From Pages to Practice

By Amanda Fernandes, MD

Published January 5, 2022


Mr. Watt is a 65-year-old man who was admitted to the medical intensive care unit for acute respiratory distress syndrome caused by bacterial pneumonia. He is currently on vasopressors and intubated for ventilatory support. Surrounded by various monitors that intermittently alarm, Mr. Watt is also attached to numerous lines, catheters, and the timed inflation and deflation of compression boots. His wife asks whether the cumbersome mechanical compression boots add any benefit to the injections her husband receives to prevent clots. 

Although pharmacologic prophylaxis has been shown to reduce the incidence of deep vein thrombosis, evidence is limited on the combined use of mechanical compression devices and pharmacologic prophylaxis. In the Pneumatic Compression for Preventing Venous Thromboembolism (PREVENT) trial, Arabi and colleagues found that use of adjunctive intermittent pneumatic compression did not lower the incidence of deep vein thrombosis compared to pharmacologic thromboprophylaxis alone in critically ill patients.

The following NEJM Journal Watch summary by Dr Patricia Kritek further explains the study and results.


No Benefit to Adding Pneumatic Compression to Pharmacologic Prophylaxis for Preventing Venous Thromboembolism

In critically ill patients, dual therapy was not more effective than drug therapy alone.

In many intensive care units (ICUs), patients commonly receive “dual therapy” for preventing venous thromboembolism (VTE): pharmacologic prophylaxis (subcutaneous unfractionated heparin or low-molecular-weight heparin) plus pneumatic compression devices. Critically ill patients clearly are at risk for VTE, but does combining two forms of prophylaxis confer benefit?

About 2000 patients at ICUs in Saudi Arabia, Canada, Australia, and India were randomized to receive pharmacologic prophylaxis alone or in combination with intermittent pneumatic compression. Most pneumatic compression was accomplished with lower limb, knee-length sleeves. Compression was applied for a median 22 hours daily and for a median 7 days. Most participants were medical patients; one half were admitted from emergency departments. Lower-extremity ultrasound assessment for deep venous thrombosis (DVT) was performed twice weekly, and clinical care continued throughout the trial.

New cases of DVT and pulmonary embolism were rare (4% and 1%, respectively), and incidences were similar in both intervention and control groups. The incidences of pressure ulcers and skin injury were similar in both groups. Subgroup analyses yielded consistent findings. The percentage of trauma patients was low, and no data were reported for high-risk patients, such as those with malignancy.

Comment: Compression devices tether patients to bed, and they are noisy and often uncomfortable. Although pneumatic compression likely is useful if a patient has a contraindication to pharmacologic prophylaxis, routine dual VTE prophylaxis use warrants reconsideration. I would consider adding compression devices for particularly high-risk patients, but, for most patients, heparin or low-molecular-weight heparin alone should suffice.

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Amanda Fernandes is a 2018-2019 NEJM editorial fellow.