Yoshinobu Ohnishi

Differences in Breathing Patterning During Wakefulness in Patients With Mixed Apnea-Dominant vs Obstructive-Dominant Sleep Apnea

BACKGROUND Mixed apneas share both central and obstructive components and are often treated as if they are obstructive events. The hypothesis is that patients with obstructive sleep apnea syndrome (OSAS) who exhibit a majority of mixed apneas will differ in ventilatory control from those with predominantly obstructive apneas during wakefulness; moreover, this difference could affect nasal continuous positive airway pressure (CPAP) adherence. METHODS In a retrospectively derived case-control study, 5 min of respiratory inductance plethysmography signals during wakefulness prior to sleep onset were extracted from a diagnostic polysomnogram in these groups: (1) mixed apnea-dominant OSAS (mix-OSAS) (n = 36), (2) obstructive apnea-dominant OSAS (pure-OSAS) (n = 20), (3) central apnea-dominant sleep apnea syndrome (pure-CSAS) (n = 6), and (4) control subjects (n = 10). Breathing patterning was compared between the groups using the coefficient of variation (CV) for breath-to-breath inspiration time (TI), expiration time (TE), TI + TE (Ttot), and tidal volume, and an information theory-based metric of signal pattern variability (sample entropy). Subsequent CPAP adherence over 12 months was determined in OSAS groups. RESULTS Breath-to-breath CV parameters and sample entropy in the mix-OSAS group were significantly greater as compared with the pure-OSAS and control groups. In a subanalysis, CV and sample entropy were similar in the mix-OSAS and the pure-CSAS groups. CPAP adherence was significantly poorer in mix-OSAS compared with pure-OSAS. CONCLUSIONS During wakefulness, both breath patterning and sample entropy in mix-OSAS are similar to pure-CSAS and more variable than in pure-OSAS. In addition, CPAP adherence was decreased in patients with mix-OSAS, which may be related to basic differences in respiratory control.

Breathing irregularity during wakefulness associates with CPAP acceptance in sleep apnea

PurposeIndividuals have different breathing patterns at rest, during wakefulness, and during sleep, and patients with sleep apnea are no different. The hypothesis for this study was that breathing irregularity during wakefulness associates with CPAP acceptance in obstructive sleep apnea (OSA).MethodsFrom a 2007–2010-database of patients with a diagnostic polysomnography (PSG) and prescribed CPAP (n = 380), retrospectively, 66 patients who quit CPAP treatment at 6 months were identified. Among them, 27 OSA patients quit despite having no side effects for discontinuing CPAP (Group A) and were compared to a matched group (age, body mass index, and apnea–hypopnea index) with good 6-month CPAP adherence (Group B; n = 21). Five minutes of respiratory signal during wakefulness at the initial PSG were extracted from respiratory inductance plethysmography recordings, and measured in a blinded fashion. The coefficients of variation (CV) for the breath-to-breath inspiration time (Ti), expiration time (Te), Ti + Te (Ttot), and relative tidal volume, as well as an independent information theory-based metric of signal pattern variability (mutual information) were compared between groups.ResultsThe CV for tidal volume was significantly greater (p = 0.001), and mutual information was significantly lower (p = 0.041) in Group A as compared to Group B.ConclusionsDifferences in two independent measures of breathing irregularity correlated with CPAP rejection in OSA patients without nasal symptoms or comorbidity. Prospective studies of adherence should examine traits of breathing stability.

Nonrapid Eye Movement-Predominant Obstructive Sleep Apnea: Detection and Mechanism.

STUDY OBJECTIVES Obstructive sleep apnea (OSA) can be severe and present in higher numbers during rapid eye movement (REM) than nonrapid eye movement (NREM) sleep; however, OSA occurs in NREM sleep and can be predominant. In general, ventilation decreases an average 10% to 15% during transition from wakefulness to sleep, and there is variability in just how much ventilation decreases. As dynamic changes in ventilation contribute to irregular breathing and breathing during NREM sleep is mainly under chemical control, our hypothesis is that patients with a more pronounced reduction in ventilation during the transition from wakefulness to NREM sleep will have NREM- predominant rather than REM-predominant OSA. METHODS A retrospective analysis of 451 consecutive patients (apnea-hypopnea index [AHI] > 5) undergoing diagnostic polysomnography was performed, and breath-to-breath analysis of the respiratory cycle duration, tidal volume, and estimated minute ventilation before and after sleep onset were examined. Values were calculated using respiratory inductance plethysmography. The correlation between the percent change in estimated minute ventilation during wake-sleep transitions and the percentage of apnea-hypopneas in NREM sleep (%AHI in NREM; defined as (AHI-NREM) / [(AHI-NREM) + (AHI-REM)] × 100) was the primary outcome. RESULTS The decrease in estimated minute ventilation during wake-sleep transitions was 15.0 ± 16.6% (mean ± standard deviation), due to a decrease in relative tidal volume. This decrease in estimated minute ventilation was significantly correlated with %AHI in NREM (r = -0.222, p < 0.01). CONCLUSIONS A greater dynamic reduction in ventilation back and forth from wakefulness to sleep contributes to the NREM predominant OSA phenotype via induced ventilatory instability.

Right Bundle Branch Block Like Pattern Recorded in Right Ventricular Endocardial Pacing

Right bundle branch block (RBBB) pattern recorded during right ventricular (RV) endocardial pacing should be given special attention in terms of safe RV pacing or lead malposition, e.g. left ventricular pacing or coronary venous pacing, even for patients with no symptoms. Paced electrocardiograms from 47 consecutive patients with a pacemaker implanted were studied. Four patients (8.5%) were found to have RBBB pattern recorded in precordial V1 and V2 leads in the usual 4th intercostal space. All of these patients showed left bundle branch block (LBBB) pattern in limb leads. When precordial V1 and V2 leads in the 5th space were recorded, RBBB pattern changed to LBBB pattern. Biplane chest X‐ray film and echocardiogram, especially 3D echo mode, confirmed that tips of pacing leads of the 4 patients were located in the distal RV septum or the apex. RBBB pattern observed during RV endocardial pacing usually represents safe RV endocardial pacing rather than perforation or malposition of pacing leads.

Long-Term Follow-Up of Endocardial Pacing Leads Implanted with Extrathoracic Subclavian Venous Approach

The extrathoracic subclavian venous approach is a new approach with the aim to exclude the disadvantages of the conventional subclavian venous approach that carries a risk of pneumothorax and may result in lead damage. We investigated long‐term survival of the leads implanted by this new approach between May 1995 and June 2005. A total of 482 leads implanted in 309 patients were analyzed. In cases of patient death, meeting criteria for lead failure or difficulty of continuing follow‐up for other reasons, the follow‐up was terminated at that time. Therefore, the follow‐up was complete for 358 leads (74.3%) and the mean followup time was 55.0 ± 32.1 months (range 1–122 months). The overall lead survival rate was 100% at 5 years and 98.3% at 7 years. This finding suggested that this approach might reduce the incidence of lead failure.