Improvements in Cognitive Function and Quantitative Sleep EEG in OSA after Six Months of CPAP Treatment

Study Objectives Untreated obstructive sleep apnea (OSA) is associated with cognitive deficits and altered brain electrophysiology. We evaluated the effect of continuous positive airway pressure (CPAP) treatment on quantitative sleep electroencephalogram (EEG) measures and cognitive function. Methods We studied 162 OSA patients (age 50±13, AHI 35.0±26.8) before and after 6 months of CPAP. Cognitive tests assessed working memory, sustained attention, visuospatial scanning and executive function. All participants underwent overnight polysomnography at baseline and after CPAP. Power spectral analysis was performed on EEG data (C3-M2) in a sub-set of 90 participants. Relative delta EEG power and sigma power in NREM and EEG slowing in REM were calculated. Spindle densities (events p/min) in N2 were also derived using automated spindle event detection. All outcomes were analysed as change from baseline. Results Cognitive function across all cognitive domains improved after six months of CPAP. In our sub-set, increased relative delta power (p<0.0001) and reduced sigma power (p=0.001) during NREM were observed after the 6-month treatment period. Overall, fast and slow sleep spindle densities during N2 were increased after treatment. Conclusions Cognitive performance was improved and sleep EEG features were enhanced when assessing the effects of CPAP. These findings suggest the reversibility of cognitive deficits and altered brain electrophysiology observed in untreated OSA following six months of treatment.

Factors Affecting Long-Term Compliance of CPAP Treatment—A Single Centre Experience

Continuous positive airway pressure (CPAP) has been the standard treatment of obstructive sleep apnoea/hypopnoea syndrome (OSA) for almost four decades. Though usually effective, this treatment suffers from poor long-term compliance. Therefore, the aim of our one centre retrospective study was to assess factors responsible for treatment failure and long-term compliance. Four hundred subsequent patients diagnosed with OSA and qualified for CPAP treatment were chosen from our database and compliance data were obtained from medical charts. Many differing factors kept patients from starting CPAP or led to termination of treatment. Overall, almost half of patients ended treatment during the mean time of observation of 3.5 years. Survival analysis revealed that 25% of patients failed at a median time of 38.2 months. From several demographic and clinical covariates in Cox’s hazard model, only the presence of a mild OSA, i.e., AHI (apnoea/hypopnoea index) below 15/h was a factor strongly associated with long term CPAP failure. The compliance results of our study are in line with numerous studies addressing this issue. Contrary to them, some demographic or clinical variables that we used in our survival model were not related to CPAP adherence.

Neurocognitive Performance Improvement after Obstructive Sleep Apnea Treatment: State of the Art

Background: Obstructive Sleep Apnea (OSA) syndrome is a respiratory sleep disorder characterized by partial or complete episodes of upper airway collapse with reduction or complete cessation of airflow. Although the connection remains debated, several mechanisms such as intermittent hypoxemia, sleep deprivation, hypercapnia disruption of the hypothalamic–pituitary–adrenal axis have been associated with poor neurocognitive performance. Different treatments have been proposed to treat OSAS patients as continuous positive airway pressure (CPAP), mandibular advancement devices (MAD), surgery; however, the effect on neurocognitive functions is still debated. This article presents the effect of OSAS treatments on neurocognitive performance by reviewing the literature. Methods: We performed a comprehensive review of the English language over the past 20 years using the following keywords: neurocognitive performance and sleep apnea, neurocognitive improvement and CPAP, OSAS, and cognitive dysfunction. We included in the analysis papers that correlated OSA treatment with neurocognitive performance improvement. All validated tests used to measure different neurocognitive performance improvements were considered. Results: Seventy papers reported neurocognitive Performance improvement in OSA patients after CPAP therapy. Eighty percent of studies found improved executive functions such as verbal fluency or working memory, with partial neural recovery at long-term follow-up. One article compared the effect of MAD, CPAP treatment on cognitive disorders, reporting better improvement of CPAP and MAD than placebo in cognitive function. Conclusions: CPAP treatment seems to improve cognitive defects associated with OSA. Limited studies have evaluated the effects of the other therapies on cognitive function.

OSA Treatment on Cardio- and Cerebrovascular Comorbidities: A Long-term Nationwide Cohort Study

Objective To compare the cardio- and cerebrovascular outcomes and survival rates of surgical and nonsurgical interventions for patients with obstructive sleep apnea (OSA) based on a national population-based database. Study Design Retrospective cohort study. Setting Taiwan National Health Insurance Research Database. Methods We analyzed all cases of OSA among adults (age >20 years and confirmed with ICD-9-CM) from January 2001 to December 2013. We compared the patients with OSA who received upper airway surgery with age-, sex-, and comorbidity index–matched controls with continuous positive airway pressure (CPAP) treatment. The risk of myocardial infarction (MI) or stroke after treatment of OSA-related surgery versus CPAP was investigated. Results During follow-up, 112 and 92 incident cases of MI occurred in the OSA surgery and CPAP treatment groups, respectively (rates of 327 and 298 per 100,000 person-years). Furthermore, 50 and 39 cases were newly diagnosed with stroke in the OSA surgery and CPAP treatment groups (rates of 144 and 125 per 100,000 person-years). Cox proportional hazard regressions showed that the OSA treatment groups (OSA surgery vs CPAP) were not significantly related to MI (hazard ratio, 1.03 [95% CI, 0.781-1.359]; P = .833) and stroke (hazard ratio, 1.12 [95% CI, 0.736-1.706]; P = .596) at follow-up, after adjustment for sex, age at index date, days from diagnosis to treatment, and comorbidities. Conclusion Our study demonstrated that there was no difference of cardio- and cerebrovascular results between CPAP and surgery for patients with OSA in a 13-year follow-up. Level of Evidence 3.

CPAP Improved Daytime Sleepiness and Memory Function in Patients With Obstructive Sleep Apnea Syndrome

Objective: Obstructive sleep apnea (OSA) is a sleep disorder which results in daytime sleepiness and impaired memory function. The aim of this study was to investigate the effect of continuous positive airway pressure (CPAP) on sleepiness and memory function in OSA patients. We also investigated whether CPAP compliance impacted the effect of this treatment.Methods: The case-control study enrolled sixty-six patients with moderate to severe OSA subjects. All subjects completed a polysomnographic study, sleepiness questionnaires (the Epworth Sleepiness Scale and the Pittsburgh Sleep Quality Index), and four memory function tests (WM: working memory; PS: processing speed; LM: logical memory; FM: face memory).Results: Prior to CPAP treatment, no significant differences (p< 0.05) were noted in the demographic data, daytime sleepiness, or memory function between the two groups (with/without CPAP). However, OSA patients treated with CPAP for two months showed significant improvements in daytime sleepiness, PS, LM, and FM compared to those who did not receive CPAP treatment. A significant improvement in LM was observed in subjects who exhibited good compliance with CPAP treatment compared to those with poor compliance. Conclusions: In conclusion, CPAP treatment for two months improved daytime sleepiness and memory function in OSA patients. Patients exhibiting good CPAP compliance demonstrated greater improvements in daytime sleepiness and LM function.

P030 The effects of continuous positive airway pressure (CPAP) therapy in moderate to severe obstructive sleep apnea (OSA): A high-density electroencephalography (EEG) study

Introduction A previous high-density EEG investigation in OSA showed regional sleep EEG deficits particularly slow wave activity (SWA) in the parietal region. It is unclear whether CPAP treatment can reverse local sleep EEG abnormalities, and whether any recovery is related to improved cognitive function. Methods Fifteen males with moderate-severe OSA (age 50.4±6.5yrs, AHI 51.7±23.5/h) underwent polysomnography with 256-channel high-density EEG at baseline and following 3 months of CPAP. Tasks assessing cognitive performance and sleep-dependent memory were administered. Topographical spectral power maps were calculated for standard frequency ranges for sleep stages. Differences in normalized power between baseline and treatment were determined by statistical nonparametric mapping. Results In 11 CPAP compliant patients (data loss: intolerant of CPAP[n=3]/high-density EEG [n=1]), total sleep time did not change after CPAP but N1 (baseline vs. treatment: 66.9 vs. 39.5 mins, p=0.008) and N2 (195.0 vs. 150.6 mins, p=0.002) sleep was lower and N3 (89.8 vs. 128.7 mins, p=0.003) was higher. Topographic high-density EEG analysis revealed a regional increase in SWA (1–4.5Hz) during N3 sleep in a cluster of 22 electrodes overlying the parietal cortex (paired t-test, t(10)=-3.9, p=0.0029). The change in N3 SWA in the parietal cluster after CPAP was correlated with improved overnight procedural memory on the motor sequence task (rho=0.79, p=0.03) and better executive functioning (Stroop accuracy, rho=0.73, p=0.01). Conclusion CPAP treatment reduces localised deficits in sleep EEG, and specific regional recovery relates to short-term improvements in memory and executive function. These data also highlight the potential for long-term therapeutic effects on cognitive outcomes.

Cardiopulmonary exercise testing in patients with moderate-severe obesity: a clinical evaluation tool for OSA?

Purpose Obstructive sleep apnea (OSA) is a widespread comorbidity of obesity. Nasal continuous positive airway pressure (CPAP) has been demonstrated very effective in treating patients with OSA. The aims of this study were to investigate whether or not cardiopulmonary exercise testing (CPET) can characterize patients with OSA and to evaluate the effect of nasal CPAP therapy. Methods An observational study was conducted on patients with moderate to severe obesity and suspected OSA. All patients underwent cardiorespiratory sleep study, spirometry, and functional evaluation with ECG-monitored, incremental, maximal CPET. Results Of the 147 patients, 94 presented with an apnea–hypopnea index (AHI) ≥ 15 events/h and were thus considered to have OSA (52 receiving nasal CPAP treatment; 42 untreated) while 53 formed a control group (AHI < 15 events/h). Patients with untreated OSA showed significantly lower oxygen uptake (VO2), heart rate, minute ventilation (VE), and end tidal carbon dioxide (PETCO2) at peak exercise compared to controls. Patients receiving nasal CPAP showed higher VE and VO2 at peak exercise compared to untreated patients. A difference in PETCO2 between the maximum value reached during test and peak exercise (ΔPETCO2 max-peak) of 1.71 mmHg was identified as a predictor of OSA. Conclusion Patients with moderate to severe obesity and untreated OSA presented a distinctive CPET-pattern characterized by lower aerobic and exercise capacity, higher PETCO2 at peak exercise associated with a lower ventilatory response. Nasal CPAP treatment was shown to positively affect these cardiorespiratory adaptations during exercise. ΔPETCO2 max-peak may be used to suggest OSA in patients with obesity.