No, I don't believe the advanced permeability of monolith columns prevent the media from becoming fouled by plasma proteins and lipids. There are applications out there for direct plasma injection, but they're highly specialized: the analyte must not interact with plasma proteins, for one thing, and must be ideally suited to the analysis method. Still, the column will last less long if your don't pre-process. Maybe, you could use online pre-processing, say with some sort of guard column for absorbing most plasma proteins, that you change often. But doing such things is frowned on -- its an auditing, documenting, regulatory, and method development nightmare.