Erythropoietin response is blunted in critically ill patients

The hematologic system as a marker of organ dysfunction in sepsis

Sepsis with acute organ dysfunction (severe sepsis) results from a systemic proinflammatory and procoagulant response to infection. Organ dysfunction in the patient with sepsis is associated with increased mortality. Although most organs have discrete anatomical boundaries and carry out unified functions, the hematologic system is poorly circumscribed and serves several unrelated functions. This review addresses the hematologic changes associated with sepsis and provides a framework for prompt diagnosis and rational drug therapy. Data sources used include published research and review articles in the English language related to hematologic alterations in animal models of sepsis and in critically ill patients. Hematologic changes are present in virtually every patient with severe sepsis. Leukocytosis, anemia, thrombocytopenia, and activation of the coagulation cascade are the most common abnormalities. Despite theoretical advantages of using granulocyte colony-stimulating factor to enhance leukocyte function and/or circulating numbers, large clinical trials with these growth factors are lacking. Recent studies support a reduction in the red blood cell transfusion threshold and the use of erythropoietin treatment to reduce transfusion requirements. Treatment of thrombocytopenia depends on the cause and clinical context but may include platelet transfusions and discontinuation of heparin or other inciting drugs. The use of activated protein C may provide a survival benefit in subsets of patients with severe sepsis. The hematologic system should not be overlooked when assessing a patient with severe sepsis. A thorough clinical evaluation and panel of laboratory tests that relate to this organ system should be as much a part of the work-up as taking the patient's blood pressure, monitoring renal function, or measuring liver enzymes.

Time course of hemoglobin concentrations in nonbleeding intensive care unit patients

OBJECTIVES

To evaluate the time course of hemoglobin concentrations in nonbleeding intensive care unit patients.

DESIGN

Prospective, observational study.

SETTING

Multidisciplinary (medicosurgical) department of intensive care.

PATIENTS

Ninety-one patients with no evidence of recent or active blood loss, no history of hematologic disease or chronic renal failure, and no need for extracorporeal epuration techniques.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data collection included primary diagnoses, Acute Physiology and Chronic Health Evaluation II and sepsis-related organ failure assessment scores, signs of sepsis, 24-hr fluid balance, and hemoglobin concentrations. For the entire intensive care unit stay, the fall in hemoglobin concentrations (calculated from the mean of individual slopes of hemoglobin concentrations over time) averaged 0.52 +/- 0.69 g/dL/day. For the 33 patients who stayed in the intensive care unit for >3 days, this decline was larger for the first 3 days than for subsequent days (0.66 +/- 0.84 g/dL/day vs. 0.12 +/- 0.29 g/dL/day; p<.01). After the third intensive care unit day, the change in hemoglobin concentrations was inversely related to the severity of the disease, as reflected by the Acute Physiology and Chronic Health Evaluation II and the sepsis-related organ failure assessment scores. Hemoglobin concentrations decreased by 0.44 +/- 0.70 g/dL/day in the nonseptic and 0.68 +/- 0.66 g/dL/day in the septic patients (p =.13). After the third intensive care unit day, hemoglobin concentrations continued to decrease in the septic patients but not in the nonseptic patients (-0.29 +/- 0.19 vs. 0.006 +/- 0.3 g/dL/day; p=.0016). The fall in hemoglobin concentrations was not significantly related to the fluid balance. The volume of blood drawn daily for laboratory studies was 40.3 +/- 15.4 mL: 49.0 +/- 11.3 mL in the septic patients and 36.7 +/- 14.9 mL in the nonseptic patients (p =.04).

CONCLUSIONS

Hemoglobin concentrations typically decline by >0.5 g/dL/day during the first days of intensive care unit stay in nonbleeding patients. Beyond the third day, hemoglobin concentrations can remain relatively constant in nonseptic patients but continue to decrease in septic patients, as well as patients with high sepsis-related organ failure assessment or Acute Physiology and Chronic Health Evaluation II scores. These observations may help in the interpretation of hemoglobin concentrations in critically ill patients.

Erythropoietin mimics the acute phase response in critical illness

BACKGROUND

In a prospective observational study, we examined the temporal relationships between serum erythropoietin (EPO) levels, haemoglobin concentration and the inflammatory response in critically ill patients with and without acute renal failure (ARF).

PATIENTS AND METHOD

Twenty-five critically ill patients, from general and cardiac intensive care units (ICUs) in a university hospital, were studied. Eight had ARF and 17 had normal or mildly impaired renal function. The comparator group included 82 nonhospitalized patients with normal renal function and varying haemoglobin concentrations. In the patients, levels of haemoglobin, serum EPO, C-reactive protein, IL-1beta, IL-6, serum iron, ferritin, vitamin B12 and folate were measured, and Coombs test was performed from ICU admission until discharge or death. Concurrent EPO and haemoglobin levels were measured in the comparator group.

RESULTS

EPO levels were initially high in patients with ARF, falling to normal or low levels by day 3. Thereafter, almost all ICU patients demonstrated normal or low EPO levels despite progressive anaemia. IL-6 exhibited a similar initial pattern, but levels remained elevated during the chronic phase of critical illness. IL-1beta was undetectable. Critically ill patients could not be distinguished from nonhospitalized anaemic patients on the basis of EPO levels.

CONCLUSION

EPO levels are markedly elevated in the initial phase of critical illness with ARF. In the chronic phase of critical illness, EPO levels are the same for patients with and those without ARF, and cannot be distinguished from noncritically ill patients with varying haemoglobin concentrations. Exogenous EPO therapy is unlikely to be effective in the first few days of critical illness.

Blood Transfusion Issues in the Critically Ill

Anemia is a common clinical problem seen in the critically ill and results in a large RBC transfusion requirement for these patients. The view that RBC transfusion is risk-free is no longer tenable today. There is the accumulating evidence that allogeneic blood transfusion is immunosuppressive. More reently, attention has focused on the age of RBCs transfused. Transfused RBCs, especially during the time period immeditely following transfusion, are not normal. The duration of RBC storage may be an important determinant of the efficacy of RBCs as oxygen carriers as well as a determinant of transusion related morbidity. Adding to the controversy about risk/benefit ratio for RBC transfusion are recent data showing that an aggressive RBC transfusion strategy may decrease the likelihood of survival in selected subpopulations of critically ill adults. The optimal hematocrit for the ICU patient remains to be determined. It seems clear that hemoglobin levels falling significantly below the “10/30” threshold can be tolerated. However, it is not clear that this is applicable to the critically ill ICU patient population. Therefore, while hemoglobin levels in the 7-10 mg/dL range are well tolerated in the “stable” “nontressed” patient, this range might not be optimal for the critcally ill patient. Conservative transfusion thresholds as well as strategies to minimize loss of blood and increase the producion of RBCs are important in the management of critically ill patients.

Severe anemia after gastrointestinal hemorrhage in a Jehovah's Witness: new treatment strategies

OBJECTIVE

Management of severe anemia in a critically ill Jehovah's Witness is challenging. In the past, conservative therapy was the only option available to the practitioner. Recently, new interventional treatment strategies have become available, including human and bovine hemoglobin substitutes and high-dose recombinant human erythropoietin.

DESIGN

Case report.

SETTING

Intensive care unit in a quaternary care center.

PATIENT

A patient with severe, life-threatening anemia caused by gastrointestinal hemorrhage who refused all blood products on religious grounds.

INTERVENTION

Bovine hemoglobin substitute and high-dose recombinant human erythropoietin.

CASE STUDY

A 50-yr-old Jehovah's Witness presented with massive upper gastrointestinal hemorrhage; initial hemoglobin was 3.5 g/dL. Endoscopy revealed a prepyloric ulcer, and hemorrhage control was achieved by epinephrine injections into the peri-ulcer mucosa. Despite control of hemorrhage, the patient became hemodynamically unstable. A total of 7 units of a bovine hemoglobin-based oxygen carrying compound (HBOC-201) was administered to enhance the patient's oxygen delivery. High-dose recombinant human erythropoietin was administered daily (500 units/kg). Hemoglobin levels were initially maintained and then slowly increased to a maximum of 7.6 g/dL on day 24 of therapy.

CONCLUSION

This case demonstrates that the concurrent administration of hemoglobin-based oxygen carriers and recombinant human erythropoietin in severe, life-threatening anemia (hemoglobin, 3.5 g/dL) was associated with patient survival and a significant increase in hemoglobin to 7.6 g/dL, without the administration of allogeneic blood. Hemoglobin-based oxygen carriers can adequately serve as initial therapy to maintain tissue oxygen delivery while awaiting the maximal effect of recombinant erythropoietin on bone marrow red blood cell production. High-dose recombinant human erythropoietin offers these patients the best chance for normalization of hematocrit and survival in the long term.

Recombinant human erythropoietin use in intensive care

OBJECTIVE

To review the literature concerning the role of recombinant human erythropoietin (rHuEPO) in reducing the need for transfusion in critically ill patients.

DATA SOURCES

Articles were obtained through searches of the MEDLINE database (from 1990 to June 2001) using the key words erythropoietin, epoetin alfa, anemia, reticulocytes, hemoglobin, critical care, intensive care, critical illness, and blood transfusion. Additional references were found in the bibliographies of the articles cited. The Cochrane library was also consulted.

STUDY SELECTION AND DATA EXTRACTION

Controlled, prospective, and randomized studies on the use of rHuEPO in critically ill adults were selected.

DATA SYNTHESIS

Anemia is a common complication in patients requiring intensive care. It is caused, in part, by abnormally low concentrations of endogenous erythropoietin and is mainly seen in patients with sepsis and multiple organ dysfunction syndrome, in whom inflammation mediator concentrations are often elevated. High doses of rHuEPO produce a rapid response in these patients, despite elevated cytokine concentrations. There have been 3 studies on rHuEPO administration in intensive care and 1 trial in acutely burned patients. Only 2 of these studies looked at the impact of rHuEPO administration on the need for transfusion.

CONCLUSIONS

Few randomized, controlled trials explore the role of rHuEPO in critical care. Only 1 was a large, randomized clinical trial, but it presents many limitations. Future outcome and safety studies comparing rHuEPO with placebo must include clinical endpoints such as end-organ morbidity, mortality, transfusion criteria, and pharmacoeconomic analysis. rHuEPO appears to provide an erythropoietic response. Optimal dosage and the real impact of rHuEPO on the need for transfusion in intensive care remain to be determined. Currently, based on the evidence available from the literature, rHuEPO cannot be recommended to reduce the need for red blood cell transfusions in anemic, critically ill patients.

Clinical Benefits of Epoetin Alfa Therapy in Patients with Lung Cancer

A retrospective subset analysis of anemic lung cancer patients who participated in three large, multicenter, community-based studies of 3-times-weekly (TIW) or once-weekly (QW) recombinant human erythropoietin (r-HuEPO, epoetin alfa) as an adjunct to chemotherapy was conducted. Patients were treated with epoetin alfa 150 U/kg in the first TIW study and with 10,000 U subcutaneously in the other study, with doubling of the dose if hemoglobin (Hb) response was inadequate. Patients in the QW study received epoetin alfa 40,000 U subcutaneously, which could be increased to 60,000 U. The maximum treatment duration for all three studies was 16 weeks. A total of 1748 lung cancer patients were evaluable for hematopoietic response; 1298 were evaluable for analyses of energy and 1300 were evaluable for analyses of activity and overall quality of life (QOL), as measured by the linear analogue scale assessment (LASA). Within 2 months of therapy, TIW and QW epoetin alfa therapy resulted in significant increases in Hb levels, decreases in transfusion requirements, and improvements in self-reported LASA scores. Increased Hb levels and reduced transfusion rates were demonstrated in the individual studies and in the analysis of data pooled from all three studies. Improvements in QOL parameters were significantly correlated with increased Hb levels. Epoetin alfa was well tolerated in all studies. The clinical benefits and safety profiles of the TIW and the QW schedules appear to be similar. In addition, the QW schedule provides greater convenience to patients and physicians alike. Given the high incidence of anemia and transfusion utilization in patients presenting with lung cancer, epoetin alfa is an effective strategy for correcting anemia in these patients, thereby improving their energy levels, activity levels, and overall QOL.

Variation in intensive care unit outcomes: a search for the evidence on organizational factors

This study was undertaken to determine the extent of empirical evidence on the role of organizational factors in the critical care literature and to categorize these factors. Studies evaluating organizational factors were identified through electronic and hand searching of the critical care literature. Sixty-three publications relating to 54 different studies were identified. The studies were grouped into eight main categories: staffing, teamwork, volume and pressure of work, protocols, admission to intensive care, technology, structure, and error. Studies evaluating organizational factors exist in the critical care literature, and there is evidence that the number is increasing each year. Results indicate that organizational factors may have an impact on mortality after case mix adjustment. Some areas have been investigated more thoroughly than others and are ripe for systematic review. Variation in case mix adjusted hospital mortality after intensive care is an old theme. This study has shown that emerging data will help us understand mortality differences and deliver better outcomes for patients.

Anemia in the critically ill: the role of erythropoietin

Anemia is a common clinical problem in critically ill patients and is associated with substantial red blood cell (RBC) transfusion requirements. However, RBC transfusion has significant risks, including adverse effects on the immune system. Although a low hemoglobin concentration may be tolerable, it may not be optimal for the critically ill patient. Thus, alternative therapies that can increase hemoglobin and avoid complications of RBC transfusion are desirable. Critically ill patients appear to have anemia identical to the anemia of chronic inflammatory disease with blunted erythropoietin production. Results of a recent randomized controlled trial in critically ill patients demonstrated that recombinant human erythropoietin (r-HuEPO, epoetin alfa) significantly reduced (by approximately 50%) the number of RBC units transfused (P <.002) and significantly increased hematocrit (P <.01) compared with placebo. There was no increase in mortality or adverse clinical events with therapy. Epoetin alfa may be an effective therapeutic approach to anemia in critically ill patients, decreasing the need for transfusion and achieving higher hemoglobin concentrations than generally attained with transfusion.

Blunted erythropoietic response to anemia in multiply traumatized patients

OBJECTIVES

To assess the relations between anemia, serum erythropoietin (EPO), iron status, and inflammatory mediators in multiply traumatized patients.

DESIGN

Prospective observational study.

SETTING

Intensive care unit.

PATIENTS

Twenty-three patients suffering from severe trauma (injury severity score > or =30).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected within 12 hrs after the accident (day 1) and in the morning on days 2, 4, 6, and 9 to determine blood cell status, serum EPO, tumor necrosis factor-alpha (TNF-alpha), soluble tumor necrosis factor-receptor I (sTNF-rI), interleukin-1 receptor antagonist (IL1-ra), interleukin-6 (IL-6), neopterin, and iron status, respectively. Hemoglobin concentration was low at admission (mean, 10.0 g/dL; range, 6.8-12.9 g/dL) and did not increase during the observation time. Serum EPO concentration was 49.8 U/L (mean value) on day 1 and did not show significant increases thereafter. No correlation was found between EPO and hemoglobin concentrations. TNF-alpha remained within the normal range. sTNF-rI was high at admission and increased further. IL1-ra was above the normal range. IL-6 was very high at admission and did not decrease thereafter. The initial neopterin concentration was normal, but increased until day 9. Serum iron was significantly decreased on day 2 posttrauma and remained low during the study. Serum ferritin increased steadily from day 2, reaching its maximum on day 9. In contrast, concentrations of transferrin were low from admission onward.

CONCLUSIONS

Multiply traumatized patients exhibit an inadequate EPO response to low hemoglobin concentrations. Thus, anemia in severe trauma is the result of a complex network of bleeding, blunted EPO response to low hemoglobin concentrations, inflammatory mediators, and a hypoferremic state.

Nutritional deficiencies and blunted erythropoietin response as causes of the anemia of critical illness

PURPOSE

The purpose of this article was to determine the prevalence of iron, vitamin B12, and folate deficiency and to evaluate the erythropoietin (EPO) response to anemia in a cohort of long-term intensive care unit (ICU) patients.

MATERIALS AND METHODS

All patients admitted to three academic medical center multidisciplinary ICUs were screened for eligibility into a randomized trial of EPO for the treatment of ICU anemia. On their second or third ICU day, patients enrolled in this trial had EPO levels drawn and were screened for iron, B12, and folate deficiency. Weekly EPO levels were obtained throughout patients' ICU stay.

RESULTS

A total of 184 patients were screened for iron, B12, and folate deficiency. Sixteen patients (9%) were iron deficient by study criteria, 4 (2%) were B12 deficient, and 4 (2%) were folate deficient. Mean hemoglobin and reticulocyte percents of the remaining 160 patients were 10.3 +/- 1.2 g/dL and 1.66 +/- 1.09%, respectively. In most patients, serum iron and total iron binding capacity levels were very low, whereas ferritin levels were very high. Mean and median day 2 EPO levels were 35.2 +/- 35.6 mIU/mL and 22.7 mIU/mL, respectively (normal = 4.2-27.8). Serial EPO levels in most persistently anemic patients remained within the normal range.

CONCLUSIONS

In this cohort, screening for iron, B12, and folate deficiency identified potentially correctable abnormalities in more than 13% of patients and should be considered in those who are anticipated to have long ICU stays. Even at an early point of critical illness, most patients had iron studies consistent with anemia of chronic disease (ACD), as well as a blunted EPO response that may contribute to this ACD-like anemia of critical illness.

Response of erythropoiesis and iron metabolism to recombinant human erythropoietin in intensive care unit patients

OBJECTIVES

Critically ill patients often are anemic, which may impair oxygen delivery. Transfusion of red cells and supplementation with vitamins or iron are the usual therapeutic strategies, whereas only sporadic data are available on the use of epoetin alfa in these patients. We investigated endogenous erythropoietin (EPO) production and the response to epoetin alfa in anemic intensive care unit (ICU) patients.

DESIGN

Randomized, open trial.

SETTING

Multidisciplinary ICU in a single secondary care center.

PATIENTS

Thirty-six critically ill patients admitted to the ICU who became anemic (hemoglobin concentration, <11.2 g/dL or <12.1 g/dL in case of cardiac disease) were randomized to one of three study groups.

INTERVENTIONS

All patients received folic acid (1 mg) daily. The control group received no additional therapy, the iron group received 20 mg of iron saccharate intravenously (iv) daily for 14 days. The EPO group received iv iron and epoetin alfa (300 IU/kg) subcutaneously on days 1, 3, 5, 7, and 9.

MEASUREMENTS AND MAIN RESULTS

Blood and reticulocyte counts were measured daily for 22 days. Serum EPO, C-reactive protein, serum transferrin receptor, and iron variables were measured on days 0, 2, 6, 10, and 21. Blood loss and red cell transfusions were recorded. Serum EPO concentrations were inappropriately low for the degree of anemia at baseline, with no difference between patients with and without renal failure. Exogenous administration of EPO increased EPO concentrations from 23+/-13 to a maximum of 166+/-98 units/L on day 10 (p < .05). Reticulocyte count increased exclusively in the EPO group from 56+/-33 x 10(9)/L to a maximum of 189+/-97 on day 13 (p < .05). Serum transferrin receptor rose only in the EPO group from 3.7+/-1.4 to 8.6+/-3.1 mg/L on day 10 (p < .05) and remained elevated on day 21, indicating an increase in erythropoiesis. Hemoglobin concentration and platelet count remained identical in the three study groups.

CONCLUSION

Endogenous EPO concentrations are low in critically ill patients. The bone marrow of these patients is able to respond to exogenous epoetin alfa, as shown by elevated concentrations of reticulocytes and serum transferrin receptors.

Important role of nondiagnostic blood loss and blunted erythropoietic response in the anemia of medical intensive care patients

OBJECTIVE

To determine incidence, severity, characteristics, and causes of anemia and transfusion requirements in medical intensive care patients.

DESIGN AND SETTING

Open prospective clinical study in a 24-bed medical intensive care unit in a tertiary-care university hospital.

PATIENTS

Patients (N = 96) treated in the intensive care unit for >3 days.

INTERVENTIONS

None.

MEASUREMENTS

Parameters of erythropoiesis and red blood cell metabolism, including hemoglobin, reticulocyte counts, serum iron, transferrin, ferritin, haptoglobin, vitamin B12, folic acid, and erythropoietin concentrations were determined serially. Diagnostic blood loss and red blood cell transfusions were recorded, and the total blood loss was estimated from changes in hemoglobin concentrations and the amount of hemoglobin transfused.

MAIN RESULTS

The median hemoglobin concentration was 12.1 g/dL at admission and 11.2 g/dL at the end of the intensive care unit stay. A total of 74 patients (77%) suffered from anemia and received 257 red blood cell units, approximately half of which were given within the first 5 days. Three patients who received 19 red blood cell units were admitted with acute gastrointestinal bleeding, but in the remainder, a median total blood loss of 128 mL/d was not (n = 60) or not solely (n = 11) a result of overt bleeding. Diagnostic blood loss declined from a median of 41 mL on day 1 to <20 mL after 3 wks and contributed 17% (median) to total blood loss. Acute renal failure, fatal outcome, and simplified acute physiology score >38 on admission were associated with a 5.8-, 7.0-, and 2.8-fold increase in total blood loss. Reticulocyte counts and erythropoietin concentrations were inappropriately low for the degree of anemia, and plasma transferrin saturation was mostly <20%.

CONCLUSIONS

Anemia is frequent and results in a high requirement for red blood cell transfusions in the medical intensive care setting. A major proportion of blood loss is not caused by overt bleeding or diagnostic blood sampling but, rather, may result from various other reasons, e.g., occult gastrointestinal bleeding and renal replacement therapy. The erythropoietic response to anemia is blunted, probably as a consequence of an inappropriate increase in erythropoietin production and diminished iron availability. (Crit Care Med 1999; 27:2630-2639)

Efficacy of recombinant human erythropoietin in the critically ill patient: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To determine whether the administration of recombinant human erythropoietin (rHuEPO) to critically ill patients in the intensive care unit (ICU) would reduce the number of red blood cell (RBC) transfusions required.

DESIGN

A prospective, randomized, double-blind, placebo-controlled, multicenter trial.

SETTING

ICUs at three academic tertiary care medical centers.

PATIENTS

A total of 160 patients who were admitted to the ICU and met the eligibility criteria were enrolled in the study (80 into the rHuEPO group; 80 into the placebo group).

INTERVENTIONS

Patients were randomized to receive either rHuEPO or placebo. The study drug (300 units/kg of rHuEPO or placebo) was administered by subcutaneous injection beginning ICU day 3 and continuing daily for a total of 5 days (until ICU day 7). The subsequent dosing schedule was every other day to achieve a hematocrit (Hct) concentration of >38%. The study drug was given for a minimum of 2 wks or until ICU discharge (for subjects with ICU lengths of stay >2 wks) up to a total of 6 wks (42 days) postrandomization.

MEASUREMENTS AND MAIN RESULTS

The cumulative number of units of RBCs transfused was significantly less in the rHuEPO group than in the placebo group (p<.002, Kolmogorov-Smirnov test). The rHuEPO group was transfused with a total of 166 units of RBCs vs. 305 units of RBCs transfused in the placebo group. The final Hct concentration of the rHuEPO patients was significantly greater than the final Hct concentration of placebo patients (35.1+/-5.6 vs. 31.6+/-4.1; p<.01, respectively). A total of 45% of patients in the rHuEPO group received a blood transfusion between days 8 and 42 or died before study day 42 compared with 55% of patients in the placebo group (relative risk, 0.8; 95% confidence interval, 0.6, 1.1). There were no significant differences between the two groups either in mortality or in the frequency of adverse events.

CONCLUSIONS

The administration of rHuEPO to critically ill patients is effective in raising their Hct concentrations and in reducing the total number of units of RBCs they require.

Nucleated red blood cells after cardiopulmonary bypass in infants and children: is there a relationship to the systemic inflammatory response syndrome?

In a retrospective case control study we aimed to evaluate whether infants and children with nucleated red blood cells (NRBCs) in their peripheral blood smears after cardiopulmonary bypass (CPB) had longer bypass times than controls without NRBCs. On review of a 3-year period, 58 children with NRBCs after CPB (and without NRBCs prior to CPB) were identified (cases). A random sample of 100 children without NRBCs after CPB over the same period served as controls. The median age (range) of the children with NRBCs and without NRBCs was 0.6 years (2 days to 20 years) and 1.4 years (2 days to 16 years), respectively (p = 0.03). The children with NRBCs had a significantly longer bypass time than the controls (mean, standard deviation (SD): 114 min, 50 vs 79 min, 46 min; p < 0.0001). For the patients with postoperative polychromasia alone, the mean CPB time (111 min, SD 46 min) was also significantly longer than the respective time in the controls (p < 0.001). Markers of organ dysfunction (renal failure, use of inotropic support, time of endotracheal intubation, stay in intensive care unit and stay in hospital) were significantly more frequent/longer in the NRBC group. Post-CPB release of NRBCs is associated with longer CPB time. This alteration may be part of the CPB-related systemic inflammatory response syndrome.

Effects of pentoxifylline on the haematologic status in anaemic patients with advanced renal failure

OBJECTIVE

Erythropoietin (EPO) deficiency is the main cause of renal anaemia. However, inhibition of erythropoiesis by cytokines such as tumour necrosis factor alpha (TNF-a) may play an important role. The aim of this work was to study the effects of pentoxifylline, an agent with anti-TNF-a properties, on the haematologic status in anaemic patients with advanced renal failure.

MATERIAL AND METHODS

In a prospective study, 7 anaemic patients with advanced renal disease (creatinine clearance <30 ml/min) were treated with pentoxifylline (400 mg orally daily) for 6 months. The evolution of haemoglobin, haematocrit, creatinine clearance and serum EPO and TNF-a a concentrations were compared with those obtained from an untreated control group.

RESULTS

Haemoglobin and haematocrit significantly increased in the pentoxifylline-treated patients (9.9+/-0.5 g/dl and 27.9+/-1.6% at baseline; 10.6+/-0.6 g/dl and 31.3+/-1.9% at the 6th month, respectively, p < 0.01), whereas no variation was seen in the control group. Serum EPO levels remained stable in all patients. However, the serum TNF-a concentration decreased significantly in patients receiving pentoxifylline (basal 623+/-366 pg/ml; 6th month 562+/-358 pg/ml, p < 0.01), but not in the control group.

CONCLUSIONS

Our findings suggest that the inhibition of erythropoiesis by cytokines may play a significant role in renal anaemia. The administration of agents with anti-cytokine properties, such as pentoxifylline, can improve the haematologic status in anaemic patients with advanced renal failure.

Red cell transfusion therapy in the critical care setting

According to our own experience and published reports the frequency of red cell transfusion in intensive care units is in the range of 0.2 to 0.4 units per patient per day and is dependent upon the local strategy, the patients involved and the kind of surgery performed. The rationale for red cell transfusion is to maintain or restore the oxygen carrying capacity of the blood to avoid tissue hypoxia which occurs when oxygen delivery drops below a certain critical value. Besides bleeding, phlebotomy is also a significant source of blood loss in critically ill patients. According to several recent reviews and consensus articles there is no basis for a fixed indicator for transfusion, such as a haemoglobin concentration of < 100 gL-1. The decision to transfuse has to be made according to the patients individual status. The major adaptive mechanism in response to acute anaemia is an increase in cardiac output and hence blood flow to tissues. As a consequence even moderate degrees of acute anaemia may not be tolerated by patients with cardiac disease, whilst marked anaemia carries a considerable risk of ischaemia in patients with brain lesions or cerebral arterial stenoses. In critically ill patients it has been postulated that supply dependency of oxygen consumption occurs over a wide range of oxygen delivery, far above the critical values of oxygen delivery seen under normal conditions. Maximising oxygen delivery was therefore formulated as a goal in these patients. However, whether pathological supply dependency of oxygen delivery really exists in critically ill patients is still under discussion and recent studies found no benefit in maximising oxygen delivery to this patient group. However, individualised triggers for red blood cell transfusion are adequate for critically ill patients considering their co-morbidities and severity of disease. Finally, the decision to transfuse must also take into account the potential risks (infectious and non-infectious), as well as benefits for the individual patient. In the future, the level of transfusions may be reduced by using blood sparing techniques such as blood withdrawal in closed systems, bedside microchemistry, intravascular monitors, or autotransfusion of drainage blood in intensive care units.