Oxygen, therefore, appears to have a reparative effect in patients with hypoxemia and pulmonary hypertension that may result in an increase in Pa02 that is due solely to the oxygen therapy itself, and not to fluctuations in clinical stability of disease. Increases in arterial oxygen tension during oxygen therapy have not been adequately studied but now have very important relevance in view of proposed regulatory changes that would require reevaluation of arterial blood gases (ABCs) within three months after oxygen therapy is begun in clinically unstable patients before LTOT is authorized. This report attempts to address the concern that increases in arterial oxygen tension occurring after three months may be due to the beneficial effects of oxygen and, therefore, any requirement to repeat ABGs for recertification beyond three months may be medically unjustified and detrimental to patient care.
Twenty-five patients with advanced COPD who were receiving LTOT volunteered to enter a six-month clinical trial using transtracheal oxygen (TTOJ catheters. All patients were required to be clinically stable prior to insertion of the transtracheal catheter and all had been receiving oxygen by nasal cannula for at least six weeks before being examined for entry into the study. The PlaO* breathing room air was ^55 mm Hg in all subjects both prior to beginning nasal oxygen therapy and before being considered as candidates for TTO, therapy.