Are blood (170 micron) transfusion filters sufficient to remove particulates?
These filters are important and have been used safely for many years. Their ability to remove the particulate matter that has been recently observed is unverified. FDA is aware of proposals to study this question in vitro but results are not yet available. Pending further studies, it is FDA’s current thinking that units with observable particulates should be quarantined rather than used, unless they are filtered with filters designed to remove leukocytes. However, medical directors may exercise independent judgment in this area.
