Hospital-Acquired Anemia: A Contemporary Review of Etiologies and Prevention Strategies

Blood over-testing: impact, ethical issues and mitigating actions

Plenty of studies demonstrate that hospital-acquired anemia (HAA) can increase transfusion rates, mortality, morbidity and cause unnecessary patient burden, including additional length of hospital stay, sleep disruption and venipuncture harms resulting from blood samples unlikely to change clinical management. Beyond patient costs, community costs should also be considered, such as laboratory time and resources waste, environmental impact, increasing pressure on labs and fewer tests available on time for patients who can benefit from them most. Blood over-testing does not support the principles of non-maleficence, justice and respect for patient autonomy, at the expense dubious beneficence. Reducing the number and frequency of orders is possible, to a certain extent, by adopting nudge strategies and raising awareness among prescribing doctors. However, reducing the orders may appear unsafe to doctors and patients. Therefore, reducing blood volume from each order is a better alternative, which is worth implementing through technological, purchasing and organizational arrangements, possibly combined according to need (smaller tubes, adequate analytic platforms, blind dilution, blood conservative devices, aggregating tests and laboratory units).

Effectiveness of closed blood sampling systems in intensive care patients: a scoping review

BACKGROUND

Anemia associated with blood extraction for diagnostic purposes is a highly prevalent entity in intensive care units (ICU) for adults. The evidence recommends its prevention through different strategies, among which we can find the use of closed blood sampling systems (CBSS). Different experimental studies support the use of these devices.

OBJECTIVE

To identify knowledge gaps regarding the effectiveness of CBSS in ICU patients.

METHODS

Scoping review with search in PubMed, CINAHL, Embase, Cochrane Library and Joanna Briggs Institute databases, between September-2021 and September-2022. No time, language, or other limits were applied to ensure the recovery of all relevant studies. Gray literature sources: DART-Europe, OpenGrey and Google Scholar. Two researchers independently reviewed titles and abstracts and assessed full texts against the inclusion criteria. The following data was extracted for each study: design and sample, inclusion and exclusion criteria, variables, type of CBSS, results and conclusions.

RESULTS

18 articles were included in the final review, 11 clinical trials (RCTs) published between 1992 and 2014. Three systematic reviews were found, but they only analyzed the effect of CBSS in reducing blood loss, hemoglobin stabilization, and the need for transfusion. Five of the RCTs analyzed the risk of infection, one catheter complications, and two alterations in blood pressure readings.

CONCLUSIONS

The use of CBSS is recommended to reduce blood loss in ICUs. However, there are discrepancies about their ability to prevent anemia and/or the need for blood transfusion. Its use does not increase catheter-related infection rates or alter the measurement of mean arterial pressure.

Evaluating Whether an Inpatient Initiative to Time Lab Draws in the Evening Reduces Anemia

BACKGROUND

Hospital acquired anemia is common during admission and can result in increased transfusion and length of stay. Recumbent posture is known to lead to lower hemoglobin measurements. We tested to see if an initiative promoting evening lab draws would lead to higher hemoglobin measurements due to more time in upright posture during the day and evening.

METHODS

We included patients hospitalized on 2 medical units, beginning March 26, 2020 and discharged prior to January 25, 2021. On one of the units, we implemented an initiative to have routine laboratory draws in the evening rather than the morning starting on August 26, 2020. There were 1217 patients on the control unit and 1265 on the intervention unit during the entire study period. First we used a linear mixed-effects model to see if timing of blood draw was associated with hemoglobin level in the pre-intervention period. We then compared levels of hemoglobin before and after the intervention using a difference-in-difference analysis.

RESULTS

In the pre-intervention period, evening blood draws were associated with higher hemoglobin compared to morning (0.28; 95% CI, 0.22-0.35). Evening blood draws increased with the intervention (10.3% vs 47.9%, P > 0.001). However, the intervention floor was not associated with hemoglobin levels in difference-in-difference analysis (coefficient of -0.15; 95% CI, -0.51-0.21).

CONCLUSIONS

While evening blood draws were associated with higher hemoglobin levels, an intervention that successfully changed timing of routine labs to the evening did not lead to an increase in hemoglobin levels.

Supine-Related Pseudoanemia in Hospitalized Patients

A patient's supine posture redistributes plasma into the vascular space, leading to dilution of blood constituents. The extent to which posture may influence identification of hospital-acquired anemia is unknown. Patients in this quasi-experimental study had blood obtained for hemoglobin measurement while recumbent for at least 6 hours, and then again after sitting upright for at least 1 hour. Of the 35 patients who completed the study, 13 were women (37%). Patients had a median increase in hemoglobin of 0.60 g/dL (range, -0.6 to 1.4 g/dL) with sitting, a 5.2% (range, (-4.5% to 15.1%) relative change (P < .001). Ten of 35 patients (29%) exhibited an increase in hemoglobin of 1.0 g/dL or more. Posture influences hemoglobin levels in hospitalized patients on general medicine wards; this knowledge may help curb unnecessary testing to evaluate small changes in hemoglobin concentration.

Transfusion-related Acute Lung Injury in the Perioperative Patient

Transfusion-related acute lung injury is a leading cause of death associated with the use of blood products. Transfusion-related acute lung injury is a diagnosis of exclusion which can be difficult to identify during surgery amid the various physiologic and pathophysiologic changes associated with the perioperative period. As anesthesiologists supervise delivery of a large portion of inpatient prescribed blood products, and since the incidence of transfusion-related acute lung injury in the perioperative patient is higher than in nonsurgical patients, anesthesiologists need to consider transfusion-related acute lung injury in the perioperative setting, identify at-risk patients, recognize early signs of transfusion-related acute lung injury, and have established strategies for its prevention and treatment.

Anemia in hospitalized patients: an overlooked risk in medical care

BACKGROUND

This study investigated the association between nadir anemia and mortality and length of stay (LOS) in a general population of hospitalized patients.

STUDY DESIGN AND METHODS

A retrospective cohort study of tertiary hospital admissions in Western Australia between July 2010 and June 2015. Outcome measures were in-hospital mortality and LOS.

RESULTS

Of 80,765 inpatients, 45,675 (56.55%) had anemia during admission. Mild and moderate/severe anemia were independently associated with increased in-hospital mortality (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.36-1.86, p = 0.001; OR 2.77, 95% CI 2.32-3.30, p < 0.001, respectively). Anemia was also associated with increased LOS, demonstrating a larger effect in emergency (mild anemia-incident rate ratio [IRR] 1.52, 95% CI 1.48-1.56, p < 0.001; moderate/severe anemia-IRR 2.18, 95% CI 2.11-2.26, p < 0.001) compared to elective admissions (mild anemia-IRR 1.30, 95% CI 1.21-1.41, p < 0.001; moderate/severe anemia-IRR 1.69, 95% CI 1.55-1.83, p < 0.001). LOS was longer in patients who developed anemia during admission compared to those who had anemia on admission (IRR 1.13, 95% CI 1.10-1.17, p < 0.001). Red cell transfusion was independently associated with 2.23 times higher odds of in-hospital mortality (95% CI 1.89-2.64, p < 0.001) and 1.31 times longer LOS (95% CI 1.25-1.37, p < 0.001).

CONCLUSION

More than one-third of patients not anemic on admission developed anemia during admission. Even mild anemia is independently associated with increased mortality and LOS; however, transfusion to treat anemia is an independent and additive risk factor.