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 PaO 2 /FiO 2 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 PaO 2 /FiO 2 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.