A study on sleep architecture in patients with chronic respiratory failure under long-term oxygen therapy—Focused on the influence of ventilatory failure (high CO 2 ) elements on the patient’s sleep architecture

Sleep disturbance related symptoms are common in patients with long-term oxygen therapy (LTOT). Essentially, there were only few previous reports about the sleep architecture in patients with respiratory disease, such as chronic obstructive pulmonary disease (COPD). This study aims to clarify the objective sleep state and the elements that affect sleep architecture in Chronic Respiratory Failure (CRF) patients with focus on clinical cases of chronic hypercapnia. 13 subjects with chronic respiratory failure were enrolled in the study. All the subjects were pre-evaluated by pulmonary function test and Arterial blood gas analysis (ABG) including exercise testing. Polysomnography (PSG) test was performed in each subject with supplemental oxygen. The estimated base line PaCO2 value that reflects overall PaCO2 including sleep period was calculated using equation of PaCO2[2.4×(HCOˉ3)-22]from obtained ABG value just before PSG test. 6 subjects were classified as hypercapnic group (base line PaCO2 ≥ 45 mmHg) and 7 subjects were non-hypercapnic group (base line PaCO2 2 were no significant difference. This study suggests that patients with estimated hypercapnia had more disturbed sleep architecture especially significant loss of sleep latency than non-hypercapnic patient with chronic respiratory failure under LTOT. Nocturnal PaCO2 level or ventilatory function may contribute to sleep disturbance in patients with estimated hypercapnia during LTOT.