What is your approach to patients with chronic hypoxemic respiratory failure who have apparent higher oxygen needs during hospitalization but no clear acute/decompensated respiratory illness?

Will work them up completely for infection, PE, COPD exacerbation, heart failure/cardiac etiology. If no convincing reason for decompensation and they are stable, I will have them do a 6 min RT walk test to determine oxygen needs and have them follow up with PCP or pulmonary for further PFTs or othe...