The impact of cardiac resynchronization therapy on obstructive sleep apnea in heart failure patients: a pilot study.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been shown to improve cardiac function and reduce Cheyne-Stokes respiration but has not been evaluated in patients with obstructive sleep apnea (OSA). In this pilot study, we investigated the impact of both CRT and CRT plus increased rate pacing in heart failure (ie, congestive heart failure [CHF]) patients with OSA. We hypothesized that through increased cardiac output CRT/pacing would reduce obstructive events and daytime symptoms of sleepiness. METHODS: Full polysomnograms were performed on CHF patients who were scheduled for CRT, and those patients with an apnea-hypopnea index (AHI) of > 5 events per hour were approached about study enrollment. Patients had a pre-CRT implant baseline echocardiogram and an echocardiogram a mean (+/- SEM) duration of 6.6 +/- 1.4 months post-CRT implant; polysomnography; and responded to the Minnesota Living with Heart Failure questionnaire, the Epworth sleepiness scale, and the Functional Outcomes of Sleep Questionnaire. An additional third polysomnography was performed combining CRT with a pacing rate of 15 beats/min above the baseline sleeping heart rate within 1 week of the second polysomnography. Assessments for the change in cardiac output during the polysomnography were performed using circulation time to pulse oximeter as a surrogate. RESULTS: Twenty-four patients were screened, and 13 patients (mean age, 68.6 years; body mass index, 28.7 kg/m(2)) had evidence of OSA. The mean AHI decreased from 40.9 +/- 6.4 to 29.5 +/- 5.9 events per hour with CRT (p = 0.04). The mean baseline ejection fraction was 22 +/- 1.7% and increased post-CRT to 33.6 +/- 2.0% (p < 0.05). The reduction in AHI with CRT closely correlated with a decrease in circulation time (r = 0.89; p < 0.001) with CRT. Increased rate pacing made no additional impact on the AHI or circulation time. CRT had a limited impact on sleep architecture or daytime symptom scores. CONCLUSIONS: CRT improved cardiac function and reduced the AHI. Reduced circulatory delay likely stabilized ventilatory control systems and may represent a new therapeutic target in OSA.

The influence of white noise on sleep in subjects exposed to ICU noise.

BACKGROUND AND PURPOSE: There is disagreement in the literature about the importance of sleep disruption from intensive care unit (ICU) environmental noise. Previous reports have assumed that sleep disruption is produced by high-peak noise. This study aimed to determine whether peak noise or the change in noise level from baseline is more important in inducing sleep disruption. We hypothesized that white noise added to the environment would reduce arousals by reducing the magnitude of changing noise levels. PATIENTS AND METHODS: Four subjects underwent polysomnography under three conditions: (1) baseline, (2) exposure to recorded ICU noise and (3) exposure to ICU noise and mixed-frequency white noise, while one additional subject completed the first two conditions. Baseline and peak noise levels were recorded for each arousal from sleep. RESULTS: A total of 1178 arousals were recorded during these studies. Compared to the baseline night (13.3+/-1.8 arousals/h) the arousal index increased during the noise (48.4+/-7.6) but not the white noise/ICU noise night (15.7+/-4.5) (P<0.004). The change in sound from baseline to peak, rather than the peak sound level, determined whether an arousal occurred and was the same for the ICU noise and white noise/ICU noise condition (17.7+/-0.4 versus 17.5+/-0.3 DB, P=0.65). CONCLUSIONS: Peak noise was not the main determinant of sleep disruption from ICU noise. Mixed frequency white noise increases arousal thresholds in normal individuals exposed to recorded ICU noise by reducing the difference between background noise and peak noise.

Effect of a nonrebreathing exhalation valve on long-term nasal ventilation using a bilevel device.

STUDY OBJECTIVE: To determine whether an exhalation valve designed to minimize rebreathing improves daytime or nocturnal gas exchange or improves symptoms compared with a traditional valve during nocturnal nasal ventilation delivered using a bilevel pressure ventilation device. DESIGN: Prospective direct comparison trial with each patient sequentially using both valves, during a 2-week run-in period with a traditional valve, a 2-week trial with the nonrebreathing valve, and a 2-week washout period with the traditional valve. SETTING: Outpatient pulmonary function laboratory and home nocturnal monitoring. PATIENTS: Seven patients who received long-term (> 1 year) nocturnal nasal bilevel pressure ventilation with an expiratory pressure of

Evaluation of the accuracy of SNAP technology sleep sonography in detecting obstructive sleep apnea in adults compared to standard polysomnography.

OBJECTIVE: To determine the accuracy of snoring and apnea analysis by SNAP (SNAP Laboratories; Glenview, IL), a technology that uses snoring recorded by a home microphone system and nasal airflow, to diagnose obstructive sleep apnea (OSA) as well as determine its severity. METHODS: For all patients who had undergone a prior SNAP study and were referred to the Sleep Disorders Center of Lifespan Hospitals for polysomnography testing from January 2000 through December 2001, we compared the results of the SNAP study to standard polysomnography (polysomnography). The severity of each apnea-hypopnea index (AHI) [mild, moderate, or severe, as defined by the AHI Severity Task Force of the American Academy of Sleep Medicine] recorded by SNAP was compared to that of the polysomnography result. All polysomnography tests were scored independently and without the prior knowledge of any SNAP results. RESULTS: For the 31 patients on whom data were available, the mean age, body mass index, and Epworth sleepiness scale scores were 50.3 years (range, 29 to 77 years), 31.6 kg/m(2) (range, 24 to 44 kg/m(2)), and 11.3 (range, 1 to 20), respectively. The mean follow-up time between the two studies was 5 months. The severity criteria indicated by the SNAP study accurately assessed the true severity confirmed by polysomnography in only 11 of 31 patients (35.5%). When the AHI severity score from the SNAP study was compared to polysomnography using a kappa statistic measure of agreement, there was overall agreement with a kappa value of 0.23 (p = 0.008), but the agreement was only fair. SNAP study severity scores were overestimated in 13 of 31 patients (41.9%) compared to the polysomnography results. In the majority of these subjects (8 of the 13 "overestimated" patients or 8 of 31 total patients [25.8%]), the SNAP study diagnosed OSA when the patient had a normal polysomnography finding. CONCLUSION: Although there may be some night-to-night variability in polysomnography testing, these results suggest that SNAP studies do not appear to accurately assess the severity of OSA.

Brief behavioral therapies reduce early positive airway pressure discontinuation rates in sleep apnea syndrome: preliminary findings.

Sleep apnea syndrome (SAS) is a serious disorder with significant daytime consequences. Treatment for SAS most commonly takes the form of positive airway pressure (PAP). Although effective, PAP adherence is often below expectations. Previous studies have suggested that the provision of information on the importance of PAP use can enhance adherence. In this study, we compare 2 brief behavioral approaches-traditional education (ED) and a motivational enhancement therapy (MET)-designed from theories of behavior change to standard clinical care. PAP discontinuation and adherence are the primary outcome measures. Both brief therapies decreased PAP discontinuation compared to standard care. The MET therapy performed best under the condition of flexible delivery of PAP, although differences were not statistically significant. Implications are discussed.