Evaluation of alternative transfusion triggers in hemodynamically stable, non-ventilated cancer patients: a prospective observational study

Anemia is highly prevalent among oncological patients and is often managed with red blood cell transfusions. Current guidelines predominantly rely on hemoglobin levels to guide transfusion, but hemoglobin alone may not accurately reflect oxygen delivery. Physiological triggers, particularly the oxygen extraction ratio (O₂ER), could provide a more individualized transfusion strategy. This prospective, single-center, observational study included 107 clinically stable adult oncology patients at the Kazakh Institute of Oncology and Radiology. All patients required red blood cell transfusion based on a restrictive trigger (Hb 70 g/L). Patients were stratified into two groups according to their baseline O₂ER (≤ 35.4% or > 35.4%). The primary outcome was the change in O₂ER before and one hour after transfusion. We also measured changes in central venous oxygen saturation (ScvO₂), central venous oxygen partial pressure (PvO₂), arteriovenous oxygen difference (A-V O₂diff), lactate, and veno-arterial carbon dioxide difference (ΔCO₂). Patients with higher baseline oxygen extraction ratio (O₂ER > 35.4%) demonstrated more pronounced improvements in oxygenation parameters-including O₂ER, ScvO₂, PvO₂, A‑V O₂ diff, and ΔCO₂-following transfusion, compared to patients with O₂ER ≤ 35.4%. Although baseline hemoglobin levels and post-transfusion increases in hemoglobin were similar between groups, significant differences were observed across all physiological markers of oxygen transport. Correlation analyses showed significant associations between baseline O₂ER and changes in PvO₂, ScvO₂, A‑V O₂ diff, ΔCO₂, and lactate. In contrast, baseline hemoglobin demonstrated no significant correlations with most physiological response parameters, except for a moderate but statistically significant correlation with the change in blood lactate levels. Lactate levels remained within normal limits in the majority of patients, indicating that critical oxygen delivery thresholds were not reached. In stable cancer patients with anemia, hemoglobin levels alone may not adequately capture oxygen delivery status. The oxygen extraction ratio and other physiological triggers offer valuable insights into which patients may benefit most from transfusion. Our findings support a more individualized transfusion strategy, though larger randomized controlled trials are warranted to confirm the safety and efficacy of physiological triggers in broader patient populations.Trial Registration The study protocol was retrospectively registered on ClinicalTrials.gov (NCT06952361, Initial Release 04/23/2025).