Heparin dosage, level, and resistance in SARS-CoV2 infected patients in intensive care unit.

INTRODUCTION: Patients with COVID-19 frequently exhibit a hypercoagulable state with high thrombotic risk, particularly those admitted to intensive care units (ICU). Thromboprophylaxis is mandatory in these patients; nevertheless, thrombosis still occurs in many cases. Thus, the problem of assessing an adequate level of anticoagulation in ICU patients becomes evident during the COVID-19 pandemic. The aim of this study was to evaluate the heparin resistance and the efficacy of heparin monitoring using an anti-Xa activity assay. METHODS: Thirty-seven heparin-treated patients admitted to ICU for SARS-CoV-2 pneumonia were retrospectively studied for antifactor Xa activity (anti-Xa), activated partial thromboplastin time (APTT), Antithrombin, Fibrinogen, D-Dimer, Factor VIII, von Willebrand Factor, and the total daily amount of heparin administered. The correlation between APTT and anti-Xa was evaluated for unfractionated heparins (UFH). The correlations between the daily dose of UFH or the dosage expressed as IU/kg b.w. for low molecular weight heparin (LMWH) and anti-Xa were also evaluated. RESULTS: Twenty-one patients received calcium heparin, 8 sodium heparin, and 8 LMWH. A moderate correlation was found between APTT and anti-Xa for UFH. APTT did not correlate with coagulation parameters. 62% of UFH and 75% of LMWH treated patients were under the therapeutic range. About 75% of patients could be considered resistant to heparin. CONCLUSIONS: SARS-COV2 pneumonia patients in ICU have frequently heparin resistance. Anti-Xa seems a more reliable method to monitor heparin treatment than APTT in acute patients, also because the assay is insensitive to the increased levels of fibrinogen, FVIII, and LAC that are common during the COVID-19 inflammatory state.

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.