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

## TL;DR

This study explores whether measuring oxygen extraction can better guide blood transfusions in cancer patients with anemia compared to using hemoglobin levels alone.

## Contribution

The study introduces oxygen extraction ratio (O2ER) as a physiological transfusion trigger in stable cancer patients, showing it better predicts transfusion benefits than hemoglobin levels.

## Key findings

- Patients with higher baseline O2ER showed greater improvements in oxygenation parameters after transfusion.
- Hemoglobin levels alone did not correlate with most physiological responses to transfusion.
- O2ER and other physiological markers offer a more individualized transfusion strategy.

## Abstract

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).

The online version contains supplementary material available at 10.1038/s41598-025-32630-6.