The role of inhaled prostacyclin in treating acute respiratory distress syndrome

The vascular perspective on acute and chronic lung disease

The pulmonary vasculature has been frequently overlooked in acute and chronic lung diseases, such as acute respiratory distress syndrome (ARDS), pulmonary fibrosis (PF), and chronic obstructive pulmonary disease (COPD). The primary emphasis in the management of these parenchymal disorders has largely revolved around the injury and aberrant repair of epithelial cells. However, there is increasing evidence that the vascular endothelium plays an active role in the development of acute and chronic lung diseases. The endothelial cell network in the capillary bed and the arterial and venous vessels provides a metabolically highly active barrier that controls the migration of immune cells, regulates vascular tone and permeability, and participates in the remodeling processes. Phenotypically and functionally altered endothelial cells, and remodeled vessels, can be found in acute and chronic lung diseases, although to different degrees, likely because of disease-specific mechanisms. Since vascular remodeling is associated with pulmonary hypertension, which worsens patient outcomes and survival, it is crucial to understand the underlying vascular alterations. In this Review, we describe the current knowledge regarding the role of the pulmonary vasculature in the development and progression of ARDS, PF, and COPD; we also outline future research directions with the hope of facilitating the development of mechanism-based therapies.

The Use of an Inspiration-Synchronized Vibrating Mesh Nebulizer for Prolonged Inhalative Iloprost Administration in Mechanically Ventilated Patients-An In Vitro Model

Mechanically ventilated patients suffering from acute respiratory distress syndrome (ARDS) frequently receive aerosolized iloprost. Because of prostacyclin's short half-life, prolonged inhalative administration might improve its clinical efficacy. But, this is technically challenging. A solution might be the use of inspiration-synchronized vibrating mesh nebulizers (VMNsyn), which achieve high drug deposition rates while showing prolonged nebulization times. However, there are no data comparing prolonged to bolus iloprost nebulization using a continuous vibrating mesh nebulizer (VMNcont) and investigating the effects of different ventilation modes on inspiration-synchronized nebulization. Therefore, in an in vitro model of mechanically ventilated adults, a VMNsyn and a VMNcont were compared in volume-controlled (VC-CMV) and pressure-controlled continuous mandatory ventilation (PC-CMV) regarding iloprost deposition rate and nebulization time. During VC-CMV, the deposition rate of the VMNsyn was comparable to the rate obtained with the VMNcont, but 10.9% lower during PC-CMV. The aerosol output of the VMNsyn during both ventilation modes was significantly lower compared to the VMNcont, leading to a 7.5 times longer nebulization time during VC-CMV and only to a 4.2 times longer nebulization time during PC-CMV. Inspiration-synchronized nebulization during VC-CMV mode therefore seems to be the most suitable for prolonged inhalative iloprost administration in mechanically ventilated patients.

Safety and tolerability of continuous inhaled iloprost in critically ill pediatric pulmonary hypertension patients: A retrospective case series

Inhaled iloprost (iILO) has shown efficacy in treating patients with hypoxic lung disease and pulmonary hypertension, inducing selective pulmonary vasodilation and improvement in oxygenation. However, its short elimination half-life of 20-30 min necessitates frequent intermittent dosing (6-9 times per day). Thus, the administration of iILO via continuous nebulization represents an appealing method of drug delivery in the hospital setting. The objectives are: (1) describe our continuous iILO delivery methodology and safety profile in mechanically ventilated pediatric pulmonary hypertension patients; and (2) characterize the initial response of iILO in these pediatric patients currently receiving iNO. Continuous iILO was delivered and well tolerated (median 6 days; range 1-94) via tracheostomy or endotracheal tube using the Aerogen® mesh nebulizer system coupled with a Medfusion® 400 syringe pump. No adverse events or delivery malfunctions were reported. Initiation of iILO resulted in an increase in oxygen saturation from 81.4 ± 8.6 to 90.8 ± 4.1%, p < 0.05. Interestingly, prior iNO therapy for >1 day resulted in a higher response rate to iILO (as defined as a ≥ 4% increase in saturations) compared to those receiving iNO <1 day (85% vs. 50%, p = 0.06). When the use of iILO is considered, continuous delivery represents a safe, less laborious alternative and concurrent treatment with iNO should not be considered a contraindication. However, given the retrospective design and small sample size, this study does not allow the evaluation of the efficacy of continuous iILO on outcomes beyond the initial response. Thus, a prospective study designed to evaluate the efficacy of continuous iILO is necessary.

Epoprostenol Exposure During Pregnancy

Institutional policies restricting pregnant providers from caring for patients receiving inhaled epoprostenol exist across the nation based on little to no data to substantiate this practice. Over the last 2 decades, the use of inhaled pulmonary vasodilators has expanded in patients with cardiac and respiratory disease providing more evidence for the safety of these medications in obstetrical patients. We propose a thoughtful consideration and review of the literature to remove this restriction to reduce the need to reveal early pregnancy status to employers, to alleviate undue stress for pregnant caregivers who are exposed to patients receiving epoprostenol, and to ensure safe, equal employment, and learning opportunities for pregnant providers.

Use of Aerosolized Prostacyclins in Critically Ill Patients and Association With Clinical Outcomes

Aerosolized prostacyclins are frequently used in patients with severe acute respiratory distress syndrome and refractory hypoxia. Previous studies have shown improvement in oxygenation with use of pulmonary vasodilators such as iloprost and epoprostenol; however, there is no head-to-head comparison between these agents.

OBJECTIVES

To compare the effects of inhaled epoprostenol and inhaled iloprost in critically ill patients with refractory hypoxia.

DESIGN SETTING AND PARTICIPANTS

We performed a retrospective cohort analysis of patients admitted to the ICUs at the University of Oklahoma Health Sciences Center between 2015 and 2018. Adult patients who received aerosolized epoprostenol or iloprost for more than 4 hours were included in the analysis.

MAIN OUTCOMES AND MEASURES

The primary endpoint measured was to compare the change in Pao₂/Fio₂ ratio between patients treated with iloprost compared with epoprostenol. Secondary outcomes measured were 90-day in-hospital mortality and improvement in vasopressor requirements.

RESULTS

A total of 126 patients were included in the study, 95 of whom received iloprost (75%) and 31 patients (25%) received epoprostenol. There were significant improvements in Pao₂/Fio₂ ratio in both the iloprost and epoprostenol group. Patients in the epoprostenol group appeared to have a higher 90-day mortality compared with the iloprost group. However, our study was not powered to detect a mortality difference and this finding likely represents a sicker population in the epoprostenol group and prescription bias. The use of iloprost was associated with higher vasopressor requirements in the first 12 hours of administration, an association was not observed in the epoprostenol group.

CONCLUSIONS AND RELEVANCE

In this retrospective cohort analysis, use of both pulmonary vasodilators was associated with similar improvement in gas exchange. The mortality difference observed likely represents difference in severity of illness. Further studies are needed to corroborate these findings.

Continuous infusion aerosol delivery of prostacyclins during mechanical ventilation: challenges, limitations, and recent advances

INTRODUCTION

Critically ill mechanically ventilated patients routinely receive aerosol delivery of epoprostenol by continuous infusion of the nebulizer by syringe pump. This procedure is 'off-label' as no FDA approved drug presently exists. Without standardized protocols, therapy is based on prior experience with bronchodilators, limited studies of delivery systems and anecdotal clinical trials. Current protocols based upon patient body weight and drug concentration determines the infusion rate of drug dose delivered to the nebulizer , which is only distantly related to dose delivered to the lung and may be altered by many factors.

AREAS COVERED

This paper reviews the background of this technique as well as current methods of managing drug delivery, technical challenges, and limitations. A recent advance in aerosol laboratory bench testing, using radiolabeled aerosols, is presented to reveal important factors defining delivery.

EXPERT OPINION

Off-label use of continuously nebulized prostacyclin in the ICU lacks the support of large clinical trials needed for FDA clearance. However, comprehensive bench studies afford the potential for clinicians to better understand and manage therapy at a level above simple dosing of the nebulizer by body weight. New research techniques are enhancing our basic comprehension of the interaction between aerosol devices and the mechanical ventilator.

Inpatient Management and OBICU Care for Pregnant Patients With Severe COVID-19 Disease

This manuscript will review intensive care management considerations for pregnant patients with severe COVID-19 disease.

Evaluation of aerosolized epoprostenol for hypoxemia in non-intubated patients with coronavirus disease 2019

Objectives

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) frequently present with a febrile illness that may progress to pneumonia and hypoxic respiratory failure. Aerosolized epoprostenol (aEPO) has been evaluated in patients with acute respiratory distress syndrome and refractory hypoxemia. A paucity of literature has assessed the impact of aEPO in patients with SARS-CoV-2 receiving oxygen support with high flow nasal cannula (HFNC). The objective of this study was to evaluate whether aEPO added to HFNC prevents intubation and/or prolong time to intubation compared to controls only treated with HFNC, guided by oxygen saturation goals.

Methods

This was a single-center, retrospective study of adult patients infected with coronavirus 2019 (COVID-19) and admitted to the medical intensive care unit. A total of 60 patients were included. Thirty patients were included in the treatment, and 30 in the control group, respectively. Among patients included in the treatment group, response to therapy was assessed. The need for mechanical ventilation and hospital mortality between responders vs. non-responders was evaluated.

Results

The primary outcome of mechanical ventilation was not statistically different between groups. Time from HFNC initiation to intubation was significantly prolonged in the treatment group compared to the control group (5.7 days vs. 2.3 days, P = 0.001). There was no statistically significant difference between groups in mortality or length of stay. Patients deemed responders to aEPO had a lower rate of mechanical ventilation (50% vs 88%, P = 0.025) and mortality (21% vs 63%, P = 0.024), compared with non-responders.

Conclusion

The utilization of aEPO in COVID-19 patients treated with HFNC is not associated with a reduction in the rate of mechanical ventilation. Nevertheless, the application of this strategy may prolong the time to invasive mechanical ventilation, without affecting other clinical outcomes.

Pulmonary artery targeted therapy in treatment of COVID-19 related ARDS. Literature review

INTRODUCTION

The most grievous complication of the COVID-19 is the acute respiratory distress syndrome. A specific, rescue treatment for rapidly deteriorating patients should emerge to improve respiratory function and help patients to survive the most challenging period. Drugs used in targeted therapy of pulmonary arterial hypertension (PAH) appears to be suitable for this task and this article describes their potential for treatment of severe cases of COVID-19.

METHODS

The authors reviewed the following databases for randomized controlled trials, reviews and meta-analyses published up to July 2020: Pubmed, Scopus, Google Scholar, Cochrane Database and ClinicalKey. The authors included every study contributory to the assessment of the potential of drugs used in targeted PAH therapy in treatment of COVID-19.

RESULTS

Endothelin receptor antagonists, phosphodiesterase 5 inhibitors, riociguat and prostacyclin have proven ani-inflammatory effect and reduce pulmonary artery blood pressure, lung oedema and remodelling. Bosentan shows antiviral properties and sildenafil, as well as epoprostenol, inhibits apoptosis of lung epithelial cells. Among patients with lung lesions the decrease of pulmonary blood pressure can lead to increase of ventilation/perfusion mismatch and decrease of blood oxygenation.

CONCLUSIONS

Among all assessed drugs bosentan, sildenafil and epoprostenol appear to be most promising and a combination of these drugs should be considered due to synergism. The targeted PAH therapy in treatment of COVID-19 associated ARDS could be a useful tool saving lives of patients with severe SARS-CoV-2 infection, however, its introduction should be investigated and monitored very carefully as it can lead to transient deterioration of patient condition.

The Use of Inhaled Epoprostenol for Acute Respiratory Distress Syndrome Secondary due to COVID-19: A Case Series

Introduction

Inhaled epoprostenol (iEpo) is a pulmonary vasodilator used to treat refractory respiratory failure, including that caused by Coronavirus 2019 (COVID-19) pneumonia.

Aim of Study

To describe the experience at three teaching hospitals using iEpo for severe respiratory failure due to COVID-19 and evaluate its efficacy in improving oxygenation.

Methods

Fifteen patients were included who received iEpo, had confirmed COVID-19 and had an arterial blood gas measurement in the 12 hours before and 24 hours after iEpo initiation.

Results

Eleven patients received prone ventilation before iEpo (73.3%), and six (40%) were paralyzed. The partial pressure of arterial oxygen to fraction of inspired oxygen (P/F ratio) improved from 95.7 mmHg to 118.9 mmHg (p=0.279) following iEpo initiation. In the nine patients with severe ARDS, the mean P/F ratio improved from 66.1 mmHg to 95.7 mmHg (p=0.317). Ultimately, four patients (26.7%) were extubated after an average of 9.9 days post-initiation.

Conclusions

The findings demonstrated a trend towards improvement in oxygenation in critically ill COVID-19 patients. Although limited by the small sample size, the results of this case series portend further investigation into the role of iEpo for severe respiratory failure associated with COVID-19.

Inhaled prostacyclin analogues in COVID-19 associated acute respiratory distress syndrome: scientific rationale

BACKGROUND

COVID-19 associated acute respiratory distress syndrome (CARDS) is a severe form of SARS CoV-2 infection and affects about 15-30% of hospitalized patients with a high mortality rate. Growing research and data suggest several available drugs with appropriate pharmacological effects to treat COVID-19.

MAIN BODY

Prostacyclin analogues are regiments for pulmonary artery hypertension. Prostacyclin analogues are expected to be beneficial in treating CARDS based on at least four rationales: (1) inhaled prostacyclin analogues improve oxygenation, V/Q mismatch, and act as an ARDS therapy alternative; (2) it alleviates direct SARS-CoV-2-related coagulopathy; (3) increases nitric oxide production; and (4) possible anti-inflammatory effect. Prostacyclin analogues are available in oral, intravenous, and inhaled forms. The inhaled form has the advantage over other forms, such as parenteral administration risks. Previously, a meta-analysis demonstrated the beneficial effects of inhaled prostaglandins for ARDS treatment, such as improved PaO2/FiO2 and PaO2 along with reduced pulmonary artery pressure. Currently, two ongoing randomized controlled trials are evaluating inhaled epoprostenol (VPCOVID [NCT04452669]) and iloprost (ILOCOVID [NCT04445246]) for severe COVID-19 patients.

CONCLUSIONS

Inhaled prostacyclin could be considered in patients with refractory, life-threatening hypoxia despite standard management.

Right Ventricular Damage in COVID-19: Association Between Myocardial Injury and COVID-19

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, is a global pandemic. It has resulted in considerable morbidity and mortality around the world. The respiratory system is the main system invaded by the virus involved in COVID-19. In addition to typical respiratory manifestations, a certain proportion of severe COVID-19 cases present with evidence of myocardial injury, which is associated with excessive mortality. With availability of an increasing amount of imaging data, right ventricular (RV) damage is prevalent in patients with COVID-19 and myocardial injury, while left ventricular damage is relatively rare and lacks specificity. The mechanisms of RV damage may be due to increased RV afterload and decreased RV contractility caused by various factors, such as acute respiratory distress syndrome, pulmonary thrombosis, direct viral injury, hypoxia, inflammatory response and autoimmune injury. RV dysfunction usually indicates a poor clinical outcome in patients with COVID-19. Timely and effective treatment is of vital importance to save patients' lives as well as improve prognosis. By use of echocardiography or cardiovascular magnetic resonance, doctors can find RV dilatation and dysfunction early. By illustrating the phenomenon of RV damage and its potential pathophysiological mechanisms, we will guide doctors to give timely medical treatments (e.g., anticoagulants, diuretics, cardiotonic), and device-assisted therapy (e.g., mechanical ventilation, extracorporeal membrane oxygenation) when necessary for these patients. In the paper, we examined the latest relevant studies to investigate the imaging features, potential mechanisms, and treatments of myocardial damage caused by COVID-19. RV damage may be an association between myocardial damage and lung injury in COVID-19. Early assessment of RV geometry and function will be helpful in aetiological determination and adjustment of treatment options.

Emergency Department Management of Severe Hypoxemic Respiratory Failure in Adults With COVID-19

Background

While emergency physicians are familiar with the management of hypoxemic respiratory failure, management of mechanical ventilation and advanced therapies for oxygenation in the emergency department have become essential during the coronavirus disease 2019 (COVID-19) pandemic.

Objective

We review the current evidence on hypoxemia in COVID-19 and place it in the context of known evidence-based management of hypoxemic respiratory failure in the emergency department.

Discussion

COVID-19 causes mortality primarily through the development of acute respiratory distress syndrome (ARDS), with hypoxemia arising from shunt, a mismatch of ventilation and perfusion. Management of patients developing ARDS should focus on mitigating derecruitment and avoiding volutrauma or barotrauma.

Conclusions

High flow nasal cannula and noninvasive positive pressure ventilation have a more limited role in COVID-19 because of the risk of aerosolization and minimal benefit in severe cases, but can be considered. Stable patients who can tolerate repositioning should be placed in a prone position while awake. Once intubated, patients should be managed with ventilation strategies appropriate for ARDS, including targeting lung-protective volumes and low pressures. Increasing positive end-expiratory pressure can be beneficial. Inhaled pulmonary vasodilators do not decrease mortality but may be given to improve refractory hypoxemia. Prone positioning of intubated patients is associated with a mortality reduction in ARDS and can be considered for patients with persistent hypoxemia. Neuromuscular blockade should also be administered in patients who remain dyssynchronous with the ventilator despite adequate sedation. Finally, patients with refractory severe hypoxemic respiratory failure in COVID-19 should be considered for venovenous extracorporeal membrane oxygenation.

Endothelial Damage in Acute Respiratory Distress Syndrome

The pulmonary endothelium is a metabolically active continuous monolayer of squamous endothelial cells that internally lines blood vessels and mediates key processes involved in lung homoeostasis. Many of these processes are disrupted in acute respiratory distress syndrome (ARDS), which is marked among others by diffuse endothelial injury, intense activation of the coagulation system and increased capillary permeability. Most commonly occurring in the setting of sepsis, ARDS is a devastating illness, associated with increased morbidity and mortality and no effective pharmacological treatment. Endothelial cell damage has an important role in the pathogenesis of ARDS and several biomarkers of endothelial damage have been tested in determining prognosis. By further understanding the endothelial pathobiology, development of endothelial-specific therapeutics might arise. In this review, we will discuss the underlying pathology of endothelial dysfunction leading to ARDS and emerging therapies. Furthermore, we will present a brief overview demonstrating that endotheliopathy is an important feature of hospitalised patients with coronavirus disease-19 (COVID-19).

The Role of Phosphodiesterase-5 Inhibitors in COVID-19: An Exploration of Literature From Similar Pathologies

Coronavirus Disease 2019 (COVID-19) has had a devastating impact on the ability of highly trained healthcare providers to render sufficient care, due to both the significant demand on resources and the unique nature of this disease that make it resistant to traditional therapies. This review sought to determine the potential role of phosphodiesterase-5 inhibitors (PDE-5) in the management of COVID-19 by extrapolating relevant data and clinical studies from other related disease states, including acute respiratory distress syndrome, acute lung injury, and high altitude pulmonary edema. Following a literature search, 4 reports were analyzed and included in this review. While the heterogenicity of data and the small number of trials included limit the interpretation and applicability, it was consistently demonstrated that PDE-5 inhibitors lowered pulmonary arterial pressures. The overall benefit of these agents is seemingly dependent upon the etiology of the respiratory failure, which warrants expanded clinical investigation for COVID-19.

Pharmacological management of adult patients with acute respiratory distress syndrome

INTRODUCTION

There is still no definite drug for acute respiratory distress syndrome (ARDS) that is capable of reducing either short-term or long-term mortality. Therefore, great efforts are being made to identify a pharmacological approach that can be really effective.

AREAS COVERED

This review focuses on current challenges and future directions in the pharmacological management of ARDS, regardless of anti-infective treatments. The authors have excluded small randomized controlled trials (RCTs) with less than 60 patients because those studies do not have statistical power for outcome data, and also anecdotal trials but have considered the last meta-analysis on any drug.

EXPERT OPINION

There has been substantial progress in our knowledge of ARDS over the past two decades and many drugs have been used in its treatment. Nevertheless, effective targeted pharmacological treatments for ARDS are still lacking. The likely reason why a pharmacological approach is beneficial for some patients, but harmful for others is that ARDS is an extremely heterogeneous syndrome. To overcome this issue, a precision approach for ARDS, whereby therapies are specifically targeted to patients most likely to benefit, has been proposed. At present, however, the application of this approach seems to be a difficult task.

Effect of Coronavirus Disease 2019 in Pulmonary Circulation. The Particular Scenario of Precapillary Pulmonary Hypertension

The Coronavirus Disease of 2019 (COVID-19) has supposed a global health emergency affecting millions of people, with particular severity in the elderly and patients with previous comorbidities, especially those with cardiovascular disease. Patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) could represent an especially vulnerable population because of the high mortality rates reported for respiratory infections. However, the number of COVID-19 cases reported among PAH and CTEPH patients is surprisingly low. Furthermore, the clinical picture that has been described in these patients is far from the severity that experts would expect. Endothelial dysfunction is a common feature between patients with PAH/CTEPH and COVID-19, leading to ventilation/perfusion mismatch, vasoconstriction, thrombosis and inflammation. In this picture, the angiotensin-converting enzyme 2 plays an essential role, being directly involved in the pathophysiology of both clinical entities. Some of these common characteristics could explain the good adaptation of PAH and CTEPH patients to COVID-19, who could also have obtained a benefit from the disease's specific treatments (anticoagulant and pulmonary vasodilators), probably due to its protective effect on the endothelium. Additionally, these common features could also lead to PAH/CTEPH as a potential sequelae of COVID-19. Throughout this comprehensive review, we describe the similarities and differences between both conditions and the possible pathophysiological and therapeutic-based mechanisms leading to the low incidence and severity of COVID-19 reported in PAH/CTEPH patients to date. Nevertheless, international registries should look carefully into this population for better understanding and management.

Successful use of inhaled epoprostenol as rescue therapy for pediatric ARDS

Severe pediatric ARDS remains a significant challenge for clinicians, and management strategies are essentially limited to lung protective ventilation strategies, and adjunct approaches such as prone positioning, steroids, surfactant, and inhaled nitric oxide in unique situations. Inhaled nitric oxide produces pulmonary vasodilation in ventilated regions of the lung, shunting blood away from poorly ventilated areas and thus optimizing the ventilation perfusion ratio. A subset of patients with ARDS are known to be non-responders to nitric oxide, and selective pulmonary vasodilators such as Epoprostenol can be useful as rescue therapy in such cases. We describe a case of severe pediatric ARDS in the setting of pre-existing pulmonary hypertension and Trisomy 21, whose clinical course improved remarkably once inhaled Epoprostenol was initiated.

A comprehensive review on drug repositioning against coronavirus disease 2019 (COVID19)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is the reason for this ongoing pandemic infection diseases termed coronavirus disease 2019 (COVID-19) that has emerged since early December 2019 in Wuhan City, Hubei Province, China. In this century, it is the worst threat to international health and the economy. After 4 months of COVID-19 outbreak, there is no certain and approved medicine against it. In this public health emergency, it makes sense to investigate the possible effects of old drugs and find drug repositioning that is efficient, economical, and riskless process. Old drugs that may be effective are from different pharmacological categories, antimalarials, anthelmintics, anti-protozoal, anti-HIVs, anti-influenza, anti-hepacivirus, antineoplastics, neutralizing antibodies, immunoglobulins, and interferons. In vitro, in vivo, or preliminary trials of these drugs in the treatment of COVID-19 have been encouraging, leading to new research projects and trials to find the best drug/s. In this review, we discuss the possible mechanisms of these drugs against COVID-19. Also, it should be mentioned that in this manuscript, we discuss preliminary rationales; however, clinical trial evidence is needed to prove them. COVID-19 therapy must be based on expert clinical experience and published literature and guidelines from major health organizations. Moreover, herein, we describe current evidence that may be changed in the future.

An Update on Current Therapeutic Drugs Treating COVID-19

The current pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has presented unprecedented challenges to the healthcare systems in almost every country around the world. Currently, there are no proven effective vaccines or therapeutic agents against the virus. Current clinical management includes infection prevention and control measures and supportive care including supplemental oxygen and mechanical ventilatory support. Evolving research and clinical data regarding the virologic SARS-CoV-2 suggest a potential list of repurposed drugs with appropriate pharmacological effects and therapeutic efficacies in treating COVID-19 patients. In this review, we will update and summarize the most common and plausible drugs for the treatment of COVID-19 patients. These drugs and therapeutic agents include antiviral agents (remdesivir, hydroxychloroquine, chloroquine, lopinavir, umifenovir, favipiravir, and oseltamivir), and supporting agents (Ascorbic acid, Azithromycin, Corticosteroids, Nitric oxide, IL-6 antagonists), among others. We hope that this review will provide useful and most updated therapeutic drugs to prevent, control, and treat COVID-19 patients until the approval of vaccines and specific drugs targeting SARS-CoV-2.

Changes in Oxygen Saturation and Mean Arterial Pressure With Inhaled Epoprostenol in Transport

OBJECTIVE

Patients with hypoxemic respiratory failure have traditionally been considered one of the riskiest patient populations to transport, given the potential for desaturation with movement. We performed a retrospective cohort study to analyze our experience using inhaled epoprostenol in transport, with a primary objective of assessing change in the oxygen saturation throughout the transport.

METHODS

The transport records of patients with severe hypoxemic respiratory failure or right heart failure, transported on inhaled epoprostenol, were reviewed. The primary outcome was the change in SpO₂ from the start of the inhaled epoprostenol transport to the time of handover of care at the receiving institution. The secondary outcome was the change in the mean arterial pressure (MAP).

RESULTS

Comparing the initial SpO₂ to the final, there was no significant difference in oxygenation between time 0 and the transfer of care at the receiving hospital at 91% versus 93% (interquartile range [IQR] 86.0-93.5 vs 87.5-96.0, P = .49). Comparing the SpO₂ for those who had inhaled epoprostenol started by the transport team showed a larger change at 86% compared to 93% (IQR: 83.0-91.0 vs 86.5-94.5, P = .04). There was no change in the median MAP from time 0 to the end of the transport (77 vs 75 mm Hg, IQR, 67.5-84.8 vs 68.5-85.8, P = .70).

CONCLUSIONS

In this study, patients with severe cardiopulmonary compromise transported on inhaled epoprostenol had no significant change in their median oxygen saturations, with the overall population increasing from 91% to 93%. When inhaled epoprostenol was initiated by the transport team, the improvement was clinically and statistically significant with an increase in SpO₂ from 86% to 93%, with a final oxygen saturation comparable to those who were on the medication at the time of the team's arrival.

Inhaled Epoprostenol to Facilitate Safe Transport in Legionnaires' Disease

Hypoxemic patients often desaturate further with movement and transport. While inhaled epoprostenol does not improve mortality, improving oxygenation allows for transport of severely hypoxemic patients to tertiary care centers with a related improvement in mortality rates. Extracorporeal membrane oxygenation (ECMO) use is increasing in frequency for patients with refractory hypoxemia, and with increasing regionalization of care, safe transport of hypoxemic patients only becomes more important. In this series, four cases are presented of young patients with severe hypoxemic respiratory failure from Legionnaires' disease transported on inhaled epoprostenol to ECMO centers for consideration of cannulation. With continued climate changes, Legionella and other pathogens are likely to be a continued threat. As such, optimizing oxygenation to allow for transport should continue to be a priority for critical care transport (CCT) services.

Inhaled epoprostenol utilization pattern after implementation of an administration policy

Epoprostenol, a pulmonary vasodilator, is used to reduce pulmonary artery pressure. Its inhaled administration results in ventilation and perfusion matching with oxygenation improvement. Epoprostenol is used as treatment for various conditions, particularly acute respiratory distress syndrome (ARDS) and pulmonary arterial hypertension. In 2018, Baylor University Medical Center implemented a policy for inhaled epoprostenol utilization aimed at standardizing clinical practice. This study analyzed epoprostenol utilization patterns in patients with ARDS after implementation of this administration policy. Drug responders and nonresponders were compared for clinical outcomes and physiologic changes before and after use, and policy compliance was evaluated. Of 79 eligible patients, 30 fulfilled inclusion criteria: 14 (47%) had ARDS and 16 (53%) had non-ARDS. In all patients with ARDS, epoprostenol was a second rescue agent after neuromuscular blockade, prone positioning, corticosteroids, and extracorporeal membrane oxygenation. Epoprostenol was associated with statistically significant improvement of oxygenation before and after utilization in patients with ARDS (ratio of arterial oxygen partial pressure to fractional inspired oxygen 70 vs 140, respectively; P = 0.04). Overall, 10 (71%) ARDS patients were epoprostenol responders; 9 (56%) were deemed responders among subjects with non-ARDS. Comparison of outcomes between responders and nonresponders showed no statistically significant variations. Policy compliance was obtained in 24 (80%) patients.

Protective Effect and Mechanism of Alprostadil in Acute Respiratory Distress Syndrome Induced by Oleic Acid in Rats

BACKGROUND This study investigated the role and mechanism of alprostadil in acute respiratory distress syndrome (ARDS) induced by oleic acid (OA) in rats. MATERIAL AND METHODS Sprague-Dawley rats were randomly divided into control, OA model, and OA + Alprostadil (2.5, 5, and 10 μg/kg, respectively) groups. The ARDS model was induced by femoral vein injection of OA, and alprostadil was administrated immediately. Lung injury was evaluated by lung wet-dry weight ratio (W/D) and histological analyses. Expressions of ACE, inflammatory mediators, apoptotic-related proteins, and proteins in the MAPKs and NF-κB signaling pathways were determined by Western blot or immunohistochemical staining. RESULTS Compared with the control group, the OA model group had significantly increased W/D, lung injury score, and collagen deposition at 3 h after OA injection. However, alprostadil (10 μg/kg) treatment significantly reduced OA-induced elevation of these indicators. Additionally, OA-induced expression of TNF-α and IL-1β were suppressed by alprostadil. The OA-induced activation of nuclear factor (NF) κB p65 was also reduced by alprostadil. Furthermore, we found that Alprostadil had an inhibitory effect on the phosphorylation of JNK, ERK1/2, and p38 MAPKs. Alprostadil inhibited Bax but increased Bcl-2, indicating a suppressive role in apoptosis. Remarkably increased expression of ACE in the OA model group was observed, which was decreased by alprostadil. CONCLUSIONS Alprostadil has a protective effect on ARDS induced by OA in rats, possibly through inhibiting apoptosis, suppressing the activation of MAPKs and NF-κB signaling pathways, and decreasing ACE protein expression. Therefore, the use of alprostadil in clinical ARDS treatment is promising.

Emerging roles of calcium-activated K channels and TRPV4 channels in lung oedema and pulmonary circulatory collapse

It has been suggested that the transient receptor potential cation (TRP) channel subfamily V (vanilloid) type 4 (TRPV4) and intermediate conductance calcium-activated potassium (KCa3.1) channels contribute to endothelium-dependent vasodilation. Here, we summarize very recent evidence for a synergistic interplay of TRPV4 and KCa3.1 channels in lung disease. Among the endothelial Ca²⁺ -permeable TRPs, TRPV4 is best characterized and produces arterial dilation by stimulating Ca²⁺ -dependent nitric oxide synthesis and endothelium-dependent hyperpolarization. Besides these roles, some TRP channels control endothelial/epithelial barrier functions and vascular integrity, while KCa3.1 channels provide the driving force required for Cl^- and water transport in some cells and most secretory epithelia. The three conditions, increased pulmonary venous pressure caused by left heart disease, high inflation pressure and chemically induced lung injury, may lead to activation of TRPV4 channels followed by Ca²⁺ influx leading to activation of KCa3.1 channels in endothelial cells ultimately leading to acute lung injury. We find that a deficiency in KCa3.1 channels protects against TRPV4-induced pulmonary arterial relaxation, fluid extravasation, haemorrhage, pulmonary circulatory collapse and cardiac arrest in vivo. These data identify KCa3.1 channels as crucial molecular components in downstream TRPV4 signal transduction and as a potential target for the prevention of undesired fluid extravasation, vasodilatation and pulmonary circulatory collapse.

Echocardiographic parameters of right ventricular function predict mortality in acute respiratory distress syndrome: a pilot study

Right ventricular (RV) dysfunction in acute respiratory distress syndrome (ARDS) contributes to increased mortality. Our aim is to identify reproducible transthoracic echocardiography (TTE) parameters of RV dysfunction that can be used to predict outcomes in ARDS. We performed a retrospective single-center cohort pilot study measuring tricuspid annular plane systolic excursion (TAPSE), Tei index, RV-fractional area change (RV-FAC), pulmonary artery systolic pressure (PASP), and septal shift, reevaluated by an independent blinded cardiologist (JK). Thirty-eight patients were included. Patients were divided on the basis of 30-day survival. Thirty-day mortality was 47%. Survivors were younger than nonsurvivors. Survivors had a higher pH, PaO2∶FiO2 ratio, and TAPSE. Acute Physiology and Chronic Health Evaluation II (APACHE II), Simplified Acute Physiology Score II (SAPS II), and Sequential Organ Failure Assessment (SOFA) scores were lower in survivors. TAPSE has the strongest association with increased 30-day mortality from date of TTE. Accordingly, TAPSE has a strong positive correlation with PaO2∶FiO2 ratios, and Tei index has a strong negative correlation with PaO2∶FiO2 ratios. Septal shift was associated with lower PaO2∶FiO2 ratios. Decrease in TAPSE, increase in Tei index, and septal shift were seen in the severe ARDS group. In multivariate logistic regression models, TAPSE maintained a significant association with mortality independent of age, pH, PaO2∶FiO2 ratios, positive end expiratory pressure, PCO2, serum bicarbonate, plateau pressures, driving pressures, APACHE II, SAPS II, and SOFA scores. In conclusion, TAPSE and other TTE parameters should be used as novel predictive indicators for RV dysfunction in ARDS. These parameters can be used as surrogate noninvasive RV hemodynamic measurements to be manipulated to improve mortality in patients with ARDS and contributory RV dysfunction.

High-flow oxygen therapy and other inhaled therapies in intensive care units

In this Series paper, we review the current evidence for the use of high-flow oxygen therapy, inhaled gases, and aerosols in the care of critically ill patients. The available evidence supports the use of high-flow nasal cannulae for selected patients with acute hypoxaemic respiratory failure. Heliox might prevent intubation or improve gas flow in mechanically ventilated patients with severe asthma. Additionally, it might improve the delivery of aerosolised bronchodilators in obstructive lung disease in general. Inhaled nitric oxide might improve outcomes in a subset of patients with postoperative pulmonary hypertension who had cardiac surgery; however, it has not been shown to provide long-term benefit in patients with acute respiratory distress syndrome (ARDS). Inhaled prostacyclins, similar to inhaled nitric oxide, are not recommended for routine use in patients with ARDS, but can be used to improve oxygenation in patients who are not adequately stabilised with traditional therapies. Aerosolised bronchodilators are useful in mechanically ventilated patients with asthma and chronic obstructive pulmonary disease, but are not recommended for those with ARDS. Use of aerosolised antibiotics for ventilator-associated pneumonia and ventilator-associated tracheobronchitis shows promise, but the delivered dose can be highly variable if proper attention is not paid to the delivery method.