No abstract

This narrative review critically evaluates the evidence for risk of anemia and red blood cell (RBC) transfusion. For this purpose, it assesses large prospective randomized-controlled trials (RCTs) in medical, surgical, and critical care patient populations in which the impact of specific hemoglobin transfusion thresholds are compared. In these trials, the risks of anemia relative to those of RBC transfusion are assessed. The results of published systematic reviews and meta-analyses are also discussed.Lastly, recommendations for patient blood management and treatment of anemia are explored. The main conclusion of this review emphasizes that the decision to transfuse RBCs is complex and depends on the interaction between multiple factors including the balance between the risk of anemia and the risk of RBC transfusion, existing patient comorbidities, and medical and surgical exposures. The transfusion thresholds recommended by current

PurposeThe kidney plays a central physiologic role as an oxygen sensor. Nevertheless, the direct mechanism by which this occurs is incompletely understood. We measured renal microvascular partial pressure of oxygen (P k O 2 ) to determine the impact of clinically relevant conditions that acutely change P k O 2 including hyperoxia and hemodilution.Methods We utilized two-wavelength excitation (red and blue spectrum) of the intravascular phosphorescent oxygen sensitive probe Oxyphor PdG4 to measure renal tissue PO 2 in anesthetized rats (2% isoflurane, n = 6) under two conditions of altered arterial blood oxygen content (C a O 2 ): 1) hyperoxia (fractional inspired oxygen 21%, 30%, and 50%) and 2) acute hemodilutional anemia (baseline, 25% and 50% acute hemodilution). The mean arterial blood pressure (MAP), rectal temperature, arterial blood gases (ABGs), and chemistry (radiometer) were measured under each condition. Blue and red light enabled measurement of Kyle Chin and Melina P. Cazorla-Bak contributed equally to this manuscript.