Inhaled Prostacyclins for Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

Studies evaluating inhaled prostacyclins for the management of acute respiratory distress syndrome (ARDS) have produced inconsistent results regarding their effect on oxygenation. The purpose of this systematic review and meta-analysis was to evaluate the change in the Pao₂/Fio₂ ratio after administration of an inhaled prostacyclin in patients with ARDS.

DATA SOURCES

We searched Ovid Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, Cochrane, Scopus, and Web of Science.

STUDY SELECTION

We included abstracts and trials evaluating administration of inhaled prostacyclins in patients with ARDS.

DATA EXTRACTION

Change in the Pao₂/Fio₂ ratio, Pao₂, and mean pulmonary artery pressure (mPAP) were extracted from included studies. Evidence certainty and risk of bias were evaluated using Grading of Recommendations Assessment, Development, and Evaluation and the Cochrane Risk of Bias tool.

DATA SYNTHESIS

We included 23 studies (1,658 patients) from 6,339 abstracts identified by our search strategy. The use of inhaled prostacyclins improved oxygenation by increasing the Pao₂/Fio₂ ratio from baseline (mean difference [MD], 40.35; 95% CI, 26.14-54.56; p < 0.00001; I² = 95%; very low quality evidence). Of the eight studies to evaluate change in Pao₂, inhaled prostacyclins also increased Pao₂ from baseline (MD, 12.68; 95% CI, 2.89-22.48 mm Hg; p = 0.01; I² = 96%; very low quality evidence). Only three studies evaluated change in mPAP, but inhaled prostacyclins were found to improve mPAP from baseline (MD, -3.67; 95% CI, -5.04 to -2.31 mm Hg; p < 0.00001; I² = 68%; very low quality evidence).

CONCLUSIONS

In patients with ARDS, use of inhaled prostacyclins improves oxygenation and reduces pulmonary artery pressures. Overall data are limited and there was high risk of bias and heterogeneity among included studies. Future studies evaluating inhaled prostacyclins for ARDS should evaluate their role in ARDS subphenotypes, including cardiopulmonary ARDS.

Unexpected Interruptions in the Inhaled Epoprostenol Delivery System: Incidence of Adverse Sequelae and Therapeutic Consequences in Critically Ill Patients

OBJECTIVES

Inhaled epoprostenol is a continuously delivered selective pulmonary vasodilator that is used in patients with refractory hypoxemia, right heart failure, and postcardiac surgery pulmonary hypertension. Published data suggest that inhaled epoprostenol administration via vibrating mesh nebulizer systems may lead to unexpected interruptions in drug delivery. The frequency of these events is unknown. The objective of this study was to describe the incidence and clinical consequences of unexpected interruption in critically ill patients.

DESIGN

Retrospective review and analysis.

SETTING

Stanford University Hospital, a 605-bed tertiary care center.

PATIENTS

Patients receiving inhaled epoprostenol in 2019.

INTERVENTIONS

No interventions.

MEASUREMENTS AND MAIN RESULTS

Clinical indication, duration of inhaled epoprostenol delivery, mode of respiratory support, and documented unexpected interruption. In 2019, there were 493 administrations of inhaled epoprostenol in 433 unique patients. Primary indications for inhaled epoprostenol were right heart dysfunction (n = 394; 79.9%) and hypoxemia (n = 92; 18.7%). Unexpected delivery interruptions occurred in 31 administrations (6.3%). Median duration of therapy prior to unexpected interruption was 2 days (interquartile range, 2-5 d). Respiratory support at the time of unexpected interruption was mechanical ventilation (61.3%), high-flow nasal cannula (35.5%), and noninvasive positive pressure ventilation (3.2%). Adverse sequelae of unexpected interruption included elevated pulmonary artery pressures (n = 12), systemic hypotension (n = 8), hypoxemia (n = 8), elevated central venous pressure (n = 4), and cardiac arrest (n = 1). Therapeutic interventions following unexpected interruption included initiation of inhaled nitric oxide (n = 21), increase in vasoactive medication (n = 2), and increase in respiratory support (n = 2). Most of the adverse events were Common Terminology Criteria for Adverse Events grade 3 and 4 (93.5%).

CONCLUSIONS

A retrospective review of patients receiving inhaled epoprostenol via vibrating mesh nebulizer in 2019 revealed interruptions in 6.3% of administrations with most of these interruptions requiring therapeutic intervention. The true incidence of unexpected interruption and subsequent rate of unexpected interruption's requiring intervention is unknown due to the reliance on unexpected interruption identification and subsequent documentation in the electronic medical record. Sudden interruption in inhaled epoprostenol delivery can result in severe cardiopulmonary compromise, and on rare occasion, death.

In-vitro and in-vivo comparisons of high versus low concentrations of inhaled epoprostenol to adult intubated patients

BACKGROUND

Inhaled epoprostenol (iEPO) has been shown to reduce pulmonary artery pressure and improve oxygenation. iEPO is mainly delivered via a syringe pump with feed tubing connected to a vibrating mesh nebulizer with high or low formulation concentration delivery.

METHODS

An in vitro study and a two-period retrospective case-control study were implemented. The in vitro study compared iEPO delivery via invasive ventilation at low concentrations of 7.5, and 15 mcg/mL and high concentration at 30 mcg/mL, to deliver the ordered dose of 30 and 50 ng/kg/min for three clinical scenarios with predicted body weight of 50, 70 and 90 kg. While in the clinical study, adult patients receiving iEPO via invasive ventilation to treat refractory hypoxemia, pulmonary hypertension, or right ventricular failure were included. 80 patients received low concentration iEPO at multiple concentrations (2.5, 7.5, and 15 mcg/mL, depending on the ordered dose) from 2015 to 2017, while 84 patients received high concentration iEPO at 30 mcg/mL from 2018 to 2019.

RESULTS

In the in vitro study, there were no significant differences in aerosol deposition between high vs low concentrations of iEPO at a dose of 50 ng/kg/min. In the clinical study, age, gender, ethnicity, and indications for iEPO were similar between high and low concentration groups. After 30-120 min of iEPO administration, both delivery strategies significantly improved oxygenation in hypoxemic patients and reduced mean pulmonary arterial pressure (mPAP) for patients with pulmonary hypertension. However, no significant differences of the incremental changes were found between two delivery groups. Compared to low concentration, high concentration delivery group had better adherence to the iEPO weaning protocol (96% vs 71%, p < 0.001), fewer iEPO syringes utilized per patient (5 [3, 10] vs 12 [6, 22], p = 0.001), and shorter duration of invasive ventilation (6 [3, 12] vs 9 [5, 18] days, p = 0.028). Intensive care unit length of stay and mortality were similar between two groups.

CONCLUSION

Compared to low concentration delivery of iEPO, high concentration iEPO via a vibrating mesh nebulizer maintained clinical benefits and increased clinician compliance with an iEPO weaning protocol, required less medication preparation time, and shortened duration of invasive ventilation.

Comparison of Fixed-Dose Inhaled Epoprostenol and Inhaled Nitric Oxide for Acute Respiratory Distress Syndrome in Critically Ill Adults

PURPOSE

Several reports have demonstrated similar effects on oxygenation between inhaled epoprostenol (iEPO) compared to inhaled nitric oxide (iNO) for acute respiratory distress syndrome (ARDS). Previous studies directly comparing oxygenation and clinical outcomes between iEPO and iNO exclusively in an adult ARDS patient population utilized a weight-based dosing strategy. The purpose of this study was to compare the clinical and economic impact between iNO and fixed-dosed iEPO for ARDS in adult intensive care unit (ICU) patients.

METHODS

This retrospective cohort study was conducted at a major academic medical center between January 1, 2014, and October 31, 2018. Patients ≥18 years of age with moderate-to-severe ARDS were included. The primary end point was to compare the mean change in partial arterial oxygen pressure to fraction of inspired oxygen (Pao ₂: Fio ₂) at 4 hours from baseline between iEPO and iNO. Other secondary aims were total acquisition drug costs, in-hospital mortality, ICU and hospital length of stay, and duration of mechanical ventilation.

RESULTS

A total of 239 patients were included with 139 (58.2%) and 100 (41.8%) in the iEPO and iNO groups, respectively. The mean change in Pao ₂: Fio ₂ at 4 hours from baseline in the iEPO and iNO groups were 31.4 ± 54.6 and 32.4 ± 42.7 mm Hg, respectively (P = .88). The responder rate at 4 hours was similar between iEPO and iNO groups (64.7% and 66.0%, respectively, P = .84). Clinical outcomes including mortality, overall hospital and ICU length of stay, and mechanical ventilation duration were similar between iEPO and iNO groups. Estimated annual cost-savings realized with iEPO was USD1 074 433.

CONCLUSION

Fixed-dose iEPO was comparable to iNO in patients with moderate-to-severe ARDS for oxygenation and ventilation parameters as well as clinical outcomes. Significant cost-savings were realized with iEPO use.

Effectiveness, Safety, and Economic Comparison of Inhaled Epoprostenol Brands, Flolan and Veletri, in Acute Respiratory Distress Syndrome

Background: No previous studies exist examining 2 inhaled epoprostenol formulations in an acute respiratory distress syndrome (ARDS) patient population. Objective: The study aim was to evaluate a formulary conversion from inhaled Flolan to Veletri to determine the impact on effectiveness, safety, and cost in patients with ARDS. Methods: This was a single-center, retrospective, matched cohort observational study at a tertiary care academic medical center. Patients included were mechanically ventilated, adult patients with ARDS receiving inhaled Flolan or Veletri for ≥1 hour in the intensive care unit. Results: A total of 132 patients were included in the matched cohort. There was no difference detected in change in partial pressure of arterial O₂/fraction of inspired O₂ (PaO₂/FiO₂) ratio after 1 hour of therapy between the inhaled Flolan and Veletri groups (27.2 ± 46.2 vs 30 ± 68 mm Hg, P = 0.78). Significant differences in secondary outcomes included incidence of hypotension (83% vs 95.5%, P = 0.04) and thrombocytopenia (9.1% vs 29.5%, P < 0.01) in the inhaled Flolan and Veletri groups, respectively, with no difference in cost per duration of therapy (P = 0.29). Conclusions and Relevance: There was no difference in the change in PaO₂/FiO₂ ratio after 1 hour of therapy between inhaled Flolan and Veletri in an ARDS patient population. The formulary conversion from inhaled Flolan to Veletri was likely justified.

Management of Pulmonary Arterial Hypertension in the ICU

Patients with pulmonary arterial hypertension (PAH) who are admitted to the intensive care unit (ICU) pose a challenge to the multidisciplinary health-care team due to the complexity of the pathophysiology of their disease state and the medication considerations that must be made to appropriately manage them. PAH is a progressive disease with the majority of patients ultimately dying as a result of right ventricular (RV) failure. During an acute decompensation, patients must be appropriately managed to optimize volume status, RV function, cardiac output, and systemic perfusion, while treating the underlying cause of the exacerbation. During times of critical illness, the ability to administer medications approved for use in PAH can be impacted by end-organ damage, hemodynamic instability, new drug interactions, or available dosage forms. Balancing the multimodal treatment approach needed to manage an acute exacerbation and the pharmacokinetic and administration concerns impacting baseline PAH therapy as a result of critical illness requires an expert multiprofessional PAH team. The purpose of this review is to evaluate specific management considerations for critically ill patients with PAH in the ICU.