M.M.
Someone mentioned the "breathable crib bumpers" but Breathable Baby also makes a "breathable crib shield" that covers over the tops of the rails down to the bottom for complete coverage. I ran across it when I was recently looking for a "breathable crib bumper" for a solid end crib. You can view the product on-line at http://www.breathablebaby.com/ where they also list the retailers who sell this specific product since Breathable Baby only sells wholesale.