Red blood cell transfusion practices in acute lung injury: what do patient factors contribute?

Evaluation of RBC Transfusion Practice in Adult ICUs and the Effect of Restrictive Transfusion Protocols on Routine Care

OBJECTIVE

Research supports the efficacy and safety of restrictive transfusion protocols to reduce avoidable RBC transfusions, but evidence of their effectiveness in practice is limited. This study assessed whether admission to an ICU with an restrictive transfusion protocol reduces the likelihood of transfusion for adult patients.

DESIGN

Observational study using data from the multicenter, cohort Critical Illness Outcomes Study. Patient-level analyses were conducted with RBC transfusion on day of enrollment as the outcome and admission to an ICU with a restrictive transfusion protocol as the exposure of interest. Covariates included demographics, hospital course (e.g., lowest hematocrit, blood loss), severity of illness (e.g., Sequential Organ Failure Assessment score), interventions (e.g., sedation/analgesia), and ICU characteristics (e.g., size). Multivariable logistic regression modeling assessed the independent effects of restrictive transfusion protocols on transfusions.

SETTING

Fifty-nine U.S. ICUs.

PATIENTS

A total of 6,027 adult ICU patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 59 study ICUs, 24 had an restrictive transfusion protocol; 2,510 patients (41.6%) were in an ICU with an restrictive transfusion protocol. The frequency of RBC transfusion among patients with severe (hematocrit, < 21%), moderate (hematocrit, 21-30%), and mild (hematocrit, > 30%) anemia in restrictive transfusion protocol ICUs was 67%, 19%, and 4%, respectively, compared with 60%, 14%, and 2% for those in ICUs without an restrictive transfusion protocol. Only 27% of transfusions were associated with a hematocrit less than 21%. Adjusting for confounding factors, restrictive transfusion protocols independently reduced the odds of transfusion in moderate anemia with an odds ratio of 0.59 (95% CI, 0.36-0.96) while demonstrating no effect in mild (p = 0.93) or severe (p = 0.52) anemia.

CONCLUSIONS

In this sample of ICU patients, transfusions often occurred outside evidence-based guidelines, but admission to an ICU with an restrictive transfusion protocol did reduce the risk of transfusion in moderately anemic patients controlling for patient and ICU factors. This study supports the effectiveness of restrictive transfusion protocols for influencing transfusions in clinical practice.

Red blood cell transfusion practices in two surgical intensive care units: a mixed methods assessment of barriers to evidence-based practice

BACKGROUND

Despite evidence supporting restrictive red blood cell (RBC) transfusion thresholds and the associated clinical practice guidelines, clinical practice has been slow to change in the intensive care unit (ICU). Our aim was to identify barriers to conservative transfusion practice adherence.

STUDY DESIGN AND METHODS

A mixed-methods study involving observation of prescriber (i.e., physicians, physician assistants, nurse practitioners) and bedside nurse daily bedside rounds, provider survey, and medical record abstraction was conducted in one cardiac surgical ICU (CSICU) and one surgical ICU (SICU) in an academic hospital in Baltimore, Maryland.

RESULTS

Of 52 patient encounters observed during bedside rounds, 38 (73%) involved patients without evidence of active bleeding or cardiac ischemia. Surveys were completed by 52 (93%) of the 56 providers participating in rounds. Prescribers in the CSICU and SICU (87 and 90%, respectively) indicated the ideal pretransfusion hemoglobin (Hb) to be not more than 7 g/dL in nonbleeding and/or nonischemic patients compared to a minority of nurses (8% [p = 0.002] and 42% [p = 0.015], respectively). Prescribers and nurses in both ICUs overestimated the typical pretransfusion Hb in their units (CSICU, p < 0.001; SICU, p = 0.019). During rounds, providers infrequently explicitly discussed Hb monitoring or transfusion thresholds (33%) despite most (60%) reporting significant variation in transfusion thresholds between individual prescribers.

CONCLUSIONS

Our study identified several provider and system barriers to evidence-based transfusion practices including knowledge differences, overly optimistic estimates of current practice, and heterogeneous transfusion practice in each ICU. Further work is necessary to develop targeted interventions to improve evidence-based RBC transfusion practices.

Changes in transfusion practice over time in the PICU

OBJECTIVES

Recent randomized clinical trials have shown the efficacy of a restrictive transfusion strategy in critically ill children. The impact of these trials on pediatric transfusion practice is unknown. Additionally, long-term trends in pediatric transfusion practice in the ICU have not been described. We assessed transfusion practice over time, including the effect of clinical trial publication.

DESIGN

Single-center, retrospective observational study.

SETTING

A 10-bed PICU in an urban academic medical center.

PATIENTS

Critically ill, nonbleeding children between the ages of 3 days and 14 years old, admitted to the University of Maryland Medical Center PICU between January 1, 1998, and December 31, 2009, excluding those with congenital heart disease, hemolytic anemia, and hemoglobinopathies.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

During the time period studied, 5,327 patients met inclusion criteria. Of these, 335 received at least one RBC transfusion while in the PICU. The overall proportion transfused declined from 10.5% in 1998 to 6.8% in 2009 (p = 0.007). Adjusted for acuity, the likelihood of transfusion decreased by calendar year of admission. In transfused patients, the pretransfusion hemoglobin level declined, from 10.5 g/dL to 9.3 g/dL, though these changes failed to meet statistical significance (p = 0.09). Neonatal age, respiratory failure, shock, multiple organ dysfunction syndrome, and acidosis were associated with an increased likelihood of transfusion in both univariate and multivariable models.

CONCLUSIONS

The overall proportion of patients transfused between 1998 and 2009 decreased significantly. The magnitude of the decrease varied over time, and no additional change in transfusion practice occurred after the publication of a major pediatric clinical trial in 2007. Greater illness acuity and younger patient age were associated with an increased likelihood of transfusion.

Red blood cell transfusion: decision making in pediatric intensive care units

The results of the Transfusion Requirements in Pediatric Intensive Care Unit study suggest that a red blood cell transfusion is not required in stable or stabilized pediatric intensive care unit children as long as their hemoglobin level is >7 g/dL. Subgroup analyses suggest that this recommendation is also adequate for stable critically ill children with a high severity of illness, respiratory dysfunction, acute lung injury, sepsis, neurological dysfunction, severe head trauma, or severe trauma, and during the postoperative period, for noncyanotic patients older than 28 days. A small randomized clinical trial suggests that a hemoglobin level of 9 g/dL is safe in the postoperative care of children with single-ventricle physiology undergoing cavopulmonary connection. Although there is consensus that blood is clearly indicated for the treatment of hemorrhagic shock, the clinical determinants that should prompt pediatric intensivists to prescribe a red blood cell transfusion to unstable PICU children are not well characterized.

Transfusion practice in the intensive care unit: a 10-year analysis

BACKGROUND

Clinical guidelines recommend a restrictive transfusion strategy in nonhemorrhaging critically ill patients.

STUDY DESIGN AND METHODS

We conducted a retrospective observational study of 3533 single-admission patients, without evidence of acute coronary syndromes, hemorrhage, or hemoglobinopathy admitted to the medical intensive care unit (MICU) of a large, academic medical center.

RESULTS

MICU admission hemoglobin (Hb) level did not change significantly over the study period. The proportion of transfused patients decreased from 31.0% in 1997 to 1998 to 18.0% in 2006 to 2007 (p<0.001). Among patients receiving transfusion, the mean pretransfusion Hb level decreased over time from 7.9±1.3 to 7.3±1.3g/dL (p<0.001). These changes in practice were not accounted for by differences in patient characteristics. The mean nadir Hb level in nontransfused patients decreased from 11.2±2.2g/dL in 1997 to 1999 to 10.4±2.3g/dL in 2006 to 2007 (p<0.001). The mean number of units per patient transfused decreased during this time from 4.3±4.7 to 3.0±3.8 units (p<0.001). The proportion of transfused patients who were transfused at a Hb level of less than 7.0g/dL increased by an estimated absolute increment of 3.2% (95% CI, 2.1%-4.3%) per interval (p<0.001), and the proportion of single-unit transfusions during the first transfusion episode increased by 1.4% per interval (95% CI, 0.2 to 2.6%; p=0.03) from 40.2% in 1997 to 1998 to 53.1% in 2006 to 2007.

CONCLUSIONS

Between 1997 and 2007, important and sustained changes have occurred in our MICU physician transfusion practices, with overall reductions in the proportion of patients transfused, mean pretransfusion Hb level, and nadir Hb level in patients who were not transfused.