A medical air tubing and anti-mismatch fluid distribution system is provided for preventing the inadvertent connection of a feed line to an incorrect source of fluid. The fluid distribution system includes an adapter that is connected permanently to the fluid supply and has an outlet end that is compatible with a coupling member on the feed line. The coupling member on the feed line is compatible with the adapter but is not compatible with the other coupling member of the second fluid supply. A feed line assembly includes a feed line with a connector fixed to a first end and a nebulizer or other medical device fixed to a second end to form a one piece, integrally formed unit. The second fluid supply can include an adapter that is different from the first adapter so that the coupling members of the feed lines are compatible only with the appropriate adapter for the desired fluid source.