Modulation of red blood cell oxygen affinity with a novel allosteric modifier of hemoglobin is additive to the Bohr effect.

PURPOSE: The Bohr effect describes hemoglobin's affinity for oxygen dependent on solution pH. Within pH range 6.0-8.5, hemoglobin's oxygen affinity decreases with decreasing pH. This results in increased oxygen delivery to metabolically active, acidic tissues and improved oxygen uptake in basic regions including lung tissue. Myo-Inositol tripyrophosphate (ITPP) translocates the erythrocyte membrane and allosterically modifies hemoglobin (Hb). We tested the hypothesis that ITPP does not abrogate the Bohr effect. METHODS: Experiments were conducted to determine the effect of increasing concentrations of ITPP on P50 with varying pH. We incubated 10 mL red blood cells at 37 °C for 1 h with ITPP concentrations from 0 to 240 mM. The Clark oxygen electrode (Hemox-Analyzer; TCS Scientific, New Hope, PA) determined oxygen affinity of each sample, in triplicate, using buffers pH 6.8, 7.4, and 7.6. A mixed linear regression model with fixed effects for ITPP concentration and pH was used. RESULTS: Increasing ITPP concentration and decreasing pH increased P50 (p < 0.0001 for ITPP concentration, p < 0.0001 for pH). ITPP modulated increased P50 in normal pH (7.4) and acidic condition pH (6.8); with no effect at alkaline pH (7.6). CONCLUSION: The Bohr effect is conserved, with ITPP augmenting the decreased oxygen affinity seen with tissue acidosis, while not affecting oxygen affinity in conditions similar to a pulmonary microenvironment.

Global sources of cryoprecipitate demonstrate variability in coagulant factor levels and functional hemostasis.

Cryoprecipitate (cryo) is a plasma-derived blood product utilized during trauma resuscitation, surgery, and other major bleeding. Although local quality control metrics exist, inherent donor variability, and processing may confer differences in hemostatic effect between sources. The purposes of this study were to quantify procoagulant content in three global sources of cryo and evaluate their functional hemostatic effect. In this Institutional Review Board exempt study, 24 units of group A cryo from three different sources, American Red Cross single donor and pooled donor, Australian Red Cross single donor, Southwestern United States single donor, and Southwest pooled donor, were evaluated. Procoagulant factors were quantified from each source using ELISA and automated clot-based assays. Functional hemostasis was evaluated using rotational Thromboelastometry (ROTEM). Microparticles isolated from cryo units were enumerated and evaluated for cellular origin by flow cytometry, as well as their capacity to support thrombin generation. Southwestern United States single donor units demonstrated highest levels of fibrinogen, fibronectin, factor VIII, and von Willebrand factor in the selected units. In the coagulopathy model, successive doses from all cryo units were significantly correlated to decreasing coagulation time (P = 0.0100), and increasing maximum clot firmness (P = 0.0002) and alpha angle (P = 0.0009). Southwest pooled donor demonstrated significantly shorter coagulation time at all three doses (P = 0.02) than other sources. Microparticles support prothrombinase activity and thrombin generation. In this study of global cryo sources, procoagulant activity and in-vitro clot formation varied by source. This could be explained by variance in production and storage protocols. Further study is warranted to assess functional variance in cryo to optimize and standardize the use of cryo products.

The effect of pathogen inactivation on cryoprecipitate: a functional and quantitative evaluation.

BACKGROUND: As a pooled donor blood product, cryoprecipitate (cryo) carries risks of pathogen transmission. Pathogen inactivation (PI) improves the safety of cryoprecipitate, but its effects on haemostatic properties remain unclear. This study investigated protein expression in samples of pathogen inactivated cryoprecipitate (PI-cryo) using non-targeted quantitative proteomics and in vitro haemostatic capacity of PI-cryo. MATERIALS AND METHODS: Whole blood (WB)- and apheresis (APH)-derived plasma was subject to PI with INTERCEPT® Blood System (Cerus Corporation, Concord, CA, USA) and cryo was prepared from treated plasma. Protein levels in PI-cryo and paired controls were quantified using liquid chromatography-tandem mass spectrometry. Functional haemostatic properties of PI-cryo were assessed using a microparticle (MP) prothrombinase assay, thrombin generation assay, and an in vitro coagulopathy model subjected to thromboelastometry. RESULTS: Over 300 proteins were quantified across paired PI-cryo and controls. PI did not alter the expression of coagulation factors, but levels of platelet-derived proteins and platelet-derived MPs were markedly lower in the WB PI-cryo group. Compared to controls, WB (but not APH) cryo samples demonstrated significantly lower MP prothrombinase activity, prolonged clotting time, and lower clot firmness on thromboelastometry after PI. However, PI did not affect overall thrombin generation variables in either group. DISCUSSION: Data from this study suggest that PI via INTERCEPT® Blood System does not significantly impact the coagulation factor content or function of cryo but reduces the higher MP content in WB-derived cryo. PI-cryo products may confer benefits in reducing pathogen transmission without affecting haemostatic function, but further in vivo assessment is warranted.

Rejuvenation solution as an adjunct cold storage solution maintains physiological haemoglobin oxygen affinity during early-storage period of red blood cells.

BACKGROUND: Red blood cell (RBC) units accumulate morphologic and metabolic lesions during storage before transfusion. Pyruvate-inosine-phosphate-adenine (PIPA) solutions (Rejuvesol, Biomet, Warsaw, IN) can be incubated with RBC units to mitigate storage lesions. This study proposes a PIPA treatment process, termed cold 'rejuvenation', using Rejuvesol as an adjunct additive solution, to prevent biomechanical storage lesions while avoiding the 1 h PIPA incubation required with standard PIPA treatment. We compared the efficacy of cold to standard 'rejuvenation' in improving metabolic lesions that occur during cold storage of RBCs, without altering function. METHODS: Twelve leucoreduced, A-positive RBC units were obtained. Each unit was aliquoted into either control (standard storage), washed (W), standard rejuvenation (SR) or cold rejuvenation (CR) groups, the latter two requiring washing. A volume-adjusted dose of Rejuvesol was instilled into the CR group upon receipt (Day 3). After 15 days of storage, p50, RBC deformability, in-bag haemolysis and mechanical fragility were analysed. 'Any treatment' is defined as W, SR and CR, with comparisons in reference to control. RESULTS: Higher p50s were seen in rejuvenated groups (>30 mmHg vs. <19 mmHg; P < 0·0001). Any treatment significantly increased elongation index (P = 0·034) but did not significantly increase in-bag haemolysis (P = 0·062). Mechanical fragility was not significantly different between groups (P = 0·055) at baseline, but the control (CTL) group was more fragile after 2 h in a cardiac bypass simulation than any treatment (P < 0·0001). CONCLUSIONS: This study demonstrates that rejuvenation (standard or cold) prevents the leftward p50 shift of storage lesions without detrimental effect on RBC deformity, in-bag haemolysis or mechanical fragility.

Palliative Care Consultation Is Underutilized in Critically Ill General Surgery Patients.

BACKGROUND: American College of Surgeons recommends palliative care and surgeons collaborate on the care of patients with poor prognoses. These collaborations are done to discuss symptom management and goals of care. However, contemporary practice patterns of palliative care consultation for surgical patients are poorly defined. We aim to describe the use of palliative care consultation for patients admitted to our institution's surgical services who died during their index hospital admission. METHODS: The Duke Enterprise Data Unified Content Explorer 2014 to 2016 was queried for patients admitted to general surgery services who died during their admission. Secondary measures included length of stay, time spent in consultation, days from consultation to death, and execution of a care plan. RESULTS: Of the 105 patients identified, 6 died on the day of admission, and 39 (37%) received palliative care consultation. Our data showed that patients who received consultation were generally older, white, and insured. Median number of days between palliative consult and death was 3 days (interquartile range: 1-8). Goals-of-care conversations were the indication for consultation in 62.5% of patients. The proposed plan by the consultants was congruent with the primary team in 66.7% of cases. CONCLUSIONS: Palliative care consultations were underutilized in surgical patients who died while admitted to the general surgical service at our institution. When palliative care is consulted, the plan of the primary surgical team and the palliative team align. Identification of barriers to consultation and promotion of the benefits of palliative care among surgical teams is warranted.

Interval decline in hemoglobin A is associated with annual clinical event rate in sickle cell anemia patients receiving maintenance apheresis RBC exchange.

BACKGROUND: Apheresis red blood cell (RBC) exchange (RCE) is a standard intervention for patients with sickle cell anemia (SCA) who have had previous thromboembolic stroke or intractable chronic pain. Replacing sickling cells with those containing hemoglobin A (HbA) minimizes microvascular pathophysiology that produces clinical crises. Limited data exist regarding the interval changes in HbA between transfusions. We sought to describe the HbA decrement between RCE procedures and its relationship to clinical status. STUDY DESIGN AND METHODS: SCA patients (all hemoglobin SS disease) treated with maintenance RCE (n = 21) over a 15-month period at two neighboring institutions were retrospectively reviewed. Time-normalized daily HbA decrement was calculated to reflect loss of transfused RBCs, and annual events of either emergency department or hospital admissions for SCA complications were noted. Associations between HbA decrement and laboratory measures were calculated using mixed linear regression models and unpaired t test was used to compare HbA decrement between high and low event rate groups. RESULTS: A total of 31 events were recorded, and mean HbA decrement per day was 0.77 ± 0.16%. The mean interval between RCEs was 36 ± 12 days. Patients with more annual events exhibited a significantly greater daily HbA decrement (p = 0.007). No significant association between RBC unit age and HbA decrement or annual event rate was observed. CONCLUSIONS: Patients exhibiting greater daily HbA decrement were more likely to have multiple emergency department visits or admissions for sickling crises. Modulating HbA decrement may merit study as an intermediate metric for interventions to improve outcomes in hemoglobin SS disease.