HVNI Ambulation Feasibility Study

The hypothesis is that HVNI therapy, when implemented in conjunction to ambulatory practices, will be more effective than TAU to improve patient mobility by reducing the patient's perceived dyspnea and exertion via maintaining oxygenation (reduced desaturation) and supporting ventilation (reduced work of breathing \[WOB\]). The primary endpoint is exercise performance, defined as the distance and duration of patient ambulation. To provide a sample data set, The investigators will enroll up to 32 subjects to complete this feasibility assessment, with a calculated sample size of N=26 plus a 20% failure rate. This will provide sufficient initial data to inform the appropriate sample size of a follow-on randomized study. This will be a feasibility study, performed as a prospective, crossover controlled trial to evaluate the potential patient improvement during ambulation while on HVNI relative to TAU. Patients who fit the criteria for inclusion will perform ambulation for each study arm: the control arm (TAU) followed by the test arm (HVNI). Control group will receive the site TAU (not HVNI), and the test group will receive HVNI therapy. In both cases the clinical management will otherwise remain unchanged based on the site SOC practices. The patient FiO2 and flow values will be recorded while on any supplemental oxygen. Subjects will wear appropriate gear and, when applicable, have mobile carts to provide supplemental oxygen therapy (e.g. HVNI VTU) during ambulation. If they meet criteria for intubation or are deemed to need intubation by the critical care team, they will undergo prompt intubation and be managed according to standard practice. After each of the study arms, the clinicians will complete perception score assessments.