A deployable tube apparatus may include a spool and a flexible sheet coiled about the spool in a laterally unfurled condition. The flexible sheet may have a first lateral margin and a second lateral margin, and may be deployable from the laterally unfurled condition with the first and the second lateral margins spaced from each other to a deployed tubular condition where the first and the second lateral margins are coupled to each other to form an enclosed lumen. The deployable tube apparatus may provide lateral support to an elongated flexible instrument, such as a catheter. Methods of creating and using the deployable tube apparatus are described.