Venous Thromboembolism: Risk Factors and Prophylaxis

Thromboembolic and bleeding events in ICU patients with COVID-19: A nationwide, observational study

BACKGROUND

Intensive care unit (ICU) patients with Coronavirus disease 2019 (COVID-19) have an increased risk of thromboembolic complications. We describe the occurrence of thromboembolic and bleeding events in all ICU patients with COVID-19 in Denmark during the first and second waves of the pandemic.

METHODS

This was a sub-study of the Danish Intensive Care Covid database, in which all patients with SARS-CoV-2 admitted to Danish ICUs from 10th March 2020 to 30th June 2021 were included. We registered coagulation variables at admission, and all thromboembolic and bleeding events, and the use of heparins during ICU stay. Variables associated with thrombosis and bleeding and any association with 90-day mortality were estimated using Cox regression analyses.

RESULTS

We included 1369 patients in this sub-study; 158 (12%, 95% confidence interval 10-13) had a thromboembolic event in ICU and 309 (23%, 20-25) had a bleeding event, among whom 81 patients (6%, 4.8-7.3) had major bleeding. We found that mechanical ventilation and increased D-dimer were associated with thrombosis and mechanical ventilation, low platelet count and presence of haematological malignancy were associated with bleeding. Most patients (76%) received increased doses of thromboprophylaxis during their ICU stay. Thromboembolic events were not associated with mortality in adjusted analysis (hazard ratio 1.35 [0.91-2.01, p = .14], whereas bleeding events were 1.55 [1.18-2.05, p = .002]).

CONCLUSIONS

Both thromboembolic and bleeding events frequently occurred in ICU patients with COVID-19. Based on these data, it is not apparent that increased doses of thromboprophylaxis were beneficial.

Prevention of Venous Thromboembolism in the ICU

BACKGROUND

Although venous thromboembolism (VTE) is an important cause of morbidity and mortality in critical care unit patients, the risk of VTE and its prevention have been poorly characterized in this population. Evidence-based thromboprophylaxis guidelines are also not available for these critically ill patients.

OBJECTIVES

To review the prevalence of VTE, to summarize the available clinical trials of thromboprophylaxis, and to outline a practical approach to the prevention of VTE in critical care unit patients.

METHODS

Systematic review of the relevant literature.

RESULTS

Most patients in critical care units have at least one major risk factor for VTE, and many patients have multiple risk factors. Objectively confirmed deep-vein thrombosis (DVT) rates varied from 13 to 31% among the four prospective studies in which critical care unit patients did not receive prophylaxis. We were able to identify only three randomized trials of thromboprophylaxis conducted in critical care units. The results of these studies suggest that both low-dose heparin and low-molecular-weight heparin are efficacious in preventing DVT compared with no prophylaxis. Fourteen studies reported that compliance with some form of thromboprophylaxis occurred in 33 to 100% of critically ill patients.

CONCLUSIONS

There is a paucity of data assessing the risks and prevention of VTE in critical care settings. Selection of prophylaxis for these challenging patients involves a consideration of the thromboembolic and bleeding risks, both of which may vary in the same patient from day to day.

Venous thromboembolism and its prevention in critical care

BACKGROUND

Evidence-based guidelines for the prevention of venous thromboembolism (VTE) are available for most major surgical and medical patient groups. Such guidelines have not been established for critically ill patients.

OBJECTIVE

To perform a systematic review of the prevalence of deep vein thrombosis (DVT), the efficacy of thromboprophylaxis, and the rates of thromboprophylaxis use in critically ill patients.

METHODS

Computerized literature search for relevant studies meeting prespecified criteria.

RESULTS

The rates of objectively confirmed DVT in 4 prospective studies ranged from 13% to 31%. We identified only 3 randomized trials (1 in abstract form) of thromboprophylaxis in critical care unit patients. These studies show the efficacy of low-dose heparin and low molecular weight heparin compared with no prophylaxis; however, we found no trials comparing these 2 interventions. Eleven compliance studies reported that some form of thromboprophylaxis was used in 33% to 100% of critically ill patients, although only 1 study addressed the issue of appropriate prophylaxis use.

CONCLUSIONS

Data on the epidemiology of VTE and its prevention in critically ill patients are very limited. Further research is needed to better define patient risk factors for VTE, optimal methods of thromboprophylaxis, and strategies to improve compliance with prophylaxis recommendations. In the meantime, prevention strategies, shown to be effective in other related patient groups, and general principles of individual pharmacotherapy should guide the routine use of prophylaxis during critical illness.