The effect of variation in donor platelet function on transfusion outcome: a semirandomized controlled trial.

The effect of variation in platelet function in platelet donors on patient outcome following platelet transfusion is unknown. This trial assessed the hypothesis that platelets collected from donors with highly responsive platelets to agonists in vitro assessed by flow cytometry (high-responder donors) are cleared more quickly from the circulation than those from low-responder donors, resulting in lower platelet count increments following transfusion. This parallel group, semirandomized double-blinded trial was conducted in a single center in the United Kingdom. Eligible patients were those 16 or older with thrombocytopenia secondary to bone marrow failure, requiring prophylactic platelet transfusion. Patients were randomly assigned to receive a platelet donation from a high- or low-responder donor when both were available, or when only 1 type of platelet was available, patients received that. Participants, investigators, and those assessing outcomes were masked to group assignment. The primary end point was the platelet count increment 10 to 90 minutes following transfusion. Analysis was by intention to treat. Fifty-one patients were assigned to receive platelets from low-responder donors, and 49 from high-responder donors (47 of which were randomized and 53 nonrandomized). There was no significant difference in platelet count increment 10 to 90 minutes following transfusion in patients receiving platelets from high-responder (mean, 21.0 × 109/L; 95% confidence interval [CI], 4.9-37.2) or low-responder (mean, 23.3 × 109/L; 95% CI, 7.8-38.9) donors (mean difference, 2.3; 95% CI, -1.1 to 5.7; P = .18). These results support the current policy of not selecting platelet donors on the basis of platelet function for prophylactic platelet transfusion.

Red blood cell hemolysis during blood bank storage: using national quality management data to answer basic scientific questions.

BACKGROUND: Hemolysis of red blood cells (RBCs) during blood bank storage is the most obvious manifestation of RBC storage system failure. However, its analysis is made difficult because the largest source of interunit difference is donor specific. Availability of data from national blood systems on large numbers of RBC units used for internal quality control (QC) purposes and stored and processed in uniform ways permits statistical analysis. STUDY DESIGN AND METHODS: Measures of hemolysis during and at the end of storage on randomly selected donor units observed for QC purposes were obtained from four national blood systems. Groups of these measures from units that had undergone similar processing and storage were sorted to create histograms and the histograms were compared statistically. RESULTS: A total of 14,087 measures were obtained under seven storage conditions, including more than 12,000 measures made in a single country under four closely related conditions. Distributions of percent hemolysis are skewed normal and outliers are random. Additive solutions appear to be equivalent, except that the 42 mmol/L mannitol in AS-1 reduces hemolysis compared to conventional 30 mmol/L mannitol in saline, adenine, glucose, and mannitol. Increasing storage from 35 to 42 days increased measured hemolysis by 30% and leukoreduction decreased it by 53%. CONCLUSIONS: Large national data sets provide useful information about the distribution of hemolysis at the end of RBC storage. This information can aid blood storage system development and regulatory science.

Tissue factor pathway inhibitor antigen and activity in 96 patients receiving heparin for cardiopulmonary bypass.

OBJECTIVE: To identify patients with poor tissue factor pathway inhibitor (TFPI) response to heparin and observe any association with increased risk of excessive coagulation activation, morbidity, or mortality. DESIGN: Prospective, observational cohort study. SETTING: University hospital. PARTICIPANTS: Patients (n = 96) undergoing cardiopulmonary bypass for various types of surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: TFPI antigen and activity were determined in patients before and after heparin administration, before cardiopulmonary bypass for cardiac surgery. The clinical progress of each patient was recorded. Median levels of TFPI activity were 0.98 U/mL (interquartile range, 0.83 to 1.14 U/mL) preheparin and 2.34 U/mL (2.18 to 2.54 U/mL) postheparin (p < 0.0001), representing a median 2.3-(2.1- to 2.8-) fold increase. Median TFPI antigen levels were 92.4 ng/mL (73.0 to 119.5 ng/mL) preheparin and 422.9 ng/mL (398.7 to 501.6 ng/mL) postheparin (p < 0.0001), representing a median 4.6-fold (3.6- to 6.2-fold) increase. Two patients had low (<300 ng/mL) postheparin levels of TFPI antigen that were not associated with low functional TFPI or adverse clinical outcome. Fourteen patients showed a low ratio of increased functional TFPI postheparin; all had a ratio of TFPI antigen increase of at least 3-fold. CONCLUSION: The TFPI response to heparin is heterogenous. Two nonresponders were identified, with low postheparin levels of TFPI antigen, who did not suffer adverse clinical outcomes.