Nonleg Venous Thrombosis in Critically Ill Adults: A Nested Prospective Cohort Study

May 30, 2014
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Authors:
Lamontagne F, McIntyre L, Dodek P, et al., for the PROTECT (Prophylaxis for Thromboembolism in Critical Care Trial) Investigators, on behalf of the Canadian Critical Care Trials Group and the Australian and New Zealand Intensive Care Society Clinical Trials Group.
Citation:
JAMA Intern Med 2014;174:689-696.
Summary By:
Geoffrey D. Barnes, MD, MSc, FACC

Study Questions:

What are the clinical characteristics and outcomes in patients with medical-surgical critical illnesses who develop nonleg deep venous thrombosis (NLDVT)?

Methods:

In the PROTECT trial, 3,746 patients in 67 medical-surgical intensive care units (ICUs) were randomized to unfractionated heparin or low molecular weight heparin prophylaxis against venous thromboembolism. In a post-hoc analysis, factors associated with development of NLDVT and the associated outcomes were explored. Screening ultrasound was limited to the lower extremities only.

Results:

NLDVT developed in 84 (2.2%) patients, 94.5% of which occurred in the upper extremities, including the jugular veins. NLDVT was more common in the distal vs. proximal arm veins (1.8% vs. 0.8%, p < 0.001). Catheter-associated NLDVT occurred in 40 (1.1%) of all patients. Cancer was the only independent predictor of developing NLDVT (hazard ratio [HR], 2.22; 95% confidence interval [CI], 1.06-4.65). After adjusting for various risk elements, NLDVTs were associated with an increased risk of pulmonary embolism (HR, 11.83; 95% CI, 4.80-29.18), but not ICU mortality (HR, 1.09; 95% CI, 0.62-1.92).

Conclusions:

The authors concluded that despite pharmacologic prophylaxis against venous thromboembolism, NLDVT was found in 2.2% of ICU patients. NLDVT in critically ill patients is associated with a significantly increased risk of pulmonary embolism, but not ICU mortality.

Perspective:

This post-hoc analysis of the PROTECT study details the clinical characteristics and outcomes associated with NLDVT in ICU patients. In this study, screening ultrasound was limited to the lower extremities, suggesting that the reported rates of NLDVT represent clinically relevant thrombosis and not incidentally found thrombosis. Given their frequent use in the ICU setting, central catheter-associated NLDVT occurred in nearly half of the identified NLDVT patients. It is not unexpected that cancer was a strong predictor of developing NLDVT. Development of a NLDVT was associated with a markedly increased hazard of subsequent pulmonary embolism, but not ICU-related mortality. However, this study did not have adequate power to adequately assess the mortality risk with NLDVT. Implementing strategies for judicious use of central catheters is important to achieve the goal of reducing ICU complications, including NLDVT and pulmonary embolism.

Keywords: Jugular Veins, Intensive Care Units, Neoplasms, Heparin, Low-Molecular-Weight, Pulmonary Embolism, Venous Thromboembolism, Critical Illness, Lower Extremity


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