Severe obstructive sleep apnea in patients with chronic obstructive pulmonary disease is associated with an increased prevalence of mild cognitive impairment

Prevalence of and factors associated with likely obstructive sleep apnea in individuals with airflow limitation

Introduction

Obstructive sleep apnea (OSA) is frequently associated with airflow limitation (AFL). However, information on the prevalence of and factors associated with likely OSA in individuals with AFL in Korea is limited.

Methods

Data from the 2019 Korea National Health and Nutrition Examination Survey (KNHANES) were used, and 3,280 individuals (2,826 individuals without AFL and 454 individuals with AFL) were included. AFL was defined as forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) < 0.7. A score ≥ 5 on the STOP-BANG questionnaire was used to identify individuals with likely OSA. The prevalence of likely OSA was compared between individuals with and without AFL. In addition, factors associated with likely OSA in individuals with AFL were evaluated using multivariable logistic regression analysis.

Results

Of 3,280 individuals, 13.8% had an AFL. The prevalence of likely OSA was significantly higher in individuals with AFL than in individuals without AFL (9.2% vs. 5.0%, p = 0.014). Among 454 individuals with AFL, obesity (adjusted odds ratio [aOR] = 14.78, 95% confidence interval [CI] = 4.20-52.02) was most strongly associated with likely OSA, followed by heavy alcohol consumption (aOR = 4.93, 95% CI = 1.91-12.70), hypertension (aOR = 4.92, 95% CI = 1.57-15.46), overweight (aOR = 4.71, 95% CI = 1.76-12.64), college graduate (aOR = 4.47, 95% CI = 1.10-18.22), and history of pulmonary tuberculosis (aOR = 3.40, 95% CI = 1.06-10.96).

Conclusion

In Korea, approximately 1 in 10 individuals with AFL had likely OSA. Overweight and obesity, heavy alcohol consumption, high educational level, hypertension, and history of pulmonary tuberculosis were associated with likely OSA in individuals with AFL.

Sleep disordered breathing: OSA-COPD overlap

INTRODUCTION

Sleep has important effects on breathing and gas exchange that may have negative consequences in patients with chronic obstructive pulmonary disease (COPD). COPD and obstructive sleep apnea (OSA) are highly prevalent and may coexist, which is referred to as the overlap syndrome.

AREAS COVERED

The probability of OSA-COPD overlap represents the balance of protective and promoting factors such as hyperinflation and fluid retention; thus, different clinical COPD phenotypes influence the likelihood of comorbid OSA. The clinical presentation of OSA-COPD overlap is nonspecific, and the diagnosis requires clinical awareness to identify patients needing overnight studies. Both COPD and OSA are associated with a range of overlapping physiological and biological disturbances including hypoxia and inflammation that contribute to cardiovascular comorbidities. The management of OSA-COPD overlap patients differs from those with COPD alone and the survival of overlap patients treated with positive airway pressure (PAP) is superior to those untreated.

EXPERT OPINION

The recognition of OSA-COPD overlap has important clinical relevance because of its impact on outcomes and management. Management of the overlap should address both sleep quality and disordered gas exchange. PAP therapy has demonstrated reductions in COPD exacerbations, hospitalizations, healthcare costs and mortality in overlap patients.

Intermittent Versus Sustained Hypoxemia from Sleep-disordered Breathing: Outcomes in Patients with Chronic Lung Disease and High Altitude

In a variety of physiologic and pathologic states, people may experience both chronic sustained hypoxemia and intermittent hypoxemia ("combined" or "overlap" hypoxemia). In general, hypoxemia in such instances predicts a variety of maladaptive outcomes, including excess cardiovascular disease or mortality. However, hypoxemia may be one of the myriad phenotypic effects in such states, making it difficult to ascertain whether adverse outcomes are primarily driven by hypoxemia, and if so, whether these effects are due to intermittent versus sustained hypoxemia.

Prevalence and Characteristics of Patients with Obstructive Sleep Apnea and Chronic Obstructive Pulmonary Disease: Overlap Syndrome

Overlap syndrome (OVS) is a distinct clinical entity that seems to result in potential cardiovascular consequences. We aimed to estimate the prevalence and risk factors for OVS in OSA patients and analyze clinical and PSG characteristics associated with OVS. In this cross-sectional study, 2616 patients evaluated for OSA underwent type-1 polysomnography (PSG). They were grouped as pure OSA (AHI > 15/h) and OVS patients. Demographics, PSG data, pulmonary function tests and arterial blood gases (ABGs) were compared between groups after adjustments for confounders. OSA was diagnosed in 2108 out of 2616 patients. Of those, 398 (19%) had OVS. Independent predictors of OVS were older age [OR: 5.386 (4.153-6.987)], current/former smoking [OR: 11.577 (7.232-18.532)], BMI [OR: 2.901 (2.082-4.044)] and ABG measurements [PaCO2 ≥ 45 OR: 4.648 (3.078-7.019), PO2 [OR: 0.934 (0.920-0.949)], HCO3- [OR: 1.196 (1.133-1.263), all p < 0.001]. OVS was also associated with prevalent hypertension [OR: 1.345 (1.030-1.758), p = 0.03] and cardiovascular disease [OR: 1.617 (1.229-2.126), p < 0.001], depressive symptoms [OR: 1.741 (1.230-2.465), p = 0.002] and nocturia [OR: 1.944 (1.378-2.742), p < 0.001], as well as with indices of OSA severity. Disturbances in sleep architecture were more prominent in OVS expressed by lower %N3 and REM% and higher arousal index. Our data suggest that OVS is prevalent among OSA patients, with distinct clinical and PSG characteristics. These characteristics could be utilized as predictive factors for early identification and further evaluation of these patients towards desirable patient-reported outcomes.

Estimating the prevalence and clinical significance of chronic obstructive pulmonary disease-obstructive sleep apnea overlap in South Korea

INTRODUCTION

Concurrent obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are referred to as COPD-OSA overlap. We investigated the prevalence and clinical significance of COPD-OSA overlap in the general population of South Korea.

METHODS

Data were obtained from the 2019 Korea National Health and Nutrition Examination Survey. Participants ≥40 years of age with complete STOP-Bang questionnaire and spirometry data were included. OSA was presumed in individuals with a STOP-Bang score of ≥3. COPD was determined using forced expiratory volume at 1 s/forced vital capacity <0.7. Participants were classified on the basis of the STOP-Bang score and spirometry findings. Clinical characteristics, comorbidities, and quality of life (using the EuroQoL 5-dimension instrument) were compared between the overlap group and COPD-alone or OSA-alone groups.

RESULTS

Among the 3157 participants, 6.9 % demonstrated COPD-OSA overlap. Individuals with OSA alone and COPD alone were 31.8 % and 5.2 %, respectively. The overlap group included more males, ever smokers, and frequent alcohol drinkers than the COPD- or OSA-alone groups. The overlap group had more diagnoses of hypertension, diabetes, and stroke than the COPD-alone group. The risk of anxiety/depression was approximately 2.5 times higher in the overlap group than in the COPD-alone group. COPD-OSA overlap was a significant risk factor for anxiety/depression after adjusting for age, sex, household income, and education levels.

CONCLUSION

COPD-OSA overlap is not rare within the general population of South Korea. Patients with overlap showed more comorbidities and higher levels of anxiety/depression than those in the COPD-alone group.

Evaluation of nocturnal apnea and airflow limitation as indicators for cognitive dysfunction in patients with chronic obstructive pulmonary disease/obstructive sleep apnea hypopnea syndrome overlap syndrome

OBJECTIVE

The aim of this study is to investigate how much intermittent hypoxemia and airflow limitation contribute to cognitive impairment in overlap syndrome (OS), which is the coexistence of two common diseases, obstructive sleep apnea hypopnea syndrome (OSAHS) and chronic obstructive pulmonary disease (COPD).

METHODS

We conducted a cross-sectional study of patients with OSAHS, COPD or OS, compared with normal controls, to determine the association between sleep apnea/pulmonary function-related indicators and cognitive dysfunction in individuals with OSAHS, COPD or OS.

RESULTS

A total of 157 participants were recruited. Both OSAHS and OS presented lower adjusted Montreal cognitive assessment (MoCA) scores compared with COPD group. In addition, the MoCA score was significantly lower in COPD group compared with control group. The incidence of cognitive impairment was 57.4% in OSAHS group, and 78% in OS group, which were significantly higher than COPD group (29%) and control group (8.8%). Furthermore, a broader range of cognitive domains were affected in OS group compared with OSAHS group. Elevated levels of oxygen desaturation index (ODI) and/or apnea hypopnea index (AHI) were positively correlated with increased Epworth sleeping scale (ESS) in OSAHS and OS. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) were positively correlated with cognitive scores in OSAHS but not in OS. Serum level of hypoxia-inducible factor-1α (HIF-1α) was significantly higher in OS. Logistic regression identified ODI as an independent risk factor for cognitive impairment in OS, while severity of snoring and PEF were independent risk factors in OSAHS.

DISCUSSION

This study revealed significant cognitive impairment in OS, OSAHS and COPD. Sleep-related indicators are warranted in OS patients for detection, differentiation and grading of cognitive impairment, whereas pulmonary functions are warranted in OSAHS patients for detection and early intervention of cognitive impairment.

Nocturnal hypoxemia and prognosis in patients with acute symptomatic pulmonary embolism

BACKGROUND

Nocturnal hypoxemia has been associated with cardiovascular and non-cardiovascular morbidity and mortality. This study aimed to investigate the prognostic value of nocturnal hypoxemia among patients with hemodynamically stable acute symptomatic pulmonary embolism (PE).

METHODS

We performed an ad hoc secondary analysis of clinical data from a prospective cohort study. Nocturnal hypoxemia was measured by the percent sleep registry with oxygen saturation <90% [TSat90]). Outcomes assessed over the 30-days after the diagnosis of PE included PE-related death, other cardiovascular deaths, clinical deterioration requiring an escalation of treatment, recurrent venous thromboembolism (VTE), acute myocardial infarction [AMI], or stroke.

RESULTS

Of the 221 hemodynamically stable patients with acute PE from which the TSat90 could be calculated and did not receive supplemental oxygen, the primary outcome occurred in 11 (5.0%; 95% confidence interval [CI], 2.5% to 8.7%) within 30-days after the diagnosis of PE. When categorized by quartiles, TSat90 was not significantly associated with the occurrence of the primary outcome in unadjusted Cox regression analysis (hazard ratio, 0.96; 95% CI, 0.57 to 1.63; P = 0.88), or after adjustment for body mass index (adjusted hazard ratio, 0.97; 95% CI, 0.57 to 1.65; P = 0.92). When examined as a completely continuous variable (between 0 and 100), TSat90 was not associated with a significant increase in the adjusted hazard of 30-day primary outcome rates (hazard ratio, 0.97; 95% CI, 0.86 to 1.10; P = 0.66).

CONCLUSIONS

In this study, nocturnal hypoxemia did not identify stable patients with acute symptomatic PE at increased risk for adverse cardiovascular events.

The Association Between Cognitive Functions and Psychological Factors in Patients with Severe COPD

Purpose

Patients with COPD experience anxiety, depression, and stress more frequently than in the age and gender-matched general population. This cross-sectional study aimed to examine the relationship between cognitive functions and the psychological factors of anxiety, depression and stress among patients with COPD.

Patients and Methods

Between January 2021 and January 2023, patients with severe COPD were recruited, along with age-matched controls. Participants completed the Hospital Anxiety and Depression Scale (HADS) and the Perceived Stress Scale (PSS). The Montreal Cognitive Assessment (MoCA), a continuous reaction time test (CRT), and a driving simulator were used to assess cognitive impairment. Hierarchical multiple linear regression analyses were used to explain the variance of the correlations.

Results

In total, 80 patients (mean age = 64yrs) and 22 controls (mean age = 61yrs) participated in the study. Patients reported significantly higher levels of psychological symptoms compared to the controls (p ≤ 0.001). We found no differences in anxiety (p = 0.31), depression (p = 0.66) and stress (p = 0.37) between patients with and without cognitive impairment. However, stress showed to be a significant predictor of decreased attention (higher stress score resulted in decreasing CRT-index, indication a reduced stability in reaction time) (p = 0.02). Psychological factors did not explain additional variance in cognitive functions beyond sociodemographic factors such as age and sex.

Conclusion

Psychological symptom levels are higher in COPD than controls and perceived stress among patients with COPD appears to be associated with decreased attention. However, psychological factors in general did not appear to contribute to the variance in cognitive functions beyond sociodemographic, physical, and self-perceived symptoms.

Cognitive decline and risk of dementia in older adults after diagnosis of chronic obstructive pulmonary disease

Cognitive screening has been proposed for older adults diagnosed with chronic obstructive pulmonary disease (COPD). Therefore, we examined the change over time in cognitive function and the risk of incident dementia in older adults after COPD diagnosis. A sample of 3,982 participants from the population-based cohort study Good Aging in Skåne was followed for 19 years, and 317 incident COPD cases were identified. The cognitive domains of episodic memory, executive function, and language were assessed using neuropsychological tests. Mixed models for repeated measures and a Cox model were implemented. Participants performed, on average, worse over time on all neuropsychological tests after COPD diagnosis in comparison to those without COPD, although statistical significance differences were only observed for episodic memory and language. The groups had a comparable risk of developing dementia. In conclusion, our results indicate that cognitive screening in the early stages of COPD may be of limited clinical relevance.

The Overlap Syndrome of Obstructive Sleep Apnea and Chronic Obstructive Pulmonary Disease: A Systematic Review

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) are common diseases that strongly impact the quality and length of life. Their coexistence is determined by overlap syndrome (OS). This systematic review aims to define the significance of these comorbidities according to the current state of knowledge. For this systematic review, we searched PubMed, Scopus, and Cochrane for studies published between 2018 and 26 October 2022, to find original, observational, human studies published in English, where the diagnosis of COPD was according to the Global Initiative for Obstructive Lung Disease guidelines and the diagnosis of OSA was based on polysomnography. The quality of studies was assessed using the Newcastle-Ottawa quality assessment tool for cohort and case-control studies, as well as its modification for cross-sectional studies. Of the 1548 records identified, 38 were eligible and included in this systematic review. The included studies covered a total population of 27,064 participants. This paper summarizes the most important, up-to-date information regarding OS, including the prevalence, meaning of age/gender/body mass index, polysomnography findings, pulmonary function, comorbidities, predicting OSA among COPD patients, and treatment of this syndrome.

Obstructive sleep apnea is associated with cognitive impairment in minor ischemic stroke

Objectives

Obstructive sleep apnea (OSA) is commonly seen in stroke patients, and its relationship with cognitive impairment remains poorly understood. This study aimed to explore the roles of OSA in cognition impairment in patients with minor ischemic stroke.

Methods

Patients with minor ischemic stroke were consecutively enrolled from January 2020 to May 2021. Every patient underwent polysomnography (PSG) to assess for OSA. Based on the apnea hypopnea index (AHI), patients were grouped into the no OSA (AHI < 5), mild OSA (5 ≤ AHI < 15), and moderate-to-severe OSA (MS OSA, AHI ≥ 15) groups. Neuropsychological assessments were performed to evaluate cognitive function, and the correlations between cognitive function and OSA were investigated.

Results

Of 94 patients, 35 had no OSA, 32 had mild OSA, and 27 had moderate-to-severe OSA. Compared to the no or mild OSA groups, the moderate-to-severe OSA group performed worse on the Chinese version of the Auditory Verbal Learning Test (CAVLT)-Recognition (p < 0.001), Digital Span Test (DST)-Backward (p < 0.001), Montreal Cognitive Assessment (MoCA) (p < 0.001), and Stroop Color and Word Test (SCWT)-Interference (p < 0.001). The severity of cognitive impairment was assessed using the MoCA, which was negatively related to the AHI (p = 0.041) and lowest SpO2 (p = 0.048).

Conclusions

The findings suggest that OSA has significant effects on cognition impairment in patients with minor ischemic stroke and that hypoxemia may be a potential pathophysiological mechanism of OSA-induced cognitive impairment.

Cognitive impairment caused by hypoxia: from clinical evidences to molecular mechanisms

Hypoxia is a state of reduced oxygen supply and excessive oxygen consumption. According to the duration of hypoxic period, it can be classified as acute and chronic hypoxia. Both acute and chronic hypoxia could induce abundant neurological deficits. Although there have been significant advances in the pathophysiological injuries, few studies have focused on the cognitive dysfunction. In this review, we focused on the clinical evidences and molecular mechanisms of cognitive impairment under acute and chronic hypoxia. Hypoxia can impair several cognitive domains such as attention, learning and memory, procession speed and executive function, which are similar in acute and chronic hypoxia. The severity of cognitive deficit correlates with the duration and degree of hypoxia. Recovery can be achieved after acute hypoxia, while sequelae or even dementia can be observed after chronic hypoxia, perhaps due to the different molecular mechanisms. Cardiopulmonary compensatory response, glycolysis, oxidative stress, calcium overload, adenosine, mitochondrial disruption, inflammation and excitotoxicity contribute to the molecular mechanisms of cognitive deficit after acute hypoxia. During the chronic stage of hypoxia, different adaptive responses, impaired neurovascular coupling, apoptosis, transcription factors-mediated inflammation, as well as Aβ accumulation and tau phosphorylation account for the neurocognitive deficit. Moreover, brain structural changes with hippocampus and cortex atrophy, ventricle enlargement, senile plaque and neurofibrillary tangle deposition can be observed under chronic hypoxia rather than acute hypoxia.

Oxygen desaturation during flexible bronchoscopy with propofol sedation is associated with sleep apnea: the PROSA-Study

BACKGROUND

Obstructive sleep apnea (OSA) is characterized by repetitive episodes of complete or partial obstruction of the upper airways during sleep. Conscious sedation for flexible bronchoscopy (FB) places patients in a sleep-like condition. We hypothesize that oxygen desaturation during flexible bronchoscopy may help to detect undiagnosed sleep apnea.

METHODS

Single-centre, investigator-initiated and driven study including consecutive patients undergoing FB for clinical indication. Patients completed the Epworth Sleepiness Scale (ESS), Lausanne NoSAS score, STOP-BANG questionnaire and the Berlin questionnaire and underwent polygraphy within 7 days of FB. FB was performed under conscious sedation with propofol. Oxygen desaturation during bronchoscopy was measured with continuous monitoring of peripheral oxygen saturation with ixTrend (ixellence GmbH, Germany).

RESULTS

145 patients were included in the study, 62% were male, and the average age was 65.8 ± 1.1 years. The vast majority of patients (n = 131, 90%) proved to fulfill OSA criteria based on polygraphy results: 52/131 patients (40%) had mild sleep apnea, 49/131 patients (37%) moderate sleep apnea and 30/131 patients (23%) severe sleep apnea. Patients with no oxygen desaturation had a significantly lower apnea-hypopnea index than patients with oxygen desaturation during bronchoscopy (AHI 11.94/h vs 21.02/h, p = 0.011). This association remained significant when adjusting for the duration of bronchoscopy and propofol dose (p = 0.023; 95% CI 1.382; 18.243) but did not hold when also adjusting for age and BMI.

CONCLUSION

The severity of sleep apnea was associated to oxygen desaturation during flexible bronchoscopy under conscious sedation. Patients with oxygen desaturation during bronchoscopy might be considered for sleep apnea screening.

TRIAL REGISTRATION

The Study was approved by the Ethics Committee northwest/central Switzerland, EKNZ (EK 16/13) and was carried out according to the Declaration of Helsinki and Good Clinical Practice guidelines. Due to its observational character, the study did not require registration at a clinical trial registry.