Inadequate prophylactic effect of low-molecular weight heparin in critically ill COVID-19 patients

J Crit Care. 2020 Dec:60:249-252. doi: 10.1016/j.jcrc.2020.08.026. Epub 2020 Sep 3.


Purpose: The aim of this study was to investigate potential markers of coagulopathy and the effects of thromboprophylaxis with low-molecular-weight heparin (LMWH) on thromboelastography (TEG) and anti-factor Xa in critically ill COVID-19 patients.

Material and methods: We conducted a prospective study in 31 consecutive adult intensive care unit (ICU) patients. TEG with and without heparinase and anti-factor Xa analysis were performed. Standard thromboprophylaxis was given with dalteparin (75-100 IU/kg subcutaneously).

Results: Five patients (16%) had symptomatic thromboembolic events. All patients had a maximum amplitude (MA) > 65 mm and 13 (42%) had MA > 72 mm at some point during ICU stay. Anti-factor Xa activity were below the target range in 23% of the patients and above target range in 46% of patients. There was no significant correlation between dalteparin dose and anti-factor Xa activity.

Conclusions: Patients with COVID-19 have hypercoagulability with high MA on TEG. The effect of LMWH on thromboembolic disease, anti-factor Xa activity and TEG was variable and could not be reliably predicted. This indicates that standard prophylactic doses of LMWH may be insufficient. Monitoring coagulation and the LMWH effect is important in patients with COVID-19 but interpreting the results in relation to risk of thromboembolic disease poses difficulties.

Keywords: COVID-19; Intensive care; Low-molecular-weight heparin; Thrombelastography; Thromboembolism.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Anticoagulants / therapeutic use*
  • Blood Coagulation / drug effects
  • Blood Coagulation Disorders / complications
  • Blood Coagulation Disorders / drug therapy
  • COVID-19 Drug Treatment*
  • Critical Illness
  • Dalteparin / adverse effects
  • Factor Xa Inhibitors / therapeutic use*
  • Female
  • Heparin, Low-Molecular-Weight / therapeutic use*
  • Humans
  • Intensive Care Units
  • Male
  • Middle Aged
  • Prospective Studies
  • Risk
  • Thrombelastography / methods*
  • Venous Thromboembolism / complications
  • Venous Thromboembolism / drug therapy


  • Anticoagulants
  • Factor Xa Inhibitors
  • Heparin, Low-Molecular-Weight
  • Dalteparin