The group 2 subjects with OSA and COPD who used home oxygen alone or with other therapies (protriptyline, N = 2; uvulopalatopharyngoplasty, N = 4) showed no improvement in pulmonary artery pressure or vascular resistance at 12 to 24 months* follow-up and no improvement in right ventricular ejection fraction (Fig 5). Group 1 and group 3 subjects who accepted tracheostomy showed improvement in all of these parameters at long-term follow-up. In the setting of combined COPD and OSA, supplemental oxygen did not appear to alter cardiopulmonary hemodynamics. In addition, the group 1 patients who received curative therapy for apnea showed improvement in arterial blood gas levels with increased daytime Pa02 from 60 to 73 mm Hg and decreased PaC02 from 49 to 41 mm Hg. The group treated with supplemental oxygen showed no change in room air blood gas levels over a two-year period.
The above study cannot be taken as conclusive evidence against chronic oxygen therapy for sleep apnea, but until further studies are done, it does challenge the efficacy of oxygen as chronic therapy for OSA. Complicating factors in interpreting this study are: 1) it was not randomized and patients were selected for oxygen therapy because of refusal of tracheostomy; 2) compliance was monitored only by word of the patient; 3) the majority of patients had severe COPD complicating the hemodynamic findings. buy diabetes drugs
Figure 5. Summary of three hemodynamic parameters (pulmonary artery pressure, [PAP], pulmonary vascular resistance [PVR], and right ventricular ejection fraction [RVEF] followed for up to 36 months in 24 patients with severe OSA. Croup 1 contained 9 patients with OSA and COPD who accepted curative tracheostomy at study onset. They showed improvement in PAP, PVR, and RVEF over the follow-up period. Group 2 subjects (N = 10) were similar in composition to group 1, but refused curative tracheostomy and accepted home supplemental oxygen and some noncurative measures such as protriptyline and uvu-lopalatopharyngoplasty. Their PAP, PVR, and RVEF either remained unchanged or showed some evidence of deterioration. The third group (N = 5) had severe OSA only and accepted curative tracheostomy. Hemodynamic parameters showed no change but were near normal to begin with. Fil = first to last follow-up.