ASSESSMENT OF OXYGEN EXTRACTION, LACTATE LEVELS, CENTRAL VENOUS OXYGEN PARTIAL PRESSURE, AND VENOUS-ARTERIAL CARBON DIOXIDE DIFFERENCE IN ONCOLOGICAL PATIENTS DURING BLOOD TRANSFUSION

Abstract

Relevance: Anemia is a common hematologic syndrome, particularly among oncological patients, where its prevalence ranges from 40% to 90%, depending on treatment. Blood transfusion remains the primary method of anemia correction; however, hemoglo-bin (Hb) level remains the sole criterion for transfusion decisions despite not always accurately reflecting tissue oxygen demand. Consequently, alternative physiological transfusion triggers are being actively studied, including oxygen extraction ratio (O2ER), central venous oxygen partial pressure (PvO2), lactate (Lac), and venous-to-arterial carbon dioxide difference (ΔCO2).
The study aimed to assess the effect of blood transfusion on O2ER, PvO2, Lac, and ΔCO2 in oncological patients with anemia and determine their potential as physiological transfusion triggers.
Methods: A prospective observational study included 107 oncological patients with anemia requiring blood transfusion. Arterial
and central venous blood samples were collected before and 1 hour after transfusion to assess Hb, PvO2, Lac, O2ER, and ΔCO2. Statistical
analysis was performed using the Wilcoxon test and Spearman’s rank correlation coefficient.
Results: After blood transfusion, a statistically significant improvement in key parameters was observed:
• O2ER decreased from 35.4% (31.8; 41.9) to 29.3% (26.0; 33.4) (p<0.001);
• PvO2 increased from 34.8 (32.7; 38) to 36 (34; 39) mmHg (p=0.005);
• ΔCO2 decreased from 7 (5.2; 8.6) to 6.3 (4.9; 7.7) mmHg (p=0.004);
• Lac changed slightly from 1.1 (0.9; 1.7) to 1.0 (0.6; 1.55) mmol/L (p=0.005), remaining within the normal range.
Correlation analysis revealed that PvO2, ΔCO2, and Lac were significantly associated with baseline O2ER levels but did not cor-relate
with baseline Hb levels (p>0.05). This confirms that the Hb level does not accurately reflect oxygen delivery needs, whereas alternative
physiological markers may serve as more reliable transfusion decision criteria.
Conclusion: Changes in O2ER, PvO2, and ΔCO2 after blood transfusion suggest their potential use as physiological transfusion triggers. Unlike the Hb level, these parameters more accurately reflect oxygen delivery changes. Although lactate correlated with baseline Hb, it cannot serve as a reliable transfusion trigger in this patient population, as its levels remained within the normal range. Further research is needed to define threshold values for physiological transfusion triggers and evaluate their impact on clinical outcomes.