People who suffer traumatic injuries face a “life-threatening” risk for blood clots, but inferior vena cava (IVC) filters don’t give them a survival benefit, according to a new study.

IVC filters are metal devices inserted into the vein of a person at risk for pulmonary embolisms – blood clots that can block the lungs.

Experts estimate pulmonary embolisms are the third-highest cause of death in trauma patients who survive more than 24 hours after a traumatic injury. The filters are supposed to block the blood clot from reaching the lungs, but reports linked some IVC filters to high perforation rates.