Fibrinogen, Coagulation, and Ageing.

The World Health Organization estimates that the world's population over 60 years of age will nearly double in the next 30 years. This change imposes increasing demands on health and social services with increased disease burden in older people, hereafter defined as people aged 60 years or more. An older population will have a greater incidence of cardiovascular disease partly due to higher levels of blood fibrinogen, increased levels of some coagulation factors, and increased platelet activity. These factors lead to a hypercoagulable state which can alter haemostasis, causing an imbalance in appropriate coagulation, which plays a crucial role in the development of cardiovascular diseases. These changes in haemostasis are not only affected by age but also by gender and the effects of hormones, or lack thereof in menopause for older females, ethnicity, other comorbidities, medication interactions, and overall health as we age. Another confounding factor is how we measure fibrinogen and coagulation through laboratory and point-of-care testing and how our decision-making on disease and treatment (including anticoagulation) is managed. It is known throughout life that in normal healthy individuals the levels of fibrinogen and coagulation factors change, however, reference intervals to guide diagnosis and management are based on only two life stages, paediatric, and adult ranges. There are no specific diagnostic guidelines based on reference intervals for an older population. How ageing relates to alterations in haemostasis and the impact of the disease will be discussed in this chapter. Along with the effect of anticoagulation, laboratory testing of fibrinogen and coagulation, future directions, and implications will be presented.

Insights into the diversity of blood donation practice across Asia: How blood collection agencies adapt donor criteria and processes to their population.

BACKGROUND AND OBJECTIVES: Securing an adequate blood supply relies on accurate knowledge of blood donors and donation practices. As published evidence on Asian populations is sparse, this study aims to gather up-to-date information on blood donors and donation practices in Asia to assist planning and strategy development. MATERIALS AND METHODS: Ten blood collection agencies (BCAs) provided 12 months' data on donors who met eligibility criteria or were deferred, as well as details of their donation practices. Body mass index and blood volumes were calculated and analysed. RESULTS: Data on 9,599,613 donations and 154,834 deferrals from six national and four regional BCAs revealed varied donation eligibility and collection practices. Seven used haemoglobin (Hb) criteria below the World Health Organization anaemia threshold. Seven accepted donors weighing <50 kg. Data collection on the weight and height of donors and on deferrals was inconsistent, often not routine. Deferred donors appear to weigh less, with corresponding lower estimated blood volume. CONCLUSION: The diversity in eligibility criteria and donation practices reflects each BCA's strategy for balancing donor health with securing an adequate blood supply. Use of lower Hb criteria substantiate their appropriateness in Asia and indicate the need to define Hb reference intervals relevant to each population. We encourage routine gathering of donor weight and height data to enable blood volume estimation and local optimization of donation volumes. Blood volume estimation formulae specific for the Asian phenotype is needed. Information from this study would be useful for tailoring donation criteria of Asian donors around the world.

World human neutrophil antigens investigation survey.

BACKGROUND AND OBJECTIVES: Human neutrophil antigens (HNAs) are categorized into five systems: HNA-1 to HNA-5. Given the importance of neutrophils in immunity, we sought to create awareness of the role of HNA diagnostic services in managing immune neutropenia and transfusion-related acute lung injury. To provide health communities all around the world with access to these services, we conducted a survey to create a directory of these HNA diagnostic services. MATERIALS AND METHODS: An Excel table-based survey was created to capture information on the laboratory's location and was emailed to 55 individuals with known or possible HNA investigation activity. The collected data were then summarized and analysed. RESULTS: Of contacted laboratories, the surveys were returned from 23 (38.2%) laboratories; 17 have already established HNA diagnostic (of them 12 were regular participants of the International Granulocyte Immunobiology Workshop [ISBT-IGIW]), 4 laboratories were in the process of establishing their HNA investigation and the remaining 2 responder laboratories, did not conduct HNA investigations. In established laboratories, investigation for autoimmune neutropenia (infancies and adults) was the most frequently requested, and antibodies against HNA-1a and HNA-1b were the most commonly detected. CONCLUSION: The directory of survey respondents provides a resource for health professionals wanting to access HNA diagnostic services. The present study offers a comprehensive picture of HNA diagnostics (typing and serology), identifying weak points and areas for improvement for the first time. Identifying more laboratories involved in HNA diagnostics with limited access to international societies in the field will globally improve HNA diagnostics.

Outcomes following perioperative red blood cell transfusion in patients undergoing elective major abdominal surgery: a systematic review and meta-analysis.

BACKGROUND: Perioperative red blood cell transfusion is a double-edged sword for surgical patients. While transfusion of red cells can increase oxygen delivery by increasing haemoglobin levels, its impact on short- and long-term postoperative outcomes, particularly in patients undergoing elective major abdominal surgery, is unclear. METHODS: We conducted a systematic review and meta-analysis on the effect of perioperative blood transfusions on postoperative outcomes in elective major abdominal surgery. PubMed, Cochrane, and Scopus databases were searched for studies with data collected between January 1, 2000 and June 6, 2020. The primary outcome was short-term mortality, including all-cause 30-day or in-hospital mortality. Secondary outcomes included long-term all-cause mortality, any morbidity, infectious complications, overall survival, and recurrence-free survival. No randomised controlled trials were found. Thirty-nine observational studies were identified, of which 37 were included in the meta-analysis. RESULTS: Perioperative blood transfusion was associated with short-term all-cause mortality (odds ratio [OR] 2.72, 95% confidence interval [CI] 1.89-3.91, P<0.001), long-term all-cause mortality (hazard ratio 1.35, 95% CI 1.09-1.67, P=0.007), any morbidity (OR 2.18, 95% CI 1.81-2.64, P<0.001), and infectious complications (OR 1.90, 95% CI 1.60-2.26, P<0.001). Perioperative blood transfusion remained associated with short-term mortality in the sensitivity analysis after excluding studies that did not control for preoperative anaemia (OR 2.27, 95% CI 1.59-3.24, P<0.001). CONCLUSIONS: Perioperative blood transfusion in patients undergoing elective major abdominal surgery is associated with poorer short- and long-term postoperative outcomes. This highlights the need to implement patient blood management strategies to manage and preserve the patient's own blood and reduce the need for red blood cell transfusion. TRIAL REGISTRATION: PROSPERO (CRD42021254360).

Determining sex-specific preoperative haemoglobin levels associated with intraoperative red blood cell transfusion in cardiac surgery: a retrospective cohort study.

BACKGROUND: Anaemic cardiac surgery patients are at greater risk of intraoperative red blood cell transfusion. This study questions the application of the World Health Organization population-based anaemia thresholds (haemoglobin <120 g L-1 in non-pregnant females and <130 g L-1 in males) as appropriate preoperative optimisation targets for cardiac surgery. METHODS: A retrospective cohort study was conducted on adults ≥18 yr old undergoing cardiopulmonary bypass surgery. Logistic regression was applied to define sex-specific preoperative haemoglobin concentrations with reduced probability of intraoperative red blood cell transfusion for cardiac surgery patients. RESULTS: Data on 4384 male and 1676 female patients were analysed. Binarily stratified multivariable logistic regression odds of receiving intraoperative red blood cell transfusion increased in cardiac surgery patients >45 yr old (odds ratio [OR] 1.84; 95% confidence interval [CI] 1.33-2.55), surgery urgency <30 days (OR 2.03; 95% CI 1.66-2.48), combined coronary artery bypass grafting and valve surgery, or other surgery types (OR 2.24; 95% CI 1.87-2.67), and female sex (OR 1.92; 95% CI 1.62-2.28). The odds decreased by 8.4% with each 1 g L-1 increase in preoperative haemoglobin (OR 0.92; 95% CI 0.91-0.92). Logistic regression predicted females required a preoperative haemoglobin concentration of 133 g L-1 and males 127 g L-1 to have a 15% probability of intraoperative transfusion. CONCLUSIONS: The World Health Organization female anaemia threshold of haemoglobin <120 g L-1 disproportionately disadvantages female cardiac surgery patients. A preoperative haemoglobin concentration ≥130 g L-1 in adult cardiac surgery patients would minimise their overall probability of intraoperative red blood cell transfusion to <15%.

The contribution and potential of older blood donors in Asia Pacific regions.

OBJECTIVES: To investigate the blood supply contribution of older donors in five Asia Pacific regions. BACKGROUND: Older people are often the largest blood user group. Thus, as the population ages blood supply needs increase. Minimum and maximum donation age criteria potentially constrain the size of the donor pool. MATERIALS AND METHODS: Haemoglobin values and demographic frequency analytics (sex, age and blood type) were analysed on blood donors aged 60 years or more, from Hong Kong, Indonesia, Japan, Singapore and South Korea over 12 months. RESULTS: Data on 434357 donations was analysed. ABO Rh(D) frequencies of older donors matched that of national frequencies. Older donors were a disproportionately smaller proportion of the total donor pool for each country. Indonesia was the only region with no maximum age limit. Median haemoglobin for older males ranged from 14.2 to 14.8 g/dl and for females 13.1 to 13.9 g/dl. The frequency of female donors was between 15% and 33% of older donors. Older donors had higher donation frequency and lower deferral rates. CONCLUSION: Older donors are loyal and regular donors but under-represented in all regions studied. They could help meet future blood supply needs, especially post-menopausal female donors. Studies including ferritin levels are needed to determine if upper age limits can be safely modified.

Ovine red cell concentrates for transfusion research - is the storage lesion comparable to human red cell concentrates?

BACKGROUND AND OBJECTIVES: Sheep are increasingly being used as a large in vivo animal model of blood transfusion because they provide several advantages over small animals. Understanding the effects of storage duration on ovine (ov) red cell concentrates (RCCs) and how these changes compare with stored human (hu) RCCs is necessary to facilitate clinical translation of research findings. MATERIALS AND METHODS: OvRCCs (n = 5) collected and processed in standard human blood collection packs, and equivalent huRCCs provided by Australian Red Cross Lifeblood (n = 5), were stored at 2-6°C for 42 days, with samples collected weekly. Haemolysis index was determined by measuring supernatant haemoglobin concentration. Biochemical parameters were evaluated using a blood gas analyser. Energy metabolites and biologically active lipids were measured using commercial assays. Osmotic fragility was determined by lysis in various saline concentrations. Extracellular vesicles were characterized by nanoparticle tracking analysis. RESULTS: Ovine red blood cells (RBCs) are double in number, smaller in size and more fragile than human RBCs. Haematological values were unchanged throughout storage. In contrast, biochemical and metabolic values, and haemolysis index in three of the five ovRCCs exceeded huRCCs licensing criteria by day 42. Accumulation of extracellular vesicles and biologically active lipids was comparable between huRCCs and ovRCCs. CONCLUSION: This study documents similarities and differences in the storage lesion of ovRCCs and huRCCs. This new information will guide the design of ovine transfusion models to enhance translation of findings to human transfusion settings.

Cost-utility analysis comparing hospital-based intravenous immunoglobulin with home-based subcutaneous immunoglobulin in patients with secondary immunodeficiency.

BACKGROUND AND OBJECTIVE: Immunoglobulin replacement therapy (IRT) is often used to support patients with primary immunodeficiency disease (PID) and secondary immunodeficiency disease (SID). Home-based subcutaneous immunoglobulin (SCIg) is reported to be a cheaper and more efficient option compared to hospital-based intravenous immunoglobulin (IVIg) for PID. In contrast, there is little information on the cost-effectiveness of IRT in SID. However, patients who develop hypogammaglobulinaemia secondary to other conditions (SID) have different clinical aetiology compared to PID. This study assesses whether SCIg provides a good value-for-money treatment option in patients with secondary immunodeficiency disease (SID). METHODS: A Markov cohort simulation model with six health states was used to compare cost-effectiveness of IVIg with SCIg from a healthcare system perspective. The costs of treatment, infection and quality-adjusted life years (QALYs) for IVIg and SCIg treatment options were modelled with a time horizon of 10 years and weekly cycles. Deterministic and probabilistic sensitivity analyses were performed around key parameters. RESULTS: The cumulative cost for IVIg was A$151 511 and for SCIg A$144 296. The QALYs with IVIg were 3·07 and with SCIg 3·51. Based on the means, SCIg is the dominant strategy with better outcomes and at lower cost. The probabilistic sensitivity analysis shows that 88·3% of the 50 000 iterations fall below the nominated willingness to pay threshold of A$50 000 per QALY. Therefore, SCIg is a cost-effective treatment option. CONCLUSION: For SID patients in Queensland (Australia), the home-based SCIg treatment option provides better health outcomes and cost savings.

Blood management in hip fractures; are we leaving it too late? A retrospective observational study.

BACKGROUND: Anaemia in hip fracture patients has been associated with increased risk of allogenic blood transfusion (ABT), poorer functional outcomes and increased mortality. Few studies have reported the prevalence of anaemia on admission or its progression prior to surgery in this cohort. We aimed to measure the prevalence of anaemia on admission in older persons who sustain a hip fracture, identify if anaemia develops or progresses prior to surgery, and to report associations with outcome. METHODS: A retrospective, observational study was undertaken in a regional hospital. All patients aged 60 and over, admitted with a primary hip fracture resulting from a simple fall, in the 12 months of 2014 were included. The World Health Organization (WHO) definition of anaemia was used. Pathology databases and clinical records were reviewed to collect data. Repeated measures ANOVA's were used to quantify the progression of anaemia prior to surgery, and Chi square test were used to report associations with outcome variables. RESULTS: Two hundred sixty-one patients were identified, median age was 81 years. There were twice as many females as males and just over half the sample had extracapsular fractures. Anaemia was present on admission in 45% (n = 117), highest incidence of anaemia occurred in males 52.0% (n = 39), extracapsular fractures 41.9% (n = 78) and those aged over 80 years 49.7% (n = 91). Progression of anaemia prior to surgery was significant in all groups (p < 0.05), with the greatest reduction seen in extracapsular fractures. Pre-surgery reduction in Hb was recorded in 82.3% of patients between admission and day 1, and in 71.4% between admission and day 2. There was significant association between anaemia on admission and PRBC transfusion (p < 0.05), in hospital mortality (p < 0.05) however no association with the use of antiplatelet or anticoagulant medication, nor LOS. CONCLUSIONS: The findings demonstrate that pre-surgical anaemia in older hip fracture patients is associated with a PRBC transfusion and increased hospital mortality. Importantly, it also identified that patients continue to bleed after admission, leading to the development of or worsening anaemia. Thus, identification anaemia in the pre-surgical period provides an opportunity for treatment to avoid transfusions and improve patient outcomes.

Recipient T lymphocytes modulate the severity of antibody-mediated transfusion-related acute lung injury.

Transfusion-related acute lung injury (TRALI) is a serious complication of transfusion and has been ranked as one of the leading causes of transfusion-related fatalities. Nonetheless, many details of the immunopathogenesis of TRALI, particularly with respect to recipient factors are unknown. We used a murine model of antibody-mediated TRALI in an attempt to understand the role that recipient lymphocytes might play in TRALI reactions. Intravenous injection of an IgG2a antimurine major histocompatibility complex class I antibody (34-1-2s) into BALB/c mice induced moderate hypothermia and pulmonary granulocyte accumulation but no pulmonary edema nor mortality. In contrast, 34-1-2s injections into mice with severe combined immunodeficiency caused severe hypothermia, severe pulmonary edema, and approximately 40% mortality indicating a critical role for T and B lymphocytes in suppressing TRALI reactions. Adoptive transfer of purified CD8(+) T lymphocytes or CD4(+) T cells but not CD19(+) B cells into the severe combined immunodeficiency mice alleviated the antibody-induced hypothermia, lung damage, and mortality, suggesting that T lymphocytes were responsible for the protective effect. Taken together, these results suggest that recipient T lymphocytes play a significant role in suppressing antibody-mediated TRALI reactions. They identify a potentially new recipient mechanism that controls the severity of TRALI reactions.

Unplanned blood use within 24 hours of emergency department presentation: A cohort study in an ageing population.

OBJECTIVE: This research aims to elucidate drivers of blood use in an older population, with a focus on unplanned transfusions following ED presentation. METHODS: In a retrospective cohort study we examined 2015 data for ED presentations and blood use in two hospitals serving a population containing a high proportion (21%) of adults aged ≥65 years. Unplanned blood use was defined as any transfusion ≤24 h of presentation. Data were analysed by age, sex, Major Diagnostic Category, triage category and time to transfusion. RESULTS: A total of 5294 blood components were transfused, comprising red cells (n = 3784), fresh frozen plasma (n = 657), platelets (n = 563) and cryoprecipitate (n = 290). Men aged ≥65 years were the highest users (40%, 2107 components). Unplanned transfusions accounted for 28% (n = 1057) of annual red cell use. Of 85 014 ED presentations, 494 (0.6%) were associated with unplanned red cell transfusion. Four Major Diagnostic Categories accounted for 81% (n = 853) of unplanned red cell use: gastrointestinal (n = 375), haematology (n = 267), trauma (n = 144) and cardiovascular (n = 67). Over one-fifth of unplanned transfusions (21%, n = 222 of 1057) were associated with ICD-10 codes for anaemia as a reason for presentation within the Haematology Major Diagnostic Category. Adults aged ≥65 years accounted for 62% of overall red cell use and 61% of transfusions ≤24 h of presentation. Odds of unplanned red cell transfusion increased with age, peaking at odds ratio 28.5 (95% confidence interval 14.2-57.4) in those aged 85 years and above. CONCLUSIONS: Unplanned blood use accounted for 28% of annual hospital blood consumption. Blood component use increased with age and was greatest in older men. A significant burden of anaemia treatment was identified by the ED.

Transfusion-related acute lung injury (TRALI): Potential pathways of development, strategies for prevention and treatment, and future research directions.

Transfusion-related acute lung injury (TRALI) can occur during or after a transfusion, and remains a leading cause of transfusion-associated morbidity and mortality. TRALI is caused by the transfusion of either anti-leukocyte antibodies or biological response modifiers (BRMs). Experimental evidence suggests at least six different pathways that antibody-mediated TRALI might follow: (i) two hit neutrophil activation; (ii) monocyte and neutrophil dependent; (iii) endothelial cell, neutrophil Fc receptor, platelet and neutrophil extracellular trap dependent; (iv) direct monocyte activation; (v) direct endothelial cell activation; and (vi) endothelial cell, complement and monocyte dependent. Two of these pathways (i and v) also apply to BRM-mediated TRALI. Different antibodies or BRMs might initiate different pathways. Even though six pathways are described, these might not be distinct, and might instead be interlinked or proceed concurrently. The different pathways converge upon reactive oxygen species release which damages pulmonary endothelium, precipitating fluid leakage and the clinical symptoms of TRALI. Additional pathways to the six described are likely to also contribute to TRALI pathogenesis, and this requires further investigation. This review also discusses evidence of protective mechanisms and their implications for clinical TRALI treatment. Finally, it suggests directions for future research to support the translation of these findings into strategies to prevent and treat clinical TRALI.

Longitudinal study of intravenous versus subcutaneous immunoglobulin replacement therapy in hematological malignancy.

AIM: To present findings from a longitudinal study on infection risk, mortality, and patient perspective of intravenous immunoglobulin (IVIg) and subcutaneous immunoglobulin (SCIg) treatment for patients with hypogammaglobulinemia secondary to hematological malignancy or its treatment (abbreviated as SID). METHODS: Observational study period included final year of IVIg (13 patients) and of the first 3 years of SCIg (17 patients) with SID. Data were collected on clinical outcomes from medical records and patient perception via study specific questionnaire. RESULTS: The median age was 63 years (53-76 years), and for 82.4% of patients their hematological malignancy was in complete remission. The annual mean serum IgG trough levels remained stable over the 4 years and were 7.0 g/L (±2.77 g/L) with IVIg, and 8.0 g/L (±1.75 g/L), 8.7 g/L (±2.75 g/L), and 7.6 g/L (±2.89 g/L) (year 1, 2, and 3, respectively) with SCIg. While the annual infection rate was similar, the rate of hospitalization due to infection fluctuated, with 37%, 9%, 15%, and 32% in year 1, 2, 3, and 4 respectively. There were no systemic adverse events with IVIg or SCIg. Patients reported a strong preference for SCIg. One patient died due to progression of underlying disease and infection within the study period. CONCLUSION: SCIg was the preferred treatment mode over IVIg in our cohort, but both were well tolerated without any systemic adverse events in 4-year follow up. The dosage and serum IgG levels were stable throughout. However, the number of infections requiring hospitalization fluctuated. It is anticipated that these findings encourage more hospitals to offer SCIg for SID patients.

Investigating Age Appropriate Coagulation Reference Intervals to Support Patient Blood Management in the Elderly: A Verification Study.

Reference intervals are vital for interpreting coagulation results. Current interval ranges have no upper age limit, although there is evidence that coagulation function changes with age. This study compared coagulation results from healthy people aged >60 years against adult reference intervals for routine clotting assays and thromboelastography (TEG) to determine if reference intervals are relevant to older adults.Samples from healthy blood donors aged >60 years (n=30 male, n=30 female) were tested by TEG® 6s, prothrombin time (PT), activated partial thromboplastin time (aPTT), and derived fibrinogen.All older donor-derived fibrinogen results were within the adult reference intervals, however levels were significantly higher in females. A proportion of TEG® 6s and aPTT results were not within the reference intervals. As populations around the world live longer, these findings question whether older adults require age specific coagulation reference intervals.

Respiratory burst function of ovine neutrophils.

BACKGROUND: Respiratory burst function resulting in the release of reactive oxygen species such as superoxide anion (O2-) from neutrophils is one of the key mechanisms of the innate immune system, and maladaptive control of this mechanism is thought to play a pivotal role in the development of pathologies such as acute lung injury and sepsis. Ovine models of these pathologies are limited by the poor understanding of ovine neutrophil respiratory burst function. RESULTS: Aspects of ovine neutrophil respiratory burst function to be characterised were: i) the maximum rate of O2- generated (Vmax); ii) the time taken to reach Vmax; iii) the total amount of O2- generated during the reaction; and iv) the duration of the reaction. As well as for unstimulated neutrophils, these aspects were also characterised after incubation with a priming agonist (platelet activating factor [PAF], tumour necrosis factor alpha [TNF-alpha] and lipopolysaccharides [LPS]) activating agonists (N-formylmethionyl-leucyl-phenylalanine [fMLP] and phorbol 12-myristate 13-acetate [PMA]) or a combination of a priming and an activating agonist. In the absence of priming or activating agonists, ovine neutrophils displayed a low level of respiratory burst function which was not enhanced by either PAF, TNF-alpha, LPS or fMLP, but was significantly enhanced by PMA. The PMA-induced respiratory burst function was further enhanced by pre-incubation with PAF, but not with TNF-alpha or LPS. By varying the length of pre-incubation with PAF it was demonstrated that this effect decreased as the duration of pre-incubation with PAF increased, and that PAF was enhancing PMA's effects rather than PMA enhancing PAF's effects. CONCLUSION: This study successfully adapted a commonly used method of measuring human neutrophil respiratory burst function to characterise different aspects of ovine neutrophil respiratory burst function. This improved understanding of ovine neutrophils will facilitate the validitation of ovine biomedical models of human pathologies in which neutrophils have been implicated.

Clinical scale ex vivo manufacture of neutrophils from hematopoietic progenitor cells.

Dose-intensive chemotherapy results in an obligatory period of severe neutropenia during which patients are at high risk of infection. While patient support with donor neutrophils is possible, this option is restricted due to donor availability and logistic complications. To overcome these problems, we explored the possibility of large scale ex vivo manufacture of neutrophils from hematopoietic progenitor cells (HPC). CD34+ HPC isolated from umbilical cord blood (UCB) and mobilized peripheral blood (mPB) were expanded in serum-free medium supplemented with stem cell factor, granulocyte colony stimulating factor, and a thrombopoietin peptide mimetic. After 15 days of cultivation a 5,800-fold expansion in cell number was achieved for UCB, and up to 4,000-fold for mPB, comprising 40% and 60% mature neutrophils respectively. Ex vivo expanded neutrophils exhibited respiratory burst activity similar to that for donor neutrophils, and were capable of killing Candida albicans in vitro. These yields correspond to a more than 10-fold improvement over current methods, and are sufficient for the production of multiple neutrophil transfusion doses per HPC donation. To enable clinical scale manufacture, we adapted our protocol for use in a wave-type bioreactor at a volume of 10 L. This is the first demonstration of a large scale bioprocess suitable for routine manufacture of a mature blood cell product from HPC, and could enable prophylactic neutrophil support for chemotherapy patients.

Impacts of Aging on Anemia Tolerance, Transfusion Thresholds, and Patient Blood Management.

Evidence-based patient blood management guidelines commonly recommend restrictive hemoglobin thresholds of 70 to 80 g/L for asymptomatic adults. However, most transfusion trials have enrolled adults across a broad age span, with few exclusive to older adults. Our recent meta-analysis of transfusion trials that focused on older adults paradoxically found lower mortality and fewer cardiac complications when these patients were managed using higher hemoglobin thresholds. We postulate that declining cardiac output with age contributes to deteriorating oxygen delivery capacity which impacts anemia-associated outcomes in older adults and propose a model to explain this age-related difference. We reviewed evidence concerning the pathophysiology of aging to explore the disparity in transfusion trial outcomes related to hemoglobin thresholds in different age groups. The literature was searched for normative cardiac output values at different ages in healthy adults. Using normative peak cardiac output data, we modeled oxygen delivery capacity in young, middle-aged, and older adults at a range of hemoglobin levels. Cardiovascular and pulmonary systems are impacted by age-related pathophysiological changes. Diminishing peak cardiac output associated with aging reduces the maximal oxygen delivery achievable under metabolic stress. Hence, at low hemoglobin levels, older adults are more susceptible to tissue hypoxia than younger adults. Our model predicts that an older adult with a hemoglobin of 100 g/L has a similar peak oxygen delivery capacity to a young adult with a hemoglobin of 70 g/L. Age-related pathophysiological changes provide some explanation as to why older adults have a lower tolerance for anemia than younger adults. This indicates the need for patient blood management hemoglobin thresholds specific to older as distinct from younger adults. The primary application of this model is in the consideration of patients rehabilitating to life outside hospital. It is important to note that pathophysiological changes associated with critical illness and major surgery are more complex than can be described in a simple model based on cardiac output and hemoglobin concentration. However, our review of oxygen transport and delivery in health and disease states allows the model to be considered in the context of treatment decisions for anemic adults in a range of hospital and community settings.

Outcomes of restrictive versus liberal transfusion strategies in older adults from nine randomised controlled trials: a systematic review and meta-analysis.

BACKGROUND: Guidelines for patient blood management recommend restrictive transfusion practice for most adult patients. These guidelines are supported by evidence from randomised controlled trials (RCTs); however, one of the patient groups not explicitly examined in these studies is the geriatric population. We examined RCTs relevant to transfusion outcomes in older patients. Our aim was to determine whether special guidelines are warranted for geriatric patients, recognising the different pathophysiological characteristics of this group. METHODS: For this systematic review and meta-analysis, we searched PubMed, Scopus, and the Cochrane Library databases from their inception to May 5, 2017, for evidence relating to transfusion outcomes in adults aged 65 years and older. This criterion was widened to include RCTs where a substantial proportion of the study population was older than 65 years. We also included study populations of all clinical settings, and did not limit the search by date, language, or study type. For articles not in English, only available translations of the abstracts were reviewed. Studies were excluded if they did not specify age. Observational studies and duplicate patient and outcome data from studies that generated multiple publications were also excluded. We screened bibliographies of retrieved articles for additional publications. We analysed data extracted from published RCTs comparing restrictive and liberal transfusion strategies in older adults. We generated fixed effects risk ratios (RR) for pooled study data using the Mantel-Haenszel method. Primary outcomes were 30-day and 90-day mortality events for patients enrolled in restrictive and liberal transfusion study groups. We included intention-to-treat outcome data in the meta-analysis when available, otherwise we used per-protocol outcome data. FINDINGS: 686 articles were identified by the search, and a further 37 by the snowball approach. Of these articles, 13 eligible papers described findings from nine RCTs (five trials investigating orthopaedic surgery, three cardiac surgery, and one oncology surgery; including 5780 patients). The risk of 30-day mortality was higher in older patients who followed a restrictive transfusion strategy than in those who followed a liberal transfusion strategy (risk ratio [RR] 1·36, 95% CI 1·05-1·74; p=0·017). The risk of 90-day mortality was also higher in those who followed a restrictive transfusion strategy than in those who followed a liberal transfusion strategy (RR 1·45, 95% CI 1·05-1·98; p=0·022). INTERPRETATION: Liberal transfusion strategies might produce better outcomes in geriatric patients than restrictive transfusion strategies. This outcome contradicts current restrictive transfusion approaches. Population ageing will challenge resources globally, and this finding has implications for blood supply and demand, and optimal care of older adults. Further research is needed to formulate evidence-based transfusion practice across clinical specialties specific to the geriatric population, and to examine resource effects. FUNDING: Australia's National Blood Authority.

Subcutaneous Immunoglobulin Therapy for Hypogammaglobulinemia Secondary to Malignancy or Related Drug Therapy.

Immunoglobulin replacement therapy (IRT) has an important role in minimizing infections and improving the health-related quality of life (HRQoL) in patients with immunodeficiency, who would otherwise experience recurrent infections. These plasma-derived products are available as intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg). The global demand for these products is growing rapidly and has placed pressure on supply. Some malignancies and their treatment (as well as other medical therapies) can lead to secondary hypogammaglobulinemia or secondary immunodeficiency (SID) requiring IRT. Although IVIg use in this cohort has well-established therapeutic benefits, little is known about SCIg use. A literature search in July 2015 found only 7 published articles on SCIg use. These articles found that both IRT modes had equivalent efficacy in regard to reduction of bacterial infections. In addition, SCIg was reported to produce higher serum IgG trough levels compared with IVIg on equivalent dosage with the added benefit of fewer adverse effects. Patient HRQoL reports demonstrate preference for SCIg because of reduced adverse effects and hospital visits. There are no health economic models published on SCIg use in SID, but models on primary immunodeficiency disease and IRT conclude that SCIg provided greater economic benefits than IVIg. The findings of this small number of reports suggest that SCIg therapy for patients with SID is likely to be beneficial for both the patient and health care providers. To substantiate wider use of SCIg in SID, larger and more detailed studies are needed to accurately quantify the effectiveness of SCIg.

The impact of acute lung injury, ECMO and transfusion on oxidative stress and plasma selenium levels in an ovine model.

The purpose of this study was to determine the effects of smoke induced acute lung injury (S-ALI), extracorporeal membrane oxygenation (ECMO) and transfusion on oxidative stress and plasma selenium levels. Forty ewes were divided into (i) healthy control (n=4), (ii) S-ALI control (n=7), (iii) ECMO control (n=7), (iv) S-ALI+ECMO (n=8) and (v) S-ALI+ECMO+packed red blood cell (PRBC) transfusion (n=14). Plasma thiobarbituric acid reactive substances (TBARS), selenium and glutathione peroxidase (GPx) activity were analysed at baseline, after smoke injury (or sham) and 0.25, 1, 2, 6, 7, 12 and 24h after initiation of ECMO. Peak TBARS levels were similar across all groups. Plasma selenium decreased by 54% in S-ALI sheep (1.36±0.20 to 0.63±0.27µmol/L, p<0.0001), and 72% in sheep with S-ALI+ECMO at 24h (1.36±0.20 to 0.38±0.19, p<0.0001). PRBC transfusion had no effect on TBARS, selenium levels or glutathione peroxidase activity in plasma. While ECMO independently increased TBARS in healthy sheep to levels which were similar to the S-ALI control, the addition of ECMO after S-ALI caused a negligible increase in TBARS. This suggests that the initial lung injury was the predominant feature in the TBARS response. In contrast, the addition of ECMO in S-ALI sheep exacerbated reductions in plasma selenium beyond that of S-ALI or ECMO alone. Clinical studies are needed to confirm the extent and duration of selenium loss associated with ECMO.