High Flow Nasal Oxygen at Extubation for Adults Requiring a Breathing Tube for Treating Severe Breathing Difficulties

The goal of this feasibility study is to learn whether a new approach to breathing tube removal within the Intensive Care Unit is safe and acceptable to participants who require a breathing tube for the management of severe breathing difficulties. The main questions it aims to answer are: * What is the recruitment rate to the study over 12 months? * Is the study design acceptable and safe to participants? Participants will receive high flow nasal oxygen before their breathing tube is removed. The investigators will compare this with standard practice of applying conventional, low-flow oxygen after the breathing tube removed to see if this effects the rate of repeat breathing tube insertion. The investigators hypothesise that they will recruit 30 participants to the study protocol (15 participants in each group) over 12 months and that our study protocol will be tolerable and acceptable to participants.