Iatrogenic Anemia in the ICU

1. Iatrogenic Anemia in the ICU Anh Nguyen, MD, MPH, PGY2

2. 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.

3. 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

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

5. Analysis • Using SAS • Student t-tests

6. Results

7. 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.

8. 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

9. 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

10. 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)

11. 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

12. 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.