A study on sleep architecture in patients with chronic respiratory failure under long-term oxygen therapy—Focused on the influence of ventilatory failure (high CO₂) elements on the patient’s sleep architecture

Abstract

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 PaCO 2 value that reflects overall PaCO 2 including sleep period was calculated using equation of PaCO 2[2.4×(HCO ˉ 3 )-22] from obtained ABG value just before PSG test. 6 subjects were class ified as hypercapnic group (base line PaCO 2 ≥ 45 mmHg) and 7 subjects were non-hypercapnic group (base line PaCO 2 < 45 mmHg). Latency persistent sleep of PSG data was significant higher in patients with hypercapnic than non-hypercapnic (p < 0.01). Periodic Limb Movement was seen in 23.6% of the subjects, however there was no contribution for arousals. Other PSG data include mean SpO 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 PaCO 2 level or ventilatory function may contribute to sleep disturbance in patients with estimated hypercapnia during LTOT.