Nebulized Epinephrine Improves Oxygenation During Extracorporeal Membrane Oxygenation in Sheep with Smoke Inhalation-Induced Acute Respiratory Distress Syndrome

Introduction: – Smoke inhalation injury induces airway edema, obstruction, and bronchospasm, leading to hypoxia and acute respiratory distress syndrome (ARDS). When ARDS is refractory to conventional therapy, veno-venous extracorporeal membrane oxygenation (VV ECMO) is used as a rescue strategy. We hypothesized that nebulized epinephrine improves oxygenation by alleviating airway dysfunction during VV ECMO support. Methods: – Twelve female Merino sheep were surgically instrumented and subjected to smoke inhalation injury. VV ECMO was initiated when the PaO₂/FiO₂ ratio dropped below 150 mmHg. The sheep were randomized to receive either saline nebulization (control group, n = 7) or epinephrine nebulization (treatment group, n = 5) every 4 hours. Extracorporeal membrane oxygenation (ECMO) blood flow was maintained at 60–80 mL/kg/min; the sheep remained conscious in cages after ECMO initiation. Cardiopulmonary variables, blood gases, and respiratory mechanics were monitored for 72 hours. Results: – Survival was significantly higher in the treatment group (P = 0.03). The PaO₂/FiO₂ ratio improved significantly in the treatment group at 30 and 36 hours compared with the control group (P < 0.05), with a positive correlation between oxygenation and time (correlation coefficient = 0.8, P < 0.01). The tracheal wet-to-dry weight ratio was lower in the treatment group (P < 0.05), indicating reduced airway edema. No significant systemic cardiovascular effects were observed. Conclusions: – This study demonstrates that nebulized epinephrine improved oxygenation, reduced airway edema, and enhanced survival in an ovine model of smoke inhalation-induced ARDS supported with VV ECMO. These findings suggest that epinephrine nebulization may provide a promising adjunctive therapy to improve outcomes and facilitate shorter ECMO duration in smoke inhalation–associated ARDS.