Evaluation of Response Rate to Fixeddose Inhaled Epoprostenol

ABSTRACT

INTRODUCTION: Inhaled epoprostenol (iEPO) is adjunctive therapy for acute respiratory distress syndrome (ARDS) in addition to prone positioning and neuromuscular blockade. Previous studies report mixed improvement in PaO2/FiO2 (PF) ratios using fixed-dose and weight-based protocols. The aim of this study was to evaluate patient response rate to fixed-dose iEPO via palladium vibrating mesh nebulizer and the rate of rebound hypoxemia following abrupt iEPO discontinuation without titration per local protocol. METHOD(S) Single-center, retrospective, descriptive study of adult patients admitted to an ICU at a Veterans Affairs hospital who received iEPO for ARDS between 5/23/14 and 4/1/21. Patients were included if they received iEPO 1500 mcg/75 mL (120 mcg load, then 160 mcg/hr continuous nebulization) for at least 12 hours. Patients receiving iEPO for an indication other than ARDS were excluded. Response was defined as an increase in PF >10% within 12 hours. Safety was assessed via decline in PF after iEPO stop. RESULT(S) Of the 29 patients included, 72.4% had a baseline PF < 100 mmHg (median 76.8, range 38-250). Diagnosis included direct ARDS in 44.8% and COVID ARDS in 24.1%. Adjunctive therapies included paralytics (58.6%), corticosteroids (44.8%) and pronation (27.6%). Seventeen patients (58.6%) were responders with a median PF increase of 41.6% (range 11.6-322.1) at 3.8 hours (0.1-20.3) after iEPO initiation. iEPO was given for a median of 3 days (0.5-18.6) overall, and 3.4 days (0.5-8.7) in non-responders. The median best PF during iEPO was 140 mmHg (59.9-423.0) at 24 hours (1.1-299). Eight of 14 patients with an ABG drawn a median of 7.6 hours after iEPO cessation had a drop in PF. Other adverse outcomes following iEPO initiation included ICU mortality in 65.5% and new hypotension in 67%. CONCLUSION(S) In a small heterogenous cohort of patients with ARDS, fixed-dose iEPO had a modest response rate. A majority of patients who survived to iEPO cessation without down-titration experienced a drop in PF. Protocol revision to include guidance on therapeutic response and down-titration may be warranted.