Blood transfusion-related change in circulating plasma-free hemoglobin levels and its impact on microvascular oxygenation: A prospective, observational study

Abstract

Background and Objectives: Transfusion of stored, packed red blood cells (PRBCs) is a common therapeutic intervention; however, development of hemolysis during storage might contributes to some negative consequences due to the release of free hemoglobin (fHb), a potent nitric oxide scavenger, which may impair vasodilation and microcirculatory perfusion after transfusion. We undertook this study to find out the change in fHb levels in recipients, whether this affects microvascular oxygenation posttransfusion. Methods: Eighty stable transfusion recipients were selected for this prospective observational study and were divided into three groups as per the age of blood transfused (14 days). Blood samples were collected to analyze the plasma levels of fHb in the bag. The patient's circulating plasma Hb (FHb) and pO2 by venous blood gas analysis were studied before and after 1 h of transfusion. Data were analyzed through paired t-test, ANOVA, and Pearson's correlation coefficient using the SPSS version 23. Results: Overall, there was a significant difference between the three groups in terms of change in plasma fHb (g/dL) from pretransfusion to the 1 h posttransfusion time points (P < 0.05). Significant increase in pO2 Levels was noticed from the pretransfusion to 1 h posttransfusion time points in bags <7 days old (t = −4.6, P < 0.001). Furthermore, a strong negative correlation was obtained between FHb and pO2 using Pearson's correlation coefficient (r = −0.738; P < 0.001). Conclusion: This study concludes that red blood cell transfusion can significantly increase posttransfusion plasma Hb levels depending upon the age of PRBC units and has an implication on microvascular oxygenation. However, the effect on the clinical outcome of the patient was not studied, and it would be worthwhile to investigate whether the age of the blood transfused affects the patient morbidity or mortality.

Keywords

• blood storage lesions
• fresh versus old packed red blood cell
• microcirculation
• nitric oxide
• plasma hemoglobin