Anaemia and red blood cell transfusion in the critically ill patient

Measuring Mitochondrial Oxygen Tension during Red Blood Cell Transfusion in Chronic Anemia Patients: A Pilot Study

In light of the associated risks, the question has been raised whether the decision to give a blood transfusion should solely be based on the hemoglobin level. As mitochondria are the final destination of oxygen transport, mitochondrial parameters are suggested to be of added value. The aims of this pilot study were to investigate the effect of a red blood cell transfusion on mitochondrial oxygenation as measured by the COMET device in chronic anemia patients and to explore the clinical usability of the COMET monitor in blood transfusion treatments, especially the feasibility of performing measurements in an outpatient setting. To correct the effect of volume load on mitochondrial oxygenation, a red blood cell transfusion and a saline infusion were given in random order. In total, 21 patients were included, and this resulted in 31 observations. If patients participated twice, the order of infusion was reversed. In both the measurements wherein a blood transfusion was given first and wherein 500 mL of 0.9% saline was given first, the median mitochondrial oxygen tension decreased after red blood cell transfusion. The results of this study have strengthened the need for further research into the effect of blood transfusion tissue oxygenation and the potential role of mitochondrial parameters herein.

The effect of red blood cell transfusion on peripheral tissue oxygen delivery and consumption in septic patients

OBJECTIVES

The impact of blood transfusion on tissue oxygen delivery (DO₂) and tissue oxygen consumption (VO₂) is a subject of current clinical studies. The primary objective of this observational study is to evaluate and measure the parameters involved in determining DO₂ and VO₂, in early phase of septic patients. A secondary objective of this study is to assess the potential benefit of blood transfusion on tissue metabolism by serial measurements of lactic acid (Ac. Lac.).

MATERIAL AND METHODS

A group of 29 patients were studied, each patient received between one to three units of fresh packed red blood cells (pRBC). Clinical and paraclinical criteria for sepsis as well as the plasma value of haemoglobin (Hb) below 10g/dL represented the inclusion criteria in this study. We evaluated Hb, haematocrit (HCT), arterial blood oxigen saturation (SAO₂), central venous oxygen saturation (SCVO₂), parameters which are involved in determination of DO₂ and VO₂, before and after the transfusion of one unit of pRBC. Values of Ac. Lac. were also assessed in order to determine the type of metabolism (aerobic or anaerobic). SCVO₂, SAO₂, Hb, HCT and Ac. Lac. were determined using Epoc blood analyser. The cardiac output (CO) and systemic vascular resistance (SVR) were monitored during blood transfusion, using Vigileo monitor (Edward's Life Science, PreSep catheter kit). SAO₂ was also monitored by pulse-oximetry.

RESULTS

Changes in Hb, HCT and SCVO₂ before and after pRBC transfusion (which further determine VO₂) were statistically significant (P<0.001). A statistically significant increase (P<0.001) was obtained in Ac. Lac. values, before and after pRBC transfusion. SAO₂ and CO directly involved in producing DO₂, were clinically monitored during blood transfusion and the results remained constant.

CONCLUSION

Results obtained in this clinical study show an increase in DO2 in critically ill septic patients and also an increase in oxygen tissue uptake which is similar to VO2, clearly pointing out the benefit of pRBC transfusion. The benefits of pRBC transfusion on tissue metabolism in critically ill septic patients remain elusive because of lactic acid values increase during and after transfusion. Based on our findings we recommend that Hb values used as a single trigger for pRBC transfusion should be further studied and that additional parameters such as SCVO₂ and lactic acid should be considered as possible triggers for transfusion. Values of Hb and HCT should never be neglected.

Patient Blood Management: transfusion appropriateness in the post-operative period

BACKGROUND

Within the context of Patient Blood Management (PBM) policy for the peri-operative period, the transfusion medicine unit of our institution adopted a series of strategies to support and enhance red blood cell (RBC) transfusion best practices. This study aimed to evaluate the appropriateness of RBC transfusion therapy in the post-operative period, before and after starting a multifactorial PBM policy.

MATERIALS AND METHODS

A 2-phase observational study was conducted on patients who underwent major surgery. The study was designed as follows: 3 months of preliminary audit, followed by multifactorial PBM policy, and a final audit. The policy comprised seminars, teaching lessons, periodic consultations and the insertion of Points of Care. RBC transfusion appropriateness was evaluated in both audits.

RESULTS

The preliminary audit, performed on 168 patients, showed that 37.7% of the patients were appropriately transfused. The final audit, performed on 205 patients, indicated a significant increase of RBC transfusion appropriateness to 65.4%.

DISCUSSION

In our experience, our multifactorial PBM policy improved the RBC transfusion appropriateness in the post-operative period. We believe that our multifactorial PBM policy, which comprises the insertion of Points of Care, supported the healthcare workers in the transfusion decision-making process. This enhancement of transfusion appropriateness implies clinical and managerial advantages, such as reduced transfusion-related risks, optimisation of health care resources, and reduction in costs.

Implementing a protocol to optimize blood use in a cardiac surgery service: results of a pre-post analysis and the impact of high-volume blood users

BACKGROUND

Blood transfusions are a common and costly intervention for cardiac surgery patients. Evidence suggests that a more restrictive transfusion strategy may reduce costs and transfusion-related complications without increasing perioperative morbidity and mortality.

STUDY DESIGN AND METHODS

A transfusion-limiting protocol was developed and implemented in a cardiovascular surgery unit. Over a 5-year period, data were collected on patient characteristics, procedures, utilization of blood products, morbidity, and mortality, and these were compared before and after the protocol was implemented.

RESULTS

After the protocol was put in place, fewer patients required transfusions (38.2% vs. 45.5%, p = 0.004), with the greatest reduction observed in postoperative blood use (29.1% vs. 37.2%, p = 0.001). In-hospital morbidity and mortality did not increase. When patients who received transfusions were stratified by procedure, the protocol was most effective in reducing transfusions for patients undergoing isolated coronary artery bypass grafting (CABG; 4.09 units vs. 2.51 units, p = 0.009) and CABG plus valve surgery (10.32 units vs. 4.77 units, p = 0.014). A small group of patients were disproportionate recipients of transfusions, with approximately 6% of all patients receiving approximately half of the blood products.

CONCLUSION

A protocol to limit transfusions decreased the proportion of cardiothoracic surgery patients who received blood products. A very small group of patients received a large number of transfusions, and within that group the observed mortality was significantly higher than in the general patient population. Current protocols cannot possibly account for these patients, and this should be considered when analyzing the performance of protocols designed to reduce unnecessary transfusions.

Toxicological evaluation of the aqueous stem bark extract of Bridelia ferruginea (Euphorbiaceae) in rodents

Bridelia ferruginea is a woody shrub that grows in the Savannah or rain forests of Africa and has traditionally been used to treat diabetes, arthritis and boils. Despite all these uses, extensive toxicological evaluation has not been carried out. The aim of the present investigation was to evaluate the sub-chronic toxicological effects of the stem bark aqueous extract of Bridelia ferruginea in rats. The lethal dose (LD₅₀) was determined using probit analysis and graded doses of the extract (250–4000 mg/kg) were administered to the animals via oral and intraperitoneal routes and observed for mortality, behavioral changes and signs of toxicity. Sub-chronic toxicity study was carried out at doses of 1 000, 2 000 and 4 000 mg/kg administered daily for 60 days. The animals were sacrificed after 60 days. Blood was collected for biochemical (renal and hepatic), hematological, oxidative stress, sperm and histopathological examinations, using standard methods. LD₅₀ of the extract was estimated as >4 000 mg/kg orally; neither significant visible signs of toxicity nor mortality were observed. There were no significant differences in the animals and organ weights, hematological and biochemical parameters in the treated groups compared to the control group. However, a significant increase (p<0.05) in the level of lipid peroxidation and a significant (p<0.05) decrease in sperm count were observed in the treated animals compared with the control group. The stem-bark aqueous extract of Bridelia ferruginea was found to be relatively safe, though it has the potential to cause lipid peroxidation and damage sperm quality and should thus be used with caution.

Association between hypoxemia and anemia following arthroplasty: A pilot clinical study

Hypoxia and anemia are common complications following joint arthroplasty. Whether hypoxia indicates that a patient is anemic and whether anemia causes a decline in arterial oxygen pressure accompanied by hypoxemia are not completely understood. The aim of the present study was to determine the association between hypoxemia and anemia following arthroplasty. A total of 135 patients who underwent arthroplasty at the China-Japan Friendship Hospital between January and May 2013 were retrospectively analyzed. The patients were divided into five groups depending on the type of arthroplasty they had experienced: Unilateral total knee arthroplasty (TKA), bilateral TKA, unilateral total hip arthroplasty (THA), bilateral THA or unilateral unicompartmental knee arthroplasty. Perioperative peripheral oxygen saturation (SpO2) and hemoglobin (Hb) levels were assessed, and the associations between the changes in SpO2 (ΔSpO2) and hemoglobin (ΔHb) levels on the first and third postoperative days (PODs) were analyzed using Pearson's correlation test for each group. The perioperative SpO2 curves for the various groups were typically at their lowest on the day of surgery. Significant hypoxemia was observed on POD 0-2, although a stable recovery curve was observed on POD 3-5. Trends in ΔHb were observed among the 5 groups, with the lowest Hb value observed predominantly on POD 2 and 3. By POD 4 and 5 Hb levels had recovered, with a steadily and consistently increasing curve. There was no statistically significant correlation between ΔSpO2 and decrease in Hb levels (P>0.05). SpO2 levels should not serve as a clinical indicator of the incidence and severity of anemia in patients who have undergone primary arthroplasty. To a point, the degree of postoperative anemic status does not affect SpO2 levels.

Comparative study on the effects of aqueous extracts of viscum album (mistletoe) from three host plants on hematological parameters in albino rats

BACKGROUND

The extract of the leaves of Viscum album (mistletoe) has been used for centuries in traditional medicine in many parts of the world. However, like many medicinal plants, the belief that things of natural origin are safe may not be entirely true. The blood is a good indicator of health and pathological mirror of the entire body.

OBJECTIVE

Therefore, in this study, the acute effects of extracts of mistletoe, harvested from three hosts, on haematology indices of wistar albino rats was investigated.

METHODS

Graded doses (400, 800, 1600 and 3200mg/kg body weight) of aqueous extracts of mistletoe from three different host plants, coffee (Coffee arabica), kola (Kola nitida), cocoa (Theobromae cacao), were administered orally to wistar albino rats for 14 days. Full haematological parameters were evaluated on whole blood collected from rats twenty four hours after the administration of the last dose.

RESULTS

Mistletoe from kola caused a concentration dependent and statistically significant (p<0.05) reduction in platelets count in rats. Administration of mistletoe extract from cocoa and coffee led to reduction in hemoglobin concentration. Reductions in packed cell volume (PCV) and red blood cell (RBC) and increase in white blood cells (WBC) were also observed in rats administered all the extracts.

CONCLUSION

Increase in the WBC count observed in rats administered mistletoe suggests that mistletoe extract contains agents that could stimulate the production of leucocytes and could serve as immune booster. However, there is need to be cautious in administration at high doses to prevent the risk of anaemia.

Toxicity Effect of Sub-Chronic Oral Administration of Class Bitters® - A Polyherbal Formula on Serum Electrolytes and Hematological Indices in Male Wistar Albino Rats

The indiscriminate administration of ready-to-use herbal formulations has become a major concern due to their potential health risk. The study investigated the effect of class bitters^® (CB) - a polyherbal formula prepared with Mondia whitei, Khaya senegalensis, Capparis erythrocarpus, Thoningia sanguinea and Xylopia aethiopica on serum electrolytes and hematological parameters in male Wistar albino rats. Two doses (500 and 1000 mg kg^–1) of the polyherbal drugs were administered orally to male Wistar albino rats for a period of 9 weeks. The results showed that administration of 500 and 1000 mg kg^–1 body weight of CB recorded a marked increase in the levels of sodium and chlorum when compared with control. However, there was a marked reduction in the levels of potassium and hydrogen carbonate. The results of the study also showed a significant (P≤0.05) decrease in the level of hematological parameters such as hemoglobin (Hb), packed cell volume (PCV), red blood cells (RBCs) and platelets levels in the male Wistar albino rats, when compared with control. The marked decrease in Hb, PCV, RBCs and platelets concentrations observed in experimental rats in this study suggest that CB may have an adverse effect on erythropoiesis. These observations therefore showed that long-term administration of CB might cause renal disease and anemia.

Anaemia secondary to critical illness: an unexplained phenomenon

Almost all patients suffering critical illness become anaemic during their time in intensive care. The cause of this anaemia and its management has been a topic of debate in critical care medicine for the last two decades. Packed red cell transfusion has an associated cost and morbidity such that decreasing the number of units transfused would be of great benefit. Our understanding of the aetiology and importance of this anaemia is improving with recent and ongoing work to establish the cause, effect and best treatment options. This review aims to describe the current literature whilst suggesting that the nature of the anaemia should be considered with reference to the time point in critical illness. Finally, we suggest that using haemoglobin concentration as a measure of oxygen-carrying capacity has limitations and that ways of measuring haemoglobin mass should be explored.

Ameliorative Effects of Operculina turpethum and its Isolated Stigma-5,22dien-3-o-β-D-glucopyranoside on the Hematological Parameters of Male Mice Exposed to N-Nitrosodimethylamine, a Potent Carcinogen

OBJECTIVES

Enormous propensity of plants to synthesize a variety of structurally diverse bioactive compounds, has made the plant kingdom a potential source of chemical constituents with various therapeutic values, including antitumor and cytotoxic activities. Blood is a good indicator to determine the physiological and pathological status of man and animal. The objective of the present study is to determine the effect of Operculina turpethum root extract and its isolated glycoside treatment on the hematological parameters in the mice with N-Nitrosodimethylamine (NDMA) induced cancer.

MATERIALS AND METHODS

The body weights of the animals were recorded before and after the experiment. Non-coagulated blood was tested for total erythrocyte count, total leukocyte count, hemoglobin, differential leukocyte count (DLC) and for other blood indices.

RESULTS

A significant (P < 0.01), (P < 0.001) recovery of the red blood cell and white blood cell counts, packed cell volume and hemoglobin content in the host after 21 day treatment was shown.

CONCLUSION

These results show that the extract of Operculina turpethum is relatively safe following oral administration and have possible stimulatory effect on red blood cell production and there was dose dependent therapeutic effect.

Impact of guideline implementation on transfusion practices in a surgical intensive care unit

BACKGROUND

Anemia is a common clinical problem in cardiac surgery patients in the postoperative period and may result in transfusion in up to 90% of this population. There is tremendous variation in transfusion rates by hospital and individual physician. It is unknown if implementation of a clinical practice guideline lowers unnecessary transfusion in hospital practices that already have a restrictive transfusion culture .

OBJECTIVE

To evaluate transfusion practice before and after implementation of a clinical practice guideline.

DESIGN

Pre/post intervention study.

SETTING

Sixteen bed surgical intensive care unit in an academic hospital.

PARTICIPANTS

Four hundred ninety-five adult patients undergoing cardiac surgery.

INTERVENTIONS

Implementation of an anemia clinical practice guideline reinforced with education and retrospective audit/feedback.

MEASUREMENTS AND MAIN RESULTS

A total of 252 pre-intervention and 243 postintervention cases were examined. Unnecessary transfusion occurred in 14.7% of pre-intervention patients and decreased to a rate of 8.1% after guideline implementation (p = 0.016).

CONCLUSIONS

This study suggests that clinical guideline implementation utilizing guideline development, education, and compliance audit/feedback may reduce unnecessary transfusion in cardiac surgery patients. A fully powered prospective trial would be necessary to validate these findings.

Leucocytosis following Transfusion with Leucodepleted Red Cells to Non-Bleeding Critically Ill Patients

Previous studies have shown that transfusion of non-leucodepleted red blood cells can cause leucocytosis in recipients. A small study suggested that pre-storage leucodepletion removed this phenomenon, but has not been further substantiated. We explored whether recipient leucocytosis occurs when leucodepleted red blood cells were transfused to non-bleeding intensive care patients. We used routinely collected data for 95 transfusions in 54 patients. Overall, no leucocytosis was found on the first routine blood sample following transfusion (mean change 0.6 × 109/L; 95% confidence interval - 0.2 to 1.3; p=0.145). However, for the 32 transfusions in patients with normal pre-transfusion leucocyte count there was a clinically small but statistically significant leucocytosis following transfusion, unlikely to have occurred by chance (mean change 1.5 × 109/L; 0.5 to 2.5; p=0.005). No significant change was observed in patients with pre-transfusion leucocytosis. We found no relation between leucocytosis and storage age of red cells. Our data suggest that transfusions with leucodepleted red cells can increase leucocyte counts in recipients. The mechanism of this effect and its clinical importance are uncertain.

Red blood cell transfusions--are we narrowing the evidence-practice gap? An observational study in 5 Israeli intensive care units

PURPOSE

The aim of the study was to document transfusion practices in a cross section of general intensive care units (ICUs) in Israel and to determine whether current guidelines are being applied.

MATERIALS AND METHODS

This prospective study was performed in 5 general ICUs in Israel over a 3-month period. Red cell transfusion data collected on consecutive patients included the trigger, units transfused per transfusion event, and indications, categorized either to treat a specified condition for which transfusions may be beneficial (acute hemorrhage, acute myocardial ischemia, or severe sepsis) or to treat a low hemoglobin concentration.

RESULTS

Of the 238 patients studied, 50% received at least one red blood cell transfusion. The main indication for transfusion (43.7%, or 162/368 U transfused) was to treat a low hemoglobin concentration, in the absence of one of the specified conditions. Total red cell use was 3.0 ± 2.9 U per admission, and patients received a mean of 1.2 ± 0.4 U per transfusion event. The transfusion trigger for the whole group was 7.9 ± 1.1 g/dL. This did not differ significantly between the indications apart from a significantly higher trigger for patients with acute myocardial ischemia (8.8 ± 0.9 g/dL). In addition, patients with a history of heart disease had a higher trigger irrespective of the primary indication for transfusion and received significantly more units per transfusion event. Patients receiving a transfusion had significantly longer ICU stay and hospital mortality.

CONCLUSIONS

Our study showed that evidence-practice gaps continue to exist, and it appears that physician behavior is mainly driven by the absolute level of hemoglobin. Educational interventions focused on these factors are required to limit the widespread and often unnecessary use of this scarce and potentially harmful resource.

Ambient overnight hold of whole blood prior to the manufacture of blood components

Blood services routinely separate whole blood into components that are then stored under different conditions. The storage conditions used for whole blood prior to separation must therefore be a compromise between the needs of the red cells (which benefit from refrigeration) and plasma and platelets (which are better preserved at ambient temperature). For many years, the approach has been to manufacture plasma and platelet components on the day of blood collection, and to refrigerate any unprocessed blood for manufacture into red cell components on the following day. However, this can make it challenging to maintain adequate stocks of all components. The European practice of 'ambient hold' of whole blood for up to 24 hours prior to processing allows greater flexibility in blood component manufacture, and the data reviewed suggest there is relatively little impact on the quality of red cell or plasma components, and an improvement in the quality of platelet components.

The effect of storing whole blood at 22 degrees C for up to 24 hours with and without rapid cooling on the quality of red cell concentrates and fresh-frozen plasma

BACKGROUND

Storage of whole blood (WB) for less than 24 hours at ambient temperature is permitted in Europe, but data directly comparing storage with and without active cooling are lacking, which was investigated and compared to current standard methods.

STUDY DESIGN AND METHODS

WB was stored in one of four different ways for 24 hours after donation before processing on Day 1 to red cell concentrates (RCCs) in saline-adenine-glucose-mannitol and fresh-frozen plasma (FFP; n = 20 each): 1) at 22 degrees C in plastic trays, 2) in cooling devices (Compocool II, NPBI), 3) at 4 degrees C, or 4) processed from WB without storage less than 8 hours from donation (Day 0).

RESULTS

2,3-Diphosphoglycerate (2,3-DPG) in RCCs were lower after ambient storage compared with those processed on Day 0 or after 4 degrees C storage. Rapid cooling slowed the loss of 2,3-DPG but levels were undetectable by Day 21 with any method. On Day 42 of RCC storage, there was no significant difference between storage methods in levels of adenosine triphosphate or hemolysis. Potassium levels were lower in RCCs from WB stored at ambient compared with those produced on Day 0, regardless of the use of cooling plates. FFP produced from WB on Day 0 or after storage at ambient with or without active cooling met UK specifications (>75% of units >0.70 IU/mL Factor VIII).

CONCLUSION

These data suggest that RCCs and FFP produced from WB that has been stored at ambient temperature with or without active cooling are of acceptable quality compared with those produced using current standard methods in the United Kingdom.

Survival of red blood cells after transfusion: a comparison between red cells concentrates of different storage periods

BACKGROUND

The use of fresh red blood cells (RBCs) is recommended for critically ill patients and patients undergoing surgery, although there is no conclusive evidence that this is beneficial. In this follow-up study, the short-term and the long-term recovery of irradiated, leukoreduced RBCs transfused after either a short storage (SS) or a long storage (LS) period were compared. By consecutive transfusion of RBCs with a SS and LS period, a direct comparison of their survival within the same patient was possible.

STUDY DESIGN AND METHODS

Ten transfusion-requiring patients each received a SS RCCs (stored 0-10 days) and a LS RCCs (stored 25-35 days) consecutively. Short-term and long-term survival of the transfused RBCs was followed by flow cytometry using natural differences in RBC antigens between donors and patients. Posttransfusion recovery (PTR) was measured at several time points after transfusion.

RESULTS

The mean 24-hour PTR of SS RBCs is 86.4 +/- 17.8 percent and that of LS RBCs 73.5 +/- 13.7 percent. After the first 24 hours, the mean times to reach a PTR of 50 percent of the 24-hour PTR (T50) and mean potential life spans (mPLs) of the surviving SS and LS RBCs (41 and 116 days and 41 and 114 days, respectively) do not differ.

CONCLUSIONS

The mean 24-hour PTR of both SS and LS RBCs complies with the guidelines, even in a compromised patient population. The 24-hour PTR of SS RBCs, however, is significantly higher than that of LS RBCs. The remaining population of SS and LS RBCs has a nearly identical long-term survival. Therefore, depletion of the removal-prone RBCs before transfusion may be an efficient approach for product improvement.

Factors predicting loss and gain of red cell volume in cardiac surgery patients

Haemoglobin may be a poor indicator of changes in red cell volume (RCV) because of factors such as haemodilution. This study has been designed to analyse what peri-operative variables may be associated with loss or gain in RCV due to bleeding or transfusion. Prospective observational study. Single centre study based in a regional cardiac surgery centre. Twenty-nine elective adult cardiac surgery patients. Loss and gain of RCV were measured in theatre and for the first 24 h post-operatively. Patient and operative factors analysed were age, sex, height, weight, body surface area (BSA), induction haematocrit (Hct), estimated pre-operative RCV and antiplatelet therapy taken less than 7 days before operation, cardiopulmonary bypass (CPB) time, aortic occlusion time, minimum and maximum CPB temperatures and fluid administered. Age, sex, height, weight, BSA and induction Hct were found to predict red cell transfusion but not RCV loss. The total number of red cells transfused was significantly associated with RCV lost when expressed as a percentage reduction in the estimated pre-operative RCV but not the absolute RCV lost. Pre-operative RCV, as predicted by the variables outlined above, is more important than RCV lost in triggering red cell transfusion.

Red blood cell 2,3-diphosphoglycerate concentration and in vivo P50 during early critical illness

OBJECTIVE

To measure red blood cell 2,3-diphosphoglycerate (RBC 2,3-DPG) concentrations in early critical illness; to investigate factors associated with high or low RBC 2,3-DPG levels; to calculate in vivo P50 in patients with early critical illness; and to explore the relationship between RBC 2,3-DPG and intensive care mortality.

DESIGN

Prospective cohort study.

SETTING

General medical-surgical intensive care unit (ICU) of a major Scottish teaching hospital.

PATIENTS

One-hundred eleven critically ill patients during the first 24 hrs in the ICU with no history of chronic hematologic disorders or RBC transfusion within 24 hrs and 34 age- and sex-matched healthy reference subjects.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured RBC 2,3-DPG concentration, plasma biochemistry values, and arterial blood gas parameters. On average, RBC 2,3-DPG was lower among critically ill patients than controls (mean [sd], 14.1 [6.3] vs. 16.7 [3.7] mumol/g hemoglobin; p = .004) and had a wider range of values (patients, 3.2-32.5 mumol/g hemoglobin; reference group, 9.1-24.3). Regression analysis indicated a strong independent association between plasma pH and RBC 2,3-DPG (B, 32.15 [95% confidence interval, 19.07-46.22], p < .001) and a weak association with plasma chloride (B, -0.196 [95% confidence interval, -0.39 to -0.01], p = .044) but not with hemoglobin or other measured biochemical parameters. The mean calculated in vivo P50 level was normal (3.8 kPa) but varied widely among patients (range, 2.0-5.5 kPa). RBC 2,3-DPG concentration was similar for ICU survivors and nonsurvivors.

CONCLUSIONS

RBC 2,3-DPG concentrations vary widely among critically ill patients. Acidosis is associated with lower RBC 2,3-DPG concentrations, but anemia is not associated with a compensatory increase in RBC 2,3-DPG early in critical illness. Lower RBC 2,3-DPG concentrations during the first 24 hrs of intensive care are not associated with higher ICU mortality.

The application of a new quantitative assay for the monitoring of integrin-associated protein CD47 on red blood cells during storage and comparison with the expression of CD47 and phosphatidylserine with flow cytometry

BACKGROUND

After the introduction of universal leukoreduction, the role of factors other than white blood cells in red cell (RBC) storage lesion is attracting increasing attention. These include changes in the levels of CD47 and phosphatidylserine (PS) markers on RBCs during storage. The aim of this study was to monitor these changes with both flow cytometry (FACS) and a newly developed quantitative enzyme-linked immunosorbent assay (ELISA).

STUDY DESIGN AND METHODS

A new quantitative ELISA (monoclonal antibody immobilization of RBC antigens [MAIRA]) was developed. The assay yielded consistent linear curves that enabled the measurement of CD47 expression on RBCs. In addition, FACS was used to measure both CD47 expression and PS on RBCs (n = 3 units) during storage (Days 4, 10, 24, and 31).

RESULTS

A significant reduction in CD47 expression was observed both by MAIRA assay and by FACS by Days 24 and 31 (p < 0.01), and the correlation between the two assays was significant (p < 0.01). In addition, a significant increase in PS was observed by the same storage days with FACS (p < 0.01).

CONCLUSION

The MAIRA assay appears to be suitable for the quantitative measurement of RBC markers during storage. Significant changes in CD47 and PS levels were observed during storage, which may have detrimental immunomodulatory and hemostatic effects on the transfused RBCs.

Red cell storage lesion: The potential impact of storage-induced CD47 decline on immunomodulation and the survival of leucofiltered red cells

Red blood cells undergo major biochemical and biomechanical changes during storage that could effect their post transfusion performance. Biochemical effects include changes in 2,3-diphosphoglycerate (2,3-DPG), ATP, and calcium levels, as well as metabolic modulation and release of Annexin V, a cytosolic component of blood cells, as a global marker of cellular injury and fragmentation. Biomechanical changes include alterations in cellular membrane, shape changes, phospholipid content, phospholipid asymmetry, and antigenic markers. Although the extent of these changes under various storage conditions has been well documented, their clinical effects remain unclear. In the current era of universal leucodepletion, the immunomodulatory effects of some essential markers such as CD47 and phosphatidyl serine become the focus of interest as highlighted in this manuscript.

Allogeneic red blood cell transfusions: efficacy, risks, alternatives and indications

Careful assessment of risks and benefits has to precede each decision on allogeneic red blood cell (RBC) transfusion. Currently, a number of key issues in transfusion medicine are highly controversial, most importantly the influence of different transfusion thresholds on clinical outcome. The aim of this article is to review current evidence on blood transfusions, to highlight 'hot topics' with respect to efficacy, outcome and risks, and to provide the reader with transfusion guidelines. In addition, a brief synopsis of transfusion alternatives will be given. Based on up-to-date information of current evidence, together with clinical knowledge and experience, the physician will be able to make transfusion decisions that bear the lowest risk for the patient.

Red cell requirements for intensive care units adhering to evidence-based transfusion guidelines

BACKGROUND

Anemia commonly complicates critical illness. Restrictive transfusion triggers are appropriate in this setting, but no large studies have measured red cell (RBC) requirements for intensive care patients when evidence-based transfusion guidelines are followed consistently.

STUDY DESIGN AND METHODS

Data were recorded daily for 1023 of 1042 sequential admissions to 10 intensive care units (ICUs) over 100 days. The sample comprised 44 percent of all ICU admissions in Scotland during this period. RBC transfusions and the occurrence of clinically significant hemorrhage were recorded for every ICU day. Transfusion episodes were classified as either associated with or not associated with hemorrhage. Measures of RBC use were derived for the cohort and for Scotland with national audit data.

RESULTS

A total of 39.5 percent (95% confidence interval [CI], 36.5%-42.5%) of admissions received transfusions. Eighteen percent of admissions received at least one transfusion associated with hemorrhage and 26 percent received at least one transfusion not associated with hemorrhage. The median (interquartile range) transfusion trigger in the absence of hemorrhage was 78 (73-78) g/L. The overall mean RBC use was 1.87 (95% CI, 1.79-1.96) units per admission or 0.34 (95% CI, 0.33-0.36) units per ICU-day. Forty-seven percent of RBCs administered were not associated with clinically significant hemorrhage. Mean RBC requirements for intensive care in Scotland were estimated to be 3950 (95% CI, 3780-4140) per million-adult-population per year. This represented 7 to 8 percent of the Scottish blood supply.

CONCLUSIONS

Despite evidence-based transfusion practice, 40 percent of ICU patients receive transfusions, which account for 7 to 8 percent of the national blood supply.

Scope of the problem: epidemiology of anemia and use of blood transfusions in critical care

Anemia is a common problem in critically ill patients. It is caused, in part, by blood loss related to phlebotomy for diagnostic testing, occult gastrointestinal bleeding, renal replacement therapies, surgical intervention, and traumatic injuries. Reduced red cell life span and nutritional deficiencies (iron, folate, vitamin B₁₂) may be other contributing factors. In addition, critically ill patients have impaired erythropoiesis because of blunted endogenous erythropoietin production and the direct inhibitory effects of inflammatory cytokines on red blood cell production by the bone marrow. Blood transfusions are commonly utilized for treatment of anemia in critical care, resulting in high use of blood transfusions in the intensive care unit (ICU). The percentage of patients transfused in the ICU is inversely related to admission hemoglobin and directly related to age and severity of illness. Patients with an increased length of stay in the ICU are also at increased risk for receiving blood transfusions. Studies are needed to improve our understanding of the pathophysiology of ICU-acquired anemia, to determine the efficacy of blood transfusions in critical care, and to investigate alternatives to blood transfusion for the treatment of anemia in the ICU.