Influence Of Inhaled Nitric Oxide On Stored Red Blood Cell autotransfusion In Overweight Volunteers With Endothelial Dysfunction: Preliminary Results

Abstract

IntroductionTransfusion of stored packed erythrocytes is associated with excessive intra and extravascular hemolysis. High plasma cell-free hemoglobin levels rapidly scavenge endogenous nitric oxide (NO) leading in many species to systemic and pulmonary vasoconstriction, and a pro-inflammatory, pro-thrombotic state. MethodsWe conducted a crossover randomized interventional study of autologous stored blood transfusion. We enrolled fourteen overweight adults (BMI 28 to 40 Kg/m2) who also had evidence of impaired endothelial function.Endothelial dysfunction was determined by a reduced Reactive Hyperemia Index following 5 minutes of forearm tourniquet ischemia (RHI<1.8).Over 8 months each volunteer returned to the blood bank on 3 occasions to donate a unit of blood. In a randomized scheme,autologous blood was leukoreduced and stored in AS-3, and re-infused after a) 3-days of storage (3-d), b) 40-days of storage (40-d), or c) 40-days of storage and breathing 80 parts per million (ppm) NO (40-d+NO).Venous blood was sampled before and at 10min, 1h, 2h, 4h and 24h after autotransfusion.Plasma hemoglobin measurement Plasma hemoglobin was measured with a QuantiChrom Hemoglobin Assay Kit (BioAssaySystems, Hayward, CA). These samples were collected using 16 G catheters avoiding negative aspirating pressures to minimize ex vivo hemolysis (1).Plasma NO consumption The ability of plasma hemoglobin to scavengeNO was measured with an NO consumption assay with a NO chemiluminescenceanalyzer (Sievers, Boulder, CO) (2) ResultsEleven volunteers completed the entire study. Volunteer characteristics at baseline were (mean ± SD): age: 41± 13 years; sex: 9 males, 5 females; BMI 33.2 ± 4.9 Kg/m2; reactive hyperemia index 1.59±0.18, and plasma levels of C-Reactive Protein 4.75 ±3.44 md/L.After autotransfusion the plasma hemoglobin and serum iron concentrations were increased from 1 to 4 hours after transfusing 40-days stored blood. No increase was detected after transfusing 3-days stored blood (p<0.01 value differs from b and c) (Figures 1a and 2). [Display omitted] [Display omitted] The plasma NO consumption assay showed an increased level in the 40-d group (p<0.05 value differs from both b and c) (Figure 1b). Plasma concentrations of potassium, lactate dehydrogenase, haptoglobin, cytokines, and systemic blood pressure did not differ between a, b and c and all remained within the normal range. ConclusionsTransfusion of autologous packed erythrocytes stored for 40 days in AS3 is associated with increased hemolysis and increased plasma NO consumption,the latter is prevented by breathing 80 ppm NO.