REDOX-AHF: Less Oxygen May Be More for Hospitalized Acute HF Patients

Why It Matters

Oxygen is administered to roughly three‑quarters of acute HF admissions; refining targets could improve decongestion, shorten stays, and reduce iatrogenic hyperoxia without compromising safety.

Key Takeaways

• Restrictive oxygen (90% SpO₂) cut lung fluid 2.4% more than liberal
• No increase in dyspnea or serious adverse events with lower oxygen targets
• 30‑day hospital‑free days higher (23 vs 21) under restrictive strategy
• Current guidelines lack upper SpO₂ limit; trial challenges liberal oxygen use

Pulse Analysis

Oxygen therapy has been a cornerstone of acute heart‑failure management for decades, yet the evidence base for optimal saturation targets remains thin. European guidelines recommend supplemental oxygen only when SpO₂ falls below 90% or PaO₂ under 60 mm Hg, but they stop short of defining an upper ceiling. Clinicians often default to liberal supplementation, aiming for saturations in the mid‑90s, despite physiological data showing that hyperoxia can cause pulmonary vasodilation and coronary vasoconstriction—effects that may worsen cardiac performance in a failing heart.

The REDOX‑AHF study, presented at ESC Heart Failure 2026, provides the first blinded, randomized comparison of restrictive versus liberal oxygenation in acute HF. Over 135 patients (average age 78, 52% female) were assigned to a target SpO₂ of 90% or 96% using an automated delivery device. The primary endpoint—change in lung‑fluid content measured by remote dielectric sensing—favored the restrictive arm by 2.4 % after 24 hours, a statistically significant improvement. Secondary analyses revealed more hospital‑free days at 30 days (median 23 vs 21) and a non‑significant trend toward lower mortality, while patient‑reported dyspnea and adverse‑event rates remained comparable across groups.

These results have immediate practice implications. By avoiding unnecessary high‑flow oxygen, hospitals could reduce equipment use, lower costs, and potentially accelerate decongestion, shortening length of stay. The trial also underscores a gap in current guidelines, which do not set an upper SpO₂ limit. Incorporating a restrictive target into future guideline updates could standardize care and prompt further large‑scale trials to confirm mortality benefits. For clinicians, the takeaway is clear: aim for the lowest safe saturation—typically around 90%—instead of defaulting to liberal oxygenation in acute heart‑failure patients.