Selinger et al showed that removal of oxygen therapy from patients with COPD who had been receiving LTOT for four to six months caused an increase in pulmonary vascular resistance requiring only 2 to 3 h to reach a new steady state. The increase in Ppa caused by stopping oxygen therapy correlated with the reduction in arterial saturation (p<0.01). Removing oxygen therapy also reduced stroke volume index during both rest and exercise. The authors concluded that the removal of oxygen therapy from hypoxemic patients with COPD who had been treated with LTOT adversely affects pulmonary hemodynamics, cardiac function, and gas transport. The entire role of hypoxic pulmonary vasoconstriction in pulmonary hypertension deserves further examination in light of studies of necropsy material from the British and North American LTOT trials.
In the current environment of escalating medical costs, it appears evident that regulating agencies are likely to take the approach that if waiting a given period for clinical stability to occur can save funds by avoiding unnecessary oxygen therapy, then waiting even longer is likely to save more. Additionally, some Medicare carriers are now requiring yearly ABG measurements for recertification.