Prevalence Of Central Sleep Apnea Research Articles

Central sleep apnea in obese children with sleep-disordered breathing

In contrast to obstructive sleep apnea (OSA), central sleep apnea (CSA) in obese children has received lesser attention. As pediatric CSA is more prevalent than expected and adversely impacts health, this study aims to elucidate the major factors associated with central apnea index (CAI) and compare CSA between obese and non-obese children. Retrospective analysis was performed in a tertiary referral medical center. Children with sleep-disordered breathing (SDB) ranging from 2-18 years old were enrolled. All participants completed history taking, otolaryngological examination and overnight polysomnography. CSA was defined as having CAI exceeding 1 h(-1). CAI and the prevalence of CSA were analyzed in children of different age groups, weight statuses and adenotonsillar sizes. A total of 487 cases were included. The prevalence of CSA was 13.3% (65/487). CAI was negatively correlated with age (r=-0.32, P<0.001). Obese children had a significantly lower CAI than that of non-obese ones (0.20 ± 0.36 vs 0.48 ± 0.82 h(-1), P<0.001). Multiple linear regression analysis demonstrated a relationship between CAI, age and obesity as 'CAI=0.883-0.055 × Age -0.22 × (Obesity)'. In children with SDB, younger ones have a significantly higher CAI than older ones. Additionally, obese children had a lower CAI than non-obese ones.

Central sleep apnea and complex sleep apnea in patients with epilepsy

We sought to examine the prevalence of central sleep apnea (CSA) and complex sleep apnea (CompSA) in patients with epilepsy and to examine their clinical profile, with respect to epilepsy type, etiology, medication use, and EEG abnormalities. We undertook a retrospective analysis of 719 consecutive patients with epilepsy who underwent polysomnography (PSG) at our institution between 2004 and 2011. Of the 458 patients with complete data, we excluded 42 patients with congestive heart failure or left ventricular ejection fraction <40 %. Comparison of clinical and PSG variables between the three groups were conducted with Fisher exact test and analysis of variance. Out of 416 patients tested, 315 (75 %) had obstructive sleep apnea (OSA), 16 (3.7 %) had CSA, 33 (7.9 %) had CompSA. There were more males in the CSA and CompSA groups than in the OSA group (81.2, 81.8, and 59.6 %, respectively, p=0.04). Focal seizures were more prevalent in patients with CSA than in patients OSA or CompSA (62.5, 265, and 21.1 %, respectively, p=0.02). About 11 % of epilepsy patients have sleep-breathing disorders with central apneas, which is not higher than that in a general population. These data should be expanded with future research investigating the role of interictal, ictal, and postictal central apneas in epileptogenesis and epilepsy.

Prevalence of obstructive sleep apnea in Asian adults: a systematic review of the literature

BackgroundObstructive sleep apnea (OSA) is a common disease, affecting approximately 2% of women and 4% of men residing in Western communities. No systematically reviewed data are available about the prevalence of this disease in Asia, the most heavily populated continent.MethodsPubMed/Medline, Scopus and Google Scholar were searched for articles published from 1993 to May 2012 that reported the prevalence of OSA diagnosed via sleep monitoring and the prevalence of patients at risk for OSA as assessed by symptomatology and/or sleep questionnaires. We have also searched abstract database of major pulmonary and sleep scientific societies for relevant abstracts presented from 2010 to 2012. The following inclusion criteria were used: articles published in English, age ≥ 18 years, ≥ 100 participants in studies using sleep monitoring for the diagnosis of OSA, ≥ 300 participants in studies using questionnaires to detect patients at high risk for OSA. Exclusion criteria: duplicate publications, studies reporting the prevalence of central sleep apnea only, hospital based studies as well as studies assessing OSA prevalence among patients with resistant arterial hypertension, chronic kidney disease, heart failure and in patients with concomitant neurological disease.ResultsTwenty four articles were found to meet the inclusion criteria, covering 47,957 subjects (26,042 men and 21,915 women) and four relevant abstracts were noted. OSA prevalence ranged from 3.7% to 97.3%. Male gender, older age, a higher BMI and waist to hip ratio, greater neck circumference, arterial hypertension, smoking, snoring and daytime sleepiness were associated with OSA. Sample size, difference between the populations studied and the fact that some works included patients with a high pre-test probability of OSA explain the difference in prevalence rates.ConclusionThis systematic review highlights the lack of data regarding the prevalence of OSA in Asians. Only a few studies provide an approximate estimate of the OSA burden in some Asian communities.

Prevalence of central sleep apnea in different age groups of children with sleep apnea-hypopnea

To explore the prevalence of central sleep apnea in different age groups of children with sleep apnea-hypopnea (SAH). A total of 431 children with SAH diagnosed by overnight polysomnography at our Sleep Center were retrospectively studied. They were divided into 3 groups based on their ages: toddler group (1 - < 3 years old), preschool group (3 - < 6 years old) and school group (6 - < 13 years old). The relationship between age and different types of apnea-hyponea index (AHI) was analyzed. And the prevalence of central sleep apnea and sleep structure were compared between the groups. A negative correlation existed between age and central sleep apnea index (r = -0.322, P < 0.01). However, there was no correlation between age and obstructive apnea index (P > 0.05). AHI was similar in different age groups, but the medians of central sleep apnea index for toddler, preschool and school groups were 2.35, 1.50 and 0.90 events/h respectively (all P < 0.01). Sleep structure was similar between the groups (P > 0.05). Central sleep apnea is common in children with sleep disordered breathing. The younger their ages, a higher prevalence of central sleep apnea.

Role of nocturnal rostral fluid shift in the pathogenesis of obstructive and central sleep apnoea.

Obstructive sleep apnoea (OSA) is common in the general population and increases the risk of motor vehicle accidents due to hypersomnolence from sleep disruption, and risk of cardiovascular diseases owing to repetitive hypoxia, sympathetic nervous system activation, and systemic inflammation. In contrast, central sleep apnoea (CSA) is rare in the general population. Although their pathogenesis is multifactorial, the prevalence of both OSA and CSA is increased in patients with fluid retaining states, especially heart failure, where they are associated with increased mortality risk. This observation suggests that fluid retention may contribute to the pathogenesis of both OSA and CSA. According to this hypothesis, during the day fluid accumulates in the intravascular and interstitial spaces of the legs due to gravity, and upon lying down at night redistributes rostrally, again owing to gravity. Some of this fluid may accumulate in the neck, increasing tissue pressure and causing the upper airway to narrow, thereby increasing its collapsibility and predisposing to OSA. In heart failure patients, with increased rostral fluid shift, fluid may additionally accumulate in the lungs, provoking hyperventilation and hypocapnia, driving below the apnoea threshold, leading to CSA. This review article will explore mechanisms by which overnight rostral fluid shift, and its prevention, can contribute to the pathogenesis and therapy of sleep apnoea.

Sleep apnea in precapillary pulmonary hypertension

Pilot studies have described the occurrence of sleep apnea in patients with precapillary pulmonary hypertension (PH). However, there are no data on the prevalence of sleep-related breathing disorders in larger patient cohorts with PH. 169 patients with a diagnosis of PH confirmed by right heart catheterisation and clinically stable in NYHA classes II or III were prospectively investigated by polygraphy (n = 105 females, mean age: 61.3 years, mean body mass index: 27.2 kg/m(2)). Recruitment was independent of sleep-related symptoms and the use of vasodilator drugs or nasal oxygen. 45 patients (i.e. 26.6%) had an apnea-hypopnea-index (AHI) >10/h. Of these, 27 patients (i.e. 16%) had obstructive sleep apnea (OSA) and 18 patients (i.e. 10.6%) had central sleep apnea (CSA). The mean AHI was 20/hour. As a polygraphy had been performed with nasal oxygen in half of the patients without evidence for sleep apnea, the frequency of CSA was probably underestimated. Patients with OSA were characterized by male gender and higher body mass index whereas, those with CSA were older and hypocapnic. At least every fourth patient with PH suffers from mild-to-moderate sleep apnea. Considering the anthropometric characteristics of the patients studied, the prevalence of both OSA and CSA seem to be higher in PH than in the general population.

Prevalence and treatment of central sleep apnoea emerging after initiation of continuous positive airway pressure in patients with obstructive sleep apnoea without evidence of heart failure

This study aimed to assess the prevalence of complex sleep apnoea (CompSA), defined as central sleep apnoea (CSA) emerging after the initiation of continuous positive airway pressure (CPAP) therapy for obstructive sleep apnoea (OSA), in patients with normal brain natriuretic peptide (BNP) levels, along with assessing the prevalence of CSA persisting in such patients after the onset of CPAP therapy. We hypothesised that the prevalence of CompSA and persistent CSA after CPAP initiation would be low in patients with OSA and normal BNP levels. Between April 2004 and July 2007, CPAP was initiated for all patients with OSA for two nights using a standardised protocol. The prevalence of CompSA syndrome (CompSAS) and persisting CSA [central apnoea index (CAI) >5/h and apnoea-hypopnoea index (AHI) >15/h with >50% central events during CPAP therapy] was prospectively assessed in patients with normal BNP levels. Patients with CompSAS or persisting CSA upon CPAP treatment received adaptive servoventilation (ASV). Of 1,776 patients with OSA receiving CPAP, 28 patients (1.57%) had CSA at the time of CPAP therapy and normal BNP levels. Additionally, 10 patients had CompSAS (0.56%) and 18 patients (1.01%) had persisting CSA. In patients with CompSA or persisting CSA, the AHI was significantly lower with CPAP therapy than at the time of diagnosis (34 ± 15/h vs. 47 ± 20/h, p = 0.005). The CAI increased from 10 ± 10/h to 18/h ± 13/h (p = 0.009) upon initiation of CPAP therapy. ASV reduced the AHI to 6 ± 12/h (p < 0.001) during the first night of use. The prevalence of CompSA or persisting CSA in patients with OSA and normal BNP levels who are receiving CPAP therapy is low (1.57%). ASV is an effective treatment for these patients.

Prevalence of central sleep apnea in heart failure patients in the era of beta-blockers

Background: Central sleep apnea (CSA) has been shown to improve with beta-blocker use in heart failure patients. It is unknown if the overall prevalence of CSA has decreased since the introduction of beta-blockers. Recent publications have reported that the addition of beta-blockers to the medical regimen of a patient with CSA has been shown to decrease the severity of CSA (Tamura 2009). Therefore, it is possible that CSA and SDB has decreased in overall prevalence with the use of beta-blockers.

Characteristics of sleep-disordered breathing in Japanese patients with type 2 diabetes mellitus

Sleep-disordered breathing (SDB), especially sleep apnea-hypopnea syndrome, is often observed in patients with type 2 diabetes mellitus; but there are only a few studies on SDB in Japanese diabetic subjects. We investigated the prevalence of SDB in diabetic patients; associations between severity of sleep apnea (SA) and clinical factors, visceral fat, and adiponectin; and associations between type of SA and clinical factors. In the present study, 40 Japanese diabetic patients underwent overnight cardiorespiratory monitoring, and night and morning measurements of serum adiponectin concentrations. Sleep apnea was detected in Japanese diabetic patients at a high prevalence (77.5%). The following variables were associated with SDB: age, body mass index, estimated visceral fat area, and nocturnal reduction in serum adiponectin concentrations. The prevalence of central sleep apnea (CSA, ≥5/h) was 32.3% among diabetic SDB patients. Diabetic SDB patients with CSA had higher hemoglobin, increased intima-media thickness, and higher plasma brain natriuretic peptide levels than those without CSA (<5/h). In conclusion, our study demonstrated a high prevalence of SDB in Japanese diabetic patients, which correlated with visceral fat area and adiponectin. A high frequency of CSA was noted in diabetic SDB patients, together with high hemoglobin, high brain natriuretic peptide, and increased intima-media thickness. The present results of prevalence of SDB may be relevant to the higher incidence of cardiovascular disease in diabetic patients, which need to be clarified in future studies.

The Prevalence and Natural History of Complex Sleep Apnea

Central sleep apnea (CSA) may occasionally occur in patients with obstructive sleep apnea during titration with a continuous positive airway pressure (CPAP) device. To determine the prevalence and the natural history of CPAP-emergent CSA. This is a retrospective study of 1286 patients with a diagnosis of OSAwho underwent titration with a positive airway device during a 1-year period. Patients were seen in consultation and underwent full-night attended polysomnography followed by full-night attended CPAP titration. Four weeks after CPAP therapy, patients returned to the clinic for follow-up, and objective adherence to CPAP was recorded. In patients who had CSA on CPAP, a second full-night attended CPAP titration was recommended. Eighty-four of the 1286 patients developed a central apnea index (CAI) of 5 or greater per hour while on CPAP. The incidence of CSA varied from 3% to 10% monthly, with an overall incidence of 6.5%. Forty-two of the 84 patients returned for a second CPAP titration. In 33 patients, CSA was eliminated. In each of the remaining 9 patients, the CAI remained at 5 or greater per hour, with an average of 13 per hour. These patients characteristically had the most severe OSA, and 5 had a CAI of 5 or more per hour at baseline. Two of the 9 patients were on opioids In this large retrospective study of 1286 patients with a diagnosis of OSA, 6.5% had CPAP-emergent or persistent CSA. However, CPAP-emergent CSA was generally transitory and was eliminated within 8 weeks after CPAP therapy. The prevalence of CPAP-persistent CSA was about 1.5%. Severity of OSA, a CAI of 5 or greater per hour, and use of opioids were potential risk factors.

Pulmonary capillary wedge pressure and pulmonary arterial pressure in heart failure patients with sleep-disordered breathing

Background There is a high prevalence of central sleep apnea (CSA) in patients with chronic heart failure (CHF). The present study investigates the hypotheses that CSA in CHF patients reflects heart failure severity as measured by cardiac index (CI), pulmonary artery pressure (PAP) and pulmonary capillary wedge pressure (PCWP). Methods In 105 patients with stable CHF (NYHA ⩾ II, LV-EF ⩽ 40%) cardiorespiratory polygraphy and simultaneous right and left heart catheterization was performed. Results CSA was present in 58% and obstructive sleep apnea (OSA) in 23% of patients. In CSA patients, PAP and PCWP were significantly higher when compared to patients without SDB. In CSA patients, but not in OSA patients, PCWP showed a significant correlation with apnea–hypopnea index (AHI; r = 0.41, p = 0.005), apnea index (AI; r = 0.44, p = 0.003) and central AI (cAI; r = 0.358, p = 0.015). Cardiac index was more impaired in CSA (1.93 ± 0.5 l/min/m 2) than in OSA patients (2.55 ± 1.0 l/min/m 2) or those without SDB (2.22 ± 0.4 l/min/m 2). A negative correlation of CI and cAI ( r = −0.344, p = 0.008), AI ( r = −0.31, p = 0.02) and AHI ( r = −0.21, p < 0.05) was documented exclusively in CSA patients. Conclusion The present study supports the hypotheses that the occurrence and severity of CSA in CHF patients reflects heart failure severity.

Prevalence and management of central sleep apnea in heart failure patients

There is increasing awareness of sleep-disordered breathing, which may manifest as obstructive sleep apnea, central sleep apnea (CSA), or a mixture of the two. Obstructive sleep apnea and CSA are strongly associated with heart failure (HF) and risk factors for developing HF. CSA may be considered a manifestation of the pathophysiology of HF; hence, approaches to optimize pharmacologic and nonpharmacologic treatment of HF should help to ameliorate CSA. However, if CSA also contributes to HF progression, CSA may represent a potential therapeutic target. There was hope that CSA prevalence would decline with better HF therapies. However, contemporary studies of HF patients on optimal medical therapy have shown that CSA prevalence remains 30% to 40%. Treating CSA poses significant challenges. Presently, the role of routine continuous positive airway pressure remains unclear, although newer ventilatory strategies may prove effective. Currently, CSA treatment involves standard optimal HF therapies, although growing evidence indicates that newer ventilation modes and cardiac resynchronization therapy may prove to be useful.

Central Sleep Apnea on Commencement of Continuous Positive Airway Pressure in Patients With a Primary Diagnosis of Obstructive Sleep Apnea-Hypopnea

Central sleep apnea (CSA) may occur in patients with snoring and obstructive sleep apnea-hypopnea (OSAH) during commencement of continuous positive airway pressure (CPAP) therapy. The presence of CSA may limit the effectiveness of CPAP therapy. The aims of this study were to assess the prevalence of CSA amongst patients starting CPAP for OSAH and to identify possible predictors of this condition. We reviewed the polysomnograms (PSGs) and clinical records of 99 consecutive patients with a primary diagnosis of OSAH who were referred for an in-laboratory CPAP titration study. Patients with a CSA Index of > or =5 per hour at or near (+/-1 cm H2O) prescribed CPAP level formed the CSA-CPAP group. The remaining patients made up the noCSA-CPAP group. Demographic, baseline and CPAP titration PSG variables were compared between the 2 two groups. 13 subjects (13.1%) had CSA-CPAP. Patients with and without CSA-CPAP did not differ with respect to age or body mass index. 46% of patients with CSA-CPAP had CSA on their baseline PSGs compared with 8% in the noCSA-CPAP group (p <0.01). CSA-CPAP patients also had a higher apnea-hypopnea index (72.1 vs. 52.7 p = 0.02), a higher arousal index (43.3 vs. 29.2 p <0.01), and a higher mixed apnea index (6.8 vs. 1.3 p = 0.03), on their baseline PSGs. Therapeutic CPAP could not be determined in 2 CSA-CPAP patients due to a very high frequency (of severe) central apneas. In the remaining 11, the CPAP prescription to eliminate obstructive events was higher than in the noCSA-CPAP group (11.0 vs. 9.3 p = 0.08). AHI was greater both at or near prescribed CPAP (48.8 vs. 6.7 p <0.01) and overall (47.4 vs. 14.9 p <0.01). A history of ischemic heart disease or heart failure was more frequent amongst patients with CSA-CPAP than those without (p = 0.03). A significant minority of patients with a primary diagnosis of OSAH have either emergence or persistence of CSA on CPAP. Risk factors include male sex, history of cardiac disease, and CSA on baseline PSG.

Causality in the relationship between central sleep apnea and paroxysmal atrial fibrillation

The prevalence of central sleep apnea (CSA) is increased in patients with atrial fibrillation (AF) in addition to congestive heart failure [1]. Conversely, the prevalence of AF is increased in patients with idiopathic CSA in the absence of other cardiac disease [2]. The causality between CSA and AF and the etiologic relevance of congestive heart failure is not clear yet. A 52-year-old man with a stable three-vessel coronary artery disease was admitted because of suspected obstructive sleep apnea syndrome. The cardiorespiratory polygraphy revealed periodic breathing patterns following the onset of intermittent AF with a fast ventricular response and a heart rate up to 140 bpm (Figs. 1 and 2). CSA was not related to supine body position (Fig. 2). There were no ischemia-like electrocardiographic (ECG) changes associated with the development of CSA. Episodes of sinus rhythm with a heart rate of 60–80 bpm were accompanied by stable breathing patterns (Figs. 1 and 2). This finding was verified in a second polygraphy (Fig. 1). Transthoracic echocardiography revealed a marginal left ventricular hypertrophy and left ventricular diastolic dysfunction (ratio of early diastolic velocity to atrial velocity: e/a 85%). Holter-ECG and nocturnal capnometry remained without pathological findings.

Sleep-disordered breathing and cardiovascular disease.

Sleep apnea is defined as repetitive episodes of decreased or total cessation of respiratory airflow during sleep, leading to a fall in oxygen saturation of ≥4% and sleep fragmentation. Sleep apnea can be central or obstructive. Central sleep apnea (CSA) is characterized by apneas secondary to diminution or cessation of thoraco-abdominal respiratory movements (due to dysfunction of central respiratory control mechanisms). Obstructive sleep apnea (OSA) is caused by upper airway collapse during inspiration and is accompanied by strenuous breathing efforts. When defined as >5 episodes of apnea or hypopnea per hour of sleep, OSA is relatively common, affecting 24% and 9% of middle-aged men and women, respectively.1 CSA is primarily seen in patients with congestive heart failure (CHF), although it occasionally may occur in healthy normal subjects, in people at high altitudes, and in association with central neural lesions. Sleep apnea constitutes a major public health problem because of its high prevalence and its emerging association with cardiovascular morbidity. ### Central Sleep Apnea CSA is especially relevant to CHF. The prevalence of CSA in CHF patients is dependent on various factors, such as heart failure etiology, gender, age, ejection fraction, and hemodynamic status, and has been estimated at 40% to 60%.2,3 Cheyne-Stokes respiration occurs during CSA and is a distinct pattern of periodic breathing with alternating crescendo-decrescendo sequences of hyperventilation and apnea (ie, complete breathing cessation). CSA may have an important influence on prognosis, in that its presence is associated with increased mortality in CHF patients.3 This effect appears to be independent of other known risk factors, such as left ventricular ejection fraction or peak oxygen consumption. Although the association of CSA with CHF has been recognized for decades, it is unclear whether CSA directly affects CHF pathophysiology and can therefore be causally linked to prognosis, or whether it is rather …

Central sleep apnea in left ventricular dysfunction: prevalence and implications for arrhythmic risk.

The prevalence and characteristics of sleep-disordered breathing in patients with asymptomatic left ventricular (LV) dysfunction are unknown. Therefore, we evaluated the prevalence of sleep-disordered breathing in patients with LV dysfunction without overt heart failure and tested the hypothesis that sleep-disordered breathing is linked to greater hemodynamic and autonomic impairment. We studied 47 patients with LV ejection fractions <or=40% without any history of heart failure. Central sleep apnea (CSA), as defined by an apnea-hypopnea index >or=15/h, was present in 26 patients (55%), 17 (36%) of whom had severe CSA (apnea-hypopnea index >or=30/h). Obstructive sleep apnea was evident in 5 patients (11%). The prevalence and severity of CSA were higher in patients with ischemic cardiomyopathy than in patients with nonischemic cardiomyopathy (P<0.05). Exercise tolerance and echocardiographic indices of systolic and diastolic function were similar in patients without CSA, with mild CSA, and with severe CSA. Heart rate variability was markedly depressed in patients with CSA (P<0.05). Patients with severe CSA also had a higher incidence of nonsustained ventricular tachycardia (P=0.05). CSA is highly prevalent in patients with asymptomatic LV dysfunction. The severity of CSA may not be related to the severity of hemodynamic impairment. Severe CSA is associated with impaired cardiac autonomic control and with increased cardiac arrhythmias.

Sleep apnea in renal patients.

In Western societies, sleep apnea (SA) has emerged as a major medical problem with important social ([1][1]) and financial implications. The issue may be even more relevant in nephrology because some of the factors involved in the pathogenesis of renal disease are the same that cause, or are

Sleep-disordered breathing in stable methadone programme patients: a pilot study.

To explore the possibility that stable MMP patients have sleep-disordered breathing (SDB) and abnormal sleep architecture defined by nocturnal sleep stages and sleep efficiency. Observational. Regional Methadone Service and sleep disorders laboratory in a university affiliated hospital. Participants and measurements. Ten stable MMP patients and nine normal subjects were assessed clinically and with overnight polysomnography. There were no differences in age, sex and body mass index between the groups. The methadone dose ranged between 50 and 120 mg/day. Six patients had central apnoea index (CAI) greater than 5, four had a CAI greater than 10 and three of these exhibited periodic breathing. No normal subject had central sleep apnoea. The patients had lower sleep efficiency (p < 0.05), less slow wave sleep (p < 0.01), less rapid eye movement sleep (p < 0.05) and more Stage 2 sleep (p < 0.05) than controls. Stable MMP patients have more sleep architecture abnormalities than controls and a higher prevalence of central sleep apnoea. Further studies are needed to confirm these findings, to delineate the mechanisms for the abnormalities and to assess whether the SDB is related to sudden death in stable MMP patients. We recommend that MMP patients have awake and sleep respiration assessed to identify those potentially at risk.

Clinical Significance of Arterial Blood Gas Analysis for Detection and/or Treatment of Central Sleep Apnea in Patients With Heart Failure

To the Editor: In a recent issue of Circulation , Javaheri et al1 demonstrated that sleep-disordered breathing (SDB), including central sleep apnea (CSA) and periodic breathing (eg, Cheyne-Strokes respiration), is extremely common in patients with stable heart failure and that atrial fibrillation, ventricular arrhythmia, and low left ventricular function are associated with sleep apnea in these patients. Because the reversal of SDB by nasal continuous positive pressures and oxygen may lead to improvements in markers of cardiovascular outcome in selected patients with congestive heart failure (CHF), all cardiologists should pay attention to the recent study. However, the mechanisms of SDB in patients with CHF were not extensively discussed in the article. The same authors recently proposed that low Paco2 resulted in ventilatory instability and central apnea during sleep.2 In the previous study, the values of Paco2 were 37±5 and 39±4 mm Hg in patients with SDB and those without SDB, respectively. Although the differences in resting …

Association of low PaCO2 with central sleep apnea and ventricular arrhythmias in ambulatory patients with stable heart failure.

Central sleep apnea frequently occurs in patients with heart failure. Because it is not practical to perform sleep studies on all patients, readily available laboratory tests that predict sleep apnea would be clinically useful. Arterial PCO2 has a profound influence on breathing during sleep: When it decreases below a certain threshold, apnea occurs. To study the value of a low PaCO2 while patients are awake in predicting central sleep apnea in patients with stable, treated heart failure. Prospective study. Referral sleep laboratory of a Department of Veterans Affairs Medical Center. 59 patients with left ventricular ejection fractions of 45% or less. Arterial blood gases and hydrogen ion concentrations were measured, and cardiac radionuclide ventriculography, Holter monitoring, and polysomnography were done. Patients were classified as eucapnic (PaCO2 > 35 and < 44 mm Hg [n = 41]) or hypocapnic (PaCO2 < or = 35 mm Hg [n = 18]). The mean (+/- SD) hourly episodes of apnea or hypopnea (36 +/- 25 and 20 +/- 27; P = 0.015), the prevalence of central sleep apnea (78% and 39%; P = 0.01), and the mean hourly occurrences of ventricular tachycardia (2 +/- 3 and 0.1 +/- 0.1; P = 0.003) were significantly greater in hypocapnic patients than in eucapnic patients. Data on patients with heart failure in this study are consistent with the physiologic notion that a low PaCO2 results in ventilatory instability and central apnea during sleep. The positive predictive value of a low PaCO2 for central sleep apnea is 78%. The prevalence of ventricular tachycardia was 20 times greater in hypocapnic patients than in eucapnic patients.