after ACA. Nitrite rapidly entered CSF and increased brain mitochondrial S-nitrosation. Nitrite reduced in vitro mitochondrial superoxide generation and improved survival of neurons after oxygen glucose deprivation. Protection was maintained with inhibition of soluble guanylate cyclase but lost with NO scavenging and ultraviolet irradiation. Nitrite therapy results in direct neuroprotection from ACA mediated by reductions in brain mitochondrial ROS in association with protein S-nitrosation. Neuroprotection is dependent on NO and S-nitrosothiol generation, not soluble guanylate cyclase.

Brief inhalation of nitric oxide increases resuscitation success and improves 7-day-survival after cardiac arrest in rats: a randomized controlled animal study

Introduction

Inhaled nitric oxide (iNO) improves outcomes when given post systemic ischemia/reperfusion injury. iNO given during cardiopulmonary resuscitation (CPR) may therefore improve return of spontaneous circulation (ROSC) rates and functional outcome after cardiac arrest (CA).

Methods

Thirty male Sprague-Dawley rats were subjected to 10 minutes of CA and at least 3 minutes of CPR. Animals were randomized to receive either 0 (n = 10, Control), 20 (n = 10, 20 ppm), or 40 (n = 10, 40 ppm) ppm iNO during CPR until 30 minutes after ROSC. A neurological deficit score was assessed daily for seven days following the experiment. On day 7, brains, hearts, and blood were sampled for histological and biochemical evaluation.

Results

During CPR, 20 ppm iNO significantly increased diastolic arterial pressure (Control: 57 ± 5.04 mmHg; 20 ppm: 71.57 ± 57.3 mmHg, p < 0.046) and decreased time to ROSC (Control: 842 ± 21 s; 20 ppm: 792 ± 5 s, (p = 0.02)).

Thirty minutes following ROSC, 20 ppm iNO resulted in an increase in mean arterial pressure (Control: 83 ± 4 mmHg; 20 ppm: 98 ± 4 mmHg, p = 0.035), a less pronounced rise in lactate and inflammatory cytokine levels, and attenuated cardiac damage. Inhalation of NO at 20 ppm improved neurological outcomes in rats 2 to 7 days after CA and CPR. This translated into increases in 7 day survival (Control: 4; 20 ppm: 10; 40 ppm 6, (p ≤ 0.05 20 ppm vs Control and 40 ppm).

Conclusions

Our study revealed that breathing NO during CPR markedly improved resuscitation success, 7-day neurological outcomes and survival in a rat model of VF-induced cardiac arrest and CPR. These results support the beneficial effects of NO inhalation after cardiac arrest and CPR.

Ischemic Postconditioning and Nitric Oxide Administration Failed to Confer Protective Effects in a Porcine Model of Extracorporeal Cardiopulmonary Resuscitation

The protective effects of ischemic postconditioning (IPC) and nitric oxide (NO) administration have been demonstrated in several ischemic scenarios. However, current evidence regarding the effect of IPC and NO in extracorporeal cardiopulmonary resuscitation remains lacking. Fifteen female swine (body weight 45 kg) underwent veno-arterial extracorporeal membrane oxygenation (ECMO) implantation; cardiac arrest-ventricular fibrillation was induced by rapid ventricular pacing. After 20 min of cardiac arrest, blood flow was restored by increasing the ECMO flow rate to 4.5 L/min. The animals (five per group) were then randomly assigned to receive IPC (three cycles of 3 min ischemia and reperfusion), NO (80 ppm via oxygenator), or mild hypothermia (HT; 33.0°C). Cerebral oximetry and aortic blood pressure were monitored continuously. After 90 min of reperfusion, blood samples were drawn for the measurement of troponin I, myoglobin, creatine-phosphokinase, alanine aminotransferase, neuron-specific enolase, cystatin C, and reactive oxygen metabolite (ROM) levels. Significantly higher blood pressure and cerebral oxygen saturation values were observed in the HT group compared with the IPC and NO groups (P < 0.05). The levels of troponin I, myoglobin, creatine phosphokinase, and alanine aminotransferase were significantly lower in the HT group (P < 0.05); levels of neuron-specific enolase, cystatin C, and ROM were not significantly different. IPC and NO were comparable in all monitored parameters. The results of the present study indicate that IPC and NO administration are not superior interventions to HT for the maintenance of blood pressure, cerebral oxygenation, organ protection, and suppression of oxidative stress following extracorporeal cardiopulmonary resuscitation.

Noteworthy articles in 2014 for cardiothoracic anesthesiologists

In 2014, cardiothoracic anesthesiology again generated high-quality scientific work published in highly regarded journals. Our specialty continues to make significant strides in the creation and implementation of protocols to improve outcomes in our patients, which undoubtedly contribute to a safer hospital environment for patients and employees alike. Another theme that stirred a lot of interest in the past year is the search for patient-centered treatment plans. Even though we are still some time away from truly personalized medicine, our specialty starts to ask and answer exciting questions: Would we treat patient A any different from patient B if their genetic profiles were easily accessible? Could individualized treatment choices influence our patients' immediate and long-term outcomes? For this review, we selected a sample of relevant contributions to the field of cardiothoracic anesthesiology in 2014 with potential impact on our clinical routine.

The role of the nitric oxide pathway in brain injury and its treatment--from bench to bedside

Nitric oxide (NO) is a key signalling molecule in the regulation of cerebral blood flow. This review summarises current evidence regarding the role of NO in the regulation of cerebral blood flow at rest, under physiological conditions, and after brain injury, focusing on subarachnoid haemorrhage, traumatic brain injury, and ischaemic stroke and following cardiac arrest. We also review the role of NO in the response to hypoxic insult in the developing brain. NO depletion in ischaemic brain tissue plays a pivotal role in the development of subsequent morbidity and mortality through microcirculatory disturbance and disordered blood flow regulation. NO derived from endothelial nitric oxide synthase (eNOS) appears to have neuroprotective properties. However NO derived from inducible nitric oxide synthase (iNOS) may have neurotoxic effects. Cerebral NO donor agents, for example sodium nitrite, appear to replicate the effects of eNOS derived NO, and therefore have neuroprotective properties. This is true in both the adult and immature brain. We conclude that these agents should be further investigated as targeted pharmacotherapy to protect against secondary brain injury.

Perinatal nitric oxide therapy prevents adverse effects of perinatal hypoxia on the adult pulmonary circulation

Adverse events in utero are associated with the occurrence of chronic diseases in adulthood. We previously demonstrated in mice that perinatal hypoxia resulted in altered pulmonary circulation in adulthood, with a decreased endothelium-dependent relaxation of pulmonary arteries, associated with long-term alterations in the nitric oxide (NO)/cyclic GMP pathway. The present study investigated whether inhaled NO (iNO) administered simultaneously to perinatal hypoxia could have potential beneficial effects on the adult pulmonary circulation. Indeed, iNO is the therapy of choice in humans presenting neonatal pulmonary hypertension. Long-term effects of neonatal iNO therapy on adult pulmonary circulation have not yet been investigated. Pregnant mice were placed in hypoxia (13% O₂) with simultaneous administration of iNO 5 days before delivery until 5 days after birth. Pups were then raised in normoxia until adulthood. Perinatal iNO administration completely restored acetylcholine-induced relaxation, as well as endothelial nitric oxide synthase protein content, in isolated pulmonary arteries of adult mice born in hypoxia. Right ventricular hypertrophy observed in old mice born in hypoxia compared to controls was also prevented by perinatal iNO treatment. Therefore, simultaneous administration of iNO during perinatal hypoxic exposure seems able to prevent adverse effects of perinatal hypoxia on the adult pulmonary circulation.