VTE in the ICU: Characteristics, Diagnosis,Thromboprophylaxis
VTE in the ICU: Characteristics, Diagnosis,Thromboprophylaxis
ICU patients share similar general risk factors for VTE with other patients: age, immobilization, obesity, past history of personal or familial VTE, past history of neoplasm, sepsis, stroke, respiratory or heart failure, pregnancy, trauma, or recent surgery.
Additional, specific risk factors for the ICU population have also been described (Table 3).
Mechanical ventilation, by decreasing venous return and requiring sedation (and immobilization) increases the risk of VTE. Although critically ill patients with DVT had a longer duration of mechanical ventilation than those who did not, the causal relationship between length of mechanical ventilation and VTE is unclear. Sedation is not an independent risk factor in itself.
Central venous catheterization is another important risk factor for ICU-acquired VTE, especially when inserted in femoral veins, with a catheter-related thrombosis occurrence rate ranging from 2.2 % up to 69 %. Catheter-related thrombosis was originally described by Chastre et al.. The incidence of thrombosis is 2 to 10 % with subclavian catheter but may reach 10 to 69 % with femoral catheter and 40 to 56 % with internal jugular catheter. In superior vena cava catheter-related thrombosis, the risk of associated PE is 7 to 17 %. Lower-limb DVT was associated with a four-fold increase in the risk of PE, whereas upper-limb DVT was not a significant risk factor for PE. Catheter-related thrombosis risk increases with the duration of catheter placement. In the ICU, catheter-related thrombosis is more frequent in older patients, with femoral catheters, when catheters are inserted in an emergency situation, and in patients not receiving therapeutic heparin. Sepsis may induce procoagulant status and favor catheter-related thrombosis. Catheter-related sepsis is often associated with catheter-related thrombosis, and also in ICU patients.
Vasopressor administration was found to be an independent risk factor for DVT (hazard ratio 2.8, 95 % confidence interval 1.1 to 7.2), certainly explained by reduced absorption of subcutaneous heparin linked to the vasoconstriction of peripheral blood vessels. This mechanism could explain the lower anti-Xa factor activity after thromboprophylaxis with low molecular weight heparin (LMWH) in critically ill patients on vasopressors.
Platelet transfusion (hazard ratio 3.2, 95 % confidence interval 1.2 to 8.4) and high levels of platelets (odds ratio 1.003, 95 % confidence interval 1.000 to 1.006) have been identified as risk factors for VTE, certainly related to increased platelet activation and adherence to vessel walls with subsequent fibrin clot formation, as described in inflammatory processes and sepsis.
The level of risk of VTE in critically ill patients also depends on the underlying illness leading to ICU admission.
Venous Thromboembolism Risk Factors More Specific to Critically Ill Patients
ICU patients share similar general risk factors for VTE with other patients: age, immobilization, obesity, past history of personal or familial VTE, past history of neoplasm, sepsis, stroke, respiratory or heart failure, pregnancy, trauma, or recent surgery.
Additional, specific risk factors for the ICU population have also been described (Table 3).
Mechanical ventilation, by decreasing venous return and requiring sedation (and immobilization) increases the risk of VTE. Although critically ill patients with DVT had a longer duration of mechanical ventilation than those who did not, the causal relationship between length of mechanical ventilation and VTE is unclear. Sedation is not an independent risk factor in itself.
Central venous catheterization is another important risk factor for ICU-acquired VTE, especially when inserted in femoral veins, with a catheter-related thrombosis occurrence rate ranging from 2.2 % up to 69 %. Catheter-related thrombosis was originally described by Chastre et al.. The incidence of thrombosis is 2 to 10 % with subclavian catheter but may reach 10 to 69 % with femoral catheter and 40 to 56 % with internal jugular catheter. In superior vena cava catheter-related thrombosis, the risk of associated PE is 7 to 17 %. Lower-limb DVT was associated with a four-fold increase in the risk of PE, whereas upper-limb DVT was not a significant risk factor for PE. Catheter-related thrombosis risk increases with the duration of catheter placement. In the ICU, catheter-related thrombosis is more frequent in older patients, with femoral catheters, when catheters are inserted in an emergency situation, and in patients not receiving therapeutic heparin. Sepsis may induce procoagulant status and favor catheter-related thrombosis. Catheter-related sepsis is often associated with catheter-related thrombosis, and also in ICU patients.
Vasopressor administration was found to be an independent risk factor for DVT (hazard ratio 2.8, 95 % confidence interval 1.1 to 7.2), certainly explained by reduced absorption of subcutaneous heparin linked to the vasoconstriction of peripheral blood vessels. This mechanism could explain the lower anti-Xa factor activity after thromboprophylaxis with low molecular weight heparin (LMWH) in critically ill patients on vasopressors.
Platelet transfusion (hazard ratio 3.2, 95 % confidence interval 1.2 to 8.4) and high levels of platelets (odds ratio 1.003, 95 % confidence interval 1.000 to 1.006) have been identified as risk factors for VTE, certainly related to increased platelet activation and adherence to vessel walls with subsequent fibrin clot formation, as described in inflammatory processes and sepsis.
The level of risk of VTE in critically ill patients also depends on the underlying illness leading to ICU admission.
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