The feasibility of introducing a whole blood component for traumatic haemorrhage in the UK

BACKGROUND

The interest in re-introducing whole blood (WB) transfusion for the management of traumatic major haemorrhage is increasing. However, due to the current leucodepletion filters used in the UK a WB component was not readily available. Instead, an alternative but similar component, leucocyte depleted red cell and plasma (LD-RCP), which provided a unique experience in assessing the feasibility of a WB component was used whilst a WB component was being manufactured.

STUDY DESIGN AND METHODS

Between November 2018 and October 2020, LD-RCP replaced RBC as standard of care for all trauma patients with major haemorrhage in London. The aims of the study were to assess (a) deliverability, (b) component wastage and (c) safety.

RESULTS

Over the study period a total of 1208 LD-RCP units were delivered, of which 96.5% were delivered 'On Time In Full' (OTIF). Of the 1208 units, 733 (60.68%) were transfused and 475 (39.3%) units were wasted. Component wastage reduced significantly throughout the study (p = 0.001). A total of 177 patients had a blood group recorded, 86 were group O and 91 were non-group O. There was no statistically significantly difference between haemoglobin (p = 0.422), or bilirubin levels (p = 0.084) between group O and non-group O patients.

DISCUSSION

It was feasible for NHS Blood and Transplant to deliver LD-RCP on time in full, however component wastage was high due to short shelf life and limited use of the component. Low titre group O LD-RCP units were not associated with clinical evidence of haemolysis.

Discovery of Streptococcus pneumoniae serogroup 35 variants in Australian patients

OBJECTIVES

Streptococcus pneumoniae isolates from Australian invasive pneumococcal disease cases displaying an atypical 35B phenotype. Whole genome sequencing was used to analyse these strains and identify changes to the capsule gene regions.

METHODS

Four atypical serogroup 35 isolates from Australian reference laboratories were unable to be assigned to one of the four known group 35 serotypes by the Quellung serotyping method. Genetic characterization of the capsule locus was performed by bioinformatic analysis of whole genome sequencing data for all isolates.

RESULTS

Genetic analysis identified four independent disruptions to the wciG gene, which encodes an O-acetyltransferase responsible for the O-acetylation of the 6Galβ1 residue in the capsular polysaccharide repeat unit of serotype 35B.

CONCLUSIONS

This is the first published report on the incidence and capsular gene characteristics of a S. pneumoniae 35B variant.

Transfusion of prion-filtered red cells does not increase the rate of alloimmunization or transfusion reactions in patients: results of the UK trial of prion-filtered versus standard red cells in surgical patients (PRISM A)

This study, conducted for the UK Blood Transfusion Services (UKBTS), evaluated the clinical safety of red cells filtered through a CE-marked prion removal filter (P-Capt™). Patients requiring blood transfusion for elective procedures in nine UK hospitals were entered into a non-randomized open trial to assess development of red cell antibodies to standard red cell (RCC) or prion-filtered red cell concentrates (PF-RCC) at eight weeks and six months post-transfusion. Patients who received at least 1 unit of PF-RCC were compared with a control cohort given RCC only. About 917 PF-RCC and 1336 RCC units were transfused into 299 and 291 patients respectively. Twenty-six new red cell antibodies were detected post-transfusion in 10 patients in each arm, an overall alloimmunization rate of 4.4%. Neither the treatment arm [odds ratio (OR) 0.93, 95% confidence interval (CI) 0.3, 2.5] nor number of units transfused (OR 0.95, 95% CI 0.8, 1.1) had a significant effect on the proportion of patients who developed new alloantibodies. No pan-reactive antibodies or antibodies specifically against PF-RCC were detected. There was no difference in transfusion reactions between arms, and no novel transfusion-related adverse events clearly attributable to PF-RCC were seen. These data suggest that prion filtration of red cells does not reduce overall transfusion safety. This finding requires confirmation in large populations of transfused patients.

Prion reduction of red blood cells: impact on component quality

BACKGROUND

A filter has been developed (P-Capt, MacoPharma) to remove infectious prions from red blood cells (RBCs). We sought to assess 1) its operational use, 2) the quality of filtered components, and 3) whether filtration resulted in any significant changes to blood group antigens.

STUDY DESIGN AND METHODS

A total of 272 leukoreduced RBC units, including units processed using "top-and-top" (TAT) and "bottom-and-top" (BAT) methods, were prion reduced using the P-Capt filter. All RBCs were assessed using standard in vitro tests of RBC quality. Changes to blood group antigen expression were also investigated, including the exposure of cryptantigens and the ability of filtered RBCs to be crossmatched.

RESULTS

Ninety-nine percent of TAT units and 58% of BAT units had a hemoglobin (Hb) content of more than 40 g. Hemolysis increased immediately after filtration, but units remained within UK specification throughout storage. Prion reduction resulted in the loss of 7 to 8 g of Hb and reductions in hematocrit of 6% to 9% due to the filter containing 40 mL of saline, adenine, glucose, and mannitol. Other RBC quality data, including extracellular potassium, 2,3-diphosphoglycerate, and adenosine triphosphate were similar to historical control data. There was no evidence of any immunologic changes of clinical relevance to the RBC membrane after filtration.

CONCLUSIONS

Prion filtration does not appear to have a detrimental effect on basic in vitro measures of RBC quality or on blood group antigens as assessed by in vitro methods. However, prion filtration using the P-Capt filter results in loss of Hb.

Growing older and wiser. Part 1--What is life all about?

This is an edited version of a presentation given at the 1999 RACGP Annual Scientific Meeting, held in Adelaide. Lady Valerie Hicks is the widow of Sir Stanton Hicks a renowned South Australian physiologist. As 1999 was the Year of the Older Person, Lady Valerie was asked for her reflections on what getting older means, the place of the older person in today's society and for her thoughts on life in general. Her erudite and thought provoking response to this task will be published over the next three issues.