A novel pre-clinical strategy to deliver antimicrobial doses of inhaled nitric oxide.

Effective treatment of respiratory infections continues to be a major challenge. In high doses (≥160 ppm), inhaled Nitric Oxide (iNO) has been shown to act as a broad-spectrum antimicrobial agent, including its efficacy in vitro for coronavirus family. However, the safety of prolonged in vivo implementation of high-dose iNO therapy has not been studied. Herein we aim to explore the feasibility and safety of delivering continuous high-dose iNO over an extended period of time using an in vivo animal model. Yorkshire pigs were randomized to one of the following two groups: group 1, standard ventilation; and group 2, standard ventilation + continuous iNO 160 ppm + methylene blue (MB) as intravenous bolus, whenever required, to maintain metHb <6%. Both groups were ventilated continuously for 6 hours, then the animals were weaned from sedation, mechanical ventilation and followed for 3 days. During treatment, and on the third post-operative day, physiologic assessments were performed to monitor lung function and other significative markers were assessed for potential pulmonary or systemic injury. No significant change in lung function, or inflammatory markers were observed during the study period. Both gas exchange function, lung tissue cytokine analysis and histology were similar between treated and control animals. During treatment, levels of metHb were maintained <6% by administration of MB, and NO2 remained <5 ppm. Additionally, considering extrapulmonary effects, no significant changes were observed in biochemistry markers. Our findings showed that high-dose iNO delivered continuously over 6 hours with adjuvant MB is clinically feasible and safe. These findings support the development of investigations of continuous high-dose iNO treatment of respiratory tract infections, including SARS-CoV-2.

Inhaled high dose nitric oxide is a safe and effective respiratory treatment in spontaneous breathing hospitalized patients with COVID-19 pneumonia.

BACKGROUND: Inhaled nitric oxide (NO) is a selective pulmonary vasodilator. In-vitro studies report that NO donors can inhibit replication of SARS-CoV-2. This multicenter study evaluated the feasibility and effects of high-dose inhaled NO in non-intubated spontaneously breathing patients with Coronavirus disease-2019 (COVID-19). METHODS: This is an interventional study to determine whether NO at 160 parts-per-million (ppm) inhaled for 30 min twice daily might be beneficial and safe in non-intubated COVID-19 patients. RESULTS: Twenty-nine COVID-19 patients received a total of 217 intermittent inhaled NO treatments for 30 min at 160 ppm between March and June 2020. Breathing NO acutely decreased the respiratory rate of tachypneic patients and improved oxygenation in hypoxemic patients. The maximum level of nitrogen dioxide delivered was 1.5 ppm. The maximum level of methemoglobin (MetHb) during the treatments was 4.7%. MetHb decreased in all patients 5 min after discontinuing NO administration. No adverse events during treatment, such as hypoxemia, hypotension, or acute kidney injury during hospitalization occurred. In our NO treated patients, one patient of 29 underwent intubation and mechanical ventilation, and none died. The median hospital length of stay was 6 days [interquartile range 4-8]. No discharged patients required hospital readmission nor developed COVID-19 related long-term sequelae within 28 days of follow-up. CONCLUSIONS: In spontaneous breathing patients with COVID-19, the administration of inhaled NO at 160 ppm for 30 min twice daily promptly improved the respiratory rate of tachypneic patients and systemic oxygenation of hypoxemic patients. No adverse events were observed. None of the subjects was readmitted or had long-term COVID-19 sequelae.

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.

A Novel Inhalation Mask System to Deliver High Concentrations of Nitric Oxide Gas in Spontaneously Breathing Subjects.

Nitric Oxide (NO) is administered as gas for inhalation to induce selective pulmonary vasodilation. It is a safe therapy, with few potential risks even if administered at high concentration. Inhaled NO gas is routinely used to increase systemic oxygenation in different disease conditions. The administration of high concentrations of NO also exerts a virucidal effect in vitro. Owing to its favorable pharmacodynamic and safety profiles, the familiarity in its use by critical care providers, and the potential for a direct virucidal effect, NO is clinically used in patients with coronavirus disease-2019 (COVID-19). Nevertheless, no device is currently available to easily administer inhaled NO at concentrations higher than 80 parts per million (ppm) at various inspired oxygen fractions, without the need for dedicated, heavy, and costly equipment. The development of a reliable, safe, inexpensive, lightweight, and ventilator-free solution is crucial, particularly for the early treatment of non-intubated patients outside of the intensive care unit (ICU) and in a limited-resource scenario. To overcome such a barrier, a simple system for the non-invasive NO gas administration up to 250 ppm was developed using standard consumables and a scavenging chamber. The method has been proven safe and reliable in delivering a specified NO concentration while limiting nitrogen dioxide levels. This paper aims to provide clinicians and researchers with the necessary information on how to assemble or adapt such a system for research purposes or clinical use in COVID-19 or other diseases in which NO administration might be beneficial.

Effects of inhaled nitric oxide in COVID-19-induced ARDS - Is it worthwhile?

BACKGROUND: Changes in pulmonary hemodynamics and ventilation/perfusion were proposed as hallmarks of Coronavirus disease 2019 (COVID-19)-induced acute respiratory distress syndrome (ARDS). Inhaled nitric oxide (iNO) may overcome these issues and improve arterial oxygenation. METHODS: We retrospectively analyzed arterial oxygenation and pulmonary vasoreactivity in seven COVID-19 ARDS patients receiving 20 ppm iNO for 15-30 minutes. RESULTS: The inhalation of NO significantly improved oxygenation. All patients with severe ARDS had higher partial pressures of oxygen and reduced pulmonary vascular resistance. Significant changes in pulmonary shunting were not observed. CONCLUSION: Overall, iNO could provide immediate help and delay respiratory deterioration in COVID-19-induced moderate to severe ARDS.

Implication of inhaled nitric oxide for the treatment of critically ill COVID-19 patients with pulmonary hypertension.

AIMS: This study aims to analyse whether inhaled nitric oxide (iNO) was beneficial in the treatment of coronavirus disease 2019 (COVID-19) patients with pulmonary hypertension. METHODS AND RESULTS: Five critically ill COVID-19 patients with pulmonary hypertension designated Cases 1-5 were retrospectively included. Clinical data before and after iNO treatment were serially collected and compared between patients with or without iNO treatment. The five cases experienced pulmonary artery systolic pressure (PASP) elevation (≥50 mmHg) at 30, 24, 33, 23, and 24 days after illness onset (d.a.o), respectively. Cases 1-3 received iNO treatment on the 24th, 13th, and 1st day after the first elevation of PASP, with concentrations varied from 10 to 20 ppm based on the changes of PASP and blood pressure for 10, 9, and 5 days, respectively. Upon iNO treatment, PASP of Cases 1 and 2 returned to normal on the 10th day and 1st day, and maintained between 50 and 58 mmHg in Case 3. Pa02 /Fi02 increased from 88 to 124, 51 to 118, and 146 to 244, respectively. SPO2 increased from 91% to 97% for Case 1 and maintained a high level above 97% for Case 2. Cardiac function remained normal in the three patients after treatment. Moreover, Cases 1 and 3 survived from severe acute respiratory syndrome coronavirus 2 infection, while Case 2 finally died on the 36th day after the first elevation of PASP due to severe complications. Both cases who did not receive iNO treatment experienced a sudden decrease of PASP and Pa02 /Fi02 due to right heart failure and then died. CONCLUSIONS: Inhaled nitric oxide treatment was beneficial in reducing and stabilizing the PASP and might also reduce the risk of right heart failure in COVID-19 with pulmonary hypertension.

Nitric oxide's physiologic effects and potential as a therapeutic agent against COVID-19.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for COVID-19 pneumonia, a pandemic that precipitates huge pressures on the world's social and economic systems. Disease severity varies among individuals. SARS-CoV-2 infection can be associated with e.g. flu-like symptoms, dyspnoea, severe interstitial pneumonia, acute respiratory distress syndrome, multiorgan dysfunction, and generalized coagulopathy. Nitric oxide (NO), is a small signal molecule that impacts pleiotropic functions in human physiology, which can be involved in the significant effects of COVID-19 infection. NO is a neurotransmitter involved in the neural olfactory processes in the central nervous system, and some infected patients have reported anosmia as a symptom. Additionally, NO is a well-known vasodilator, important coagulation mediator, anti-microbial effector and inhibitor of SARS-CoV replication. Exhaled NO is strongly related to the type-2 inflammatory response found in asthma, which has been suggested to be protective against SARS-CoV-2 infection. Several reports indicate that the use of inhaled NO has been an effective therapy during this pandemic since the ventilation-perfusion ratio in COVID-19 patients improved afterwards and they did not require mechanical ventilation. The aim of this mini-review is to summarize relevant actions of NO that could be beneficial in the treatment of COVID-19.

Nitric oxide (NO) and nanoparticles - Potential small tools for the war against COVID-19 and other human coronavirus infections.

The endogenous free radical nitric oxide (NO) plays a pivotal role in the immunological system. NO has already been reported as a potential candidate for use in the treatment of human coronavirus infections, including COVID-19. In fact, inhaled NO has been used in clinical settings for its antiviral respiratory action, and in the regulation of blood pressure to avoid clot formation. In this mini-review, we discuss recent progress concerning the antivirus activity of NO in clinical, pre-clinical and research settings, and its beneficial effects in the treatment of clinical complications in patients infected with coronaviruses and other respiratory viral diseases, including COVID-19. We also highlight promising therapeutic effects of NO donors allied to nanomaterials to combat COVID-19 and other human coronavirus infections. Nanomaterials can be designed to deliver sustained, localized NO release directly at the desired application site, enhancing the beneficial effects of NO and minimizing the side effects. Challenges and perspectives are presented to open new fields of research.

High Concentrations of Nitric Oxide Inhalation Therapy in Pregnant Patients With Severe Coronavirus Disease 2019 (COVID-19).

BACKGROUND: Rescue therapies to treat or prevent progression of coronavirus disease 2019 (COVID-19) hypoxic respiratory failure in pregnant patients are lacking. METHOD: To treat pregnant patients meeting criteria for severe or critical COVID-19 with high-dose (160-200 ppm) nitric oxide by mask twice daily and report on their clinical response. EXPERIENCE: Six pregnant patients were admitted with severe or critical COVID-19 at Massachusetts General Hospital from April to June 2020 and received inhalational nitric oxide therapy. All patients tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. A total of 39 treatments was administered. An improvement in cardiopulmonary function was observed after commencing nitric oxide gas, as evidenced by an increase in systemic oxygenation in each administration session among those with evidence of baseline hypoxemia and reduction of tachypnea in all patients in each session. Three patients delivered a total of four neonates during hospitalization. At 28-day follow-up, all three patients were home and their newborns were in good condition. Three of the six patients remain pregnant after hospital discharge. Five patients had two negative test results on nasopharyngeal swab for SARS-CoV-2 within 28 days from admission. CONCLUSION: Nitric oxide at 160-200 ppm is easy to use, appears to be well tolerated, and might be of benefit in pregnant patients with COVID-19 with hypoxic respiratory failure.

Design and study of nitric oxide portable producing device using continuous discharging arc plasma reaction keeping low energy efficiency for viral pneumonia emergency therapy.

This study investigated the efficiency of a portable nitric oxide (NO) inhalation device through optimizing its design and structure. The portable rescue device could be used in clinical applications in outbreaks of viral pneumonia such as SARS. To reduce energy consumption for battery-powered portable usage, NO micro-channel plasma reactions induced by a continuous discharge arc were employed. A single-use airway tube could be combined with an intubation tube in clinical applications. In the experiment, a switching transistor controlled high frequency DC (12.5 kHz) was used to create a continuous discharge arc between two stainless steel electrodes (1-mm separation) after high-voltage breakthrough. A rotate instrument was employed to change the direction angle between the airflow and discharge arc, tube filled with Calcium hydroxide connected with gas outlet for reducing NO2, gas flow rate and input voltage were evaluated separately with concentration of NO and NO2/NO ratio. Results showed that a 2 L/min air flow direction from the cathode to the anode of electrodes (direction angle was zero) under 4 V input voltages produced 32.5±3.8 ppm NO, and the NO2/NO ratio reduced to less than 10%, stable output of nitric oxide might be convenient and effective for NO inhalation therapy. Modularization of the design produced a portable NO inhalation device that has potential for use in clinical applications as it is low cost, easy to disinfect, consumes low levels of energy and is ready to use.

High dose folic acid is a potential treatment for pulmonary hypertension, including when associated with COVID-19 pneumonia.

BACKGROUND: Pulmonary hypertension is a significant complication for some patients with COVID-19 pneumonia, especially those requiring intensive care. Tachyphylaxis to the current therapy, inhaled nitric oxide (iNO), is also common. In vitro, folic acid directly increases nitric oxide (NO) production and extends its duration of action; effects which could be of benefit in reversing pulmonary hypertension and severe hypoxaemia. Our work has shown that, in the systemic circulation, folic acid in high dose rapidly improves nitric oxide mediated vasodilation, by activating endothelial nitric oxide synthase (eNOS). HYPOTHESIS: A similar effect of high dose folic acid on pulmonary endothelial function would be expected from the same mechanism and would lead to improvement in pulmonary perfusion. We therefore hypothesise that folic acid, 5 mg or greater, is a useful therapeutic option for pulmonary hypertension and/or refractory severe hypoxaemia, in patients with severe COVID-19 associated pneumonia in whom NO therapy is considered, with a very low risk of adverse effects.

Harnessing nitric oxide for preventing, limiting and treating the severe pulmonary consequences of COVID-19.

The ongoing outbreak of COVID-19 has quickly become a daunting challenge to global health. In the absence of targeted therapy and a reported 5.5% case fatality rate in the United States, treatments preventing rapid cardiopulmonary failure are urgently needed. Clinical features, pathology and homology to better understood pathogens suggest that uncontrolled inflammation and a cytokine storm likely drive COVID-19's unrelenting disease process. Interventions that are protective against acute lung injury and ARDS can play a critical role for patients and health systems during this pandemic. Nitric oxide is an antimicrobial and anti-inflammatory molecule with key roles in pulmonary vascular function in the context of viral infections and other pulmonary disease states. This article reviews the rationale for exogenous nitric oxide use for the pathogenesis of COVID-19 and highlights its potential for contributing to better clinical outcomes and alleviating the rapidly rising strain on healthcare capacity.

Nitric oxide dosed in short bursts at high concentrations may protect against Covid 19.

It has long been suggested that NO may inhibit an early stage in viral replication. Furthermore, in vitro tests have shown that NO inhibits the replication cycle of severe acute respiratory syndrome coronavirus. Despite smoking being listed as a risk factor to contract Covid-19, only a low proportion of the smokers suffered from SARS-corona infection in China 2003, and from Covid-19 in China, Europe and the US. We hypothesize, that the intermittent bursts of high NO concentration in cigarette smoke may be a mechanism in protecting against the virus. Mainstream smoke from cigarettes contains NO at peak concentrations of between about 250 ppm and 1350 ppm in each puff as compared to medicinal use of no more than 80 to a maximum of 160 ppm. The diffusion of NO through the cell wall to reach the virus should be significantly more effective at the very high NO concentration in the smoke, according to classic laws of physics. The only oxide of nitrogen in the mainstream smoke is NO, and the NO2 concentration that is inhaled is very low or undetectable, and methemoglobin levels are lower in smokers than non-smokers, reasonably explained by the breaths of air in between the puffs that wash out the NO. Specialized iNO machines can now be developed to provide the drug intermittently in short bursts at high concentration dose, which would then provide both a preventative drug for those at high risk, as well as an effective treatment, without the health hazards associated with smoking.

COVID-19: The Potential Role of Copper and N-acetylcysteine (NAC) in a Combination of Candidate Antiviral Treatments Against SARS-CoV-2.

BACKGROUND: On March 11, 2020, the World Health Organization (WHO) declared the outbreak of coronavirus disease (COVID-19) a pandemic. Since then, thousands of people have suffered and died, making the need for a treatment of severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) more crucial than ever. MATERIALS AND METHODS: The authors carried out a search in PubMed, ClinicalTrials.gov and New England Journal of Medicine (NEJM) for COVID-19 to provide information on the most promising treatments against SARS-CoV-2. RESULTS: Possible COVID-19 agents with promising efficacy and favorable safety profile were identified. The results support the combination of copper, N-acetylcysteine (NAC), colchicine and nitric oxide (NO) with candidate antiviral agents, remdesivir or EIDD-2801, as a treatment for patients positive for SARS-CoV-2. CONCLUSION: The authors propose to study the effects of the combination of copper, NAC, colchicine, NO and currently used experimental antiviral agents, remdesivir or EIDD-2801, as a potential treatment scheme for SARS-COV-2.