We flew SW this past spring to go to Disney and had no problems. Call them ahead of time and tell them you are bringing neb/meds./vest. We did not check any of it and were not charged. We were allowed to pre-board, also. They checked everything through security, but it did not take long at all. I wondered if they were just not being very thorough or if it was because I had called in advance and "declared" our liquids. We used a baby bottle cooler for Luke's pulm. They are small coolers meant to hold one or two bottles --found in the baby aisle at Wal Mart. Ours came with a gel ice pack, too. It worked perfect for us. If you had a lot of meds. that needed to be kept cool, you would probably want a small lunch bag.