Iatrogenic Anemia in the ICU

Anh Nguyen, MD, MPH, PGY2

Background Patients who were admitted to the ICU need to have a lot of

blood tests related to their illness and for further treatment. However, that can cause decrease Hgb/Hct or iatrogenic

anemia. Conflicting evidence of the association between anemia

among ICU patients and excessive diagnostic blood draws. The increased laboratory use leads to increasing other costs

such as electrolyte repletion, blood transfusion (in patients with anemia attributable to laboratory testing).

These higher costs did not have significant different ICU lengths of stay or hospital mortality.

Methodology Cross-sectional study, patient charts review Inclusion criteria: ICU stay > 3 days Exclusion criteria: ICU stay < 3 days, GI

bleed, trauma bleeding, pancytopenia, pulmonary hemorrhage

Main variables: baseline Hgb/Hct, Hgb/Hct when leave the ICU, length of stay in the ICU

Effect modification variable: Anemia of chronic disease

Methodology Reviewed 33 ICU charts Included 15 charts in the study Excluded 18 charts based on exclusion criteria

Analysis Using SAS Student t-tests

Results

Conclusion This cross-sectional study showed that

iatrogenic blood loss for laboratory investigation is one of the causes of anemia in the ICU.

Physicians should only order phlebotomy for necessary investigation and for the most effective of diagnosis and treatment.

Discussion Lack of evidence of benefit of the current practice of frequent

laboratory testing in the ICU. Excessive costs, potential risks, and no proof of benefit which

mandates a re-evaluation of the current approach to routine laboratory testing in the ICU

Unknown whether normalization of abnormal routine laboratory values compared to reference range among patients in the ICU confers net benefit.

In addition to correcting abnormal laboratory values, there is a tendency to recheck laboratory tests after the intervention

Discussion Risks associated with transfusion: transmission of

infectious agents, an increased risk of nosocomial infections, transfusion-related acute lung injury, transfusion-associated circulatory overload, and transfusion-related graft-versus-host disease

Admission laboratory tests are valuable to establish baseline values for comparisons with later values

Routine, undirected, daily laboratory evaluation (eg. homeostatic laboratory testing) is a practice of questionable utility, and efforts to reduce it are warranted

Plan for Improving Current Practice

Small volume collection tubes Transfuse to maintain Hgb 7-9 g/dL Decrease the number of daily ABG’s, CMP’s,

and CBC’s if possible Increase the intervals at which homeostatic

laboratory tests are obtained (decrease from daily to every 3 days)

Plan for Improving Current Practice The practice of bundling multiple lab tests together

(eg. BMP) should be abandoned Laboratory testing should be pursued as a part of

therapeutic response to a clinical problem rather than as a search for abnormal values to be corrected.

Testing in the context of higher pretest probabilities of disease should be emphasized

Train ICU house officers to be thoughtful in ordering routine ICU laboratory tests during first-year orientation

References Ezzie ME, Aberegg SK, O’Brien JM. Laboratory testing in

the intensive care unit. Crit Care Clin 2007;23:435-465. Shander A. Anemia in the critically ill. Crit Care Clin

2004;20(2):159-78 Tarpey J, Lawler PG. Iatrogenic anaemia? A survey of

venesection in patients in the intensive therapy unit. Anaesthesia 1990;45(5)396-8.

Tosiri P, Kanitsap N, Kanitsap A. Approximate iatrogenic blood loss in medical intensive care patients and the cause of anemia. J Med Assoc Thai 2010;93(7):S271-6.