Hypoxia, not the frequency of sleep apnea, induces acute hemodynamic stress in patients with chronic heart failure

Association of hypoxic burden metrics with cardiovascular outcomes in heart failure and sleep-disordered breathing

AIMS

Heart failure (HF) and sleep-disordered breathing (SDB) frequently coexist. We aimed to compare the prognostic value of different nocturnal hypoxic burden metrics in hospitalized HF patients.

METHODS AND RESULTS

HF patients underwent polygraphy screening for SDB in this prospective cohort. Hypoxic burden metrics assessed using pulse oximetry included time < 90% oxygen saturation (T90), proportion of total recording time < 90% oxygen saturation (TRT90), oxygen desaturation index (ODI), and mean oxygen saturation (meanSO2 ). The prespecified endpoints were the composite of cardiovascular death or admission for worsening HF. This study included 764 hospitalized HF patients, 16.5% and 36.6% of whom had obstructive and central sleep apnoea, respectively. With a median follow-up time of 2.2 years, endpoint events occurred in 410 (53.7%) patients. In univariate and multivariate analyses, T90, TRT90, and meanSO2 were substantially associated with the composite outcome, whereas ODI was not. After multivariate Cox model adjustment, patients with 5.0 ≤ T90 ≤ 52.0 min [hazard ratio (HR) 1.32, 95% confidence interval (CI): 1.02-1.71, P = 0.034] or T90 > 52.0 min (HR 1.56, 95% CI: 1.21-2.02, P = 0.001) had a greater risk of the composite outcome than those with T90 < 5.0 min. The TRT90 and T90 results were similar. Compared with meanSO2  > 95%, meanSO2  < 93% (HR 1.47, 95% CI: 1.16-1.88, P = 0.002) was correlated with adverse outcomes.

CONCLUSIONS

The hypoxic burden metrics T90, TRT90, and meanSO2 , but not ODI, were independent predictors of cardiovascular death or readmission for worsening HF. Indicators of duration and severity, not just the frequency of nocturnal hypoxaemia, should be valued and considered for intervention to improve outcomes in HF patients.

Cardiovascular outcomes in obstructive sleep apnoea and implications of clinical phenotyping on effect of CPAP treatment

BACKGROUND

There is a growing awareness of the heterogeneity of obstructive sleep apnoea (OSA). Clinical trials of CPAP treatment on cardiovascular protection have been mostly negative. We aimed to assess the association between polysomnographic parameters and incident major adverse cardiovascular events (MACEs), and to investigate if the CPAP effect could be better delineated among clinical subgroups.

METHODS

This sleep cohort study was conducted using a clinical database and territory-wide electronic health administration data in Hong Kong. Cox regressions were used to calculate HRs. Latent class analysis was used to cluster patients with OSA according to clinical and polysomnographic features.

RESULTS

Of 1860 eligible Chinese subjects who underwent polysomnography (2006-2013), 1544 (83%) had OSA. Over median follow-up of 8.3 years, 278 (14.9%) experienced MACEs. Apnoea-hypopnoea index (AHI) did not predict MACEs (HR: 0.95; 95% CI 0.76 to 1.17), whereas sleep time with oxygen saturation <90% (TST90) (HR: 1.41; 95% CI 1.10 to 1.81) was an independent predictor of MACEs, as were wake and nocturnal heart rate. In moderate-severe OSA (n=1108) who were indicated for CPAP treatment, regular CPAP was not associated with reduction of incident MACEs. Further cluster analysis identified a subgroup (n=333) who was younger, more obese, had more severe OSA (higher AHI and TST90) and more cardiovascular risks, in whom regular CPAP was associated with a lower risk of MACEs (HR:0.49, 95% CI 0.25 to 0.95).

CONCLUSIONS

OSA-related TST90 and mean heart rate, but not AHI, were robust predictors of MACEs. A clinical phenotype subgroup who demonstrated beneficial effect of CPAP treatment was identified.

Sleep-disordered breathing is independently associated with elevated natriuretic peptide levels in patients with cardiovascular diseases

Sleep disorders and sleep duration have attracted considerable attention as potential modifiable risk factors for the development and progression of heart failure (HF). However, whether these sleep behaviors could aggravate the underlying cardiac condition remains ambiguous. We evaluated the associations between the levels of plasma B-type natriuretic peptide (BNP) and sleep-disordered breathing (SDB), sleep quality and quantity, or daytime sleepiness in cardiovascular diseases (CVD) patients. A total of 1717 consecutive patients with CVD [median age, 66 years (55-74 years); female, 27.5%] were enrolled. SDB was screened by nocturnal pulse oximetry; sleep quality and quantity were determined by Pittsburg Sleep Quality Index, and daytime sleepiness was examined by Epworth Sleepiness Scale. The median plasma BNP level was 54.9 pg/ml (23.5-146.4 pg/ml). Multiple regression analyses showed that the BNP level in the highest quintile (BNP > 181.8 pg/ml) was associated with SDB (severe: OR, 5.88; 95% CI 3.17-10.88; moderate: OR, 3.62; 95% CI 2.17-6.02; mild: OR, 2.22: 95% CI 1.42-3.47). There were no significant associations between other sleep parameters and higher BNP levels. The relationship between SDB and BNP levels was unchanged regardless of the previous history of symptomatic HF. SDB was independently associated with the elevated plasma BNP level in patients with a variety of CVD.

Effect of Intermittent Hypoxia on Metabolic Syndrome and Insulin Resistance in the General Male Population

Background and objectives: Obstructive sleep apnea (OSA) is closely associated with insulin resistance (IR) and is an independent risk factor for incident type 2 diabetes mellitus (T2DM). Most studies evaluate the correlation between OSA and IR in only obese or T2DM patients. Therefore, we tried to investigate the effect of OSA on metabolic syndrome and IR in the general healthy male population. Materials and Methods: 184 subjects who visited a preventive health examination program were recruited for this study. All subjects received overnight polysomnography by a portable device (Watch-PAT 200). We examined several metabolic parameters and a homeostasis model of assessment for insulin resistance index (HOMA-IR). The subjects were divided into three groups by AHI (Apnea-hyponea index): normal group (AHI < 5), mild OSA group (5 ≤ AHI < 15), and moderate-severe OSA group (AHI ≥ 15). They were also divided into two groups according to minimum oxygen saturation: low group, Min-SpO2 < 88%; and high group, Min-SpO2 ≥ 88%. Results: Parameters of metabolic syndrome, including waist circumference, systolic and diastolic blood pressure, triglyceride, and high-density lipoprotein cholesterol showed significant differences among the AHI groups. Furthermore, HOMA-IR showed significant differences among the AHI groups. Those parameters, including metabolic syndrome and HOMA-IR, also showed differences between Min-SpO2 groups. Conclusions: In summary, this study helps confirm that AHI is associated with HOMA-IR in the general male population. Furthermore, the severity of AHI correlated with the parameters of metabolic syndrome. Therefore, AHI might be an indicator for evaluating both T2DM and metabolic syndrome, even in the general male population.

[Sleep disordered breathing in patients with chronic heart failure: prognosis and management]

Sleep disordered breathing is a frequent comorbidity (50-75%) in patients with chronic heart failure, but it is usually underestimated. This review analyzes sleep disordered breathing in patients with chronic heart failure, demonstrates pathogenetic relationships and the prognostic role of sleep apnea. The authors present modern treatment options for sleep apnea in this cohort (from non-invasive ventilation to implantable devices), highlight the role of drug therapy and outline perspectives of different treatment approaches. This clinical problem is designated as multidisciplinary, which requires a dialogue between researchers and doctors of various specialties to organize comprehensive effective care for this cohort of patients.

Prognostic value of sleep apnea and nocturnal hypoxemia in patients with decompensated heart failure

Background

Nocturnal hypoxemia is an important factor underlying the impact of sleep apnea on heart failure. It remains unclear whether nocturnal hypoxemia has a greater prognostic value in acute decompensated heart failure (ADHF) compared with the frequency of sleep apnea.

Hypothesis

Nocturnal hypoxemia might be better than the frequency of sleep apnea in predicting the outcomes in ADHF.

Methods

Sleep studies were prospectively performed during an ADHF hospitalization from January 2015 to December 2017. Sleep apnea was defined as the apnea‐hypopnea index (AHI) ≥15/h. The severity of nocturnal hypoxemia was determined by the percentage of time with saturation below 90% (T90%). The endpoint was the first event of all‐cause death, heart transplantation, implantation of left ventricular assist device, unplanned hospitalization for worsening heart failure, acute coronary syndrome, significant arrhythmias, or stroke.

Results

Of 382 patients, 189 (49.5%) had sleep apnea. The endpoint incidence did not differ between AHI categories (≥15/h vs <15/h: 52.4% vs 44.6%, log rank P = .353), but did between T90% categories (≥3.6% vs <3.6%: 54.5% vs 42.4%, log rank P = .023). Multivariate Cox regression analysis showed that T90% was independently associated with the endpoint (hazard ratio [HR] 1.008, 95% confidence interval [CI] 1.001‐1.016, P = .033), whereas AHI was not; the risk of the endpoint increased by 40.8% in patients with T90% ≥3.6% (HR 1.408, 95%CI 1.030‐1.925, P = .032).

Conclusion

Nocturnal hypoxemia had a greater prognostic value in ADHF than the frequency of sleep apnea.

The Clinical Value of N-Terminal Pro B-Type Natriuretic Peptide in Evaluating Obstructive Sleep Apnea in Patients With Coronary Artery Disease

STUDY OBJECTIVES

Natriuretic peptides have been identified as biomarkers of increased myocardial wall stress in the context of obstructive sleep apnea (OSA) in the general population. However, the relationship between N-terminal pro B-type natriuretic peptide (NT-proBNP) and OSA remains unclear in patients with coronary artery disease (CAD). Hence, we aimed to investigate the clinical value of NT-proBNP in evaluating OSA in a large population of patients with CAD.

METHODS

Consecutive patients with CAD were prospectively enrolled between February 2015 and March 2018. Portable respiratory monitoring was applied to facilitate the diagnosis of sleep apnea. Patients were as assigned to the non-OSA (when the respiratory events index [REI] or 3% oxygen desaturation index [ODI] < 15 events/h) and OSA (when the REI or 3% ODI ≥ 15 events/h) groups. Multivariate analyses were used to explore the independent association between NT-proBNP levels and OSA.

RESULTS

A total of 1,292 consecutive patients were included with a mean NT-proBNP value of 826.57 μg/L. Patients with high levels of NT-proBNP experienced increasing severity of OSA in those with CAD (P = .0004). Univariate analysis demonstrated that NT-proBNP was a risk factor for OSA (odds ratio [OR] 1.10, 95% confidence interval [CI] 1.03-1.18, P = .005). In addition, multivariate analysis revealed that NT-proBNP was independently associated with the presence of OSA (OR 1.11, 95% CI 1.02-1.20, P = .012) even after adjusting for other cofounding factors.

CONCLUSIONS

Elevated levels of NT-proBNP were independently associated with a higher likelihood of OSA in patients with CAD. Periodically screening for NT-proBNP levels may provide early identification of OSA.

The Factors Affecting the Non-dipper Pattern in Japanese Patients with Severe Obstructive Sleep Apnea

Objective Obstructive sleep apnea (OSA) is assumed to influence the circadian blood pressure (BP) fluctuation, particularly causing nocturnal hypertension and changing the dipping pattern of nocturnal BP. This study aimed to clarify the triggers of the non-dipper pattern in nocturnal BP in Japanese patients with severe OSA (the apnea-hypopnea index ≥30/h). Methods Of 541 patients with OSA diagnosed using polysomnography (PSG) and ambulatory BP monitoring (ABPM), 163 patients <60 years of age (Younger group) and 101 patients ≥60 years of age (Older group) were stratified into the dipper or non-dipper pattern groups. Results A logistic regression analysis was performed using a non-dipper pattern as a dependent variable. A multivariate analysis demonstrated that the cumulative percentage of time at saturation below 90% was the only independent risk factor for the non-dipper and riser patterns in the Younger group (odds ratio, 1.022; 95% confidence interval, 1.001-1.044; p=0.035), whereas slow-wave sleep (odds ratio, 0.941; 95% confidence interval, 0.891-0.990; p=0.019) and the use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers (odds ratio, 2.589; 95% confidence interval, 1.051-6.848; p=0.039) were risk factors in the Older group. Conclusion These findings suggested that the degree of desaturation in young OSA patients and sleep quality in old OSA patients might influence the dipping patterns in nocturnal BP.

Biomarkers in Sleep Apnea and Heart Failure

PURPOSE OF REVIEW

Sleep-disordered breathing (SDB) is highly prevalent in heart failure (HF) and may confer significant stress to the cardiovascular system and increases the risk for future cardiovascular events. The present review will provide updates on the current understanding of the relationship of SDB and common HF biomarkers and the effect of positive airway pressure therapy on these biomarkers, with particular emphasis in patients with coexisting SDB and HF.

RECENT FINDINGS

Prior studies have examined the relationship between HF biomarkers and SDB, and the effect of SDB treatment on these biomarkers, with less data available in the context of coexisting SDB and HF. Overall, however, the association of SDB and circulating biomarkers has been inconsistent. Further research is needed to elucidate the relationship between biomarkers and SDB in HF, to evaluate the clinical utility of biomarkers over standard methods in large, prospective studies and also to assess the impact of treatment of SDB on these biomarkers in HF via interventional studies.

The effect of surgical and non-surgical weight loss on N-terminal pro-B-type natriuretic peptide and its relation to obstructive sleep apnea and pulmonary function

Background

Obesity is a major risk factor for obstructive sleep apnea, impaired pulmonary function and heart failure, but obesity is also associated with paradoxically low levels of serum N-terminal pro-B-type natriuretic peptide (NT-proBNP). In subjects with severe obesity undergoing weight loss treatment, we assessed the associations between changes in severity of obstructive sleep apnea, pulmonary function and serum NT-proBNP levels.

Methods

One-year non-randomized controlled clinical trial. Participants, 69.6 % women, mean (SD) age 44.6 (10.8) years and body mass index (BMI) 45.1 (5.6) kg/m², underwent gastric bypass surgery (n = 76) or intensive lifestyle intervention (n = 63), resulting in 30 (8) % and 8 (9) % weight loss, respectively. The reference group included 30 normal weight, healthy, gender and age matched controls. Sleep recordings, arterial blood gases, pulmonary function and blood tests were assessed before and 1 year after the interventions.

Results

NT-proBNP concentrations increased significantly more after surgery than after lifestyle intervention. The post intervention values in both groups were significantly higher than in a normal weight healthy reference group. In the whole study population changes (∆) in NT-proBNP correlated significantly with changes in both BMI (r = −0.213) and apnea hypopnea index (AHI, r = −0.354). ∆NT-proBNP was, independent of age, gender and ∆BMI, associated with ∆AHI (beta −0.216, p = 0.021). ∆AHI was, independent of ∆BMI, significantly associated with changes in pO₂ (beta −0.204), pCO₂ (beta 0.199), forced vital capacity (beta −0.168) and forced expiratory volume first second (beta −0.160).

Conclusions

Gastric bypass surgery was associated with a greater increase in NT-proBNP concentrations than non-surgical weight loss treatment. Reduced AHI was, independent of weight loss, associated with increased NT-proBNP levels and improved dynamic lung volumes and daytime blood gases.

Clinical Trial Registration ClinicalTrials.gov NCT00273104, retrospectively registered Jan 5, 2006 (study start Dec 2005)

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-016-2241-x) contains supplementary material, which is available to authorized users.

Prognostic Importance of Novel Oxygen Desaturation Metrics in Patients With Heart Failure and Central Sleep Apnea

BACKGROUND

Sleep-disordered breathing, particularly central sleep apnea (CSA), is highly prevalent in heart failure (HF) and an independent prognostic marker. We assessed the hypothesis that an increased hypoxemic burden during sleep may have greater prognostic value than the frequency of apneic and hypopneic episodes.

METHODS AND RESULTS

We prospectively conducted overnight cardiorespiratory polygraphy on consecutive HF patients referred to our hospital from 2008 to 2011. We studied CSA defined by an apnea-hypopnea index (AHI) of ≥5 events/h with >75% of all events being central in origin. We determined the AHI, proportion of the sleep time with SpO₂ <90% (T90%), and proportion of the recording time that 4% desaturation events occurred (4%POD). We studied 112 HF patients with either systolic or diastolic dysfunction. During a follow-up period of 37 ± 25 months, 32 patients (29%) died. Nonsurvivors had a higher 4%POD compared with survivors (11 ± 6.4% vs 19 ± 13%; P = .001), but did not differ significantly from survivors regarding AHI and T90%. An adjusted logistic regression analysis revealed that the 4%POD was the best independent predictor of mortality.

CONCLUSIONS

The 4%POD, a novel metric for the nocturnal hypoxemic burden, is an independent prognostic marker in HF patients affected by CSA.

Prevalence, Severity, and Prognostic Value of Sleep Apnea Syndromes in Cardiac Amyloidosis

STUDY OBJECTIVES

To assess prevalence, severity, and prognostic value of sleep-disordered breathing (SDB), in the three main cardiac amyloidosis (CA) types, i.e., light-chain (AL), transthyretin-related familial (m-TTR), or senile (WT-TTR).

METHODS

Patients consecutively referred for CA diagnosis work-up underwent cardiac assessment and nocturnal polygraphy. SDB was defined as apnea-hypopnea index (AHI) ≥ 5/h. Multivariate analysis was used to identify predictors of a major adverse cardiac event (MACE) defined as death, heart transplantation and acute heart failure.

RESULTS

Seventy CA patients were included (31 AL, 22 m-TTR, 17 WT-TTR). The mean ± standard deviation age and left ventricular ejection fraction were 71 ± 12 years and 49% ± 13% and median (interquartile range) N terminal pro brain natriuretic peptide (NT-proBNP) was 3,932 (1,607; 7,028) pg/mL. The prevalence of SDB was 90% without difference between amyloidosis types. SDB was central in 27% and obstructive in 73%. AL had less frequent severe SDB compared to m-TTR and WT-TTR (P = 0.015) but longer time with peripheral capillary oxygen saturation (SpO2) < 90% (P = 0.037). After a median follow-up of 7.5 (2.8; 14.9) months, 49% patients experienced MACE. Time with nocturnal SpO2 < 90% was the only independent predictor of MACE. The best-identified threshold was 30 min. Values > 30 min were associated with bad prognosis (Log-rank χ(2): 8.01, P value = 0.005). Using binomial logistic regression, determinants of time with nocturnal SpO2 < 90% were New York Heart Association class (P = 0.011), and log-NT-proBNP (P = 0.04) but not AHI.

CONCLUSIONS

In CA population, prevalence of SDB is high (90%) and dominated by the obstructive pattern. Bad prognosis in this population was driven by nocturnal desaturation, reflecting heart failure severity and respiratory involvement.

Adaptive servoventilation versus oxygen therapy for sleep disordered breathing in patients with heart failure: a randomised trial

BACKGROUND

Both adaptive servoventilation (ASV) and nocturnal oxygen therapy improve sleep disordered breathing (SDB), but their effects on cardiac parameters have not been compared systematically.

METHODS AND RESULTS

43 patients with chronic heart failure (CHF; left ventricular ejection fraction (LVEF) ≤50%) with SDB were randomly assigned to undergo ASV (n=19, apnoea hypopnoea index (AHI)=34.2±12.1/h) or oxygen therapy (n=24, 36.9±9.9/h) for 3 months. More than 70% of SDB events in both groups were central apnoeas or hypopnoeas. Although nightly adherence was less for the ASV group than for the oxygen group (4.4±2.0 vs 6.2±1.8 h/day, p<0.01), the improvement in AHI was larger in the ASV group than in the oxygen group (-27.0±11.5 vs -16.5±10.2/h, p<0.01). The N-terminal pro-brain natriuretic peptide (NT-proBNP) level in the ASV group improved significantly after titration (1535±2224 to 1251±2003 pg/mL, p=0.01), but increased slightly at follow-up and this improvement was not sustained (1311±1592 pg/mL, p=0.08). Meanwhile, the level of plasma NT-proBNP in the oxygen group did not show a significant change throughout the study (baseline 1071±1887, titration 980±1913, follow-up 1101±1888 pg/mL, p=0.19). The significant difference in the changes in the NT-proBNP level throughout the study between the 2 groups was not found (p=0.30). Neither group showed significant changes in echocardiographic parameters.

CONCLUSIONS

Although ASV produced better resolution of SDB in patients with CHF as compared with oxygen therapy, neither treatment produced a significant improvement in cardiac function in the short term. Although we could not draw a definite conclusion because of the small number of participants, our data do not seem to support the routine use of ASV or oxygen therapy to improve cardiac function in patients with CHF with SDB.

TRIAL REGISTRATION NUMBER

NCT01187823 (http://www.clinicaltrials.gov).

Intradialytic Hypoxemia and Clinical Outcomes in Patients on Hemodialysis

BACKGROUND AND OBJECTIVES

Intradialytic hypoxemia has been recognized for decades, but its associations with outcomes have not yet been assessed in a large patient cohort.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our retrospective cohort study was conducted between January of 2012 and January of 2015. We recorded blood oxygen saturation every minute during hemodialysis in patients with arteriovenous access. A 6-month baseline period with at least 10 treatments with oxygen saturation measurements preceded a 12-month follow-up. Patients were stratified by the presence or absence of prolonged intradialytic hypoxemia defined as oxygen saturation <90% for at least one third of the treatment time. Demographic, laboratory, and treatment data and hospitalization and mortality rates were compared between the groups. Multivariate Cox regression analysis was used to assess baseline predictors of all-cause mortality during follow-up.

RESULTS

In total, 100 (10%) of 983 patients had prolonged intradialytic hypoxemia. These patients were older (+3.6 years; 95% confidence interval, 0.8 to 6.3), had longer dialysis vintage (+1.2 years; 95% confidence interval, 0.3 to 2.1), and had higher prevalence of congestive heart failure (+10.8%; 95% confidence interval, 1.6 to 20.7) and chronic obstructive pulmonary disease (+13%; 95% confidence interval, 5 to 21.2). They also resembled an inflammatory phenotype, with lower serum albumin levels (-0.1 g/dl; 95% confidence interval, -0.2 to 0) and higher neutrophil-to-lymphocyte ratios (+1; 95% confidence interval, 0.5 to 1.6). They had lower hemoglobin levels (-0.2 g/dl; 95% confidence interval, -0.4 to 0) and required more erythropoietin (+1374 U per hemodialysis treatment; 95% confidence interval, 343 to 2405). During follow-up, all-cause hospitalization (1113 hospitalizations; univariate hazard ratio, 1.46; 95% confidence interval, 1.22 to 1.73) and mortality (89 deaths; adjusted hazard ratio, 1.98; 95% confidence interval, 1.14 to 3.43) were higher in patients with prolonged intradialytic hypoxemia.

CONCLUSIONS

Prolonged intradialytic hypoxemia was associated with laboratory indicators of inflammation, higher erythropoietin requirements, and higher all-cause hospitalization and mortality.

Nocturnal Intermittent Hypoxia Is Associated With Left Ventricular Hypertrophy in Middle-Aged Men With Hypertension and Obstructive Sleep Apnea

BACKGROUND

Obstructive sleep apnea (OSA) and left ventricular (LV) hypertrophy are considered to be closely associated. However, the relationship has not yet been fully demonstrated and is hence still controversial. The purpose of this study was to assess in hypertensive male patients the relationship between OSA and cardiac structure using a new index, namely, integrated area of desaturation (IAD), in addition to the apnea-hypopnea index (AHI) that is currently the most frequently used index of sleep-disordered breathing.

METHODS

In our cross-sectional study, 223 hypertensive men younger than 65 years with sleep apnea and normal cardiac function were enrolled. All subjects were evaluated by fully attended polysomnography. Cardiac structure and function were evaluated by echocardiography.

RESULTS

LV mass index significantly correlated with IAD (r = 0.203, P < 0.05), but not with AHI. Multivariate linear regression analyses showed that IAD, brain natriuretic peptide (BNP), and age are independent variables affecting the LV mass index (β = 0.262, 0.237, and 0.173, respectively, P < 0.05). IAD was the one and only determinant among the indices of sleep-disordered breathing.

CONCLUSIONS

Nocturnal intermittent hypoxia defined by IAD may be associated with LV hypertrophy in men with well-controlled hypertension and obstructive sleep apnea.

Prevalence of Sleep Disordered Breathing among Patients with Nocturia at a Urology Clinic

OBJECTIVE

We assessed the prevalence of sleep disordered breathing (SDB) and characteristics among patients who visited a urology clinic complaining of nocturia (URO group) and those who visited a sleep apnea (SA) clinic complaining of excessive daytime sleepiness (EDS) (SA group). Additionally, we evaluated the effects of continuous positive airway pressure (CPAP) therapy in the URO group patients with nocturia and SDB resistant to conventional therapy for nocturia.

METHODS

Questionnaires were used to assess EDS, nocturia and lower urinary tract symptoms in 34 URO group patients and 49 age-matched SA group patients. We also compared these factors in the male patients in both groups and the male and female patients in the SA group. Significant SDB was diagnosed as a 3% oxygen desaturation index (3%ODI) on pulse oximeter of >5/h. The treatment response was analyzed in six URO group patients treated with CPAP after not responding to the conventional medical treatment.

RESULTS

SDB was found in 91.8% of the SA group patients and 70.6% of the URO group patients. The level of EDS and lower urinary tract symptoms were similar in both groups. The SA group showed higher 3%ODI values, while the frequency of urination during bedtime was higher in the URO group. The frequency of nocturnal urination was reduced after CPAP in the subjects resistant to conventional therapy.

CONCLUSION

SDB is as prevalent in patients who visit a urology clinic complaining of nocturia as in those who visit a sleep apnea clinic. Patients who complains of nocturia must be assessed for SDB before starting therapy for nocturia.

Apnea-hypopnea and desaturations in heart failure with reduced ejection fraction: Are we aiming at the right target?

BACKGROUND

Sleep disordered breathing (SDB) is common in patients with heart failure with reduced ejection fraction (HFrEF). An increased apnea-hypopnea index (AHI) is associated with poor outcomes. We examined whether an analysis of nocturnal desaturations (NDs) can improve the risk stratification.

METHODS

Three-hundred seventy-six consecutive patients with stable chronic HFrEF and LVEF ≤ 45% were prospectively screened using polygraphy. Sleep apnea (SA) was defined as an AHI ≥ 15. The mean age was 59 ± 13 years, the mean LVEF was 30 ± 6%, and the median AHI was 18 [IQR: 9.33). The composite end-point of death, heart transplantation or LV assistance occurred in 98 patients (26%) within 3 years. Minimal oxygen saturation (MOS) during sleep, the number of desaturations <90%/h and the time spent with oxygen saturation <90% were significantly associated with adverse events (adjusted HR 1.25 [1.03-1.52], 1.25 [1.03-1.53], and 1.28 [1.04-1.59]), whereas the AHI was not (1.10 [0.86-1.39]). The best MOS cut-off value for poor outcomes was ≤ 88%. The patients with an MOS ≤ 88% had a significantly higher event rate (31.9%) than those with an MOS >88% (15.6%; p<0.01). The risk assessment using an MOS of ≤ 88% in addition to established prognostic markers yielded a net reclassification index (NRI) of nearly 6% and was particularly useful in the subgroup of patients with events (NRI: 8.4%).

CONCLUSIONS

In HFrEF patients, ND ≤ 88% appears to be predictive of adverse events, independent of the presence of SA. This suggests that the risk assessment in HFrEF should also include ND in top of AHI.

Sleep Disordered Breathing in Four Resource-Limited Settings in Peru: Prevalence, Risk Factors, and Association with Chronic Diseases

STUDY OBJECTIVES

Sleep disordered breathing (SDB) is a highly prevalent condition in high-income countries, with major consequences for cardiopulmonary health, public safety, healthcare utilization, and mortality. However, its prevalence and effect in low- and middle-income countries are less well known. We sought to determine the prevalence, risk factors, and comorbidities of SDB symptoms in four resource-limited settings.

DESIGN

Cross-sectional analysis of the CRONICAS Cohort, a population-based age- and sex-stratified sample.

SETTING

Four resource-limited settings in Peru varying in altitude, urbanization, and air pollution.

PARTICIPANTS

There were 2,682 adults aged 35 to 92 y.

MEASUREMENTS AND RESULTS

Self-reported SDB symptoms (habitual snoring, observed apneas, Epworth Sleepiness Scale), sociodemographics, medical history, anthropometrics, spirometry, blood biomarkers were reported. We found a high prevalence of habitual snoring (30.2%, 95% confidence interval [CI] 28.5-32.0%), observed apneas (20.9%, 95% CI 19.4-22.5%) and excessive daytime sleepiness (18.6%, 95% CI 17.1-20.1%). SDB symptoms varied across sites; prevalence and adjusted odds for habitual snoring were greatest at sea level, whereas those for observed apneas were greatest at high altitude. In multivariable analysis, habitual snoring was associated with older age, male sex, body mass index (BMI), and higher socioeconomic status; observed apneas were associated with BMI; and excessive daytime sleepiness was associated with older age, female sex, and medium socioeconomic status. Adjusted odds of cardiovascular disease, depression, and hypertension and total chronic disease burden increased progressively with the number of SDB symptoms. A threefold increase in the odds of having an additional chronic comorbid disease (adjusted odds ratio 3.57, 95% CI 2.18-5.84) was observed in those with all three versus no SDB symptoms.

CONCLUSIONS

Sleep disordered breathing symptoms were highly prevalent, varied widely across four resource-limited settings in Peru, and exhibited strong independent associations with chronic diseases.

Hemoglobinopathies and sleep--The road less traveled

Sickle cell disease and thalassemia are common hereditary blood disorders associated with increased systemic inflammation, tissue hypoxia, endothelial dysfunction and end-organ damage, the latter accounting for the substantial morbidity and abbreviated lifespan associated with these conditions. Sleep perturbations in general, and sleep-disordered breathing in particular are also highly prevalent conditions and the mechanisms underlying their widespread end-organ morbidities markedly and intriguingly overlap with the very same pathways implicated in the hemoglobinopathies. However, little attention has been given to date to the potential contributing role of sleep disorders to sickle cell disease manifestations. Here, we comprehensively review the pathophysiological mechanisms and clinical manifestations linking disturbed sleep and hemoglobinopathies, with special emphasis on sickle cell disease. In addition to a broad summary of the available evidence, we identify many of the research gaps that require attention and future investigation, and provide the scientific contextual setting that should enable opportunities to investigate the intertwined pathophysiological mechanisms and clinical outcomes of sleep disorders and hemoglobinopathies.

End-of-life care in patients with heart failure

Stage D heart failure (HF) is associated with poor prognosis, yet little consensus exists on the care of patients with HF approaching the end of life. Treatment options for end-stage HF range from continuation of guideline-directed medical therapy to device interventions and cardiac transplantation. However, patients approaching the end of life may elect to forego therapies or procedures perceived as burdensome, or to deactivate devices that were implanted earlier in the disease course. Although discussing end-of-life issues such as advance directives, palliative care, or hospice can be difficult, such conversations are critical to understanding patient and family expectations and to developing mutually agreed-on goals of care. Because patients with HF are at risk for rapid clinical deterioration or sudden cardiac death, end-of-life issues should be discussed early in the course of management. As patients progress to advanced HF, the need for such discussions increases, especially among patients who have declined, failed, or been deemed to be ineligible for advanced HF therapies. Communication to define goals of care for the individual patient and then to design therapy concordant with these goals is fundamental to patient-centered care. The objectives of this white paper are to highlight key end-of-life considerations in patients with HF, to provide direction for clinicians on strategies for addressing end-of-life issues and providing optimal patient care, and to draw attention to the need for more research focusing on end-of-life care for the HF population.

The contribution of hypoxia to the association between sleep apnoea, insomnia, and cardiovascular mortality in community-dwelling elderly with and without cardiovascular disease

AIMS

This study explores if nightly hypoxia (i.e. percentage of sleep time with oxygen saturation lower than 90% (SaO2<90%)) contributed to the association between sleep-disordered breathing (SDB) and insomnia in community-dwelling elderly with and without cardiovascular disease (CVD). A second aim was to explore a potential cut-off score for hypoxia to predict insomnia and the association of the cut-off with clinical characteristics and cardiovascular mortality.

METHOD

A total of 331 community-dwelling elderly aged 71-87 years underwent one-night polygraphic recordings. The presence of insomnia was recorded by a self-report questionnaire. The presence of CVD was objectively established and mortality data were collected after three and six years.

RESULTS

In both patients with CVD (n=119) or without CVD (n=212) SDB was associated with hypoxia (p<0.005). Only in the patients with CVD was hypoxia associated with insomnia (p<0.001) which mediated an indirect effect (p<0.05) between SDB and insomnia. Hypoxia of more than 1.5% of sleep time with SaO2<90% was found to be a critical level for causing insomnia. According to this criterion 32% (n=39) and 26% (n=55) of those with and without CVD had hypoxia, respectively. These groups did not differ with respect to age, gender, body mass index, diabetes, hypertension, respiratory disease or levels of SDB. However, in the CVD group, hypoxia was associated with cardiovascular mortality at the three-year follow-up (p=0.008) and higher levels of insomnia (p=0.002).

CONCLUSION

In the elderly with CVD, SDB mediated by hypoxia can be associated with more insomnia and a worse prognosis.

Resuscitation and auto resuscitation by airway reflexes in animals

Various diseases often result in decompensation requiring resuscitation. In infants moderate hypoxia evokes a compensatory augmented breath - sigh and more severe hypoxia results in a solitary gasp. Progressive asphyxia provokes gasping respiration saving the healthy infant - autoresuscitation by gasping. A neonate with sudden infant death syndrome, however, usually will not survive. Our systematic research in animals indicated that airway reflexes have similar resuscitation potential as gasping respiration. Nasopharyngeal stimulation in cats and most mammals evokes the aspiration reflex, characterized by spasmodic inspiration followed by passive expiration. On the contrary, expiration reflex from the larynx, or cough reflex from the pharynx and lower airways manifest by a forced expiration, which in cough is preceded by deep inspiration. These reflexes of distinct character activate the brainstem rhythm generators for inspiration and expiration strongly, but differently. They secondarily modulate the control mechanisms of various vital functions of the organism. During severe asphyxia the progressive respiratory insufficiency may induce a life-threatening cardio-respiratory failure. The sniff- and gasp-like aspiration reflex and similar spasmodic inspirations, accompanied by strong sympatho-adrenergic activation, can interrupt a severe asphyxia and reverse the developing dangerous cardiovascular and vasomotor dysfunctions, threatening with imminent loss of consciousness and death. During progressive asphyxia the reversal of gradually developing bradycardia and excessive hypotension by airway reflexes starts with reflex tachycardia and vasoconstriction, resulting in prompt hypertensive reaction, followed by renewal of cortical activity and gradual normalization of breathing. A combination of the aspiration reflex supporting venous return and the expiration or cough reflex increasing the cerebral perfusion by strong expirations, provides a powerful resuscitation and autoresuscitation potential, proved in animal experiments. They represent a simple but unique model tested in animal experiments.

Association between obstructive sleep apnea and elevated levels of type B natriuretic peptide in a community-based sample of women

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular disease. One contributory factor may be hemodynamic stress due to the negative intrathoracic pressure during each episode of apnea. Type B natriuretic peptide (BNP) is secreted by the cardiac ventricles in response to volume expansion and pressure load and the authors hypothesized that there would be an association between indices of OSA during the night and levels of BNP in the morning.

SETTING

Community-based in Uppsala, Sweden.

PARTICIPANTS

There were 349 women who participated.

MEASUREMENTS AND RESULTS

Participants underwent full-night polysomnography and anthropometric measurements, and answered questionnaires about medical conditions and current medication. The morning after the polysomnography, blood samples were drawn for analysis of plasma BNP, C-reactive protein, creatinine, and hemoglobin. There was an increase in mean BNP as the severity of sleep apnea increased, increasing from a mean value of 8.5 ng/L among women with an apnea-hypopnea index (AHI) < 5 to 18.0 ng/L in women with an AHI ≥ 30. Elevated BNP levels (≥ 20 ng/L) were found in 29.8% of the women, whereas 70.2% had normal levels. The odds ratio was 2.2 for elevated BNP levels for women with an AHI of 5-14.9 in relation to women with an AHI < 5, 3.1 for women with an AHI of 15-29.9, and 4.6 for women with an AHI ≥ 30 after adjustment for age, body mass index, systolic blood pressure, antihypertensive drugs, and creatinine.

CONCLUSIONS

There is a dose-response relationship in women between the severity of sleep apnea during the night and the levels of BNP in the morning.

Treatment of cardiomyopathy with PAP therapy in a patient with severe obstructive sleep apnea

Obstructive sleep apnea is common in patients with heart failure. This case illustrates that treatment with PAP therapy can improve cardiac function in patients with both conditions. CPAP-emergent central apnea, as seen in this patient, has multiple etiologies. It is commonly seen in patients with severe sleep apnea, usually resolves over time, and does not need treatment with adaptive servoventilation.

Effective sleep apnoea treatment improves cardiac function in patients with chronic heart failure

BACKGROUND

Sleep disordered breathing (SDB) is highly prevalent in patients with chronic heart failure (CHF) and is associated with adverse effects on cardiac geometry and function. Continuous positive airway pressure (CPAP) has been proved an effective treatment modality for obstructive sleep apnoea (OSA), whereas adaptive servoventilation (ASV) is more effective in patients with central sleep apnoea (CSA). The impact of selection of therapy and effective apnoea alleviation on cardiac performance and reverse left ventricular remodelling (r-LVR) has not yet been evaluated.

METHODS

Eighty five patients with stable CHF were screened for SDB and underwent polysomnography and treatment according to the type of SDB. Clinical evaluation and a comprehensive echocardiographic study was performed before initiation of therapy and after six months of effective treatment (ventilator use >5h/day with AHI <5 events/h).

RESULTS

Seventeen compliant patients under effective treatment were included in the analysis (8 OSA under Autoset CPAP and 9 CSA under ASV). In both groups, a significant improvement in all measured, conventional and TDI LV systolic indexes was recorded, including LVEF (32% ± 6% vs. 27% ± 6%, p<0.001). A decrease in LV end-systolic volume (189 ± 94 ml vs. 211 ± 88 ml, p=0.015, difference >10%) was indicative of r-LVR. Furthermore, RV systolic parameters were also increased (TAPSE, p<0.001; systolic TDI wave from lateral tricuspid annular aspect, p=0.001), whereas right heart dimensions and areas were diminished, indicating better pulmonary haemodynamics. Moreover, a significant improvement in patients' clinical status, as evaluated by New York Heart Association Class was also documented at the end of six months follow-up.

CONCLUSIONS

Effective alleviation of SDB in CHF patients is associated with significant improvements in LV and RV systolic function and r-LVR. Longitudinal studies are needed to evaluate effects on morbidity and mortality.

Pulmonary acceleration time to optimize the timing of lung transplant in cystic fibrosis

Pulmonary hypertension (PH) may affect survival in cystic fibrosis (CF) and can be assessed on echocardiographic measurement of the pulmonary acceleration time (PAT). The study aimed at evaluating PAT as a tool to optimize timing of lung transplant in CF patients. Prospective multicenter longitudinal study of patients with forced expiratory volume in 1 second (FEV1) ≤60% predicted. Echocardiography, spirometry and nocturnal oximetry were obtained as part of the routine evaluation. We included 67 patients (mean FEV1 42±12% predicted), among whom 8 underwent lung transplantation during the mean follow-up of 19±6 months. No patients died. PAT was determined in all patients and correlated negatively with systolic pulmonary artery pressure (sPAP, r=-0.36, P=0.01). Patients in the lowest PAT tertile (<101 ms) had lower FEV1 and worse nocturnal oxygen saturation, and they were more often on the lung transplant waiting list compared to patients in the other tertiles. Kaplan-Meier curves showed a shorter time to lung transplantation in the lowest PAT tertile (P<0.001) but not in patients with sPAP>35 mmHg. By multivariate analysis, FEV(1)and nocturnal desaturation were the main determinants of reduced PAT. A PAT<101 ms reduction is a promising tool for timing of lung transplantation in CF.

Importance and management of chronic sleep apnoea in cardiology

Sleep apnoea is a common, yet underestimated, chronic disorder with a major impact on morbidity and mortality in the general population. It is quickly becoming recognized as an independent risk factor for cardiovascular impairment. Hypertension, coronary artery disease, diabetes, cardiovascular rhythm and conduction abnormalities, cerebrovascular disease, and heart failure have all been linked to this syndrome. This review will explore the critical connection between sleep apnoea and chronic cardiovascular diseases while highlighting established and emerging diagnostic and treatment strategies.

Mal-effects of obstructive sleep apnea on the heart

OBJECTIVE

This study aims to examine the impact of chronic intermittent hypoxia on hearts in patients with obstructive sleep apnea (OSA).

METHODS

Two hundred twenty patients were divided into groups based on (1) severity of the disease, (2) years of disease history, and (3) with or without secondary hypertension. All subjects underwent blood pressure measurements, polysomnogram monitoring, and cardiac Doppler ultrasound examinations.

RESULTS

The left ventricular ejection fraction (LVEF), fractional shortening (FS), and the ratio of early to late diastolic filling (E/A) in patients with severe OSA were lower than in those with moderate OSA and in healthy controls. The inner diameters of the main pulmonary artery (inD of MPA), the inner diameters of the right cardiac ventricle (inD of RV), and the thickness of anterior wall of the right ventricle (TAW of RV) were increased in patients with severe OSA compared to those with moderate disease and worsened as a function of time with disease. The tissue Doppler imaging-derived Tei index and pulmonary artery systolic pressure were also increased along with the severity of OSA. LVEF and FS in patients who had suffered from OSA for >10 years were decreased compared with those suffering from OSA for a shorter time. LVEF and FS in patients with secondary hypertension were decreased significantly relative to non-hypertensive OSA patients and healthy controls. E/A was decreased in OSA patients whether they had secondary hypertension or not.

CONCLUSION

OSA affected the left ventricular diastolic function in the early stage of the disease. Extended exposure to OSA resulted in left ventricular dysfunction with increased hypertension. Right ventricle dysfunction and abnormalities became more severe as the disease progressed.

Effects of sleep apnea on nocturnal free fatty acids in subjects with heart failure

STUDY OBJECTIVES

Sleep apnea is common in patients with congestive heart failure, and may contribute to the progression of underlying heart disease. Cardiovascular and metabolic complications of sleep apnea have been attributed to intermittent hypoxia. Elevated free fatty acids (FFA) are also associated with the progression of metabolic, vascular, and cardiac dysfunction. The objective of this study was to determine the effect of intermittent hypoxia on FFA levels during sleep in patients with heart failure.

DESIGN AND INTERVENTIONS

During sleep, frequent blood samples were examined for FFA in patients with stable heart failure (ejection fraction < 40%). In patients with severe sleep apnea (apnea-hypopnea index = 65.5 ± 9.1 events/h; average low SpO₂ = 88.9%), FFA levels were compared to controls with milder sleep apnea (apnea-hypopnea index = 15.4 ± 3.7 events/h; average low SpO₂ = 93.6%). In patients with severe sleep apnea, supplemental oxygen at 2-4 liters/min was administered on a subsequent night to eliminate hypoxemia.

MEASUREMENTS AND RESULTS

Prior to sleep onset, controls and patients with severe apnea exhibited a similar FFA level. After sleep onset, patients with severe sleep apnea exhibited a marked and rapid increase in FFA relative to control subjects. This increase persisted throughout NREM and REM sleep exceeding serum FFA levels in control subjects by 0.134 mmol/L (P = 0.0038). Supplemental oxygen normalized the FFA profile without affecting sleep architecture or respiratory arousal frequency.

CONCLUSION

In patients with heart failure, severe sleep apnea causes surges in nocturnal FFA that may contribute to the accelerated progression of underlying heart disease. Supplemental oxygen prevents the FFA elevation.

Sleep disordered breathing in community dwelling elderly: associations with cardiovascular disease, impaired systolic function, and mortality after a six-year follow-up

INTRODUCTION

Sleep disordered breathing (SDB), cardiovascular disease (CVD) and impaired cardiac function are common in elderly people. We investigated the association of SDB and mortality in a community dwelling elderly population, considering CVD and objectively measured impaired cardiac function have been poorly studied thus far.

AIM

To investigate whether SDB is a factor that affects mortality in elderly people, with a focus on those with CVD and/or signs of impaired cardiac function.

METHODS

A prospective cohort design was used and 331 community dwelling elderly aged 71-87 years underwent one-night polygraphic recordings in the subjects' homes. CVD and systolic function were objectively established. Mortality data were collected after 6 years.

RESULTS

In the total population there were no significant associations between mortality and SDB. In those with CVD and impaired systolic function, as measured by NT-proBNP, oxygen desaturation index (ODI) ≥10 was associated with mortality. The hazard ratio of 3.0 (CI 95% 1.1-8.6, p=0.03) remained statistically significant after adjustments for age, gender, diabetes and plasma values of NT-proBNP.

CONCLUSION

SDB in community dwelling elderly has no overall association to mortality irrespective of degree of SDB. However, hypoxic events (i.e., ODI ≥10) were associated with mortality in the group who had CVD in combination with impaired systolic function.

Brain natriuretic peptide and acute hypobaric hypoxia in humans

In animal models, the secretion of the cardiac hormone, brain natriuretic peptide (BNP), and its closely related peptide, atrial natriuretic peptide (ANP), are stimulated by acute hypoxia. There is extensive human evidence for a rise in ANP under acute hypoxic conditions but very little evidence regarding the BNP response to acute hypoxia in humans. We therefore subjected seven healthy subjects to an acute hypobaric hypoxic stimulus to examine if BNP secretion increases rapidly. Significant hypoxaemia (mean nadir oxygen saturation 62.3%) was induced but no significant rise in BNP occurred. This suggests that either such acute hypoxaemia is well tolerated by the healthy human heart or it is not a stimulus for BNP secretion.

Predictors of oxidative stress in heart failure patients with Cheyne-Stokes respiration

PURPOSE

Cheyne-Stokes respiration during sleep is associated with increased mortality in heart failure. The magnitude of oxidative stress is a marker of disease severity and a valuable predictor of mortality in heart failure. Increased oxidative stress associated with periodic breathing during Cheyne-Stokes respiration may mediate increased mortality in these patients. We hypothesized that the presence of Cheyne-Stokes respiration is associated with oxidative stress by increasing the formation of reactive oxygen species in patients with heart failure.

METHODS AND RESULTS

Twenty-three patients with heart failure [left ventricular ejection fraction 30.2 ± 9% (mean ± standard deviation)] and 11 healthy controls underwent nocturnal polysomnography. Subjects with obstructive sleep apnea were excluded. The majority (88%) of patients with heart failure had Cheyne-Stokes respiration during sleep. The intensity of oxidative stress in neutrophils was greater in patients with heart failure (4,218 ± 1,706 mean fluorescence intensity/cell vs. 1,003 ± 348 for controls, p < 0.001) and correlated with the duration of Cheyne-Stokes respiration. Oxidative stress was negatively correlated with SaO(2) nadir during sleep (r = -0.43, p = 0.039). The duration of Cheyne-Stokes respiration predicted severity of oxidative stress in patients with heart failure (beta = 483 mean fluorescence intensity/cell, p < 0.02).

CONCLUSIONS

Levels of oxidative stress are increased in patients with heart failure and Cheyne-Stokes respiration during sleep compared with healthy controls. The duration of Cheyne-Stokes respiration predicts the magnitude of oxidative stress in heart failure. Increased oxidative stress may mediate increased mortality associated with Cheyne-Stokes respiration in patients with heart failure.

Nocturnal hypoxemia and periodic limb movement predict mortality in patients on maintenance hemodialysis

BACKGROUND AND OBJECTIVES

Sleep disorders, including sleep-disordered breathing and periodic limb movements during sleep, are associated with an increased risk for cardiovascular diseases, which are the leading causes of death in patients with ESRD. This study investigated the association between sleep disorders and mortality in patients with ESRD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Thirty patients on maintenance hemodialysis, who were clinically stable for >2 months, underwent overnight polysomnography to evaluate sleep parameters.

RESULTS

All patients were followed for a median of 48 months (range: 14 to 62 months), and 14 of them died during the follow-up period. Among the sleep parameters, the percent of sleep time with arterial oxygen saturation <90% (T <90%), mean arterial oxygen saturation, and periodic limb movement index score were associated with significant increases in the risk of death. However, associations of the apnea-hypopnea index or oxygen desaturation index with mortality were NS. The hazard ratios (95% confidence intervals) for death per one SD increment in the log-transformed T <90% and periodic limb movement index score were 2.10 (1.06 to 4.15) and 2.48 (1.11 to 5.52), respectively, after adjusting for age.

CONCLUSIONS

We found that nocturnal hypoxemia and periodic limb movement during sleep, rather than apnea itself, were associated with an increased risk for death in patients with ESRD. However, conclusions from this study should be drawn with caution, because they are limited by the small sample size.