The impact of providing blood to the scene of an accident on transfusion laboratory practice.

BACKGROUND: Haemorrhage is the leading cause of mortality during trauma. In 2012, London's Air Ambulance introduced Blood on Board (BOB), transfusing group O red cells (RBC) to trauma patients at the scene. OBJECTIVES: This study assessed the impact of BOB on the number of mixed field samples received by the laboratory, the number of group O RBC transfused to non-group O patients and the ratio of RBC to fresh frozen plasma (FFP) transfused in the initial 24 h. METHODS: Three major trauma centres collected data on patients for whom the major haemorrhage protocol was activated between August 2008 and February 2012 pre-BOB and March 2012 and December 2013 post-BOB. RESULTS: A total of 233 trauma patients were identified pre-BOB and 119 post-BOB. There was no significant difference in the percentage of group O units transfused to non-group O patients (75 vs 82%, P = 0·21) or the RBC : FFP ratio (pre-BOB mean 1·6 [interquartile range (IQR) 1·0-2·0]; post-BOB mean 1·7 [IQR 1·1-2·2], P = 0·24). There was no significant difference in the percentage of mixed field samples received (23% vs 27%, P = 0·3). CONCLUSION: The introduction of BOB did not change the proportion of group O RBC transfused or the RBC : FFP ratio; however, the proportion of acceptable samples decreased. This is largely due to an increase in blood samples not received from the post-BOB cohort, which we believe is probably due to patients who died at the scene. We have introduced robust systems to indicate reasons for not obtaining samples.

Ongoing risk of thrombosis with factor XI concentrate: 5 years experience in two centres.

INTRODUCTION: Factor XI (FXI) deficiency is the commonest of the rare bleeding disorders, affecting 2079 individuals in the United Kingdom. Treatment options for bleeding or surgery include antifibrinolytics, fresh frozen plasma or plasma-derived (pd) FXI concentrates. There were a number of reports of thrombosis following treatment with FXI concentrates prior to changes in their manufacturing processes made in the mid-1990's. AIMS: The aim of the study was to determine the occurrence of adverse events (haemorrhagic and thrombotic) following usage of pd-FXI concentrates at two large UK haemophilia centres. Retrospective chart review of all consecutively treated patients with BPL Factor XI(®) or Hemoleven(®) over a 5-year period (11/06-11/11) was performed. RESULTS: Twenty-nine patients (median age = 57.1 years) received treatment over 64 treatment episodes (surgery = 56, bleeding = 5, other = 3), using 126 000 U of concentrate. Median baseline FXI:C was 9 U dL(-1) (range = <1-51), with 21 having severe and eight partial deficiency. BPL Factor XI(®) was used in 39 episodes (79 110 U) and Hemoleven(®) 25 episodes (46 890 U). There were six clinically significant bleeding events, managed either with a single additional dose of FXI concentrate (n = 4) or requiring no further intervention (n = 2). One patient required blood transfusion and one oral iron replacement. Two thrombotic events (transient ischaemic attack and pulmonary emboli), occurred in two patients with severe FXI deficiency, despite cautious FXI concentrate usage in the perioperative period. CONCLUSIONS: FXI concentrate use is efficacious and safe in the majority of cases although physicians should remain mindful of the possibility of thrombotic complications.

Use of thromboelastography to assess the combined role of pregnancy and obesity on coagulation: a prospective study.

BACKGROUND: Thromboelastography (TEG®) is a point of care monitor of whole blood coagulation and has previously demonstrated hypercoagulability in both pregnant and obese populations. However, the individual and combined contribution of pregnancy and obesity on coagulation status has not been defined. We carried out a study to assess the effect of both pregnancy and body mass index (BMI) on blood coagulation using laboratory tests of coagulation and thromboelastography. METHODS: This was a prospective study of 96 women divided into four equal groups; non-pregnant lean (NPL) BMI <25kg/m(2), pregnant lean (PL) BMI <25kg/m(2), non-pregnant obese (NPO) BMI >35kg/m(2) and pregnant obese (PO) BMI >35kg/m(2). Women were of either >36weeks of gestation presenting for elective caesarean delivery; non-pregnant women with BMI >35kg/m(2) presenting for bariatric surgery; or non-pregnant volunteers with BMI <25kg/m(2). Eligible women were then allocated to a group based on BMI and pregnancy status. TEG® analysis, full blood count and coagulation profiles were performed on all patients. The main outcome measures were TEG® profile (including r time, k time, α angle, maximum amplitude and coagulation index), platelet count, activated partial thromboplastin time, prothrombin time, and fibrinogen levels. RESULTS: The coagulation index was significantly higher in the obese patient groups compared with the lean groups (NPL -4.5 vs. NPO 1.9, P<0.001; PL -4.3 vs. PO 2.5, P<0.001). However, comparisons between the pregnant and non-pregnant groups when matched for BMI demonstrated no significant difference in coagulation. CONCLUSIONS: The combined effect of pregnancy and obesity on coagulation has not previously been investigated. Thromboelastographic comparison of pregnant and non-pregnant females separated into low or high BMI cohorts in the current study suggests that obesity correlates more with a hypercoagulable state than with pregnancy, particularly in pregnant patients at the extremes of low and high body weight.

Factor IX replacement to cover total knee replacement surgery in haemophilia B: a single-centre experience, 2000-2010.

Total knee replacement (TKR) is a well recognized treatment for haemophilic arthropathy. Successful haemostasis can be achieved by bolus doses or continuous infusion (CI) using either recombinant (r) or plasma-derived (pd) factor IX (FIX). We retrospectively analysed our experience of factor replacement to cover TKR in haemophilia B patients and explored factors related to FIX use during surgery. Between 2000 and 2010, 13 primary TKRs were performed in 11 haemophilia B patients. Operations were performed by the same surgeon using standard techniques. Median age was 58 years (42-79). An adjusted CI protocol was used for 5 days followed by bolus doses. FIX:C was maintained at 100 IU dL(-1) in the immediate postoperative period. There was no excess haemorrhage. There was no evidence of thrombosis or infection. All patients received mechanical thromboprophylaxis and only one chemical. CI was used in seven cases. Ten patients received pdFIX. Median hospital stay was 14 days (8-17). Median factor usage was 999 IU kg(-1) (768-1248). During CI, factor consumption was 695 IU kg(-1), 691 IU kg(-1) and 495 IU kg(-1) for BeneFix®, Replenine® and Haemonine, respectively. Clearance of both pdFIX and rFIX reduced during CI. All operations were uncomplicated. The decreased clearance in the CI setting reduced the amount of FIX required to maintain a therapeutic level. This reduction was greater with pdFIX and may be related to pharmacokinetic differences between pdFIX and rFIX. Given the excellent safety profile of the pdFIX products, CI of FIX and particularly pdFIX is safe, efficacious and convenient.

British Society of Haematology, Slide Session presented at the Annual Scientific Meeting, Brighton 2009.

Seven cases were discussed by an expert panel at the 2009 Annual Scientific Meeting of the British Society of Haematology. These cases are presented in a similar format to that adopted for the meeting. There was an initial discussion of the presenting morphology, generation of differential diagnoses and then, following display of further presenting and diagnostic information, each case was concluded with provision of a final diagnosis.

Haemopoietic stem cell transplantation induces tolerance to donor antigens but not to foreign FVIII peptides.

A 22-year-old male with severe haemophilia A and high responding factor VIII (FVIII) inhibitor underwent sibling haematopoietic stem cell transplantation in an attempt to eradicate the inhibitor. A reduced intensity conditioning regimen was followed by bone marrow infusion and continuous FVIII administration during immune reconstitution. Although substantial levels of FVIII:C (>100 IU dL(-1)) were maintained initially, at day +23 inhibitor titres rose, indicating boosting of recipient memory repertoire, despite complete donor chimerism. On day +46, he developed Klebsiella pneumoniae septicaemia and died. This case shows that, despite very successful transplantation tolerance, the procedure failed to control long-term memory effector immune cells.