IVC filter and Pulmonary embolism- make it make sense!

Hi all, Would really appreciate someone explaining this one to me. For patients that have an established pulmonary embolism that have a contraindication to anticoagulation how do IVC filters actually help? My understanding is that the embolism is now sitting in the lungs and so has passed the IVC filter. Or am I just being a simpleton? Thanks in advance!
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: Pulmonary / Critical Care Medicine Source Type: forums