Erythropoietin response is blunted in critically ill patients

Anemia, bleeding, and blood transfusion in the intensive care unit: causes, risks, costs, and new strategies

The definition of anemia is controversial and varies with the sex, age, and ethnicity of the patient. Anemia afflicts half of hospitalized patients and most elderly hospitalized patients. Acute anemia in the operating room or intensive care unit is associated with increased morbidity as well as other adverse outcomes, including death. The risks of anemia are compounded by the added risks associated with transfusion of red blood cells, the most common treatment for severe anemia. The causes of anemia in hospitalized patients include iron deficiency, suppression of erythropoietin and iron transport, trauma, phlebotomy, coagulopathies, adverse effects of and reactions to medications, and stress-induced gastrointestinal bleeding. The types and causes of anemia and the increased health care utilization and costs associated with anemia and undetected internal bleeding are described. The potential benefits and risks associated with transfusion of red blood cells also are explored. Last, the strategies and new tools to help prevent anemia, allow earlier detection of internal bleeding, and avoid unnecessary blood transfusions are discussed.

Pathophysiology of perioperative anaemia

Perioperative anaemia is a common clinical entity. It is usually due to combination of various mechanisms, including: pre-existing anaemia prior to surgery; anaemia due to impaired erythropoiesis, including alterations of metabolism of iron and erythropoietin (EPO); anaemia due to increased destruction of red blood cells (RBCs); and anaemia due to iatrogenic causes. Postoperatively, anaemia resembles anaemia of chronic disease and is probably related to the effects of inflammatory mediators released during and after surgery on the production and survival of RBCs. Pro-inflammatory cytokines, such as tumour necrosis factor, impair erythropoietin-dependent signalling and iron homeostasis. Iatrogenic causes, notably excessive phlebotomies, remain a major cause of perioperative anaemia. With increasing emphasis on restrictive blood transfusion strategies, understanding these mechanisms is important for the clinician.

Impact of erythropoietin on intensive care unit patients

Anemia is common in intensive care unit (ICU) patients. Red blood cell (RBC) transfusions are mainstays of their treatment and can be life-saving. Allogeneic blood components inherently bear risks of infection and immune reactions. Although these risks are rare in developed countries, recombinant human erythropoietin (rhEpo) and other erythropoiesis-stimulating agents (ESAs) have been considered alternative anti-anemia treatment options. As summarized herein, however, most of the clinical studies suggest that ESAs are not usually advisable in ICU patients unless approved indications exist (e.g., renal disease). First, ESAs act in a delayed way, inducing an increase in reticulocytes only after a lag of 3-4 days. Second, many critically ill patients present with ESA resistance as inflammatory mediators impair erythropoietic cell proliferation and iron availability. Third, the ESA doses used for treatment of ICU patients are very high. Fourth, ESAs are not legally approved for general use in ICU patients. Solely in distinct cases, such as Jehovah's Witnesses who refuse allogeneic blood transfusions due to religious beliefs, ESAs may be considered an exceptional therapy.

The impact of anemia in moderate to severe traumatic brain injury

PURPOSE

The impact of anemia and restrictive transfusion strategies in traumatic brain injury (TBI) is unclear. The purpose of this study was to examine the outcome of varying degrees of anemia in patients who have sustained a TBI.

METHODS

We performed a retrospective study of all adult patients with isolated blunt TBI admitted between January 2003 and June 2010. The impact of increasing severity of anemia (Hb ≤8, ≤9, or ≤10 g/dl measured on three consecutive draws within the first 7 days of admission) and transfusions on complications, length of stay, and mortality was examined using univariate and multivariate analysis.

RESULTS

Of the 31,648 patients with blunt trauma admitted to the trauma service during the study period, 812 had an isolated TBI, among which 196 (24.1 %) met at least one of the anemia thresholds within the first 7 days [78 % male, mean age 47 ± 23 years, Injury Severity Score 16 ± 8, and head Abbreviated Injury Scale 3.3 ± 1.0]. Using a logistic regression model, anemia even as low as 8 g/dl was not associated with an increase in mortality [AOR8 = 0.8 (0.2, 3.2), p = 0.771; AOR9 = 0.8 (0.4, 1.6), p = 0.531; AOR10 = 0.6 (0.3, 1.3), p = 0.233] or complications. However, for all patients, the transfusion of packed red blood cells was associated with a significant increase in septic complications [AOR = 3.2 (1.5, 13.7), p = 0.030].

CONCLUSION

The presence of anemia in patients with TBI as low as 8 g/dl was not associated with increased mortality or complications, while the transfusion of red blood cells was associated with a significant increase in septic complications. Prospective evaluation of an optimal transfusion trigger in head-injured patients is warranted.

Serum Soluble-Fas, Inflammation, and Anemia in Acute Kidney Injury

Anemia is a common feature in critically ill patients. Serum soluble-Fas (sFas) levels are associated with anemia in chronic kidney disease. It is possible that sFas levels are also associated with anemia in acute kidney injury (AKI) patients. The study aims to investigate the relationship between serum levels of sFas, erythropoietin (Epo), inflammatory cytokines, and hemoglobin (Hb) concentration in critically ill patients with AKI. We studied 72 critically ill patients with AKI (AKI group; n = 53) or without AKI (non-AKI group; n = 19), and 18 healthy volunteers. Serum sFas, Epo, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-10, iron status, and Hb concentration were analyzed in all groups. We also investigated the correlation between these variables in the AKI group. Critically ill patients (AKI and non-AKI groups) had higher serum levels of Epo than healthy volunteers. Hb concentration was lower in the AKI group than in the other groups. Serum sFas, IL-6, TNF-α, and ferritin levels were higher in the AKI group. Hb concentration correlated negatively with serum IL-6 (r = -0.37, P = 0.008), sFas (r = -0.35, P = 0.01), and Epo (r = -0.27, P = 0.04), while serum sFas correlated positively with iron levels (r = 0.36, P = 0.008) and IL-6 (r = 0.28, P = 0.04) in the AKI group. In multivariate analysis, after adjusting for markers of inflammation and iron stores, only serum sFas levels (P = 0.03) correlated negatively with Hb concentration in the AKI group. Serum Epo and inflammatory cytokine levels are elevated in critically ill patients with or without AKI. Serum levels of sFas are elevated and independently associated with anemia in critically ill patients with AKI.

The use of erythropoiesis-stimulating agents in the intensive care unit

Anemia is common in critically ill patients, but treatment with red blood cell transfusions can have unwanted effects. Limiting the occurrence and severity of anemia by using erythropoietic agents (iron and/or recombinant erythropoietin), therefore, remains an attractive option during the intensive care unit stay but also after hospital discharge. Moreover, these agents may have additional beneficial properties. In this article the authors review the rationale for the administration of iron and/or erythropoietin in critically ill patients.

Anemia in the ICU: anemia of chronic disease versus anemia of acute illness

Anemia is common in the ICU, increasing morbidity and mortality. Its etiology is multifactorial but anemia of inflammation is the most common cause, followed closely by iron deficiency. The two conditions often coexist and it can be difficult to diagnose iron deficiency in the context of anemia of inflammation. Blood transfusions and use of erythropoietin agonists are two modalities used to correct anemia in critically ill patients. Randomized controlled trials have not supported the use of either therapy except in well defined clinical situations. Better understanding of the pathophysiology of anemia of inflammation may lead to development of novel therapies.

Red blood cell clearance in inflammation

SUMMARY

Anemia is a frequently encountered problem in the critically ill patient. The inability to compensate for anemia includes several mechanisms, collectively referred to as anemia of inflammation: reduced production of erythropoietin, impaired bone marrow response to erythropoietin, reduced iron availability, and increased red blood cell (RBC) clearance. This review focuses on mechanisms of RBC clearance during inflammation. We state that phosphatidylserine (PS) expression in inflammation is mainly enhanced due to an increase in ceramide, caused by an increase in sphingomyelinase activity due to either platelet activating factor, tumor necrosis factor-α, or direct production by bacteria. Phagocytosis of RBCs during inflammation is mediated via RBC membrane protein band 3. Reduced deformability of RBCs seems an important feature in inflammation, also mediated by band 3 as well as by nitric oxide, reactive oxygen species, and sialic acid residues. Also, adherence of RBCs to the endothelium is increased during inflammation, most likely due to increased expression of endothelial adhesion molecules as well as PS on the RBC membrane, in combination with decreased capillary blood flow. Thereby, clearance of RBCs during inflammation shows similarities to clearance of senescent RBCs, but also has distinct entities, including increased adhesion to the endothelium.

Red cell distribution width and outcome in patients with septic shock

INTRODUCTION

Red cell distribution width (RDW) is reflective of systemic inflammation. The objective of this study was to investigate the association between RDW (on day 1 of development of septic shock) and mortality.

METHODS

A total of 279 patients with septic shock were included. We categorized the patients into quintiles based on RDW as follows: <13.5%, 13.5% to 15.5%, 15.6% to 17.5%, 17.5% to 19.4%, and >19.4%.

RESULTS

Red cell distribution width was a strong predictor of hospital mortality with a significant risk gradient across RDW quintiles after multivariable adjustment: RDW 13.5% to 15.5% (odds ratio [OR], 4.6; 95% confidence interval [CI], 1.0-23.4; P = .06); RDW 15.6% to 17.5% (OR, 8.0; 95% CI, 1.5-41.6; P = .01); RDW 17.6% to 19.4% (OR, 25.3; 95% CI, 4.3-149.2; P < .001); and RDW >19.4% (OR, 12.3; 95% CI, 2.1-73.3; P = .006), all relative to patients with RDW <13.5%. Similar significant robust associations were present for intensive care unit mortality. Estimating the receiver-operating characteristic area under the curve (AUC) showed that RDW has very good discriminative power for hospital mortality (AUC = 0.74). The AUC was 0.69 for Acute Physiologic and Chronic Health Evaluation II (APACHE II) and 0.69 for sequential organ failure assessment (SOFA). When adding RDW to APACHE II, the AUC increased from 0.69 to 0.77.

CONCLUSIONS

Red cell distribution width on day 1 of septic shock is a robust predictor of mortality. The RDW is inexpensive and commonly measured. The RDW fared better than either APACHE II or SOFA, and the sum of RDW and APACHE II was a stronger predictor of mortality than either one alone.

Anemia in critical illness: insights into etiology, consequences, and management

Anemia is common in the intensive care unit, and may be associated with adverse consequences. However, current options for correcting anemia are not without problems and presently lack convincing efficacy for improving survival in critically ill patients. In this article we review normal red blood cell physiology; etiologies of anemia in the intensive care unit; its association with adverse outcomes; and the risks, benefits, and efficacy of various management strategies, including blood transfusion, erythropoietin, blood substitutes, iron therapy, and minimization of diagnostic phlebotomy.

Blood transfusion practice in critically ill patients: a single institutional experience

OBJECTIVES

To assess the transfusion practice in the intensive care unit (ICU) in a general hospital in Kuwait relative to indications, pretransfusion hemoglobin, red blood cell (RBC) use and outcome.

SUBJECTS AND METHODS

475 patients were admitted to the ICU during the study period (January 2009 to February 2010). Ninety-nine received RBC transfusion. Demographic, clinical and transfusion data were prospectively collected for the 99 patients who were followed up for 30 days, until hospital discharge, or death, whichever occurred first. Indications for RBC transfusion included hemorrhage in 39 patients, improving oxygen-carrying capacity in 55, and hemolysis in 5.

RESULTS

Of the 99 transfused patients, 22 (22.22%) were also transfused after discharge from the ICU. Transfusions were more frequent in patients admitted with respiratory failure (30, 30.3%), hemorrhagic shock (24, 24.2%), and septic shock (18, 18.4%). The mean pretransfusion hemoglobin in ICU transfusions was statistically different (70.9 ± 12.7 g/l) from transfusions after discharge (79.7 ± 9.4 g/l) (p < 0.001). Longer ICU stay was associated with more RBC units transfused per transfusion episode per patient (p < 0.001). The Sequential Organ Failure Assessment (SOFA) score was significantly associated with the number of RBC units transfused per patient (p = 0.006). Mortality was significantly associated with Acute Physiology and Chronic Health Evaluation II and SOFA scores, the need and duration for mechanical ventilation, and the length of stay in hospital.

CONCLUSION

Intensivists in our center followed a restrictive transfusion practice, by adopting a low pretransfusion hemoglobin threshold. Decisions on RBC transfusions seemed in most cases to be based on a 'transfusion trigger' rather than a physiologic need.

Red cell distribution width and all-cause mortality in critically ill patients

OBJECTIVE

Red cell distribution width is a predictor of mortality in the general population. The prevalence of increased red cell distribution width and its significance in the intensive care unit are unknown. The objective of this study was to investigate the association between red cell distribution width at the initiation of critical care and all cause mortality.

DESIGN

Multicenter observational study.

SETTING

Two tertiary academic hospitals in Boston, MA.

PATIENTS

A total of 51,413 patients, aged ≥ 18 yrs, who received critical care between 1997 and 2007.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The exposure of interest was red cell distribution width as a predictor of mortality in the general population. The prevalence of increased red cell distribution width and its significance in the intensive care unit are unknown and categorized a priori in quintiles as ≤ 13.3%, 13.3% to 14.0%, 14.0% to 14.7%, 14.7% to 15.8%, and >15.8%. Logistic regression examined death by days 30, 90, and 365 postcritical care initiation, inhospital mortality, and bloodstream infection. Adjusted odds ratios were estimated by multivariable logistic regression models. Adjustment included age, sex, race, Deyo-Charlson index, coronary artery bypass grafting, myocardial infarction, congestive heart failure, hematocrit, white blood cell count, mean corpuscular volume, blood urea nitrogen, red blood cell transfusion, sepsis, and creatinine. Red cell distribution width was a particularly strong predictor of all-cause mortality 30 days after critical care initiation with a significant risk gradient across red cell distribution width quintiles after multivariable adjustment: red cell distribution width 13.3% to 14.0% (odds ratio [OR], 1.19; 95% confidence interval [CI], 1.08-1.30; p <.001); red cell distribution width 14.0% to 14.7% (OR, 1.28; 95% CI, 1.16-1.42; p <.001); red cell distribution width 14.7% to 15.8% (OR, 1.69; 95% CI, 1.52-1.86; p <.001); red cell distribution width >15.8% (OR, 2.61; 95% CI, 2.37-2.86; p <.001), all relative to patients with red cell distribution width ≤ 13.3%. Similar significant robust associations postmultivariable adjustments are seen with death by days 90 and 365 postcritical care initiation as well as inhospital mortality. In a subanalysis of patients with blood cultures drawn (n = 18,525), red cell distribution width at critical care initiation was associated with the risk of bloodstream infection and remained significant after multivariable adjustment. The adjusted risk of bloodstream infection was 1.40- and 1.44-fold higher in patients with red cell distribution width values in the 14.7% to 15.8% and >15.8% quintiles, respectively, compared with those with red cell distribution width ≤ 13.3%. Estimating the receiver operating characteristic area under the curve shows that red cell distribution width has moderate discriminative power for 30-day mortality (area under the curve = 0.67).

CONCLUSION

Red cell distribution width is a robust predictor of the risk of all-cause patient mortality and bloodstream infection in the critically ill. Red cell distribution width is commonly measured, inexpensive, and widely available and may reflect overall inflammation, oxidative stress, or arterial underfilling in the critically ill.

Red blood cell transfusion in critically ill children: a narrative review

OBJECTIVE

To review the pathophysiology of anemia, as well as transfusion-related complications and indications for red blood cell (RBC) transfusion, in critically ill children. Although allogeneic blood has become increasingly safer from infectious agents, mounting evidence indicates that RBC transfusions are associated with complications and unfavorable outcomes. As a result, there has been growing interest and efforts to limit RBC transfusion, and indications are being revisited and revamped. Although a so-called restrictive RBC transfusion strategy has been shown to improve morbidity and mortality in critically ill adults, there have been relatively few studies on RBC transfusion performed in critically ill children.

DATA SOURCES

Published literature on transfusion medicine and outcomes of RBC transfusion. STUDY SELECTION, DATA EXTRACTION, AND SYNTHESIS: After a brief overview of physiology of oxygen transportation, anemia compensation, and current transfusion guidelines based on available literature, risks and outcomes of transfusion in general and in critically ill children are summarized in conjunction with studies investigating the safety of restrictive transfusion strategies in this patient population.

CONCLUSIONS

The available evidence does not support the extensive use of RBC transfusions in general or critically ill patients. Transfusions are still associated with risks, and although their benefits are established in limited situations, the associated negative outcomes in many more patients must be closely addressed. Given the frequency of anemia and its proven negative outcomes, transfusion decisions in the critically ill children should be based on individual patient's characteristics rather than generalized triggers, with consideration of potential risks and benefits, and available blood conservation strategies that can reduce transfusion needs.

Inflammation-induced hepcidin-25 is associated with the development of anemia in septic patients: an observational study

INTRODUCTION

Anemia is a frequently encountered problem during inflammation. Hepcidin is an interleukin-6 (IL-6)-induced key modulator of inflammation-associated anemia. Human sepsis is a prototypical inflammatory syndrome, often complicated by the development of anemia. However, the association between inflammation, hepcidin release and anemia has not been demonstrated in this group of patients. Therefore, we explored the association between hepcidin and sepsis-associated anemia.

METHODS

92 consecutive patients were enrolled after presentation on the emergency ward of a university hospital with sepsis, indicated by the presence of a proven or suspected infection and ≥ 2 extended systemic inflammatory response syndrome (SIRS) criteria. Blood was drawn at day 1, 2 and 3 after admission for the measurement of IL-6 and hepcidin-25. IL-6 levels were correlated with hepcidin concentrations. Hemoglobin levels and data of blood transfusions during 14 days after hospitalisation were retrieved and the rate of hemoglobin decrease was correlated to hepcidin levels.

RESULTS

53 men and 39 women with a mean age of 53.3 ± 1.8 yrs were included. Hepcidin levels were highest at admission (median[IQR]): 17.9[10.1 to 28.4]nmol/l and decreased to normal levels in most patients within 3 days (9.5[3.4 to 17.9]nmol/l). Hepcidin levels increased with the number of extended SIRS criteria (P = 0.0005). Highest IL-6 levels were measured at admission (125.0[46.3 to 330.0]pg/ml) and log-transformed IL-6 levels significantly correlated with hepcidin levels at admission (r = 0.28, P = 0.015), day 2 (r = 0.51, P < 0.0001) and day 3 (r = 0.46, P < 0.0001). Twelve patients received one or more blood transfusions during the first 2 weeks of admission, not related to active bleeding. These patients had borderline significant higher hepcidin level at admission compared to non-transfused patients (26.9[17.2 to 53.9] vs 17.9[9.9 to 28.8]nmol/l, P = 0.052). IL-6 concentrations did not differ between both groups. Correlation analyses showed significant associations between hepcidin levels on day 2 and 3 and the rate of decrease in hemoglobin (Spearman's r ranging from -0.32, P = 0.03 to -0.37, P = 0.016, respectively).

CONCLUSIONS

These data suggest that hepcidin-25 may be an important modulator of anemia in septic patients with systemic inflammation.

Erythropoetin as a novel agent with pleiotropic effects against acute lung injury

Current pharmacotherapy for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is not optimal, and the biological and physiological complexity of these severe lung injury syndromes requires consideration of combined-agent treatments or agents with pleiotropic action. In this regard, exogenous erythropoietin (EPO) represents a possible candidate since a number of preclinical studies have revealed beneficial effects of EPO administration in various experimental models of ALI. Taken together, this treatment strategy is not a single mediator approach, but it rather provides protection by modulating multiple levels of early signaling pathways involved in apoptosis, inflammation, and peroxidation, potentially restoring overall homeostasis. Furthermore, EPO appears to confer vascular protection by promoting angiogenesis. However, only preliminary studies exist and more experimental and clinical studies are necessary to clarify the efficacy and potentially cytoprotective mechanisms of EPO action. In addition to the attempts to optimize the dose and timing of EPO administration, it would be of great value to minimize any potential toxicity, which is essential for EPO to fulfill its role as a potential candidate for the treatment of ALI in routine clinical practice. The present article reviews recent advances that have elucidated biological and biochemical activities of EPO that may be potentially applicable for ALI/ARDS management.

Hepcidin in trauma: linking injury, inflammation, and anemia

BACKGROUND

Anemia is almost universal in trauma patients admitted to the intensive care unit (ICU). Hepcidin is a liver-derived peptide that is a negative regulator of iron stores. Hepcidin synthesis is suppressed by erythropoiesis and iron deficiency and upregulated by iron overload and inflammation. Hepcidin has been shown to have an important role in the anemia of chronic inflammatory diseases but has not been previously studied in the setting of trauma. We sought to define the link between traumatic injury, hepcidin, and inflammation.

METHODS

One hundred fifty trauma patients admitted to the ICU were prospectively enrolled in the study. Urine was collected at regular time points for hepcidin measurement. Serum for iron studies and measurement of those cytokines associated with acute inflammation was also collected.

RESULTS

The study population comprised 73% men. Mean age was 46 years, with a median Injury Severity Score (ISS) of 27. The mean lactate level was 2.9 mmol/L, and mean hemoglobin was 12.4 g/dL. More than 50% of patients were anemic on ICU admission, and nearly all were anemic by postinjury day 10. Urinary hepcidin levels were among the highest reported to date and had a rightward skew. Iron studies confirmed functional iron deficiency. Log hepcidin values were positively correlated with ISS and negatively correlated with admission Pao₂/FiO₂. Every increase in ISS by 10 was associated with a 40% increase in hepcidin. Initial hepcidin levels were positively correlated with duration of anemia.

CONCLUSIONS

Hepcidin levels rise to extremely high but variable levels after trauma and are positively correlated with injury severity measured by ISS and duration of anemia and negatively correlated with hypoxia. Hepcidin is likely a key factor in the impaired erythropoiesis seen in critically injured trauma patients.

Effects of blood conservation on the incidence of anemia and transfusions in pediatric parapneumonic effusion: a hospitalist perspective

BACKGROUND

Children with pneumonia may develop parapneumonic effusion (PNE). The associated inflammatory process and nutritional compromise can blunt erythropoesis. Traditional treatment for these children with PNE includes repeated phlebotomy and surgical intervention, resulting in ongoing blood losses. Blood transfusions used to treat acquired anemia are associated with multiple complications.

OBJECTIVES

This study evaluated the effect of hospitalists' implementation of blood conservation guidelines (BCG) on the incidence of anemia and transfusion requirements in children with PNE.

DESIGN

Retrospective cohort study of hospitalized children with PNE.

SETTINGS

University affiliated Children's Hospital.

PATIENTS

Children who were admitted to the hospital with PNE and managed using BCG (Group I) were compared to simultaneous no intervention group (S) and historical no intervention group (H). Group (I) and (S) were admitted from year 2000 to 2004 and the Group (H) were admitted from year 1997 to 1999.

MEASUREMENTS

Phlebotomy frequency and volume, measured hemoglobin (Hgb) levels, and the need for red blood transfusions.

RESULTS

Children in the BCG group (n = 24) compared to simultaneous no intervention group (n = 28) and historical no intervention group (n = 29) had lesser phlebotomy volumes (14 ± 8, 18 ± 14 and 69 ± 66 mL; P = 0.001), trend toward lesser Hgb drop (1.7 ± 1.4, 2.1 ± 1.2 and 2 ± 1.4 gm%; P ≤ 0.37), and lesser incidence of transfusion (8%, 18% and 31%; P = 0.11). Transfused children were younger (3.5 ± vs. 6.4 ± 4 years; P = 0.001) and had lower initial Hgb (9.9 ± 1 vs. 11.4 ± 1 gm%; P = 0.001), more phlebotomy (5.9 ± 7 vs. 1.1 ± 1 mL/kg., P = 0.001), longer hospitalization (18.7 ± 5 vs. 11.1 ± days; P = 0.001), and slightly higher (pediatric risk of mortality [PRISM]) scores (3.4 ± 5.7 vs. 1.6 ± 2.7; P = 0.25).

CONCLUSION

Implementing BCG lowers phlebotomy losses and the need for transfusion.

Roles of Intravenous Iron Therapy in Various Patient Settings

Objective:

To provide clinical information on intravenous iron products and their role in chronic kidney disease (CKD), dialysis, oncology, critical illness, and heart failure.

Data Sources:

Intravenous iron products information, national clinical practice guidelines, and the latest primary literature available were reviewed. PubMed and MEDLINE databases were searched from January 2000-December 2009.

Study Selection and Data Extraction:

All FDA-approved intravenous iron products information, available national clinical practice guidelines, and primary literature were included.

Data Synthesis:

Iron deficiency is common in patients with CKD, dialysis, oncology, critical illness, and heart failure. Routine supplementation with intravenous iron therapy is indicated in patients with CKD, including those receiving dialysis; however, its role in oncology, critical illness, and heart failure is not clearly defined. Assessing patients for iron deficiency, evaluating their status, and knowing the risks of adverse events are important in determining the roles of intravenous iron therapy in each setting. If patients are initiated on intravenous iron, they must be closely monitored for signs and symptoms of adverse drug reactions, as well as clinical worsening. Additionally, intravenous iron must be discontinued upon resolution of iron deficiency.

Conclusions:

The importance of intravenous iron therapy is well established in patients with CKD, including those receiving dialysis, who have iron deficiency. Its roles in oncology, critical illness, and heart failure should be assessed on a case-by-case basis.

Bench to bedside: A role for erythropoietin in sepsis

Sepsis is the systemic inflammatory response to infection and can result in multiple organ dysfunction syndrome with associated high mortality, morbidity and health costs. Erythropoietin is a well-established treatment for the anaemia of renal failure due to its anti-apoptotic effects on red blood cells and their precursors. The extra-haemopoietic actions of erythropoietin include vasopressor, anti-apoptotic, cytoprotective and immunomodulating actions, all of which could prove beneficial in sepsis. Attenuation of organ dysfunction has been shown in several animal models and its vasopressor effects have been well characterised in laboratory and clinical settings. Clinical trials of erythropoietin in single organ disorders have suggested promising cytoprotective effects, and while no randomised trials have been performed in patients with sepsis, good quality data exist from studies on anaemia in critically ill patients, giving useful information of its pharmacokinetics and potential for harm. An observational cohort study examining the microvascular effects of erythropoietin is underway and the evidence would support further phase II and III clinical trials examining this molecule as an adjunctive treatment in sepsis.

Hemoglobin concentration variations over time in general medical inpatients

BACKGROUND

A decrease in hemoglobin concentration [Hb] with no apparent cause is frequently observed in critically ill patients. Scarce information is available about this situation in general ward-admitted patients (GWAP).

OBJECTIVES

To describe [Hb] variation with no obvious cause in GWAP, and to estimate the prevalence and predictors of patients with [Hb] decreases > or =1.5 g/dL.

DESIGN, SETTING AND PATIENTS

Prospective, observational study in internal medicine GWAP, carried out at two teaching hospitals in Buenos Aires, Argentina. Patients with a history of, or admitted for diseases associated with decreases in [Hb], as well as those with length of stay less than three days, were excluded.

MEASUREMENTS

Upon hospitalization, complete personal and clinical data were recorded. Furthermore, Katz index, APACHE II acute physiology score (APS) and Charlson score were calculated. [Hb] and hematocrit (HCT) were also assessed during hospitalization.

RESULTS

A total of 338 patients were evaluated, 131 were included. A mean [Hb] decrease of 0.71 g/dL was observed between admission and discharge (P < 0.001; 95% CI, 0.47-0.97). Forty-five percent of the included patients had decreases in [Hb] > or = 1.5 g/dL. This was associated with a higher APS, a higher [Hb] at admission, and a discharge diagnosis of infectious or gastrointestinal disease. No bleeding episodes were observed.

CONCLUSIONS

An [Hb] decrease was frequently observed during GWAP hospitalization with no evident blood loss. Even though this decrease has multiple causes, the severity of the acute illness seems to play a major role.

Red blood cell transfusion in the treatment and management of anaemia: the search for the elusive transfusion trigger

Therapeutic red blood cell (RBC) transfusion is widely utilized in the management of anaemia. Critically ill intensive care unit (ICU) patients in particular, as well as medical and haematology-oncology patients, are among the largest groups of users of RBC products. While anaemia is common in these patients, its treatment and management, including appropriate thresholds for RBC transfusion, remain controversial. We review here the function of RBCs in oxygen transport and physiology, with a view to their role in supporting and maintaining systemic tissue oxygenation. Adaptive and physiological compensatory mechanisms in the setting of anaemia are discussed, along with the limits of compensation. Finally, data from clinical studies will be examined in search of evidence for, or against, a clinically relevant transfusion trigger.

A Role for Erythropoietin in the Attenuation of Radiocontrast-Induced Acute Renal Failure in Rats

BACKGROUND

Radiocontrast-induced nephropathy (CIN) remains an important iatrogenic cause of acute renal failure in high-risk patients, despite the development of safer contrast media, the improvement of hydration protocols, and the introduction of additional preventive strategies. Erythropoietin (EPO) pretreatment may confer protection against acute renal failure through the induction of stress response genes.

METHODS

The effect of EPO has been evaluated in a rat model of CIN, induced by iothalamate, following the inhibition of nitric oxide- and prostaglandin-synthesis with indomethacin and N(omega) nitro-L-arginine methyl ester (L-NAME). Twenty-two male Sprague-Dawley rats were subjected to saline (CTR) or EPO injections (3000 U/kg and 600 U/kg, 24 and 2 h before the induction of CIN, respectively).

RESULTS

The decline in creatinine clearance in CTR animals from 0.38 +/- 0.03 to 0.28 +/- 0.03 mL/min/100 g (p < 0.005), was prevented by EPO pretreatment (from 0.34 +/- 0.02 to 0.32 +/- 0.03 mL/min/100 g, NS). The extent of medullary thick ascending limb- and S3-tubular damage in the outer medulla, however, was comparable in the two experimental groups.

CONCLUSIONS

EPO pretreatment prevents renal dysfunction in a rat model of CIN. Further experimental and clinical studies are required to confirm these preliminary conclusions regarding a potential protective potency of EPO against CIN.

Randomized, double-blind, placebo-controlled trial of effects of enteral iron supplementation on anemia and risk of infection during surgical critical illness

BACKGROUND

Critical illness is characterized by hypoferremia, iron-deficient erythropoiesis (IDE), and anemia. The relative risks and benefits of iron supplementation in this setting are unknown.

METHODS

Anemic, critically ill surgical patients with an expected intensive care unit length of stay (ULOS) >or= 5 days were randomized to either enteral iron supplementation (ferrous sulfate 325 mg three times daily) or placebo until hospital discharge. Outcomes included hematocrit, iron markers (i.e., serum concentrations of iron, ferritin, and erythrocyte zinc protoporphyrin [eZPP]), red blood cell (RBC) transfusion, transfusion rate (mL RBC/study day), nosocomial infection, antibiotic days, study length of stay (LOS), ULOS, and death. Iron-deficient erythropoiesis was defined as an elevated eZPP concentration.

RESULTS

Two hundred patients were randomized; 97 received iron, and 103 received placebo. Socio-demographics, baseline acuity, hematocrit, and iron markers were similar in the two groups. No differences were observed between the iron and placebo groups with respect to either hematocrit or iron markers following up to 28 days. However, patients treated with iron were significantly less likely to receive an RBC transfusion (29.9% vs. 44.7%, respectively; p = 0.03) and had a significantly lower transfusion rate (22.0 mL/day vs. 29.9 mL/day; p = 0.03). Subgroup analysis revealed that these differences were observed in patients with baseline IDE only. Iron and placebo groups did not differ with respect to incidence of infection (46.8% vs. 48.9%; p = 0.98), antibiotic days (14 vs. 16; p = 0.45), LOS (14 vs. 16 days; p = 0.24), ULOS (12 vs. 14 days; p = 0.69), or mortality rate (9.4% vs. 9.9%; p = 0.62).

CONCLUSIONS

Enteral iron supplementation of anemic, critically ill surgical patients does not increase the risk of infection and may benefit those with baseline IDE by decreasing the risk of RBC transfusion. A trial comparing enteral and parenteral iron supplementation in this setting is warranted (ClinicalTrials.gov number, NCT00450177).

Anemia and red blood cell transfusion in neurocritical care

INTRODUCTION

Anemia is one of the most common medical complications to be encountered in critically ill patients. Based on the results of clinical trials, transfusion practices across the world have generally become more restrictive. However, because reduced oxygen delivery contributes to 'secondary' cerebral injury, anemia may not be as well tolerated among neurocritical care patients.

METHODS

The first portion of this paper is a narrative review of the physiologic implications of anemia, hemodilution, and transfusion in the setting of brain-injury and stroke. The second portion is a systematic review to identify studies assessing the association between anemia or the use of red blood cell transfusions and relevant clinical outcomes in various neurocritical care populations.

RESULTS

There have been no randomized controlled trials that have adequately assessed optimal transfusion thresholds specifically among brain-injured patients. The importance of ischemia and the implications of anemia are not necessarily the same for all neurocritical care conditions. Nevertheless, there exists an extensive body of experimental work, as well as human observational and physiologic studies, which have advanced knowledge in this area and provide some guidance to clinicians. Lower hemoglobin concentrations are consistently associated with worse physiologic parameters and clinical outcomes; however, this relationship may not be altered by more aggressive use of red blood cell transfusions.

CONCLUSIONS

Although hemoglobin concentrations as low as 7 g/dl are well tolerated in most critical care patients, such a severe degree of anemia could be harmful in brain-injured patients. Randomized controlled trials of different transfusion thresholds, specifically in neurocritical care settings, are required. The impact of the duration of blood storage on the neurologic implications of transfusion also requires further investigation.

A critical appraisal of "transfusion strategies for patients in pediatric intensive care units" by Lacroix J, Hebert PC, Hutchison, et al (N Engl J Med 2007; 356:1609-1619)

OBJECTIVE

To review the findings and discuss the implications of transfusion strategies in stable critically ill children.

DESIGN

A critical appraisal of the article "Transfusion strategies for patients in pediatric intensive care units" by Lacroix J, Hebert PC, Hutchison, et al, published in the N Engl J Med in 2007 with literature review.

FINDINGS

In this prospective, randomized, controlled, noninferiority trial the authors compared a liberal transfusion strategy, using a transfusion threshold of 9 g/dL, to a conservative transfusion strategy, using a transfusion threshold of 7 g/dL. The primary end point was multiple organ dysfunction syndrome (MODS) or progression of MODS. The authors found that when comparing the restrictive transfusion strategy to the liberal strategy, the absolute risk reduction for developing new or progressive MODS was only 0.4% (95% confidence interval, -4.6 -5.5). Using the restrictive protocol, the number needed to treat to prevent one red blood cell (RBC) transfusion was only two. The number of RBC units per patient in the restrictive group was 0.9, and in the liberal group was 1.7 (p < 0.001). When comparing the two strategies there was a relative reduction of 96% in the number of patients who had any transfusion exposure and a relative decrease of 44% in the number of transfusions administered in the restrictive strategy.

CONCLUSIONS

Using a restrictive transfusion protocol with a transfusion threshold of 7 g/dL in stable critically ill children is as safe as using a liberal protocol and can decrease the number of patients exposed to RBC transfusions.

A US multicenter, retrospective, observational study of erythropoiesis-stimulating agent utilization in anemic, critically ill patients admitted to the intensive care unit

BACKGROUND

Anemia is a common comorbid condition among patients admitted to the intensive care unit (ICU). Darbepoietin alfa and epoetin alfa are erythropoiesis-stimulating agents (ESAs) used to manage anemia in the ICU, although neither drug has an indication in critically ill patients.

OBJECTIVE

This study describes ESA practice patterns in anemic, critically ill patients admitted to the ICU.

METHODS

A total of 19 hospitals participated in this US multicenter, retrospective, observational study of adult patients not receiving chronic hemodialysis who were admitted to the ICU for >or=24 hours between February 2005 and September 2005 and who received >or=1 dose of darbepoietin alfa or epoetin alfa. Data on ESA doses, dosing frequencies, hemoglobin levels, and red blood cell (RBC) transfusions were abstracted from electronic medical records.

RESULTS

A total of 438 patients were included in the analysis, of whom 201 (46%) were treated with darbepoietin alfa and 237 (54%) were treated with epoetin alfa. In the respective groups, similar proportions were male (121/201 [60%] and 126/237 [53%]) and white (146/195 [75%] and 140/184 [76%]); age was also similar (mean [SD], 62 [19] and 60 [18] years). The mean (SD) dose during the first week of ICU stay was 96.5 (40.5) microg with darbepoietin alfa and 33,439 (23,508) U with epoetin alfa. The most commonly prescribed dosing frequency with darbepoietin alfa was once weekly (88.1% of all prescribed doses), with a mean (SD) number of injections of 1.8 (1.75). With epoetin alfa, the most common dosing frequencies were 3 times weekly (35.9%), 1-time dosing (28.5%), and once weekly (24.0%), with a mean (SD) number of injections of 2.9 (4.2). In both groups, the duration of therapy was <or=1 week in ~50% of patients, and the mean change in hemoglobin concentration was 0.8 g/dL. Overall, 47% (darbepoietin alfa) and 44% (epoetin alfa) of patients were RBC transfusion independent (ie, did not require a transfusion during their ICU or hospital stay) after receiving the first ESA dose.

CONCLUSION

Based on these results, it is apparent that the practice patterns associated with ESA treatment of critically ill patients admitted to the ICU between February 2005 and September 2005 were highly variable.

Anemia of critical illness

Anemia of critical illness, a commonly encountered clinical situation, is hematologically similar to that of chronic anemia, except that the onset is generally sudden. The etiology is usually multifactorial, occurring as a consequence of direct inhibitory effects of inflammatory cytokines, erythropoietin deficiency, blunted erythropoietic response, blood loss, nutritional deficiencies, and renal insufficiency. Although anemia is not well tolerated by critically ill patients, aggressive treatment of anemia can be just as detrimental as no treatment. Different types of anemia may coexist in a patient in the intensive care unit, making diagnosis and differentiation among these anemias complex, therefore requiring good diagnostic skills. Although several therapeutic options are available to treat anemia, critically ill patients often receive a transfusion, and yet, most recent studies indicate that blood transfusions in critically ill patients are associated with worse outcomes, including higher morbidity and mortality. These studies have generated interest in the administration of exogenous erythropoietin and iron therapy. Unfortunately, the accurate determination of iron status can be a rather difficult task, an undertaking that is made even more difficult by the presence of comorbid conditions that can affect the commonly used parameters for guiding iron therapy. The use of erythropoiesis-stimulating agents is rapidly gaining acceptance, although they also present potential problems of their own.

Anemia in the Critically Ill Patient

Anemia in critically ill patients has been described as an acute form of anemia of inflammatory disease and is characterized by a blunted erythropoietic response due in part to proinflammatory mediators. Management of anemia in critically ill patients is a complex issue and is best approached via a multiprofessional team regarding the use of allogenic blood, iron, nutritional therapy, and erythropoietic agents. Indiscriminant, ``routine'' red blood cell transfusions may not only be unnecessary, but may pose unnecessary risk to the intensive care unit patient. Most intensive care unit patients can tolerate lower hemoglobin/hematocrit concentrations than the typically accepted ``10/30 rule.'' Lower transfusion triggers with an overall transfusion strategy is warranted in the intensive care unit patient. The use of recombinant human erythropoietic agents may not be necessary with appropriate transfusion practices.

Anemia of Inflammation in Critically Ill Patients

Anemia is seen frequently in critically ill patients and has several etiologies. This article reviews the causes with an emphasis on the effects of inflammation, examines the risks and benefits of current therapies, and discusses novel treatment options.

Erythropoietin measurements in severely traumatized patients

BACKGROUND

Despite numerous studies in critically ill patients, physiological adaptation to acute anaemia and the pattern of erythropoietin (EPO) secretion has not been well described in severely injured patients. The aim of this study was to describe EPO secretion and its relationship with haemoglobin (Hb) levels in severely injured patients.

METHODS

We performed an observational, prospective clinical study in our intensive care unit (ICU). For all patients with severe trauma (Injury Severity Score>15), EPO measurement was obtained on admission, during the first 3 days and then when Hb level was measured. Maximal EPO level (EPOmax) and minimal Hb level (Hbmin) during the ICU stay was determined for all patients.

RESULTS

One hundred and seventy-one consecutives patients were included (440 EPO measurements). Seventy-nine patients (46.2%) showed an increased value (> or =25 UI/l) EPOmax value. Most EPOmax values were observed early after the trauma [within 4 days for 63 patients (82.8%)]. Plotting EPOmax to Hbmin values show that a threshold Hbmin value of 105 g/l best discriminated patients with and without an elevated EPO secretion. Less than 10% of the patients with Hbmin<105 g/l did not increase their EPO secretion.

CONCLUSION

In severely traumatized patients a marked response to acute anaemia is observed in most patients. In our study, Hb threshold for a significant EPO secretion following post-traumatic acute anaemia was 105 g/l. The peak level was achieved early in the course of the anaemia.

Impaired erythropoiesis after haemorrhagic shock in mice is associated with erythroid progenitor apoptosis in vivo

OBJECTIVE

Multiply traumatised patients often suffer from blood loss and from subsequent therapy-resistant anaemia, possibly mediated by apoptosis, necrosis, or humoral factors. Therefore, the underlying mechanisms were investigated in bone marrow (BM) and peripheral blood in a murine resuscitated haemorrhagic shock (HS) model.

METHODS

In healthy male mice, pressure-controlled HS was induced for 60 min. The BM was analysed for Annexin-V, 7-amino-actinomycin D, apoptotic enzymes (caspases-3/7, -8, and -9), expression of death receptors (CD120a, CD95), mitochondrial proteins (Bax, Bcl-2, Bcl-x), as well as erythropoietin (EPO) receptor (EPO-R). Blood cell count, peripheral EPO, and tumour necrosis factor-alpha response were additionally monitored.

RESULTS

Twenty-four and 72 h after HS, EPO and EPO-R were strongly up-regulated in peripheral blood and BM, respectively. Decreasing numbers of erythroid progenitors in BM after HS correlated with significant apoptotic changes confirmed by increased caspases-3/7, -8, -9 activity in total BM, death receptor CD95 and CD120a expression on erythroid progenitors, and down-regulated mitochondrial Bcl-2 expression in total BM. Erythroid progenitors in peripheral blood were found to be increased after 72 h.

CONCLUSION

Despite the massive EPO response and up-regulation of EPO-R, BM erythroblasts (EBs) decreased. This could be due to deficient maturation of erythroid progenitors. Furthermore, the increased intrinsic and extrinsic apoptosis activation suggests programmed death of erythroid progenitors. We propose that both apoptosis and negatively regulated erythropoiesis contribute to BM dysfunction, while erythroid progenitor egress plays an additional role.

Anemia, blood loss, and blood transfusions in North American children in the intensive care unit

RATIONALE

Minimizing exposure of children to blood products is desirable.

OBJECTIVES

We aimed to understand anemia development, blood loss, and red blood cell (RBC) transfusions in the pediatric intensive care unit (PICU).

METHODS

Prospective, multicenter, 6-month observational study in 30 PICUs. Data were collected on consecutive children (<18 yr old) in the PICU for 48 hours or more.

MEASUREMENTS AND MAIN RESULTS

Anemia development, blood loss, and RBC transfusions were measured. A total of 977 children were enrolled. Most (74%) children were anemic in the PICU (33% on admission, 41% developed anemia). Blood draws accounted for 73% of daily blood loss; median loss was 5.0 ml/day. Forty-nine percent of children received transfusions; 74% of first transfusions were on Days 1-2. After adjusting for age and illness severity, compared with nontransfused children, children who underwent transfusion had significantly longer days of mechanical ventilation (2.1 d, P < 0.001) and PICU stay (1.8 d, P = 0.03), and had increased mortality (odds ratio [OR], 11.6; 95% confidence interval [CI], 1.43-90.9; P = 0.02), nosocomial infections (OR, 1.9; 95% CI, 1.2-3.0; P = 0.004), and cardiorespiratory dysfunction (OR, 2.1; 95% CI, 1.5-3.0; P < 0.001). High blood loss per kilogram body weight from blood draws (OR, 1.11; 95% CI, 1.03-1.2; P = 0.01) was associated with RBC transfusion more than 48 hours after admission. The most common indication for transfusion was low hemoglobin (42%). Pretransfusion hemoglobin values varied greatly (mean, 9.7 +/- 2.7 g/dl).

CONCLUSIONS

Critically ill children are at significant risk for developing anemia and receiving blood transfusions. Transfusion in the PICU was associated with worse outcomes. It is imperative to minimize blood loss from blood draws and to set clear transfusion thresholds.

Erythropoietin improves skeletal muscle microcirculation and tissue bioenergetics in a mouse sepsis model

Introduction

The relationship between oxygen delivery and consumption in sepsis is impaired, suggesting a microcirculatory perfusion defect. Recombinant human erythropoietin (rHuEPO) regulates erythropoiesis and also exerts complex actions promoting the maintenance of homeostasis of the organism under stress. The objective of this study was to test the hypothesis that rHuEPO could improve skeletal muscle capillary perfusion and tissue oxygenation in sepsis.

Methods

Septic mice in three experiments received rHu-EPO 400 U/kg subcutaneously 18 hours after cecal ligation and perforation (CLP). The first experiment measured the acute effects of rHuEPO on hemodynamics, blood counts, and arterial lactate level. The next two sets of experiments used intravital microscopy to observe capillary perfusion and nicotinamide adenine dinucleotide (NADH) fluorescence post-CLP after treatment with rHuEPO every 10 minutes for 40 minutes and at 6 hours. Perfused capillary density during a three-minute observation period and NADH fluorescence were measured.

Results

rHuEPO did not have any effects on blood pressure, lactate level, or blood cell numbers. CLP mice demonstrated a 22% decrease in perfused capillary density compared to the sham group (28.5 versus 36.6 capillaries per millimeter; p < 0.001). Treatment of CLP mice with rHuEPO resulted in an immediate and significant increase in perfused capillaries in the CLP group at all time points compared to baseline from 28.5 to 33.6 capillaries per millimeter at 40 minutes; p < 0.001. A significant increase in baseline NADH, suggesting tissue hypoxia, was noted in the CLP mice compared to the sham group (48.3 versus 43.9 fluorescence units [FU]; p = 0.03) and improved with rHuEPO from 48.3 to 44.4 FU at 40 minutes (p = 0.02). Six hours after treatment with rHuEPO, CLP mice demonstrated a higher mean perfused capillary density (39.4 versus 31.7 capillaries per millimeter; p < 0.001) and a lower mean NADH fluorescence as compared to CLP+normal saline mice (49.4 versus 52.7 FU; p = 0.03).

Conclusion

rHuEPO produced an immediate increase in capillary perfusion and decrease in NADH fluorescence in skeletal muscle. Thus, it appears that rHuEPO improves tissue bioenergetics, which is sustained for at least six hours in this murine sepsis model.

A meta-analysis of randomized controlled trials in critically ill patients to evaluate the dose-response effect of erythropoietin

The use of erythropoietin in critically ill patients has been investigated in multiple randomized clinical trials and its role in decreasing the number of units of blood transfused has been demonstrated in some trials. A meta-analysis was conducted to determine the pooled estimate of the decrease in number of units of blood transfused with the use of erythropoietin and investigated its dose-response effect. A systematic search was performed of the MEDLINE, EMBASE, and the Current Controlled Trials Register to identify randomized clinical trials investigating the role of erythropoietin in critically ill patients. Of 664 studies identified in the search, 5 randomized clinical trials met the inclusion criteria. The pooled estimate of the decrease of number of units of blood transfused was -1.64 (95% CI -2.6 to -0.67). Sensitivity analysis to establish the influence of temporal bias, quality of the study and comorbidities such as age and Acute Physiology and Chronic Health Evaluation (APACHE) II score were undertaken and did not reveal a significant difference. The inclusion of studies with higher doses of erythropoietin revealed a greater decrease in the number of units of blood transfused (-2.15; 95% CI -3.06 to -1.24). Despite the limitations of a meta-analysis we believe that the use of erythropoietin significantly decreases the number of units of blood transfused per patient. Our study also reveals the possibility of a dose-response effect of erythropoietin in decreasing the number of units of blood transfused.

Efficacy and safety of epoetin alfa in critically ill patients

BACKGROUND

Anemia, which is common in the critically ill, is often treated with red-cell transfusions, which are associated with poor clinical outcomes. We hypothesized that therapy with recombinant human erythropoietin (epoetin alfa) might reduce the need for red-cell transfusions.

METHODS

In this prospective, randomized, placebo-controlled trial, we enrolled 1460 medical, surgical, or trauma patients between 48 and 96 hours after admission to the intensive care unit. Epoetin alfa (40,000 U) or placebo was administered weekly, for a maximum of 3 weeks; patients were followed for 140 days. The primary end point was the percentage of patients who received a red-cell transfusion. Secondary end points were the number of red-cell units transfused, mortality, and the change in hemoglobin concentration from baseline.

RESULTS

As compared with the use of placebo, epoetin alfa therapy did not result in a decrease in either the number of patients who received a red-cell transfusion (relative risk for the epoetin alfa group vs. the placebo group, 0.95; 95% confidence interval [CI], 0.85 to 1.06) or the mean (+/-SD) number of red-cell units transfused (4.5+/-4.6 units in the epoetin alfa group and 4.3+/-4.8 units in the placebo group, P=0.42). However, the hemoglobin concentration at day 29 increased more in the epoetin alfa group than in the placebo group (1.6+/-2.0 g per deciliter vs. 1.2+/-1.8 g per deciliter, P<0.001). Mortality tended to be lower at day 29 among patients receiving epoetin alfa (adjusted hazard ratio, 0.79; 95% CI, 0.56 to 1.10); this effect was also seen in prespecified analyses in those with a diagnosis of trauma (adjusted hazard ratio, 0.37; 95% CI, 0.19 to 0.72). A similar pattern was seen at day 140 (adjusted hazard ratio, 0.86; 95% CI, 0.65 to 1.13), particularly in those with trauma (adjusted hazard ratio, 0.40; 95% CI, 0.23 to 0.69). As compared with placebo, epoetin alfa was associated with a significant increase in the incidence of thrombotic events (hazard ratio, 1.41; 95% CI, 1.06 to 1.86).

CONCLUSIONS

The use of epoetin alfa does not reduce the incidence of red-cell transfusion among critically ill patients, but it may reduce mortality in patients with trauma. Treatment with epoetin alfa is associated with an increase in the incidence of thrombotic events. (ClinicalTrials.gov number, NCT00091910 [ClinicalTrials.gov].).

Blood tranfusion in critically ill patients: state of the art

Anemia is one of the most common abnormal findings in critically ill patients, and many of these patients will receive a blood transfusion during their intensive care unit stay. However, the determinants of exactly which patients do receive transfusions remains to be defined and have been the subject of considerable debate in recent years. Concerns and doubts have emerged regarding the benefits and safety of blood transfusion, in part due to the lack of evidence of better outcomes resulting from randomized studies and in part related to the observations that transfusion may increase the risk of infection. As a result of these concerns and of several studies suggesting better or similar outcomes with a lower transfusion trigger, there has been a general tendency to decrease the transfusion threshold from the classic 10 g/dL to lower values. In this review, we focus on some of the key studies providing insight into current transfusion practices and fueling the current debate on the ideal transfusion trigger.

Comparison of darbepoetin alfa and epoetin alfa in the management of anemia of critical illness

STUDY OBJECTIVE

To compare the effectiveness of darbepoetin alfa with epoetin alfa (recombinant human erythropoietin [rHuEPO]) for achieving transfusion independence and increasing hemoglobin concentrations in critically ill patients.

DESIGN

Retrospective, descriptive study.

SETTING

Level I trauma center intensive care units.

PATIENTS

Seventy-two patients who spent at least 3 days in the cardio-thoracic, medical, or surgery-trauma intensive care units and received at least one weekly dose of rHuEPO 40,000 units (33 patients) or darbepoetin alfa 100 microg (39 patients).

MEASUREMENTS AND MAIN RESULTS

Number of rHuEPO and darbepoetin alfa doses, hemoglobin concentrations, and cumulative number of transfusions were recorded for up to 28 days after the first dose was given, and the data were statistically analyzed. Beginning a median of 10 days after the patients were admitted to the intensive care unit, they received a median of 3.5 doses of darbepoetin alfa or 4 doses of rHuEPO. Mean hemoglobin concentrations at which treatment with darbepoetin alfa and rHuEPO were started were 8 and 8.2 g/dl, respectively (p=0.41). Transfusion independence was achieved in 44% of patients in the darbepoetin alfa group compared with 36% of patients in the rHuEPO group (p=0.63). Patients in both groups received a mean of 2.7 units of packed red blood cells during the 28-day study period. The mean change in hemoglobin levels from baseline over time did not significantly differ between groups (p=0.75).

CONCLUSIONS

Patients receiving darbepoetin alfa 100 microg/week and those receiving rHuEPO 40,000 units/week for anemia of critical illness achieved similar rates of transfusion independence and increases in hemoglobin concentrations from baseline at 28 days. Compared with previously published studies, erythropoietic agents were administered late in the course of critical illness in response to low hemoglobin concentrations.