Detecting atrial fibrillation in the polysomnography-derived electrocardiogram: a software validation study.

PURPOSE: The present study validated a software-based electrocardiogram (ECG) analysis tool for detection of atrial fibrillation (AF) and risk for AF using polysomnography (PSG)-derived ECG recordings. METHODS: The Stroke Risk Analysis® (SRA®) software was applied to 3-channel ECG tracings from diagnostic PSG performed in enrolled subjects including a subgroup of subjects with previously documented AF. No subjects used positive airway pressure therapy. All ECG recordings were visually analyzed by a blinded cardiologist. RESULTS: Of subjects enrolled in the study, 93 had previously documented AF and 178 of 186 had an ECG that could be analyzed by either method. In subjects with known history of AF, automated analysis using SRA® classified 47 out of 87 ECG as either manifest AF or showing increased risk for paroxysmal AF (PAF) by SRA® (sensitivity 0.54, specificity 0.86). On visual analysis, 36/87 ECG showed manifest AF and 51/87 showed sinus rhythm. Among the latter subgroup, an increased risk for PAF was ascribed by SRA® in 11 cases (sensitivity 0.22, specificity 0.78) and by expert visual analysis in 5 cases (sensitivity 0.1, specificity 0.90). Among 36/178 ECG with manifest AF on visual analysis, 33 were correctly identified by the SRA® software (sensitivity and specificity 0.92). CONCLUSION: Sleep studies provide a valuable source of ECG recordings that can be easily subjected to software-based analysis in order to identify manifest AF and automatically assess the risk of PAF. For optimal evaluability of data, multiple channel ECG tracings are desirable. For assessment of PAF risk, the SRA® analysis probably excels visual analysis, but sensitivity of both methods is low, reflecting that repeated ECG recording remains essential.

Respiratory parameters on diagnostic sleep studies predict survival in patients with amyotrophic lateral sclerosis.

OBJECTIVE: In amyotrophic lateral sclerosis (ALS), respiratory muscle involvement and sleep-disordered breathing relate to worse prognosis. The present study investigated whether respiratory outcomes on first-ever sleep studies predict survival in patients with ALS, specifically taking into account subsequent initiation of non-invasive ventilation (NIV). METHODS: From patients with ALS, baseline sleep study records, transcutaneous capnometry, early morning blood gas analysis, survival data and clinical disease characteristics were retrospectively analyzed. Patients were stratified according to whether enduring NIV was consecutively established ("NIV(+)") or not ("NIV(-)"). RESULTS: Among the study cohort (n = 158, 72 female, 51 with bulbar onset ALS, 105 deceased) sleep-disordered breathing was present at baseline evaluation in 97 patients. Early morning base excess (EMBE) > 2 mmol/l predicted nocturnal hypercapnia. Ninety-five patients were NIV(+) and 63 were NIV(-). Survival from baseline sleep studies was significantly reduced in NIV(-) but not in NIV(+) patients with nocturnal CO2 tension ≥ 50 mmHg, apnea hypopnea index ≥ 5/h, and EMBE > 2 mmol/l. Hazard ratio for EMBE > 2 mmol/l was increased in NIV(-) patients only, and EMBE independently predicted survival in both NIV(-) and NIV(+) patients. Furthermore, EMBE on baseline sleep studies was the only predictor for survival from symptom onset, and hazard ratio for shorter survival was markedly higher in the NIV(-) than the NIV(+) group (2.85, p = 0.005, vs. 1.71, p = 0.042). INTERPRETATION: In patients with ALS, EMBE > 2 mmol/l predicts nocturnal hypercapnia and shorter survival. Negative effects of sleep-disordered breathing on survival are statistically abolished by sustained NIV.

Disorders of sleep in spinal and bulbar muscular atrophy (Kennedy's disease).

INTRODUCTION: Spinal and bulbar muscular atrophy (SBMA) is a progressive, X-linked lower motor neuron disorder exclusively affecting men. Since knowledge on sleep disorders in SBMA is scarce compared to other motoneuron diseases, this retrospective case-control study aimed to investigate sleep and sleep-related breathing in patients with SBMA. METHODS: In 23 non-ventilated patients with SBMA (median age 52 years), clinical disease characteristics, forced vital capacity and diagnostic polysomnographies were retrospectively evaluated. In 16 patients, overnight transcutaneous capnometry was available. Twenty-three male control subjects with chronic insomnia were matched for age and body mass index. RESULTS: In patients with SBMA obstructive sleep apnoea (OSA, apnoea-hypopnoea index/AHI > 5/h) was more frequent than in control subjects (14/23 or 61% vs. 6/23 or 26%, p = 0.02), and median AHI was significantly higher in patients (9.0/h vs. 3.4/h, p < 0.01). Among SBMA patients, the AHI was not related to age or body mass index. Alveolar hypoventilation as reflected by nocturnal hypercapnia was found in 3/16 patients. Rapid eye movement (REM) sleep without atonia was present in 44% of SBMA patients but only in 4% of controls (p < 0.01). During REM and non-REM sleep, no behavioural abnormalities were observed in either group. Periodic limb movements in sleep (index > 15/h) were frequent in SBMA patients but rarely disrupted sleep. CONCLUSIONS: In patients with SBMA, sleep-disordered breathing may comprise both OSA and nocturnal hypoventilation. REM sleep without atonia may also be found, but its clinical significance remains unclear. In patients complaining of sleep-related symptoms, cardiorespiratory polysomnography and transcutaneous capnometry are recommended.

Upper airway obstruction induced by non-invasive ventilation using an oronasal interface.

BACKGROUND: On initiation of long-term non-invasive ventilation (NIV), intermittent upper airway obstruction has rarely been described as possibly treatment-induced. Inspiratory pressure effects and the use of an oronasal interface may promote obstructive events in some patients with neuromuscular disease (NMD) and amyotrophic lateral sclerosis (ALS) in particular. METHODS: We evaluated clinical data from 212 patients in whom NIV was initiated using an oronasal mask. Treatment-induced upper airway obstruction (TAO) was defined as an AHI > 5/h along with a relative increase of the AHI in the first treatment night compared to diagnostic sleep studies. RESULTS: Prevalence of TAO was 14.2% in the entire cohort, 17.0% in patients with NMD (n = 165), 20.4% in the ALS subgroup (n = 93), and 4.3% in non-NMD patients (n = 47). Fixed expiratory positive airway pressure (EPAP, n = 192) was significantly correlated with AHI reduction (r = 0.50; p < 0.001). The inspiratory-expiratory pressure interval (∆PAP, n = 191) showed inverse correlation with the AHI change achieved in the first treatment night (r = - 0.28; p < 0.001). However, ∆PAP and the effective pressure range between EPAP and the highest inspiratory PAP achieved were not predictive of TAO. In patients with ALS, TAO was associated with better bulbar function. Study results were limited by initial EPAP being significantly lower in NMD patients reflecting that sleep apnea was less frequent and severe in this subgroup. CONCLUSIONS: Initiation of NIV using an oronasal interface may be associated with TAO in a subset of patients. Since both EPAP and ∆PAP appear to play a causative role, careful titration of ventilator settings is recommended.

Prevalence of sleep apnoea and capnographic detection of nocturnal hypoventilation in amyotrophic lateral sclerosis.

OBJECTIVE: This retrospective study aimed to investigate whether overnight oxymetry and early morning blood gas analysis predict nocturnal hypoventilation (NH) as reflected by night-time hypercapnia in patients with amyotrophic lateral sclerosis (ALS). In addition, prevalence and clinical determinants of sleep apnoea in ALS were evaluated. METHODS: In 250 patients with non-ventilated ALS, transcutaneous capnometry was performed along with polysomnography or polygraphy and early morning blood gases. RESULTS: 123 patients were female, and 84 patients had bulbar-onset ALS. 40.0% showed NH, and an apnoea-hypopnoea index (AHI) >5/hour was found in 45.6%. In 22.3%, sleep apnoea and NH coincided. The obstructive apnoea index was significantly higher than the central apnoea index (p<0.0001). Both NH and sleep apnoea were significantly more common in male than in female patients. Sleep apnoea and AHI were associated with better bulbar function. Desaturation time (t<90%) and transcutaneous CO2 were negatively correlated with upright vital capacity. Early morning base excess (EMBE), bicarbonate and t<90% were independent predictors of NH. However, among 100 patients with NH, 31 were missed by t<90% >5 min and 17 were not identified when EMBE >3 mmol/L and t<90% >5 min were combined. CONCLUSION: In ALS, sleep apnoea is common and often accompanies NH. It is mainly obstructive, and central apnoea appears to be clinically irrelevant. Polygraphy or oxymetry alone are not sufficient to uncover NH. Combination of EMBE and t<90% may increase sensitivity, but transcutaneous capnography is strongly recommended for reliable detection of NH in patients with ALS.

Sleep-Disordered Breathing and Effects of Noninvasive Ventilation in Patients with Late-Onset Pompe Disease.

STUDY OBJECTIVES: In neuromuscular disease, non-invasive ventilation (NIV) is indicated if sleep-disordered breathing (SDB) or significant respiratory muscle weakness (RMW) is present. We investigated immediate and long-term effects of NIV on sleep and nocturnal ventilation in patients with late-onset Pompe disease (LOPD). METHODS: Polysomnography and transcutaneous capnometry were performed in 22 adult patients. If indicated, NIV was initiated the subsequent night and follow-up sleep studies were scheduled. Sleep quality and health-related quality of life (HRQoL) were self-assessed using standard questionnaires. RESULTS: Fourteen patients received enzyme replacement therapy (ERT), five patients were treatment-naÏve, and three individuals had previously stopped ERT. Fifteen patients reported symptoms of SDB, all showing abnormal sleep studies. Two patients had obstructive sleep apnea (OSA), three patients showed both OSA and nocturnal hypercapnia, four individuals had nocturnal hypercapnia, and two patients had both OSA and daytime hypercapnia. Four patients showed normal apnea-hypopnea index and CO2 measures but nocturnal tachypnea, orthopnea, and significant RMW were present. Supine forced vital capacity (FVC) and positional drop of FVC were independent predictors of SDB. In patients with SDB, HRQoL was significantly reduced. NIV was initiated in 15 individuals and led to significant improvement of ventilation and oxygenation in the first night of treatment. Follow-up sleep studies revealed stable normoxia and normocapnia without deterioration of sleep outcomes for up to 40 months. CONCLUSIONS: In LOPD, SDB is common and comprises both hypoventilation and OSA. NIV significantly improves respiration already in the first night of treatment. NIV warrants nocturnal long-term normoventilation without deterioration of sleep quality.

Effects of non-invasive ventilation on objective sleep and nocturnal respiration in patients with amyotrophic lateral sclerosis.

In amyotrophic lateral sclerosis (ALS), non-invasive ventilation (NIV) is indicated if sleep-disordered breathing (SDB), daytime hypercapnia, or significant diaphragmatic weakness is present. We investigated both short-term and long-term effects of NIV on objective measures of sleep and nocturnal respiration in patients with ALS. Polysomnography (PSG) and transcutaneous capnography were conducted for diagnosis of SDB (T0), for treatment initiation (T1), and follow-up 3, 9, and 15 months later (T2, T3, and T4, respectively). Records from 65 patients were retrospectively analyzed at T0 and T1. At subsequent timepoints, the number of full data sets decreased since follow-up sleep studies frequently included polygraphy rather than PSG (T2, 38 patients, T3, 17 patients, T4, 11 patients). At T0, mean age was 63.2 years, 29 patients were female, and 22 patients had bulbar ALS. Immediate sequelae of NIV initiation included significant increases of slow wave sleep, rapid eye movement sleep, and oxygen saturation. Mean apnea-hypopnea index, respiratory rate, and the maximum transcutaneous carbon dioxide tension were reduced. At T2-T4, normoxia and normocapnia were preserved. Sleep quality measures showed no alteration as diurnal use of NIV gradually increased reflecting disease progression. In contrast to previous reports, improvement of sleep and respiratory outcomes was found in both non-bulbar and bulbar patients. NIV significantly improves objective sleep quality and SDB in the first night of treatment in patients with bulbar and non-bulbar ALS. NIV warrants nocturnal normoventilation without deterioration of sleep quality in the long run with only minor changes to ventilator settings.

Aircraft noise: effects on macro- and microstructure of sleep.

OBJECTIVE: The effects of aircraft noise on sleep macrostructure (Rechtschaffen and Kales) and microstructure (American Sleep Disorders Association [ASDA] arousal criteria) were investigated. PATIENTS AND METHODS: For each of 10 subjects (mean age 35.3 years, 5 males), a baseline night without aircraft noise (control), and two nights with exposure to 64 noise events with a maximum sound pressure level (SPL) of either 45 or 65 dBA were chosen. Spontaneous and noise-induced alterations during sleep classified as arousals (ARS), changes to lighter sleep stages (CSS), awakenings including changes to sleep stage 1 (AS1), and awakenings (AWR) were analyzed. RESULTS: The number of events per night increased in the order AWR, AS1, CSS, and ARS under control conditions as well as under the two noise conditions. Furthermore, probabilities for sleep disruptions increased with increasing noise level. ARS were observed about fourfold compared to AWR, irrespective of control or noise condition. CONCLUSIONS: Under the conditions investigated, different sleep parameters show different sensitivities, but also different specificities for noise-induced sleep disturbances. We conclude that most information on sleep disturbances can be achieved by investigating robust classic parameters like AWR or AS1, although ASDA electroencephalographic (EEG) arousals might add relevant information in situations with low maximum SPLs, chronic sleep deprivation or chronic exposure.