Iatrogenic anaemia and transfusion thresholds in ICU patients with COVID-19 disease at a tertiary care hospital

Background: Patients with severe COVID-19 disease frequently develop anaemia as the result of multiple mechanisms and often receive transfusions. The aims of this study were to assess the impact of repeated blood samplings on patients' anaemic state using standard-volume tubes, in comparison with the hypothetical use of low-volume tubes and to evaluate the transfusion policy adopted. Study design and methods: Transfusion data of mechanically ventilated non-bleeding patients with COVID-19 disease hospitalized in ICU for a minimum of 20 days were recorded. The total volume of blood drawn for samplings with standard-volume tubes and the corresponding red blood cell mass (RBCM) removed during hospitalization for each patient were calculated and compared with the hypothetical use of low-volume tubes. Results: Twenty-four patients fulfilled the inclusion criteria. Ten patients were anaemic at ICU admission (41.7 %). Overall, 6658 sampling tubes were employed, for a total of 16,786 mL of blood. The median RBCM subtracted by blood samplings per patient accounted for about one third of the total patients' RBCM decrease until discharge. The use of low-volume tubes would have led to a median saving of about one third of the drawn RBCM. Eleven patients were transfused (45.8 %) at a mean Hb value of 7.7 (+/- 0.5) g/dL. Conclusion: The amount of blood drawn for sampling has a significant role in the development of anaemia and the use of low-volume tubes could minimize the problem. Large high-powered studies are warranted to assess the more appropriate transfusion thresholds in non-bleeding critically ill patients with COVID-19 disease.