Is blood transfusion good for the heart?

Blood Usage in an Australian Intensive Care Unit: Have We Met Best Practice Goals?

The transfusion of blood products, especially red cell concentrates, in critically ill patients is controversial and benefits of red cell concentrate transfusion in these patients have not been clearly demonstrated.

We performed a prospective observational study to compare best evidence to actual practice of red cell concentrate and other blood product administration in an intensive care unit (ICU) in a university-associated tertiary hospital. All primary admissions during a 28-day period were included in the study and data collected included transfusion of red cells and blood products, patient demographics and ICU and hospital outcome.

One hundred and seventy-five admissions were studied; 44% followed cardiac surgery. Forty-one patients (23%) received red cell concentrates in ICU, with 120 units transfused in 61 separate episodes. Other blood product usage was minimal. One third (20/61) of red cell concentrate transfusion episodes were of a single unit. The mean (±SD) pre-transfusion haemoglobin was 7.9±1.1 g/dl. Despite transfusion, such patients left ICU with a lower haemoglobin concentration compared with untransfused ICU patients (9.5±1.0 versus 10.5±2.1 g/dl; P<0.001). Cardiac surgical patients received similar red cell transfusion to general ICU patients. Univariate analysis showed no significant difference in mortality between patients who did or did not receive red cell concentrate transfusion (P=0.17). However, red cell concentrate transfusion was associated with a reduced adjusted mortality both in ICU (OR 0.13, 95% CI 0.02-0.73) and in hospital at 28 days (OR 0.10, 95% CI 0.02-0.58). The low red cell concentrate and blood product usage in our ICU were consistent with restrictive transfusion practice and selective red cell concentrate transfusion was associated with reduced mortality.

Minimum haemoglobin in intensive care

Multiple and complex aetiological factors contributes to anaemia in critically ill patients. This article sets out to examine the clinical evidence and physiological rationale for transfusion, traditionally based on an arbitrary haemoglobin trigger of 10 g=dL. Maintenance of haemoglobin concentration level of 10 g=dL or above may benefit only a small group of patients with an acute myocardial infarction, unstable angina or those who have severe coronary artery disease. However, most critically ill patients tolerate anaemia very well due to physiological compen satory mechanisms and clinical studies suggest that there is an increase in adverse outcome if transfusion is carried out using this traditional trigger threshold.

Blood still kills: six strategies to further reduce allogeneic blood transfusion-related mortality

After reviewing the relative frequency of the causes of allogeneic blood transfusion-related mortality in the United States today, we present 6 possible strategies for further reducing such transfusion-related mortality. These are (1) avoidance of unnecessary transfusions through the use of evidence-based transfusion guidelines, to reduce potentially fatal (infectious as well as noninfectious) transfusion complications; (2) reduction in the risk of transfusion-related acute lung injury in recipients of platelet transfusions through the use of single-donor platelets collected from male donors, or female donors without a history of pregnancy or who have been shown not to have white blood cell (WBC) antibodies; (3) prevention of hemolytic transfusion reactions through the augmentation of patient identification procedures by the addition of information technologies, as well as through the prevention of additional red blood cell alloantibody formation in patients who are likely to need multiple transfusions in the future; (4) avoidance of pooled blood products (such as pooled whole blood-derived platelets) to reduce the risk of transmission of emerging transfusion-transmitted infections (TTIs) and the residual risk from known TTIs (especially transfusion-associated sepsis [TAS]); (5) WBC reduction of cellular blood components administered in cardiac surgery to prevent the poorly understood increased mortality seen in cardiac surgery patients in association with the receipt of non-WBC-reduced (compared with WBC-reduced) transfusion; and (6) pathogen reduction of platelet and plasma components to prevent the transfusion transmission of most emerging, potentially fatal TTIs and the residual risk of known TTIs (especially TAS).

Anemia and blood transfusion practices in the critically ill: a prospective cohort review

BACKGROUND

Nearly 75% of critically ill patients develop anemia in the intensive care unit (ICU). Anemia can be treated with red blood cell (RBC) transfusions, although evidence suggests that lower hemoglobin levels are tolerated in the critically ill. Despite such recommendations, variation exists in clinical practice.

METHODS

A prospective cohort was assessed for anemia and RBC transfusion practices in 100 consecutive adults admitted to our General Systems ICU.

RESULTS

The prevalence of anemia in this cohort was 98%. Mean blood loss via phlebotomy was 25+/-10.3 mL per patient per day. The RBC transfusion rate for the ICU stay was 40%, increasing to 70% in patients whose ICU stay was >7 days. The mean pretransfusion level of hemoglobin was 7.35+/-0.47 mg/dL for the total cohort, and 8.2+/-0.65 mg/dL for those with a history of cardiovascular disease.

CONCLUSION

Anemia was common in this critically ill cohort, with hemoglobin levels continuing to drop with ICU stay. Pretransfusion hemoglobin levels were lower than reported by others, yet the RBC transfusion rate was comparable. There was no association between anemia and phlebotomy practices in our ICU.

[Patients in circulatory shock in emergency and intensive care units]

Patients in circulatory shock are being treated in emergency as well as in intensive care units. Despite different resources in personnel and technical equipment in both areas, patient management has to follow standardized protocols. Diagnosis of shock has to be based upon objective parameters (lactate, pH, standard bicarbonate, arterial blood pressure, central venous pressure, cardiac output). Aim of shock treatment is restoration of adequate tissue perfusion with the use of fluid and red blood cell replacement, vasoconstrictors, inotropics, substances improving microcirculation, and mechanical circulatory support. Target values are: mean arterial blood pressure >80 mmHg, central venous pressure >6 mmHg, hemoglobin >8.0 g/dl, cardiac index >3.5 l/min/m(2). New concepts for optimization of hemodynamics and hematocrit, cortisone, intraaortic balloon counterpulsation, mechanical ventilation with low tidal volumes, and intensive insulin therapy are discussed. However, as shock reversal is dependent on its reason, clarification and treatment of the shock causing event has to be performed with highest priority.

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.

Functional versus fractional oxygen saturation readings: bias and agreement using simulated solutions and adult blood

The purpose of this study was to examine the bias and agreement between functional oxygen saturation (SO2) and fractional oxyhemoglobin (HbO2) using simulated quality control (QC) solutions and adult blood. Using a hemoximeter, 5 analysts performed at least 5 tests each on QC solutions with 3 different hemoglobin (Hb) levels and on adult blood samples of various oxygen saturation levels representing venous or arterial samples. Bias and the limits of agreement were determined using the technique of Bland and Altman. Using QC solutions with low, normal, and high Hb levels, the bias for SO2 against HbO2 was 20.82 +/- 0.50 (n = 66), 19.14 +/- 0.56 (n = 81), and 19.59 +/- 0.43 (n = 79), respectively, with SO2 reading consistently higher. The correlation between SO2 and HbO2 was -0.49, -0.69, and -0.68, respectively. Using adult blood, the bias for SO2 against HbO2 was 1.29 +/- 0.48 for venous samples (n = 62) and 1.9 +/- 0.19 for fully oxygenated samples (n = 36), and the correlation between SO2 and HbO2 was 1.0 and 0.68, respectively. These findings suggest that the consistency between the measurements of SO2 and HbO2 may be dependent on hemoglobin levels and oxygenation status. Thus, caution is warranted when assuming that the measurements of SO2 and HbO2 are interchangeable.