Does the Age of Packed Red Blood Cells, Donor Sex or Sex Mismatch Affect the Sublingual Microcirculation in Critically Ill Intensive Care Unit Patients? — A Secondary Interpretation of a Retrospective Analysis

Abstract BackgroundIn vitro studies have thoroughly documented the impact of storage lesions in packed red blood cells (pRBC) on erythrocyte oxygen carrying capacity due to older age of blood products. While studies have examined the effect of pRBC age on patient outcome, only few data exist on the microcirculation, their primary site of action.MethodsIn this secondary analysis, we examined the relationship between the age of pRBC and changes of microcirculatory flow (MCF) in 54 patients. Data from the Basel Bedside assessment Microcirculation Transfusion Limit study (Ba2MiTraL), investigating the effects of one pRBC on the sublingual MCF provided the basis of this study. ResultsMean change from pre-to post-transfusion proportion of perfused vessels (∆PPV) was +8.8% (IQR: -0.5 – 22.5), 5.5% (IQR: 0.1–10.1), and +4.7% (IQR: -2.1 – 6.5) after transfusion of fresh (≤ 14 days old), medium (15 to 34 days old), and old (≥ 35 days old) pRBC, respectively. Values for the microcirculatory flow index (MFI) were +0.22 (IQR: -0.1 – 0.6), +0.22 (IQR: 0.0 – 0.3), and +0.06 (IQR: -0.1 – 0.3) for the fresh, medium, and old pRBC age groups, respectively.Lower ∆PPV and transfusion of older blood were correlated with a higher Sequential Organ Failure Assessment (SOFA) score of patients upon admission to the intensive care unit (ICU) (p=0.01). However, regression models showed no overall significant correlation between pRBC age and ∆PPV (p=0.2). No correlation between donor’s sex or a mismatch between donor and recipient sex was found.ConclusionWe detected no significant correlation between age of pRBC and change in MCF between pre- and post-transfusion among all investigated patients. However, in patients with a higher SOFA score upon ICU admission, there might be a negative effect on the proportion of perfused microcirculatory vessels after transfusion of older blood.