Passive reporting greatly underestimates the rate of transfusion-associated circulatory overload after platelet transfusion.

BACKGROUND: Transfusion-associated circulatory overload (TACO) is the second leading cause of reported transfusion-related fatalities in the United States. While its occurrence has been previously investigated after red cell and plasma transfusion, no data are available regarding its association with platelet transfusion. Our goal was to determine the rate of platelet-associated TACO at our university medical centre. STUDY DESIGN AND METHODS: This study had retrospective and prospective analyses. The 13-year retrospective analysis served to determine the historical rate of platelet-associated TACO by passive reporting. The 30-day prospective analysis included active surveillance of all non-emergently issued and non-operative platelet recipients ≥16 years old with no transfusions in the previous 6 h determined by analysis of blood bank product issue records. Data collected included demographics, vital signs pre- and posttransfusion, fluid balances, supplemental oxygen use, reports of dyspnoea, and infusion rates. For the prospective analysis, all variables were collected within 24 h of transfusion from the medical record and, when necessary, interviews with care providers and/or patients. RESULTS: In the retrospective analysis, 366 reactions were reported, of which 6 (1·6%) were TACO. The historical rate of TACO was 1:5997 transfused platelet units. During the prospective analysis, 225 eligible patients received a total of 334 units of platelets. The average platelet transfusion volume was 261 ± 26 ml, and the average infusion rate was 391 ± 198 ml/h. Two unreported TACO reactions were discovered and characterized by new-onset hypertension, crackles on lung auscultation, dyspnoea, hypoxia and supplemental oxygen requirements which resolved completely with diuresis. The rate of TACO during this prospective analysis was 1:167 transfused platelet units. CONCLUSION: Platelet-associated TACO is greatly underestimated by passive reporting in the adult patient population.

State of the art: massive transfusion.

The aim of this article was to review recent developments in the resuscitation of both trauma and non-trauma patients in haemorrhagic shock. Strategies for the resuscitation of massively haemorrhaging patients and the use of massive transfusion protocols (MTPs) have been a major focus of the trauma literature over the past several years. The application of haemostatic resuscitation practices and MTPs to non-trauma populations has long been in practice, but has only recently been the subject of active research. Medline and PubMed were reviewed for 'massive transfusion' (MT) from 2012 to present. Non-English and paediatric articles were excluded. Articles were systematically reviewed for their relevance to MT. There were eight major areas of development identified. In recent MT literature, there was an increased focus on massively haemorrhaging non-trauma patients, the role of acute traumatic coagulopathy, the use of thromboelastography (TEG), and the impact of MTPs on blood product waste and efficiency of product delivery. Other developments included additional MT prediction tools and The PRospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study. There was also interest in re-evaluating the clinical relevance of the current MT definition and identifying new foci for MT. These recent developments reflect efforts to better understand and manage non-traumatic haemorrhage and to address prior limitations in the trauma literature. Inevitably, new questions have been raised, which will likely direct ongoing and future research in MT.

Ascorbic acid improves membrane fragility and decreases haemolysis during red blood cell storage.

BACKGROUND: Changes that occur to red blood cells (RBCs) during routine blood bank storage include decreased deformability, increased haemolysis and oxidative damage. Oxidative injury to the RBC membrane and haemoglobin can affect changes in shape and deformability. Ascorbic acid (AA) is an antioxidant that maintains haemoglobin in a reduced state and minimises RBC oxidative injury. We hypothesised that AA would improve membrane fragility and decrease haemolysis during storage. METHODS: Whole blood derived, AS-5 preserved, pre-storage leucoreduced RBC units were exposed to either AA or saline control solutions. Several rheological and biochemical parameters were measured serially during storage, including RBC membrane mechanical fragility, percent haemolysis and methaemoglobin levels. RESULTS: AA exposure significantly reduced mechanical fragility and haemolysis over the entire storage period. The highest two concentrations of AA affected the greatest reductions in mechanical fragility and percent haemolysis. Addition of AA to the RBCs did not significantly alter their biochemical parameters compared to control RBCs incubated with saline. CONCLUSION: AA reduced RBC membrane fragility and decreased haemolysis during storage without adversely affecting other RBC biochemical parameters. The clinical significance of these findings needs to be determined.

ABO-mismatched transfusions are not over-represented in febrile non-haemolytic transfusion reactions to platelets.

ABO-mismatched plasma and platelet (PLT) transfusion have been associated with worse outcomes, including haemolysis and other reactions, compared to recipients of ABO-identical products. The immune complexes that form in a mismatched transfusion have been demonstrated to stimulate pyrogenic cytokine release in vitro. Comparing ABO identical vs. ABO mismatched PLT transfusions, we found no significant difference in the ABO compatibilities between the PLT doses implicated in causing febrile non-haemolytic transfusion reactions (FNHTR) in 162 recipients and both the baseline PLT donor/recipient ABO compatibility (P = 0·67) or the PLTs issued in the 30 days preceding the FNHTR (P = 0·92). ABO-mismatched PLT transfusions do not appear to be aetiological agents of FNHTR in a population routinely receiving both ABO-identical and ABO-mismatched transfusions.

Haemolysis and sublethal injury of RBCs after routine blood bank manipulations.

OBJECTIVES: To determine the extent of RBC sublethal injury in male donor units as measured by both the mechanical fragility index (MFI) and percentage haemolysis after RBCs underwent leucoreduction (LR), irradiation (IRRAD), and washing. BACKGROUND: RBCs frequently undergo post-collection processing to meet certain recipient's special needs. The extent of haemolysis and sublethal injury following these interventions has not been fully characterised. METHODS: Eight to ten day old male, AS-5 RBCs underwent either LR, IRRAD or washing. A control group of male, AS-5 RBCs were unmanipulated. The MFI, percent haemolysis, and plasma free haemoglobin (PFHb) were measured immediately after manipulation and, for a series of irradiated RBCs, 28 days after irradiation (IRRAD28). RESULTS: The MFI of the washed units was significantly higher than unmanipulated, LR, IRRAD, IRRAD28 units (P < 0·0001). The percent haemolysis was highest in the IRRAD28 units (1·4%) followed by the washed units (0·74%); the other three units demonstrated significantly less haemolysis (P < 0·0001). The largest mean total amount of PFHb per unit was found in the IRRAD28 units (500·5 mg/unit) followed by the washed units (149·8 mg/unit); the mean total amount of PFHb in the three other types of units was significantly less than that found in both the IRRAD28 and washed units (P at least < 0·001). CONCLUSION: There is a significant quantity of PFHb in IRRAD28 RBC units, and potentially in washed allogeneic RBC units. Clinical correlation is required to determine if this quantity of PFHb and the transfusion of potentially fragile RBCs causes adverse events.

Menopausal status affects the susceptibility of stored RBCs to mechanical stress.

The mechanical fragility index (MFI) is an in vitro measure of sublethal injury to RBCs. In our previous experiments, we demonstrated that an increase in sublethal injury (increasing MFI) was a component of the RBC storage lesion, and that the MFI was significantly higher amongst the RBC units from male donors compared to pre-menopausal female donors during storage. It was hypothesized that hormonal or menstrual factors contributed to this difference. In this study, we found that RBC units donated by post-menopausal women demonstrated an MFI that was significantly higher than those donated by pre-menopausal women throughout storage.

The use of the mechanical fragility test in evaluating sublethal RBC injury during storage.

BACKGROUND: The mechanical fragility index (MFI) is an in vitro measurement of the extent of RBC sublethal injury. Sublethal injury might constitute a component of the RBC storage lesion, thus the MFI was determined serially during routine RBC storage. METHODS: Leucoreduced AS-5- and SAGM-preserved RBCs were stored under routine blood bank conditions. The mechanical fragility (MF) of each unit was serially measured during storage. RESULTS: For both AS-5 and SAGM units, male and female RBCs demonstrated statistically significant increases in the MFI during storage. The MFI was significantly lower in AS-5 units compared to SAGM units throughout storage. Female RBCs had significantly lower MFI vs. male RBCs in both AS-5 and SAGM units at all times. No significant differences in MFI were observed between ABO groups for both genders for AS-5 RBCs. CONCLUSIONS: The MF of RBCs increases during storage. Both gender and preservation solution influenced the MFI; however, the male:female MFI ratios were similar at all time-points and remained stable, suggesting that gender-based biological differences exist independent of storage solution. The MF could be a useful test for evaluating the effect of novel interventions intended to mitigate the susceptibility of RBCs to sublethal injury during storage.