A Narrative Review on the Administration of Inhaled Prostaglandins in Critically Ill Adult Patients With Acute Respiratory Distress Syndrome

OBJECTIVE

To describe the effect of inhaled prostaglandins on both oxygenation and mortality in critically ill patients with acute respiratory distress syndrome (ARDS), with a focus on safety and efficacy in coronavirus disease 2019 (COVID-19)-associated ARDS and non-COVID-19 ARDS.

DATA SOURCES

A literature search of MEDLINE was performed using the following search terms: inhaled prostaglandins, inhaled epoprostenol, inhaled nitric oxide, ARDS, critically ill. All abstracts were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Relevant English-language reports and studies conducted in humans between 1980 and June 2023 were considered.

DATA SYNTHESIS

Data regarding inhaled prostaglandins and their effect on oxygenation are limited but show a benefit in patients who respond to therapy, and data pertaining to their effect on mortality is scarce. Concerns exist regarding the formulation of inhaled epoprostenol (iEPO) utilized in addition to modes of medication delivery; however, the limited data surrounding their use have shown a reasonable safety profile. Other avenues and beneficial effects may exist with inhaled prostaglandins, such as use in COVID-19-associated ARDS or non-COVID-19 ARDS patients undergoing noninvasive mechanical ventilation or during patient transport.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

The use of inhaled prostaglandins can be considered in critically ill patients with COVID-19-associated ARDS or non-COVID-19 ARDS who are experiencing difficulties with oxygenation refractory to nonpharmacologic strategies.

CONCLUSIONS

The use of iEPO and other inhaled prostaglandins requires further investigation to fully elucidate their effects on clinical outcomes, but it appears these medications may have a potential benefit in COVID-19-associated ARDS and non-COVID-19 ARDS patients with refractory hypoxemia but with little effect on mortality.

Current Management and Future Directions for Pulmonary Arterial Hypertension Associated with Congenital Heart Disease

Current management of patients with congenital heart disease has increased their survival into adulthood. This is accompanied by potential cardiac complications, including pulmonary hypertension associated with congenital heart disease (PAH-CHD). PAH-CHD constitutes a challenging subgroup of pulmonary hypertension and requires expert management to improve quality of life and prognosis. Novel agents have shown a significant improvement in morbidity and mortality in patients with pulmonary arterial hypertension. However, the long-term effects of these medications on PAH-CHD patients remain somewhat uncertain, necessitating treatment plans largely founded on the clinical experience of the healthcare providers. The aim of this review is to summarize the current evidence and future perspectives regarding treatment strategies for PAH-CHD to help better guide management of this complex disease.

Inhaled Epoprostenol Compared With Nitric Oxide for Right Ventricular Support After Major Cardiac Surgery

BACKGROUND

Right ventricular failure (RVF) is a leading driver of morbidity and death after major cardiac surgery for advanced heart failure, including orthotopic heart transplantation and left ventricular assist device implantation. Inhaled pulmonary-selective vasodilators, such as inhaled epoprostenol (iEPO) and nitric oxide (iNO), are essential therapeutics for the prevention and medical management of postoperative RVF. However, there is limited evidence from clinical trials to guide agent selection despite the significant cost considerations of iNO therapy.

METHODS

In this double-blind trial, participants were stratified by assigned surgery and key preoperative prognostic features, then randomized to continuously receive either iEPO or iNO beginning at the time of separation from cardiopulmonary bypass with the continuation of treatment into the intensive care unit stay. The primary outcome was the composite RVF rate after both operations, defined after transplantation by the initiation of mechanical circulatory support for isolated RVF, and defined after left ventricular assist device implantation by moderate or severe right heart failure according to criteria from the Interagency Registry for Mechanically Assisted Circulatory Support. An equivalence margin of 15 percentage points was prespecified for between-group RVF risk difference. Secondary postoperative outcomes were assessed for treatment differences and included: mechanical ventilation duration; hospital and intensive care unit length of stay during the index hospitalization; acute kidney injury development including renal replacement therapy initiation; and death at 30 days, 90 days, and 1 year after surgery.

RESULTS

Of 231 randomized participants who met eligibility at the time of surgery, 120 received iEPO, and 111 received iNO. Primary outcome occurred in 30 participants (25.0%) in the iEPO group and 25 participants (22.5%) in the iNO group, for a risk difference of 2.5 percentage points (two one-sided test 90% CI, -6.6% to 11.6%) in support of equivalence. There were no significant between-group differences for any of the measured postoperative secondary outcomes.

CONCLUSIONS

Among patients undergoing major cardiac surgery for advanced heart failure, inhaled pulmonary-selective vasodilator treatment using iEPO was associated with similar risks for RVF development and development of other postoperative secondary outcomes compared with treatment using iNO.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03081052.

A Case of Giant Goiter Associated with Airway Stenosis Caused by Long-Term Intravenous Epoprostenol Therapy for Idiopathic Pulmonary Arterial Hypertension

Idiopathic pulmonary arterial hypertension is a progressive and life-threatening disease with pulmonary vasculature remodeling, leading to right-sided heart failure. Epoprostenol (prostaglandin I2) is highly recommended for patients with severe pulmonary arterial hypertension (PAH) categorized by the World Health Organization as functional class III or IV. It has been reported that prostaglandin I2 analogs can cause thyroid gland swelling and abnormal thyroid function. A 34-year-old woman was diagnosed with idiopathic pulmonary arterial hypertension and started receiving continuous intravenous epoprostenol. Three years after starting epoprostenol, she began complaining of neck swelling and was diagnosed with Graves' disease. The patient's thyroid function was controlled by thiamazole and levothyroxine; nevertheless, her thyroid gland enlargement worsened as the epoprostenol dose was titrated. After 20 years, she developed respiratory failure with a giant goiter leading to airway stenosis, and she passed away. The pathological autopsy confirmed a massive goiter associated with hyperthyroidism and airway stenosis. We experienced a case of idiopathic pulmonary hypertension with a giant goiter and airway stenosis after long-term intravenous epoprostenol therapy.

Case report: Transected Hickman catheter and its thrombotic occlusion in a patient with idiopathic pulmonary arterial hypertension-can a catheter replacement be avoided?

A 25-year-old female with idiopathic pulmonary arterial hypertension (PAH), who had a Hickman catheter implanted for continuous intravenous epoprostenol infusion, was admitted to the clinic after inadvertently cutting the catheter with nail scissors during a routine dressing change. Approximately 7 cm of the external segment of the Hickman catheter remained intact, with the distal end knotted by paramedics. A decision was made to repair the damaged Hickman catheter. However, it was discovered that its lumen was completely occluded by thrombosis. Therefore, catheter patency was mechanically restored using a 0.035-inch stiff guidewire in a sterile operating theatre setting, under fluoroscopy guidance. Successful aspiration and catheter flushing were achieved. Continuity of the Hickman catheter was then restored using a repair kit (Bard Access Systems) as per the manufacturer's instructions, with no visible leakage thereafter. Epoprostenol infusion through the Hickman catheter was resumed 24 h later, and the patient was discharged in good general condition two days afterward.

Should We Change the Target of Therapy in Pulmonary Hypertension?

Despite the evolution of drug therapy in pulmonary arterial hypertension and the more aggressive treatment approach according to the guidelines, patients continue to have unacceptable mortality rates. Furthermore, specific drug therapy alone in chronic thromboembolic pulmonary hypertension also does not seem to have any beneficial impact on survival. As the function of the right ventricle (RV) determines the prognosis of patients with pulmonary hypertension, the treatment strategy should focus on modifying factors involved in RV dysfunction. Although some previous reports demonstrated that the survival of patients with pulmonary hypertension was associated with mPAP, nevertheless, mPAP is still not considered as a target of therapy. There are many examples of effective mPAP lowering with early and aggressive drug therapy in pulmonary arterial hypertension, or with interventions in chronic thromboembolic pulmonary hypertension. This effective mPAP reduction can lead to reverse RV remodeling, and thus, improvement in survival. In this article, the importance of mPAP lowering is stated, as well as why the change of our current strategy and considering mPAP reduction as the target of therapy could make pulmonary hypertension a chronic but not fatal disease.

Non-traumatic Acute Subdural Hematoma in a Patient With Scleroderma Complicated by Pulmonary Arterial Hypertension: A Case Report

Non-traumatic acute subdural hematoma (SDH) in patients with scleroderma is infrequently described in literature reviewing the neurologic disorders in scleroderma. We report a case of a patient with scleroderma complicated by severe pulmonary arterial hypertension (PAH), and a history of pulmonary embolism on warfarin who developed an SDH, requiring hemicraniectomy after initiating therapy with IV epoprostenol. The proposed mechanisms for SDH development and management strategy are discussed.

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.

Risk factors and treatment of oxygenator high-pressure excursions during cardiopulmonary bypass

INTRODUCTION

A high-pressure excursion (HPE) is a sudden increase in oxygenator inlet pressure during cardiopulmonary bypass (CPB). The aims of this study were to identify factors associated with HPE, to describe a treatment protocol utilizing epoprostenol in severe cases, and to assess early outcome in HPE patients.

METHODS

Patients who underwent cardiac surgery with cardiopulmonary bypass at Sahlgrenska University Hospital 2016-2018 were included in a retrospective observational study. Pre- and post-operative data collected from electronic health records, local databases, and registries were compared between HPE and non-HPE patients. Factors associated with HPE were identified with logistic regression models.

RESULTS

In total, 2024 patients were analyzed, and 37 (1.8%) developed HPE. Large body surface area (adjusted Odds Ratio (aOR): 1.43 per 0.1 m²; 95% confidence interval (CI): 1.16-1.76, p < 0.001), higher hematocrit during CPB (aOR: 1.20 per 1%; (1.09-1.33), p < 0.001), acute surgery (aOR: 2.98; (1.26-6.62), p = 0.018), and previous stroke (aOR: 2.93; (1.03-7.20), p = 0.027) were independently associated with HPE. HPE was treated with hemodilution (n = 29, 78.4%), and/or extra heparin (n = 23, 62.2%), and/or epoprostenol (n = 12, 32.4%). No oxygenator change-out was necessary. While there was no significant difference in 30-day mortality (2.7% vs 3.2%, p = 1.0), HPE was associated with a higher perioperative stroke rate (8.1% vs 1.8%, aOR 5.09 (1.17-15.57), p = 0.011).

CONCLUSIONS

Large body surface area, high hematocrit during CPB, previous stroke and acute surgery were independently associated with HPE. A treatment protocol including epoprostenol appears to be a safe option. Perioperative stroke rate was increased in HPE patients.

Case report: High-dose epoprostenol therapy in pediatric patients with pulmonary hypertension and developmental lung disease

Pulmonary hypertension (PH) with developmental lung disease is a life-threatening disease and accounts for 10%-12% of pediatric PH patients. Administration of specific pulmonary vasodilators to pediatric PH patients has brought about improvement of their long-term prognosis. Intravenous epoprostenol therapy is a gold standard therapy for severe idiopathic pulmonary arterial hypertension (IPAH), but there are few reports demonstrating the efficacy of epoprostenol for pediatric PH patients with developmental lung disease, especially when treating with high doses of epoprostenol. Two cases of pediatric PH patients with alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) and congenital diaphragmatic hernia (CDH) with bronchopulmonary dysplasia (BPD), respectively, treated with epoprostenol above 100 ng/kg/min are presented. In these two cases, severe PH was improved significantly by an aggressive increase of the epoprostenol infusion rate with administration of oral pulmonary vasodilators and appropriate respiratory management, without any significant adverse effects. High-dose epoprostenol therapy may be one of the therapeutic options in pediatric PH patients with developmental lung disease.

Inhaled Nitric Oxide vs Epoprostenol During Acute Respiratory Failure: An Observational Target Trial Emulation

BACKGROUND

The inhaled vasodilators nitric oxide and epoprostenol may be initiated to improve oxygenation in mechanically ventilated patients with severe acute respiratory failure (ARF); however, practice patterns and head-to-head comparisons of effectiveness are unclear.

RESEARCH QUESTION

What are the practice patterns and comparative effectiveness for inhaled nitric oxide and epoprostenol in severe ARF?

STUDY DESIGN AND METHODS

Using a large US database (Premier Healthcare Database), we identified adult patients with ARF or ARDS who were mechanically ventilated and started on inhaled nitric oxide, epoprostenol, or both. Leveraging large hospital variation in the choice of initial inhaled vasodilator, we compared the effectiveness of inhaled nitric oxide with that of epoprostenol by limiting analysis to patients admitted to hospitals that exclusively used either inhaled nitric oxide or epoprostenol. The primary outcome of successful extubation was modeled using multivariate Fine-Grey competing risk (death or hospice discharge) time-to-event models.

RESULTS

Among 11,200 patients (303 hospitals), 6,366 patients (56.8%) received inhaled nitric oxide first, 4,720 patients (42.1%) received inhaled epoprostenol first, and 114 patients (1.0%) received both therapies on the same day. One hundred four hospitals (34.3%; 1,666 patients) exclusively used nitric oxide and 118 hospitals (38.9%; 1,812 patients) exclusively used epoprostenol. No differences were found in the likelihood of successful extubation between patients admitted to nitric oxide-only hospitals vs those admitted to epoprostenol-only hospitals (subdistribution hazard ratio, 0.97; 95% CI, 0.80-1.18). Also no differences were found in total hospital costs or death. Results were robust to multiple sensitivity analyses.

INTERPRETATION

Large variation exists in the use of initial inhaled vasodilator for respiratory failure across US hospitals. Comparative effectiveness analyses identified no differences in outcomes based on inhaled vasodilator type.

Successful transition from intravenous epoprostenol to oral selexipag and inhaled iloprost in a case of severe pulmonary arterial hypertension associated with systemic lupus erythematosus

A 25-year-old woman was admitted to our hospital with severe pulmonary arterial hypertension associated with systemic lupus erythematosus (SLE-PAH). Her mean pulmonary arterial pressure was 56 mmHg, and her SLE Disease Activity Index-2 K score was 14 on admission. In addition to a strong immunosuppressive regimen, which included steroid pulse therapy followed by high-dose oral prednisolone (1 mg/kg) and intravenous cyclophosphamide, an upfront combination of vasodilator therapy, including oral tadalafil, macitentan, and intravenous epoprostenol, was administered in the early phase. Two months later, her mean pulmonary arterial pressure was 29 mmHg, and her other haemodynamic markers showed significant improvement. She refused to start life-long intravenous epoprostenol therapy and so was switched to oral selexipag and inhaled iloprost. The transition was successful, and she has experienced no exacerbations of SLE-PAH during the 10 months since the onset of pulmonary arterial hypertension. To the best of our knowledge, this is the first report of intravenous epoprostenol being switched to alternative oral and inhaled therapy in a patient with SLE-PAH. In combination with adequate immunosuppressive therapy, it is probably easier to make this transition in patients with SLE-PAH than in those with pulmonary arterial hypertension of a different aetiology. Continuous infusion of epoprostenol can have potentially life-threatening complications and a detrimental effect on the quality of life. Our alternative treatment strategy was successful, and we hope that it will prove beneficial in other cases.

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.

Reasons for refusing parenteral therapy: a qualitative study of patients with pulmonary arterial hypertension

While parenteral prostacyclin (pPCY) therapy, delivered either subcutaneously or intravenously, is recommended for pulmonary arterial hypertension patients with severe or rapidly developing disease, some patients refuse this treatment. This study aimed to understand, directly from patients with pulmonary arterial hypertension, why pPCY was refused and, in some cases, later accepted. Interviews were conducted with 25 pulmonary arterial hypertension patients who previously refused pPCY therapy (Group A: Refused/Never initiated (n = 9) and Group B: Refused/Initiated (n = 16)). Patients in both groups believed that pPCY could improve their symptoms, slow disease progression, and provide them a greater ability to perform activities. Reasons for refusal included concern over side effects and the perceived limitations of pPCY on daily activities. Group A perceived their decision as a balance between quality of life and prolonging life and most acknowledged they would reconsider pPCY if other treatment options were exhausted. Group B cited they initiated therapy due to a worsening of symptoms, disease progression, to improve quality of life, to be there for their family, or a desire to live. Following initiation, Group B indicated their experience met expectations with reduced symptoms, slowed disease progression, and perception of improved survival; concerns related to pPCY were described as manageable. Given the efficacy of pPCY therapy, clinicians should apply knowledge of these findings in clinical practice. Patients noted improvements to parenteral pump technologies to include smaller size, water resistance, and implantability may increase their acceptance of this modality. Development efforts should focus on technologies that increase the acceptance of pPCY when indicated.

An Adolescent Patient With Idiopathic Pulmonary Arterial Hypertension Weaned Off Intravenous Epoprostenol Following Treatment With Selexipag: A Case Report

Idiopathic pulmonary arterial hypertension (PAH) is a rare, progressive disease affecting the pulmonary arteries. Epoprostenol, a synthetic prostaglandin analog, is the most potent pharmacological treatment modality used in patients with PAH. However, it requires continuous intravenous infusion, which negatively impacts the patient's quality of life and frequently results in complications, such as catheter-related bloodstream infection. We weaned an adolescent female patient off epoprostenol by gradually introducing oral selexipag over a sustained period, following many years of continuous intravenous epoprostenol use alone. Oral selexipag might have an efficacy comparable to epoprostenol in young patients with PAH.

Strategies for optimizing intravenous prostacyclin-analog therapy in patients with pulmonary arterial hypertension

INTRODUCTION

Intravenous prostacyclin-analogs (PCA, e.g. epoprostenol, treprostinil, iloprost) have become an essential part in the therapy of patients with pulmonary hypertension (PH), mainly pulmonary arterial hypertension (PAH). They show considerable differences in pharmacology. A combination therapy including intravenous drugs is regarded as the 'gold standard' in most of PAH patients.

AREAS COVERED

This review discusses and summarizes the studies and concepts on which this therapy is based. To date, intravenous prostacyclin-analogs are mainly administered when standard therapy fails to improve patients to low-risk status. However, preliminary data from uncontrolled studies suggest that an 'upfront triple' therapy including intravenous or subcutaneous prostacyclin-analogs could be preferable in selected patients.

EXPERT OPINION

Various IV PCA have been evaluated in the treatment of patients with PAH. Today, combination therapy is the 'gold standard' for the majority of patients. Intravenous PCA is recommended from functional class III onwards. Timing of its initiation is still a point of discussion. An escalation of therapy to IV or SC PCA is always necessary if a low-risk status cannot be achieved with other targeted therapies. Preliminary data suggest that selected patients could benefit from an 'upfront triple' therapy. Controlled studies on which such recommendation could be based are lacking.

Use of Epoprostenol in the Treatment of Pulmonary Arterial Hypertension

Pulmonary Hypertension (PH) is defined as a disorder in which the mean Pulmonary Arterial Pressure (mPAP) is greater than 20 mmHg at rest. Pulmonary Arterial Hypertension (PAH) is considered when mPAP is > 20 mmHg and pulmonary vascular resistance (PVR) is ⩾ 3 WU. PAH is a chronic progressive disease resulting in right heart failure and premature death. It is postulated to be due to an inactivating mutation of a gene named bone morphogenetic protein receptor type 2 (BMPR2), whose predominant function is halting vascular proliferation. It has a lamentable prognosis if not rapidly diagnosed and adequately treated. Treatment of PAH has evolved in the past few decades since many related pathways and potential therapeutic targets have been explored. Parenteral prostanoids are the most effective therapeutic options for PAH. Epoprostenol is a synthetic analog of prostacyclin and a potent vasodilator that was Food and Drug Administration (FDA)-approved in December 1995 for intravenous use to treat PAH. It has also been used to treat different PAH subtypes, including connective tissue-related PAH like lupus and systemic sclerosis, congenital heart disease, and drug-induced PAH. It is effective in reducing mortality rates and improving survival rates. Although the use of Epoprostenol for PAH is challenging, it has been one of the most successful therapies used. In this manuscript, we review the pathophysiology of PAH and the risk stratification tool. We also discuss the mechanism of action of PAH-targeted therapies while focusing on the role of epoprostenol that has been investigated in many clinical trials. Finally, we discuss two ongoing clinical trials which highlight some potential therapeutic options. 

Evaluation of Inhaled Alprostadil in Hospitalized Adult Patients

BACKGROUND

Intermittent inhaled alprostadil (iPGE₁) may be a viable alternative to inhaled nitric oxide or epoprostenol for management of right ventricular failure, pulmonary hypertension (pHTN) or acute respiratory distress syndrome (ARDS). However, limited evidence exists regarding iPGE₁ use in adults, ideal dosing strategies, or optimal use cases.

OBJECTIVE

To describe the clinical characteristics of patients receiving iPGE₁ and identify specific sub-populations warranting further research.

METHODS

This was a single-center, retrospective, descriptive analysis of inpatients who received at least one dose of iPGE₁. The primary outcome was to describe patient characteristics and alprostadil dosing strategies. Secondary outcomes included changes in respiratory support requirements, hemodynamics, and inotropic/vasoactive use. Outcomes were stratified and compared based on primary therapeutic indication (cardiac or pulmonary).

RESULTS

Fifty-four patients received iPGE₁ 40 (75%) for pulmonary (pHTN or ARDS) and 14 (25%) for cardiac indications. There was no difference between indications in the number of patients de-escalated from level of respiratory (53% vs 57%, P = 0.76), inotropic (70% vs 57%, P = 0.39), or vasopressor support (78% vs 57%, P = 0.17). Furthermore, there was no significant improvement in cardiopulmonary parameters at multiple time intervals after iPGE₁ initiation.

CONCLUSION AND RELEVANCE

This is the largest study to date on the use of intermittent iPGE₁ in adults. Alprostadil was safely utilized in novel populations; however, efficacy as evaluated by clinical or surrogate endpoints could not be demonstrated and further investigation is needed to determine its potential and optimal place in therapy.

Factors Determining Continuous Infusion Aerosol Delivery During Mechanical Ventilation

BACKGROUND

Continuous nebulization of prostacyclins and albuterol by infusion pump during mechanical ventilation evolved as a popular off-label treatment for severe hypoxemic respiratory failure and asthma. Most institutions use a vibrating mesh nebulizer. A new breath-enhanced jet nebulizer is a potential alternative. This study was designed to compare these devices to better define factors influencing continuous infusion aerosol delivery. Device function, ventilator settings, and infusion pump flow were studied in vitro.

METHODS

Using a bench model of adult mechanical ventilation, radiolabeled saline was infused at 6 flows (1.5-12 mL/h) into test nebulizers; 4 examples of each were used in rotation to test device reproducibility. Four breathing patterns with duty cycles (percentage of inspiratory time) ranging from 0.13 to 0.34 were tested. The vibrating mesh nebulizer was installed on the "dry" side of the heated humidifier (37°C). The breath-enhanced jet nebulizer, installed on the "wet" side, was powered by air at 3.5 L/min and 50 psi. Infusion time was 1 h. Inhaled mass of aerosol was collected on a filter at the airway opening. Inhaled mass was expressed as the percentage of the initial syringe radioactivity delivered per hour. Radioactivity deposited in the circuit was measured with a gamma camera. Data were analyzed with multiple linear regression.

RESULTS

Variation in inhaled mass was significantly explained by pump flow and duty cycle (R² 0.92) and not by nebulizer technology. Duty cycle effects were more apparent at higher pump flow. Vibrating mesh nebulizers failed to nebulize completely in 20% of the test runs. Mass balance indicated that vibrating mesh nebulizers deposited 15.3% in the humidifier versus 0.2% for breath-enhanced jet nebulizer.

CONCLUSIONS

Aerosol delivery was determined by infusion pump flow and ventilator settings with comparable aerosol delivery between devices. The breath-enhanced jet nebulizer was more reliable than the vibrating mesh nebulizer; 10-12 mL/h was the maximum infusion flow for both nebulizer technologies.

Inhaled pulmonary vasodilators: a narrative review

Pulmonary hypertension (PH) is a severe disease that affects people of all ages. It can occur as an idiopathic disorder at birth or as part of a variety of cardiovascular and pulmonary disorders. Inhaled pulmonary vasodilators (IPV) can reduce pulmonary vascular resistance (PVR) and improve RV function with minimal systemic effects. IPV includes inhaled nitric oxide (iNO), inhaled aerosolized prostacyclin, or analogs, including epoprostenol, iloprost, treprostinil, and other vasodilators. In addition to pulmonary vasodilating effects, IPV can also be used to improve oxygenation, reduce inflammation, and protect cell. Off-label use of IPV is common in daily clinical practice. However, evidence supporting the inhalational administration of these medications is limited, inconclusive, and controversial regarding their safety and efficacy. We conducted a search for relevant papers published up to May 2020 in four databases: PubMed, Google Scholar, EMBASE and Web of Science. This review demonstrates that the clinical using and updated evidence of IPV. iNO is widely used in neonates, pediatrics, and adults with different cardiopulmonary diseases. The limitations of iNO include high cost, flat dose-response, risk of significant rebound PH after withdrawal, and the requirement of complex technology for monitoring. The literature suggests that inhaled aerosolized epoprostenol, iloprost, treprostinil and others such as milrinone and levosimendan may be similar to iNO. More research of IPV is needed to determine acceptable inclusion criteria, long-term outcomes, and management strategies including time, dose, and duration.

Severe thrombocytopenia in patients with idiopathic pulmonary arterial hypertension provided several strategies for lung transplantation

While the prognosis of idiopathic pulmonary arterial hypertension has improved significantly due to newer medications, lung transplantation remains a critical therapeutic option for severe pulmonary arterial hypertension. Hence, it is essential for patients awaiting lung transplantation to avoid complications, including thrombocytopenia, which may affect their surgical outcomes. Herein we present the case of a 21-year-old woman diagnosed with idiopathic pulmonary arterial hypertension at the age of 15. She developed thrombocytopenia while awaiting lung transplantation. Her medication was switched from epoprostenol to treprostinil, suspecting possible drug-induced thrombocytopenia. Furthermore, she was administered thrombopoietin receptor agonists in view of the possibility of idiopathic thrombocytopenic purpura, along with maximum support for right heart failure. Subsequently, her platelet count increased to >70,000/µL, enabling her to successfully undergo bilateral lung transplantation. Post-bilateral lung transplantation, pulmonary arterial hypertension as well as thrombocytopenia appeared to have resolved. In this case, we suspected that thrombocytopenia could have resulted owing to a combination of pulmonary arterial hypertension, right heart failure, drug interactions, and idiopathic thrombocytopenic purpura. Thrombocytopenia is a very critical condition in patients with pulmonary arterial hypertension, especially those awaiting lung transplantation. Several approaches are known to improve intractable thrombocytopenia in patients with pulmonary arterial hypertension.

Evaluation of the Efficacy and Safety of Inhaled Epoprostenol and Inhaled Nitric Oxide for Refractory Hypoxemia in Patients With Coronavirus Disease 2019

OBJECTIVES

The objectives of this study were to evaluate the efficacy and safety of inhaled epoprostenol and inhaled nitric oxide in patients with refractory hypoxemia secondary to coronavirus disease 2019.

DESIGN

Retrospective single-center study.

SETTING

ICUs at a large academic medical center in the United States.

PATIENTS

Thirty-eight adult critically ill patients with coronavirus disease 2019 and refractory hypoxemia treated with either inhaled epoprostenol or inhaled nitric oxide for at least 1 hour between March 1, 2020, and June 30, 2020.

INTERVENTIONS

Electronic chart review.

MEASUREMENTS AND MAIN RESULTS

Of 93 patients screened, 38 were included in the analysis, with mild (4, 10.5%), moderate (24, 63.2%), or severe (10, 26.3%), with acute respiratory distress syndrome. All patients were initiated on inhaled epoprostenol as the initial pulmonary vasodilator and the median time from intubation to initiation was 137 hours (68-228 h). The median change in Pao₂/Fio₂ was 0 (-12.8 to 31.6) immediately following administration of inhaled epoprostenol. Sixteen patients were classified as responders (increase Pao₂/Fio₂ > 10%) to inhaled epoprostenol, with a median increase in Pao₂/Fio₂ of 34.1 (24.3-53.9). The mean change in Pao₂ and Spo₂ was -0.55 ± 41.8 and -0.6 ± 4.7, respectively. Eleven patients transitioned to inhaled nitric oxide with a median change of 11 (3.6-24.8) in Pao₂/Fio₂. A logistic regression analysis did not identify any differences in outcomes or characteristics between the responders and the nonresponders. Minimal adverse events were seen in patients who received either inhaled epoprostenol or inhaled nitric oxide.

CONCLUSIONS

We found that the initiation of inhaled epoprostenol and inhaled nitric oxide in patients with refractory hypoxemia secondary to coronavirus disease 2019, on average, did not produce significant increases in oxygenation metrics. However, a group of patients had significant improvement with inhaled epoprostenol and inhaled nitric oxide. Administration of inhaled epoprostenol or inhaled nitric oxide may be considered in patients with severe respiratory failure secondary to coronavirus disease 2019.

Transitioning From Intravenous to Subcutaneous Prostacyclin Therapy in Neonates With Severe Pulmonary Hypertension

This article aims to present our neonatal intensive care unit experience transitioning from intravenous epoprostenol to IV and subcutaneous treprostinil in patients with persistent pulmonary hypertension of the neonate. This was a retrospective chart review at an academic teaching hospital. Neonates with a diagnosis of persistent pulmonary hypertension of the neonate (PPHN) who were started on IV prostacyclin therapy while admitted to the NICU between August 2017 and October 2019 were included. Of the 5 patients included, gestational ages ranged from 24 to 38 weeks. All patients were treated with inhaled nitric oxide and sildenafil before being initiated on IV or SQ prostacyclin therapy. Intravenous epoprostenol dosing was initiated at 1 ng/kg/min and was increased by 1 ng/kg/min every 12 hours until the provider was satisfied with the clinical response. Once the dose was stable for a few days epoprostenol was transitioned to IV treprostinil using double the last epoprostenol dose. A few days later infants were switched to SQ treprostinil using the same dose by stopping the IV infusion and starting the SQ infusion. All patients survived to hospital discharge and were sent home on SQ treprostinil. Minimal adverse effects were seen; patients experienced some slight hypotension, tachycardia, and diarrhea. Severe pulmonary hypertension is a common occurrence and a significant cause of mortality in the NICU. Our patients demonstrate that IV and SQ prostacyclin therapy is a therapeutic option for PPHN. Additionally, rapid high-dose transition from IV epoprostenol to IV treprostinil and then to SQ treprostinil is well tolerated in neonates, with minimal adverse effects.

Uninterrupted Continuous and Intermittent Nebulizer Therapy in a COVID-19 Patient Using Sequential Vibratory Mesh Nebulizers: A Case Report

Interruptions in continuous nebulized pulmonary vasodilators, such as epoprostenol, can potentially result in clinical deterioration in respiratory status. Coadministration of other intermittent nebulized therapies may require opening the ventilator circuit to facilitate administration. However, in patients with SARS-CoV2 infection, it is preferred to avoid opening the circuit whenever feasible to prevent aerosolization of the virus and exposure of health care workers. In this study, we describe a unique method of administering continuous epoprostenol nebulization and intermittent nebulized antibiotics, mucolytics, and bronchodilators, using Aerogen vibrating mesh nebulizers without interruptions in epoprostenol or opening the ventilator circuit. This technique set up consisted of stacking two Aerogen nebulizer cups, each with its own controller. This approach was successful in allowing concomitant delivery of intermittent and continuous nebulized therapy without interruptions. To our knowledge, this method has not been previously described in the literature and may be helpful to bedside clinicians facing a similar clinical scenario.

Novel Toxicology Program to Support the Development of Inhaled VentaProst

Currently, off-label continuous administration of inhaled epoprostenol is used to manage hemodynamics during mitral valve surgery. A toxicology program was developed to support the use of inhaled epoprostenol during mechanical ventilation as well as pre- and postsurgery via nasal prongs. To support use in patients using nasal prongs, a Good Laboratory Practice (GLP), 14-day rat, nose-only inhalation study was performed. No adverse findings were observed at ∼50× the dose rate received by patient during off-label use. To simulate up to 48 hours continuous aerosol exposure during mechanical ventilation, a GLP toxicology study was performed using anesthetized, intubated, mechanically ventilated dogs. Dogs inhaled epoprostenol at approximately 6× and 13× the dose rate reported in off-label human studies. This novel animal model required establishment of a dog intensive care unit providing sedation, multisystem support, partial parenteral nutrition, and management of the intubated mechanically ventilated dogs for the 48-hour duration of study. Aerosol was generated by a vibrating mesh nebulizer with novel methods required to determine dose and particle size in-vitro. Continuous pH 10.5 epoprostenol was anticipated to be associated with lung injury; however, no adverse findings were observed. As no toxicity at pH 10.5 was observed with a formulation that required refrigeration, a room temperature stable formulation at pH 12 was evaluated in the same ventilated dog model. Again, there were no adverse findings. In conclusion, current toxicology findings support the evaluation of inhaled epoprostenol at pH 12 in surgical patients with pulmonary hypertension for up to 48 hours continuous exposure.

Transitions between infused and oral prostacyclin pathway agents in pulmonary arterial hypertension: key considerations

Prostacyclin pathway agents are a critical treatment for patients with pulmonary arterial hypertension. Seven prostacyclin pathway agents are available, including agents administered by parenteral infusion, by inhalation, and orally. Pulmonary arterial hypertension patients are now transitioned from one prostacyclin pathway agent to another with increasing frequency. Such transitions require careful downtitration and uptitration to avoid decompensation from rapid withdrawal and to achieve a patient's optimal dose based on efficacy and tolerability. Clinical guidance is especially lacking for transitions involving the newer, oral prostacyclin pathway agents; specifically, selexipag and oral treprostinil. We present three case reports of patients with pulmonary arterial hypertension who underwent one or more transition between parenteral and oral prostacyclin pathway agents, including some transitions that were successful and some that were not. These cases illustrate key considerations, such as titration protocols, patient selection, side effect management, and pharmacokinetics.

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.

Drug Treatment of Pulmonary Hypertension in Children

Pulmonary arterial hypertension (PAH) is a rare disease in infants and children that is associated with significant morbidity and mortality. The disease is characterized by progressive pulmonary vascular functional and structural changes resulting in increased pulmonary vascular resistance and eventual right heart failure and death. In many pediatric patients, PAH is idiopathic or associated with congenital heart disease and rarely is associated with other conditions such as connective tissue or thromboembolic disease. PAH associated with developmental lung diseases such as bronchopulmonary dysplasia or congenital diaphragmatic hernia is increasingly more recognized in infants and children. Although treatment of the underlying disease and reversal of advanced structural changes have not yet been achieved with current therapy, quality of life and survival have improved significantly. Targeted pulmonary vasodilator therapies, including endothelin receptor antagonists, prostacyclin analogs, and phosphodiesterase type 5 inhibitors have resulted in hemodynamic and functional improvement in children. The management of pediatric PAH remains challenging as treatment decisions depend largely on results from evidence-based adult studies and the clinical experience of pediatric experts. This article reviews the current drug therapies and their use in the management of PAH in children.

Use and costs of inhaled nitric oxide and inhaled epoprostenol in adult critically ill patients: A quality improvement project

PURPOSE

Inhaled epoprostenol and inhaled nitric oxide are pulmonary vasodilators commonly used in the management of acute respiratory distress syndrome and right ventricular failure; however, they have vastly different cost profiles. The purpose of the project was to transition from nitric oxide to epoprostenol as the inhaled pulmonary vasodilator (IPV) of choice in adult critically ill patients and evaluate the effect of the transition on associated usage and costs.

METHODS

A single-center, prospective, before and after quality improvement project including adult patients receiving inhaled nitric oxide, inhaled epoprostenol, or both was conducted in 7 adult intensive care units, operating rooms, and postanesthesia care units of a tertiary care academic medical center. The total number of patients, hours of therapy, and costs for each agent were compared between stages of protocol implementation and annually.

RESULTS

Seven hundred twenty-nine patients received inhaled nitric oxide, inhaled epoprostenol, or both during the study period. The monthly inhaled nitric oxide use in number of patients, hours, and cost decreased during all stages of the project (p < 0.01). The monthly inhaled epoprostenol use in number of patients, hours, and cost increased during all stages (p < 0.01). Overall, total IPV use increased during the study. However, despite this increase in usage, there was a 47% reduction in total IPV cost.

CONCLUSION

Implementation of a staged protocol to introduce and expand inhaled epoprostenol use in adult critically ill patients resulted in decreased use and cost of inhaled nitric oxide. The total cost of all IPV was decreased by 47% despite increased IPV use.

The Clinical Impact of Flow Titration on Epoprostenol Delivery via High Flow Nasal Cannula for ICU Patients with Pulmonary Hypertension or Right Ventricular Dysfunction: A Retrospective Cohort Comparison Study

(1) Background: inhaled epoprostenol (iEPO) delivered via high-flow nasal cannula (HFNC) has been reported to be effective for pulmonary hypertension and right ventricular dysfunction. In vitro studies have identified HFNC gas flow as a key factor in trans-nasal aerosol delivery efficiency; however, little evidence is available on the clinical impact of flow titration on trans-nasal aerosol delivery. At our institution, iEPO via HFNC was initiated in 2015 and the concept of flow titration during iEPO via HFNC has been gradually accepted and carried out by clinicians in the recent years. (2) Methods: a retrospective review of the electronic medical records for all adult patients who received iEPO via HFNC in a tertiary teaching hospital. Pre- and post- iEPO responses were reported for patients whose HFNC flow was titrated or maintained constant during iEPO delivery. Positive response to iEPO was defined as the reduction of mean pulmonary arterial pressure (mPAP) > 10% for pulmonary hypertension patients or the improvement of oxygenation [pulse oximetry (SpO₂)/fraction of inhaled oxygen (F_IO₂)] > 20%. The number of responders to iEPO was compared between groups with titrated vs constant flow. (3) Results: 51 patients who used iEPO to treat pulmonary hypertension and/or right ventricular dysfunction were reviewed. Following iEPO administration via HFNC, mPAP decreased (43.6 ± 11.7 vs. 36.3 ± 9.7 mmHg, p < 0.001). Among the 51 patients, 24 had concomitant refractory hypoxemia, their oxygenation (SpO₂/F_IO₂) improved after iEPO delivery (127.8 ± 45.7 vs. 157.6 ± 62.2, p < 0.001). During iEPO initiation, gas flow was titrated in 25 patients and the remaining 26 patients used constant flow. The percentage of patients in the flow titration group who met the criteria for a positive response was higher compared to the group with constant flow (85.7% vs. 50%, p = 0.035). Pre- vs post-iEPO responses were significant in the flow titration group included improvement in cardiac output (p = 0.050), cardiac index (p = 0.021) and F_IO₂ reduction (p = 0.016). These improvements in hemodynamics and F_IO₂ were not observed in the constant flow group. (4) Conclusion: in patients with pulmonary hypertension and/or right ventricular dysfunction, trans-nasal iEPO decreased pulmonary arterial pressure. It also improved oxygenation in patients with combined refractory hypoxemia. These improvements were more evident in patients whose gas flow was titrated during iEPO initiation than those patients using constant flow.

Stress Cardiomyopathy Precipitated by Withdrawal of Epoprostenol

We describe a case of stress-induced cardiomyopathy following epoprostenol withdrawal. A patient with pulmonary arterial hypertension presented with a malfunctioning Hickman catheter. Inappropriate withdrawal of epoprostenol resulted in shock. Evaluation confirmed stress-induced cardiomyopathy. Restarting epoprostenol resolved the electrocardiographic and echocardiographic abnormalities. This case meets Taskforce on Takotsubo Syndrome Stress-Induced Cardiomyopathy criteria. (Level of Difficulty: Beginner.)

Long-term outcomes of epoprostenol therapy in sarcoid associated pulmonary hypertension

Sarcoidosis-Associated Pulmonary Hypertension (SAPH) is a common finding in patients with chronic sarcoidosis and is associated with increased mortality. The optimal treatment for SAPH is not known; however, therapies approved for Group 1 pulmonary hypertension have improved hemodynamics and functional status. Prostanoids, including epoprostenol, have been therapeutic in short-term studies of SAPH, but long-term efficacy is unknown. In this study, we evaluated the long-term effect of epoprostenol therapy in 12 patients with SAPH. Hemodynamic assessment after an average of 4.1 years of epoprostenol therapy demonstrated significant improvement in mean pulmonary arterial pressure, pulmonary vascular resistance, and cardiac output; furthermore, patients demonstrated improved NYHA functional class. To evaluate further the long-term effect of epoprostenol, we compared survival of SAPH patients to a cohort of hemodynamically matched patients from the same center treated with epoprostenol for Idiopathic Pulmonary Arterial Hypertension (IPAH). Interestingly, there was no difference in survival, despite the additional systemic disease burden of the SAPH subjects. Subgroup analysis by Scadding stage demonstrated that Scadding stages 1-3 had improved survival compared to Scadding stage 4. These observations suggest that epoprostenol is an effective long-term therapy for patients with SAPH; it improves hemodynamics, functional class, and provides survival similar to that seen in a hemodynamically-matched cohort of IPAH patients. Furthermore, we identify a subgroup of SAPH patients (nonfibrotic lung disease Scadding 1-3) who may derive significant benefit from prostanoid therapy. (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (2): 184-191).

Comparative effectiveness of pulmonary arterial hypertension drugs in treatment-naive patients: a network meta-analysis

Aim: No network meta-analysis has been conducted to study efficacy of drug therapies specific for treatment of pulmonary arterial hypertension in treatment-naive patients only. Methods: Randomized controlled trials on pulmonary arterial hypertension-specific drug therapies were searched and a Bayesian network meta-analysis was performed. The 6-min walking distance (6MWD) and all-cause mortality were efficacy outcomes, whereas discontinuation due to adverse events was a safety-related outcome. Results: Analysis included 3.713 patients from 21 trials. Combination of ambrisentan and tadalafil showed the greatest impact on 6MWD, followed by epoprostenol and intravenous treprostinil (high dose). The latter two demonstrated marked effect size on mortality, although not statistically significant. Conclusion: According to 6MWD, ambrisentan/tadalafil combination was considered as most effective among all comparisons. Prospero ID: CRD42019110832.

Effectiveness of epoprostenol in the management of pulmonary arterial hypertension: findings of an Australian retrospective chart review

BACKGROUND

Pulmonary arterial hypertension (PAH) is a progressively fatal disease. Parenteral prostanoids, including intravenous (IV) epoprostenol, are the most effective therapies for PAH. As epoprostenol requires continuous infusion, therapy is challenging and use is managed by specialist units.

AIMS

To describe the clinical outcomes for the use of IV epoprostenol in an Australian pulmonary vascular disease unit and identify opportunities to improve its use.

METHOD

We conducted a retrospective chart review of all adult patients who received IV epoprostenol for PAH at Prince Charles Hospital. Data were collected at baseline, initiation of epoprostenol and quarterly to the end of the audit period or the discontinuation of epoprostenol. Descriptive statistics were performed and comparisons made to epoprostenol initiation. Kaplan-Meier curves were used to estimate survival outcomes.

RESULTS

Thirty-nine patients received epoprostenol therapy. Most (87.2%) were female, had connective tissue disease (46.2%) or idiopathic PAH (35.9%) and had a World Health Organization functional Class of III or IV at initiation. The mean duration of epoprostenol therapy was 2.9 years. Intravenous epoprostenol was associated with favourable outcomes; 1, 3 and 5-year survival rates since initiation of 90.0, 75.8 and 68.2%; robust improvements in functional class; and improvements in 6-min walking distance of 160.4 m at 3 years; 94.9% patients experienced at least one drug-related adverse event and line complications were common.

CONCLUSION

Epoprostenol therapy was associated with impressive survival rates and durable improvements in functional outcomes. Epoprostenol therapy is challenging; however, it is manageable by the majority of patients with most experiencing positive, sustainable outcomes.

Pharmacotherapy for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a condition associated with substantial morbidity and mortality. Over the last 25 years there has been a significant evolution in the therapies to treat PAH. These therapies are effective for patients with group I PAH and group IV PH [chronic thromboembolic pulmonary hypertension (CTEPH)]. PAH is characterized by an imbalance of nitric oxide, prostacyclin and endothelin levels, and current pharmacotherapy involves these three pathways. Earlier clinical trials involving PAH-specific therapies evaluated improvements in 6-minute walk time as a primary improvement whereas contemporary trials have been larger and focused on morbidity and mortality reductions. While there may be a role for monotherapy in disease management, most patients should be considered for dual or triple therapy.

Epoprostenol Delivered via High Flow Nasal Cannula for ICU Subjects with Severe Hypoxemia Comorbid with Pulmonary Hypertension or Right Heart Dysfunction

Inhaled epoprostenol (iEPO) has been utilized to improve oxygenation in mechanically ventilated subjects with severe hypoxemia, but the evidence for iEPO via high-flow nasal cannula (HFNC) is rare. Following approval by the institutional review board, this retrospective cohort study evaluated subjects who received iEPO via HFNC for more than 30 min to treat severe hypoxemia comorbid with pulmonary hypertension or right heart dysfunction between July 2015 and April 2018. A total of 11 subjects were enrolled in the study of whom 4 were male (36.4%), age 57.5 ± 22.1 years, and APACHE II score at ICU admission was 18.5 ± 5.7. Ten subjects had more than three chronic heart or lung comorbidities; seven of them used home oxygen. After inhaling epoprostenol, subjects' SpO₂/F_IO₂ ratio improved from 107.5 ± 26.3 to 125.5 ± 31.6 (p = 0.026) within 30-60 min. Five subjects (45.5%) had SpO₂/F_IO₂ improvement >20%, which was considered as a positive response. Heart rate, blood pressure, and respiratory rate were not significantly different. Seven subjects did not require intubation, and seven subjects were discharged home. This retrospective study demonstrated the feasibility of iEPO via HFNC in improving oxygenation. Careful titration of flow while evaluating subjects' response may help identify responders and avoid delaying other interventions. This study supports the need for a larger prospective randomized control trial to further evaluate the efficacy of iEPO via HFNC in improving outcomes.

Use of epoprostenol to treat severe pulmonary vasoconstriction induced by protamine in cardiac surgery

Since there were a few articles to report the treatment of severe pulmonary vasoconstriction induced by protamine in cardiac surgery, we described the use of epoprostenol to reverse this condition.A total of 5 cases of severe pulmonary vasoconstriction induced by protamine in cardiac surgery were reviewed. The demographic, clinical data and treatment process were obtained. All the patients were followed up.Severe pulmonary vasoconstriction was occurred 4 to 10 minutes after protamine infusion. The primary sign was sudden hypotension, the pulmonary artery pressure was increased gradually, the arterial oxygen partial pressure was decreased in all the patients. Epoprostenol was infused via pulmonary artery catheter at dosage of 20 to 40 ng/kg·min in all the patients, 2 patients were underwent re-cardiac pulmonary bypass assistance. The hemodynamic instability status lasted 40 to 65 minutes respectively. All the patients were recovered uneventfully.All physicians should alert to the incidence of severe pulmonary vasoconstriction induced by protamine in cardiac surgery. Use epoprostenol through pulmonary artery catheter could treat pulmonary artery vasoconstriction effectively and safely.

Inhaled Epoprostenol Through Noninvasive Routes of Ventilator Support Systems

BACKGROUND

The administration of inhaled epoprostenol (iEPO) through noninvasive routes of ventilator support systems has never been previously evaluated.

OBJECTIVE

Describe the use of iEPO when administered through noninvasive routes of ventilator support systems.

METHODS

Critically ill patients admitted to the intensive care unit who received iEPO through noninvasive routes were analyzed. Improvements in respiratory status and hemodynamic parameters were evaluated. Safety end points assessed included hypotension, rebound hypoxemia, significant bleeding, and thrombocytopenia.

RESULTS

A total of 36 patients received iEPO through noninvasive routes: high-flow oxygen therapy through nasal cannula, n = 29 (81%) and noninvasive positive-pressure ventilation, n = 7 (19%). Sixteen patients had improvement in their respiratory status: mean decrease in fraction of inspired oxygen (FiO₂), 20% ± 13%; mean increase in partial pressure of arterial oxygen to FiO₂ (PaO₂/FiO₂) ratio, 60 ± 50 mm Hg; and mean decrease in HFNC oxygen flow rate, 6 ± 3 liters per minute (LPM). Eight patients had declines in their respiratory status (mean increase in FiO₂, 30% ± 20%; mean decrease in PaO₂/FiO₂ ratio, 38 ± 20 mm Hg; and mean increase in HFNC oxygen flow rate, 15 ± 10 LPM), and 12 patients had no change in their respiratory status. Conclusion and Relevance: This represents the first evaluation of the administration of iEPO through noninvasive routes of ventilator support systems and demonstrates that in critically ill patients, iEPO could be administered through a noninvasive route. Further evaluation is needed to determine the extent of benefit with this route of administration.

Occult catheter rupture causing episodic symptoms in a patient treated with epoprostenol

Infection, thrombosis, and catheter dislodgment are well-recognized potential complications of chronic intravenous prostanoid therapy for pulmonary arterial hypertension. As long-term outcomes of pulmonary hypertension patients improve, novel adverse events are likely to arise. We describe the sudden development of unexplained hypotension and lightheadedness in a patient receiving intravenous epoprostenol for several years, ultimately determined to be due to an unusual catheter complication, not previously described in this population.

Adjuvants to Mechanical Ventilation for Acute Respiratory Failure. Adoption, De-adoption, and Factors Associated with Selection

RATIONALE

Adoption and de-adoption of adjuvant strategies to mechanical ventilation for acute respiratory failure (ARF), and factors associated with their selection, have not been extensively evaluated.

OBJECTIVES

To evaluate change in use of adjuvants to mechanical ventilation for ARF (2008-2013), the impact of landmark publications on adoption and de-adoption, and factors associated with use.

METHODS

Changes in use of four adjuvants for ARF from 2008 to 2013, the impact of landmark publications on use, and factors associated with use were evaluated with the Premier Database. Extracorporeal membrane oxygenation (ECMO), inhaled nitric oxide, inhaled epoprostenol, and continuous neuromuscular blockading agents (cNMBAs) in adult mechanically ventilated patients were identified on the basis of International Classification of Diseases, Ninth Revision, Clinical Modification codes and billing data.

MEASUREMENTS AND MAIN RESULTS

Among 514,913 patients with ARF, 11,567 (2.3%) were treated with at least one adjuvant. cNMBAs were the most frequently used adjuvants (n = 10,073, 2.1% in capable hospitals), followed by inhaled pulmonary vasodilators (n = 1,878, 1.0% in capable hospitals; 58% nitric oxide), and ECMO (n = 195, 0.2% in capable hospitals). There was an increase in ECMO and inhaled epoprostenol over time but no change in nitric oxide or cNMBAs. Segmented regression analysis was used to evaluate whether clinical practice was in accordance with emerging evidence from landmark studies. Using the relevant landmark publication dates, these analyses did not reveal any change in use over time after publication with the exception of inhaled epoprostenol-for which rates of growth decreased over time, possibly in response to the evidence. There was a significant amount of variability in patient and hospital factors associated with use with between adjuvants.

CONCLUSIONS

Between 2008 and 2013, there was an increase in use of ECMO and inhaled epoprostenol, and no change in use of inhaled nitric oxide or continuous intravenous infusion of a neuromuscular blocking agent. There was considerable variability in patient and hospital factors associated with use across different adjuvants.

Successful Pulmonary Artery Embolization for the Management of Hemoptysis in a Patient with Eisenmenger Syndrome Caused by Patent Ductus Arteriosus

The patient was a 19-year-old woman who was diagnosed with patent ductus arteriosus complicating Eisenmenger syndrome at a previous medical institution. She was referred to our hospital and arranged for lung transplantation. She developed hemoptysis after the introduction of i.v. epoprostenol, which was administered as a bridging treatment while the patient awaited lung transplantation. She continued to suffer from recurrent hemoptysis, even after switching from i.v. epoprostenol to i.v. treprostinil. Angiography of the systemic and pulmonary arteries revealed the vessel responsible for the recurrent hemoptysis and pulmonary artery embolization was successfully performed. It is essential to identify the culprit vessel and physicians must not hesitate in performing embolization when patients develop lethal hemoptysis.

A case report

A change of oxygenator during cardiopulmonary bypass is a technically high-risk procedure with potential for a serious adverse event for the patient. This case report describes a case of increased pressure drop and pre-oxygenator blood pressure during cardiopulmonary bypass successfully treated with pre-oxygenator-administered epoprostenol.

Microbial challenge test of a novel epoprostenol sodium formulation

AIM

The aim of the current study was to present a comprehensive display of antimicrobial activity of a novel epoprostenol sodium formulation with respect to seven different microorganisms, two levels of inoculation (102-103 colony forming units [CFU]/mL and 105-106 CFU/mL), two diluents (sterile water for injection [SWI] and sterile saline [sodium chloride 0.9%] for injection [SSI]), two concentrations (3,000 ng/mL and 15,000 ng/mL), and seven different storage time points at two temperatures (up to 10 days at 2°C-8°C and 20°C-25°C).

MATERIALS AND METHODS

Antimicrobial activity was evaluated for, 1) solutions at 3,000 ng/mL inoculated with 102-103 CFU/mL and 105-106 CFU/mL; and 2) solutions at 15,000 ng/mL inoculated with 102-103 CFU/mL and 105-106 CFU/mL. All solutions were stored for up to 10 days at 2°C-8°C and 20°C-25°C. Solutions were prepared by reconstitution and further dilution of an epoprostenol sodium formulation using SWI or SSI. Antimicrobial activity was measured after inoculation with seven species of bacteria, yeast, and mold.

RESULTS

For all solutions, after 10 days, no microbial growth with respect to initial inoculum was observed, with the exception of a few early time points when using SWI as diluent. Some microorganisms died off completely, whereas others remained stable overall or returned to initial levels. Prior to decreasing, some microorganisms displayed a slight initial increase, presumed to be caused by breakup of clusters. Storage temperature had a negligible influence on the results, whereas choice of diluent (SSI or SWI) impacted growth kinetics in that SSI had a greater antimicrobial effect than SWI.

CONCLUSION

Upon reconstitution and further dilution of the novel epoprostenol formulation to concentrations of 3,000 ng/mL and 15,000 ng/mL with SWI or SSI, the resulting solutions did not support growth of the tested microorganisms when stored at 2°C-8°C or 20°C-25°C for up to 10 days.

The Effect of Nebulizer Position on Aerosolized Epoprostenol Delivery in an Adult Lung Model

BACKGROUND

Aerosolized epoprostenol is an alternative for inhaled nitric oxide in the management of pulmonary arterial hypertension and possibly acute hypoxemia. Our objective was to determine differences in drug deposition based on different nebulizer positions in the ventilator circuit, using a vibrating mesh nebulizer.

METHODS

An 8.0-mm inner diameter endotracheal tube (ETT) was connected to a training test lung, compliance of 30 mL/cm H₂O, with a collecting filter placed at the ETT-test lung junction. A mechanical ventilator, heated wire circuit, and pass-over humidifier were utilized. A syringe pump continuously instilled a 15,000-ng/mL epoprostenol solution at 30, 50, and 70 ng/kg/min into the vibrating mesh nebulizer at all 4 positions. Tidal volumes (V_T) were set at 4, 6, and 8 mL/kg for a 70-kg patient with breathing frequencies of 25, 16, and 12 breaths/min, respectively. Epoprostenol was eluted from the filters (no. = 180) and analyzed with ultraviolet-visible spectrophotometry at 205 nm to estimate drug deposition.

RESULTS

Epoprostenol deposition increased significantly (P = .02) as the dosage increased from 30 ng/kg/min (median 4,520.0 ng, interquartile range [IQR] 2,285.0-6,712.2 ng) to 50 ng/kg/min (median 6,065.0 ng, IQR 3,220.0-13,002.5 ng) and 70 ng/kg/min (median 9,890.0 ng, IQR 6,270.0-16,140.0 ng). No significant difference was found between variations in ventilator settings. No difference in deposition was found between the humidifier inlet and outlet, but these positions resulted in greater deposition compared with the inspiratory limb and between the ETT and Y-piece.

CONCLUSIONS

The greatest amount of mean epoprostenol deposition resulted with the nebulizer placed at the humidifier inlet or outlet in a ventilator with bias flow.

Cardiovascular Consequences of Prostanoid I Receptor Deletion in Microsomal Prostaglandin E Synthase-1-Deficient Hyperlipidemic Mice

BACKGROUND

Inhibitors of cyclooxygenase-2 alleviate pain and reduce fever and inflammation by suppressing the biosynthesis of prostacyclin (PGI2) and prostaglandin E2. However, suppression of these prostaglandins, particularly PGI2, by cyclooxygenase-2 inhibition or deletion of its I prostanoid receptor also predisposes to accelerated atherogenesis and thrombosis in mice. By contrast, deletion of microsomal prostaglandin E synthase 1 (mPGES-1) confers analgesia, attenuates atherogenesis, and fails to accelerate thrombogenesis, while suppressing prostaglandin E2, but increasing biosynthesis of PGI2.

METHODS

To address the cardioprotective contribution of PGI2, we generated mice lacking the I prostanoid receptor together with mPges-1 on a hyperlipidemic background (low-density lipoprotein receptor knockouts).

RESULTS

mPges-1 depletion modestly increased thrombogenesis, but this response was markedly further augmented by coincident deletion of the I prostanoid receptor (n=10-18). By contrast, deletion of the I prostanoid receptor had no effect on the attenuation of atherogenesis by mPGES-1 deletion in the low-density lipoprotein receptor knockout mice (n=17-21).

CONCLUSIONS

Although suppression of prostaglandin E2 accounts for the protective effect of mPGES-1 deletion in atherosclerosis, augmentation of PGI2 is the dominant contributor to its favorable thrombogenic profile. The divergent effects on these prostaglandins suggest that inhibitors of mPGES-1 may be less likely to cause cardiovascular adverse effects than nonsteroidal anti-inflammatory drugs specific for inhibition of cyclooxygenase-2.

Early Postmenopausal Phase Is Associated With Reduced Prostacyclin-Induced Vasodilation That Is Reversed by Exercise Training: The Copenhagen Women Study

The postmenopausal phase is associated with an accelerated rate of rise in the prevalence of vascular dysfunction and hypertension; however, the mechanisms underlying these adverse vascular changes and whether exercise training can reverse the decline in vascular function remains unclear. We examined the function of the vascular prostanoid system in matched pre- and postmenopausal women before and after 12 weeks of exercise training. Twenty premenopausal and 16 early postmenopausal (3.1±0.5 [mean±SE] years after final menstrual period) women only separated by 4 (50±0 versus 54±1) years of age were included. Before the training period, the vasodilator response to intra-arterial infusion of either the prostacyclin analog epoprostenol or acetylcholine was lower (≈13%-41%; P<0.05) in the postmenopausal compared with the premenopausal women. Acetylcholine infusion induced a similar release of prostacyclin (6-keto prostaglandin F1a). To elucidate the role of vasoconstrictor prostanoids, acetylcholine infusion was combined with the cyclooxygenase inhibitor ketorolac and here the vascular response to acetylcholine was reduced to a similar extent in pre- and postmenopausal women. Exercise training increased (P<0.05) the vasodilator response to epoprostenol (≈100%-150%) and acetylcholine (≈100%-120%) infusion in the postmenopausal group. These findings demonstrate that the early postmenopausal phase is associated with a marked reduction in vascular function. Despite of a reduced sensitivity to prostacyclin, the overall balance between vasodilator and vasoconstrictor prostanoids does not seem to be altered. Exercise training can reverse the decline in vascular sensitivity to epoprostenol and acetylcholine, suggesting that beneficial vascular adaptations with exercise training are preserved in recent postmenopausal women.