Elsevier

Critical Care Clinics

Volume 27, Issue 4, October 2011, Pages 765-780
Critical Care Clinics

Venous Thromboembolism Prophylaxis in Critically Ill Patients

https://doi.org/10.1016/j.ccc.2011.07.001Get rights and content

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VTE Rates in Critically Ill Patients Without Routine Thromboprophylaxis

Because clinical practice guidelines have recommended the routine use of thromboprophylaxis in critical care patients for more than 20 years, we review historical studies to understand the risk of VTE in patients not receiving pharmacologic or mechanical thromboprophylaxis.4 Autopsies in 436 critically ill patients in six studies detected PE in 7% to 27% of patients (mean 13%), and PE that caused or contributed to death was found in 0% to 12% (mean 3%) of these patients (Table 1).5, 6, 7, 8, 9,

Prevalence of VTE in Critically Ill Patients on Admission to ICU

Some patients newly admitted to a critical care unit will already have unsuspected DVT. Among six case series, including 1164 patients who were screened for asymptomatic DVT on admission to ICU, DVT was found in 6.3%.4 The recently published PROTECT study identified proximal DVT on the initial DUS, performed within 2 days after admission, in 3.5% of patients.17 Clinicians should be aware that many patients admitted to ICU will have been exposed to high-risk situations for the development of VTE

Clinically Silent VTE in Critically Ill Patients

Critically ill patients commonly have asymptomatic thromboembolic events. For example, in a study of 90 trauma patients with no clinical suspicion of PE, routine screening contrast CT detected PE in 24%.18 Further, ICU patients are often unable to report symptoms because of sedation and mechanical ventilation. They are also immobilized and recumbent, making leg swelling and pain less likely to be apparent. Although clinical predictive models to assess the probability of DVT and PE have been

Clinical Impact of VTE in Critically Ill Patients

The presence of DVT or PE adversely affects morbidity and mortality in critically ill patients. In a prospective cohort study, a diagnosis of DVT was associated with longer duration of mechanical ventilation (median 9 vs 6 days, P = .03), longer duration of ICU stay (median 17.5 vs 9 days, P = .005), and longer duration of hospital stay (median 51 vs 23 days, P<.001) compared with ICU patients without DVT.1 Although less is known about the impact of PE in this population, it seems likely, given

Risk Factors for VTE in Critically Ill Patients

Although the spectrum of diagnoses that result in admission to an ICU is wide, all critically ill patients are at increased risk of VTE. The vast majority will have at least one major risk factor for VTE and many will have multiple risk factors. These risk factors can be categorized into those that are present before admission to a critical care unit and those acquired during the ICU admission (Box 1).1, 4 The relative contribution of each of these risk factors is unknown, but consideration of

Pharmacologic Thromboprophylaxis Studies in Critical Care

Four randomized clinical trials of thromboprophylaxis in medical–surgical ICU patients have been completed using objective screening for DVT (Table 4).12, 13, 14, 17 In 1982, Cade and coworkers12 randomized 119 general ICU patients to receive placebo or LDUH 5000 U subcutaneously twice daily. DVT, detected using fibrinogen leg scanning, was identified in 29% of patients in the placebo group and 13% of the treatment group, a relative risk reduction of 55% (P<.05). Bleeding rates in this study

Mechanical Thromboprophylaxis Studies in Critical Care

Evidence is lacking to guide clinicians in the use of mechanical thromboprophylaxis for most patient populations, and there are no studies of mechanical thromboprophylaxis in the ICU setting.4, 32 In some patient groups, mechanical prophylaxis is less effective than anticoagulant prophylaxis.4, 33 The use of graduated compression stockings (GCS) or intermittent pneumatic compression (IPC) or both is recommended for use in patients with a contraindication to anticoagulant prophylaxis.4

Anticoagulant Thromboprophylaxis in Critically Ill Patients with Renal Insufficiency

Approximately one third of medical–surgical patients admitted to ICU have severe renal failure as defined by a calculated creatinine clearance of less than 30 mL/min.1, 38, 39 These patients are known to be at increased risk of VTE; however, because LMWH is dependent on renal clearance, there has been concern about bioaccumulation of this class of anticoagulants in patients with renal insufficiency. The DIRECT Study was conducted to assess the safety and pharmacodynamics of prophylactic

Screening for Asymptomatic DVT in Critically Ill Patients

As a result of the poor correlation between symptoms and signs of VTE in critically ill patients and the high rate of VTE, a number of studies, including PROTECT, have used serial DUS screening of asymptomatic patients to assess for DVT.17 This raises the question of whether this method should be used to screen all or a high-risk subset of critically ill patients for DVT. However, DUS is costly and time consuming, and the clinical importance of DVT detected by asymptomatic screening is unclear.

Special Considerations for LMWH Use in Critically Ill Patients

Several studies have reported a lower plasma anti-factor Xa activity after LMWH administration in patients receiving vasopressors.28, 42 In a small study of ICU patients with normal renal function and not receiving vasopressors, anti-factor Xa levels were measured after administration of dalteparin 2500 IU, subcutaneously daily in seven patients with peripheral edema and seven patients without.43 No significant differences were found. However, another small study documented lower anti-factor Xa

Practical Recommendations

Practical recommendations for the management of thromboprophylaxis in critical care patients are outlined in Fig. 1. All patients should be assessed on admission to the ICU and daily for their individual thrombosis and bleeding risks. Patients with active or high risk of clinically important bleeding should receive mechanical thromboprophylaxis with graduated compression stockings or intermittent pneumatic compression until their bleeding risk is reduced and anticoagulant thromboprophylaxis can

Summary

Considerable progress has been made in our understanding of VTE epidemiology, risk factors, and appropriate thromboprophylaxis in this challenging patient population. The use of anticoagulant thromboprophylaxis significantly decreases the risk of VTE in ICU patients. Prophylactic LMWH (or LDUH) can be safely administered to the majority of critically ill patients while those at high risk for clinically important bleeding should receive mechanical thromboprophylaxis until the bleeding risk

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  • Cited by (32)

    • Updated clinical models for VTE prediction in hospitalized medical patients

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      Restricted mobility and immobilization as well as recent previous hospitalization are important risk factors for VTE in medical patients [19,20]. Hospitalization in medical intensive care unit further increases the risk of VTE [21–24]. Established risk factors for VTE are part of the inclusion criteria in the three major clinical trials assessing the efficacy and safety of thromboprophylaxis with LMWH or fondaparinux in acutely ill hospitalized medical patients (Table 1).

    View all citing articles on Scopus

    Dr McLeod and Dr Geerts have both received program and personal support from Bayer Healthcare, Boehringer-Ingelheim, Pfizer and Sanofi Aventis.

    View full text