PaO₂/FiO₂ Ratio As an Exploratory Indicator of Oxygenation Changes in Acute Decompensated Heart Failure Treated with...

Pulmonary congestion leading to dyspnea is the main cause of hospitalization in patients with acute decompensated heart failure (ADHF). Intravenous tolvaptan (TLV) is an option for acute decongestion, but its effects on pulmonary congestion remain unclear, due to limited objective tools. The arterial oxygen partial pressure to inspired oxygen fraction (PaO₂/FiO₂ [P/F]) ratio is a practical index of oxygenation and may serve as an exploratory indicator of oxygenation changes in this setting. This exploratory study evaluated whether adding intravenous TLV to furosemide improves the 24-hour P/F ratio and factors associated with improved oxygenation.

We retrospectively analyzed adults hospitalized for ADHF between January 2022 and December 2023. Patients receiving TLV plus furosemide (TLV+F) were compared with those receiving furosemide (F alone). The primary endpoint was the 24-hour P/F ratio; secondary endpoints were urine output and safety (serum sodium, potassium, creatinine, and hemodynamics). Logistic regression identified factors associated with improved oxygenation. Subgroup analyses were by left ventricular ejection fraction (< 40% vs ≥ 40%).

Among 120 patients (TLV+F n = 48; F alone n = 72), the TLV+F group achieved a higher 24-hour P/F ratio (340 ± 89 vs 281 ± 87; P < 0.001) and greater urine output, both in absolute terms (3925 ± 1890 vs 3097 ± 1181 mL; P = 0.004) and when indexed to body weight (63.3 ± 24.3 vs 52.3 ± 21.1 mL/kg; P = 0.01). Serum sodium level rose modestly , with no apparent short-term renal or hemodynamic differences. TLV use independently predicted improved oxygenation. In subgroup analyses by left ventricular ejection fraction, no significant interaction was observed (P = 0.38).

In ADHF, use of adjunctive intravenous TLV was associated with improved early oxygenation and diuresis without an apparent increase in short-term adverse events. These exploratory findings suggest that intravenous TLV may be a useful component of acute decongestive therapy, warranting prospective validation.