Diagnosing sleep disordered breathing in patients with chronic pulmonary disease: which test for which patient?

Untreated Obstructive Sleep Apnea in Interstitial Lung Disease and Impact on Interstitial Lung Disease Outcomes

Subjects with interstitial lung disease (ILD) often suffer from nocturnal cough, insomnia, and poor sleep quality. Subjects with ILD and obstructive sleep apnea (OSA) seem to have relatively mild symptoms from sleep fragmentation compared to subjects with only ILD. The overlap of ILD, OSA, and sleeping hypoxemia may be associated with poor outcome, even though there is no agreement on which sleep parameter is mostly associated with worsening ILD prognosis. Randomized controlled trials are needed to understand when positive airway pressure (PAP) treatment is required in subjects with ILD and OSA and the impact of PAP treatment on ILD progression.

Paradoxical breathing during sleep is associated with increased sleep apnea and reduced ventilatory capacities in high-level spinal cord injury

Sleep-disordered breathing is highly prevalent in individuals with high-level spinal cord injury. In addition, chest mechanics are known to be altered, leading to paradoxical breathing. Here we investigated the interaction between paradoxical breathing and sleep quality in these patients, and its association with measurements of respiratory function, hypercapnic ventilatory response and peak exercise ventilation. Home-based polysomnography was performed in 13 patients with spinal cord injury (C4 to T4) untreated for sleep-disordered breathing. We defined paradoxical breathing as counterphase between thoracic and abdominal movements during slow-wave and rapid eye movement sleep. Sleep quality, pulmonary function, hypercapnic ventilatory responses and peak exercise ventilation were compared between those with and without paradoxical breathing. Half of individuals presented with nocturnal paradoxical breathing. Despite similar age, body mass index, injury level, time since injury, and respiratory function, those with paradoxical breathing had higher apnea-hypopnea index (13 ± 8 versus 5 ± 3 events per hr) and average sleep heart rate (67 ± 12 versus 54 ± 4 bpm; p < 0.05). Moreover, paradoxical breathing was associated with lower hypercapnic ventilatory response (slope: 0.35 ± 0.17 versus 0.96 ± 0.38) and lower peak exercise ventilation (33 ± 4 versus 48 ± 12 L min-1 ; p < 0.05). Nocturnal respiratory muscle desynchronization could play a role in the pathophysiology of sleep apnea, and could relate to low ventilatory responses to both hypercapnia and exercise in high-level spinal cord injury. Polysomnography may be an important diagnostic tool for these patients for whom therapeutic approaches should be considered to treat this abnormality.

Sleep disordered breathing assessment in patient with slowly progressive neuromuscular disease

BACKGROUND

Sleep-disordered breathing (SDB) is common in patients with neuromuscular diseases (NMD). Focusing on hypercapnia may lead to the neglect of other SDB such as obstructive and/or central sleep apnea syndrome (SAS). Our objectives were to assess the risk of inappropriate SDB management according to different screening strategies and to evaluate the prevalence and determinants of isolated and overlapping sleep apnea in patients with slowly progressive NMD.

METHODS

This monocentric, cross-sectional, retrospective study analyzed medical records of adult NMD patients referred to a sleep department. Diagnostic strategies, including respiratory polygraphy (RP), nocturnal transcutaneous capnography (tcCO2), and blood gases (BG), were assessed for their performance in diagnosing SDB. Demographics and pulmonary function test results were compared between patients with or without SDB to identify predictors.

RESULTS

Among the 149 patients who underwent a full diagnostic panel (RP + tcCO2 + BG), 109 were diagnosed with SDB. Of these, 33% had isolated SAS, and central apneas were predominant. Using single diagnostic strategies would lead to inappropriate SDB management in two thirds of patients. A combination of 2 diagnostic tools resulted respectively in 21.1, 22.9 and 42.2 % of inappropriate SDB management for RP + tcCO2, RP + BG and tcCO2 + BG.

CONCLUSION

The significant prevalence of sleep apnea syndrome in patients with slowly progressive NMD highlights the need for increased awareness among clinicians. Improved diagnostics involve a systematic approach addressing both sleep apnea and diurnal and nocturnal alveolar hypoventilation to avoid inappropriate management and limit the consequences of SDB.