Noninvasive pressure preset ventilation for the treatment of Cheyne-Stokes respiration during sleep

APAP, BPAP, CPAP, and New Modes of Positive Airway Pressure Therapy

Positive airway pressure (PAP) is the primary treatment of sleep-disordered breathing including obstructive sleep apnea, central sleep apnea, and sleep-related hypoventilation. Just as clinicians use pharmacological mechanism of action and pharmacokinetic data to optimize medication therapy for an individual, understanding how PAP works and choosing the right mode and device are critical to optimizing therapy in an individual patient. The first section of this chapter will describe the technology inside PAP devices that is essential for understanding the algorithms used to control the airflow and pressure. The second section will review how different comfort settings including ramp and expiratory pressure relief and modes of PAP therapy including continuous positive airway pressure (CPAP), autotitrating CPAP, bilevel positive airway pressure, adaptive servoventilation, and volume-assured pressure support control the airflow and pressure. Proprietary algorithms from several different manufacturers are described. This chapter derives its descriptions of algorithms from multiple sources including literature review, manufacture publications and websites, patents, and peer-reviewed device comparisons and from personal communication with manufacturer representatives. Clinical considerations related to the technological aspects of the different algorithms and features will be reviewed.

All You Need Is Sleep: the Effects of Sleep Apnea and Treatment Benefits in the Heart Failure Patient

PURPOSE OF REVIEW

Recognition and treatment of sleep apnea is an important but easily overlooked aspect of care in the heart failure patient. This review summarizes the data behind the recommendations in current practice guidelines and highlights recent developments in treatment options.

RECENT FINDINGS

Neuromodulation using hypoglossal nerve stimulation has been increasingly used for treatment of OSA; however, it has not been studied in the heart failure population. Alternatively, phrenic nerve stimulation for treatment of CSA is effective for heart failure patients, and cardiac resynchronization therapy can be effective in improving CSA in pacing-induced cardiomyopathy. In patients suspected to have sleep apnea, polysomnography is recommended to better understand the prognosis and treatment options. Positive airway pressure is the standard treatment for sleep apnea; however, neurostimulation can be especially effective in those with predominantly central events. Understanding the pathophysiology of sleep apnea can guide further management decisions.

Heart failure and sleep-disordered breathing

PURPOSE OF REVIEW

Sleep-disordered breathing, which includes both obstructive and central sleep apnoea (OSA and CSA, respectively), is highly prevalent in patients with heart failure. In this review, we outline our current understanding of the bidirectional relationship between these disorders and heart failure. We also explore the role of recent advances in therapeutics.

RECENT FINDINGS

Although early studies suggest promise of adaptive servoventilation in treating sleep-disordered breathing, particularly CSA with associated Cheyne-Stokes respiration, the recent clinical trial in the heart failure patient population has demonstrated worse cardiovascular outcome in symptomatic patients.

SUMMARY

Both OSA and CSA are highly prevalent in patients with heart failure. Effective treatment of OSA with continuous positive airway pressure can improve cardiovascular outcome in these patients. However, recent evidence suggests that adaptive servoventilation cannot be safely recommended as a therapy for CSA in the context of heart failure, as a result of increased risk of cardiovascular mortality.

Treatment of sleep-disordered breathing with positive airway pressure devices: technology update

Many types of positive airway pressure (PAP) devices are used to treat sleep-disordered breathing including obstructive sleep apnea, central sleep apnea, and sleep-related hypoventilation. These include continuous PAP, autoadjusting CPAP, bilevel PAP, adaptive servoventilation, and volume-assured pressure support. Noninvasive PAP has significant leak by design, which these devices adjust for in different manners. Algorithms to provide pressure, detect events, and respond to events vary greatly between the types of devices, and vary among the same category between companies and different models by the same company. Many devices include features designed to improve effectiveness and patient comfort. Data collection systems can track compliance, pressure, leak, and efficacy. Understanding how each device works allows the clinician to better select the best device and settings for a given patient. This paper reviews PAP devices, including their algorithms, settings, and features.

Central sleep apnoea-a clinical review

Central sleep apnoea (CSA) is characterised by recurrent apnoeas during sleep with no associated respiratory effort. It mostly results from withdrawal of the wakefulness drive in sleep leaving ventilation under metabolic control. A detailed physiological understanding of the control of breathing in wakefulness and sleep is essential to the understanding of CSA. It encompasses a diverse group of conditions with differing aetiologies and pathophysiology. Likewise treatment varies according to underlying aetiology. Some of the conditions such as idiopathic (primary) CSA (ICSA) are relatively rare and benign. On the other hand Cheyne-Stokes breathing (CSB) pattern is quite common in patients with heart failure and might be a prognostic indicator of poor outcome. Unfortunately modern medical management of heart failure does not seem to have significantly reduced the prevalence of CSA in this group. Since the adoption of positive airway pressure (PAP) as a common treatment modality of obstructive sleep apnoea (OSA), complex CSA has been increasingly observed either as treatment emergent or persistent CSA. Depending on the particular condition, various treatment strategies have been tried in the past two decades which have included hypnotic therapy, respiratory stimulants, judicious administration of carbon dioxide, oxygen therapy, PAP and bi-level ventilatory support with a backup rate. In the past decade adaptive servo ventilation (ASV) has been introduced with much promise. Various studies have shown its superiority over other treatment modalities. Ongoing long term studies will hopefully shed more light on its impact on cardiovascular morbidity and mortality. Other rare forms are still poorly understood and treatments remain suboptimal.

Positive airway pressure therapy for heart failure

Heart failure (HF) is a life-threatening disease and is a growing public health concern. Despite recent advances in pharmacological management for HF, the morbidity and mortality from HF remain high. Therefore, non-pharmacological approaches for HF are being developed. However, most non-pharmacological approaches are invasive, have limited indication and are considered only for advanced HF. Accordingly, the development of less invasive, non-pharmacological approaches that improve outcomes for patients with HF is important. One such approach may include positive airway pressure (PAP) therapy. In this review, the role of PAP therapy applied through mask interfaces in the wide spectrum of HF care is discussed.

Complex sleep apnea syndrome

Complex sleep apnea is the term used to describe a form of sleep disordered breathing in which repeated central apneas (>5/hour) persist or emerge when obstructive events are extinguished with positive airway pressure (PAP) and for which there is not a clear cause for the central apneas such as narcotics or systolic heart failure. The driving forces in the pathophysiology are felt to be ventilator instability associated oscillation in PaCO2 arterial partial pressure of Carbon Dioxide, continuous cositive airway pressure (CPAP) related increased CO2 carbon dioxide elimination, and activation of airway and pulmonary stretch receptors triggering these central apneas. The prevalence ranges from 0.56% to 18% with no clear predictive characteristics as compared to simple obstructive sleep apnea. Prognosis is similar to obstructive sleep apnea. The central apnea component in most patients on followup using CPAP therap, has resolved. For those with continued central apneas on simple CPAP therapy, other treatment options include bilevel PAP, adaptive servoventilation, permissive flow limitation and/or drugs.

Nocturnal non-invasive ventilation for cardio-respiratory disorders in adults

Following the classic 'iron lung' non-invasive negative pressure ventilator, non-invasive positive pressure ventilation (NIPPV), particularly used 'nocturnally' has developed a broad role in both the acute hospital setting and domiciliary long-term use for many cardio-respiratory disorders associated with acute and chronic ventilatory failure. This role is based in part upon the perceived relative ease of application and discontinuation of NIPPV, ability to avoid intubation or tracheostomy and their associated morbidities and availability of increasingly portable pressure and volume cycled NIPPV devices. Nevertheless, the many methodologies necessary for optimal NIPPV use are often underappreciated by health care workers and patients alike. This review focuses on the rationale, practice, and future directions for 'nocturnal' use of non-invasive positive pressure ventilation (nNIV) in cardio-respiratory disorders in adults which are commonly associated with sleep-related apnea, hypoventilation and hypoxemia: congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), obesity hypoventilation syndrome (OHS), cystic fibrosis (CF) and neuromuscular disorders.

Randomized controlled trial of noninvasive positive pressure ventilation (NPPV) versus servoventilation in patients with CPAP-induced central sleep apnea (complex sleep apnea)

STUDY OBJECTIVES

To compare the treatment effect of noninvasive positive pressure ventilation (NPPV) and anticyclic servoventilation in patients with continuous positive airway pressure (CPAP)-induced central sleep apnea (complex sleep apnea).

DESIGN

Randomized controlled trial.

SETTING

Sleep center.

PATIENTS

Thirty patients who developed complex sleep apnea syndrome (CompSAS) during CPAP treatment.

INTERVENTIONS

NPPV or servoventilation.

MEASUREMENTS AND RESULTS

Patients were randomized to NPPV or servo-ventilation. Full polysomnography (PSG) was performed after 6 weeks. On CPAP prior to randomization, patients in the NPPV and servoventilator arm had comparable apnea-hypopnea indices (AHI, 28.6 ± 6.5 versus 27.7 ± 9.7 events/h (mean ± standard deviation [SD])), apnea indices (AI,19 ± 5.6 versus 21.1 ± 8.6 events/h), central apnea indices (CAI, 16.7 ± 5.4 versus 18.2 ± 7.1 events/h), oxygen desaturation indices (ODI,17.5 ± 13.1 versus 24.3 ± 11.9 events/h). During initial titration NPPV and servoventilation significantly improved the AHI (9.1 ± 4.3 versus 9 ± 6.4 events/h), AI (2 ± 3.1 versus 3.5 ± 4.5 events/h) CAI (2 ± 3.1 versus 2.5 ± 3.9 events/h) and ODI (10.1 ± 4.5 versus 8.9 ± 8.4 events/h) when compared to CPAP treatment (all P < 0.05). After 6 weeks we observed the following differences: AHI (16.5 ± 8 versus 7.4 ± 4.2 events/h, P = 0.027), AI (10.4 ± 5.9 versus 1.7 ± 1.9 events/h, P = 0.001), CAI (10.2 ± 5.1 versus 1.5 ± 1.7 events/h, P < 0.0001)) and ODI (21.1 ± 9.2 versus 4.8 ± 3.4 events/h, P < 0.0001) for NPPV and servoventilation, respectively. Other sleep parameters were unaffected by any form of treatment.

CONCLUSIONS

After 6 weeks, servoventilation treated respiratory events more effectively than NPPV in patients with complex sleep apnea syndrome.

Sleep-disordered breathing in patients with heart failure: new trends in therapy

Heart failure (HF) is a growing health problem which paradoxically results from the advances in the treatment of etiologically related diseases (especially coronary artery disease). HF is commonly accompanied by sleep-disordered breathing (SDB), which may directly exacerbate the clinical manifestations of cardiovascular disease and confers a poorer prognosis. Obstructive sleep apnoea predominates in mild forms while central sleep apnoea in more severe forms of heart failure. Identification of SDB in patients with HF is important, as its effective treatment may result in notable clinical benefits to the patients. Continuous positive airway pressure (CPAP) is the gold standard in the management of SDB. The treatments for central breathing disorders include CPAP, bilevel positive airway pressure (BPAP), and adaptive servoventilation (ASV), with the latter being the most modern method of treatment for the Cheyne-Stokes respiration and involving ventilation support with a variable synchronisation dependent on changes in airflow through the respiratory tract and on the patient's respiratory rate. ASV exerts the most favourable effect on long-term prognosis. In this paper, we review the current state of knowledge on the diagnosis and treatment of SDB with a particular emphasis on the latest methods of treatment.

Treatment of central sleep apnea in U.S. veterans

BACKGROUND

There are no standard therapies for the management of central sleep apnea (CSA). Either positive pressure therapy (PAP) or supplemental oxygen (O(2)) may stabilize respiration in CSA by reducing ventilatory chemoresponsiveness. Additionally, increasing opioid use and the presence of comorbid conditions in US veterans necessitates investigations into alternative titration protocols to treat CSA. The goal was to report on the effectiveness of titration with PAP, used alone or in conjunction with O(2), for the management of CSA associated with varying comorbidities and opioid use.

METHODS

This was a retrospective chart review over 3 years, performed at a VA sleep disorders center. The effects of CPAP, CPAP+O(2), and BPAP+O(2), used in a step-wise titration protocol, on consecutive patients diagnosed with CSA were studied.

RESULTS

CSA was diagnosed in 162 patients. The protocol was effective in eliminating CSA (CAI ≤ 5/h) in 84% of patients. CPAP was effective in 48%, while CPAP+O(2) combination was effective in an additional 25%, and BPAP+O(2) in 11%. The remaining 16% were non-responders. Forty-seven patients (29%) were on prescribed opioid therapy for chronic pain, in whom CPAP, CPAP+O(2), or BPAP+O(2) eliminated CSA in 54%, 28%, and 10% cases, respectively. CPAP, CPAP+O(2), and BPAP+O(2) each produced significant declines in the AHI, CAI, and arousal index, and an increase in the SpO(2).

CONCLUSION

The data demonstrate that using a titration protocol with CPAP and then PAP with O(2) effectively eliminates CSA in individuals with underlying comorbid conditions and prescription opioid use. Comparative studies with other therapeutic modalities are required.

Dynamic CO₂ inhalation: a novel treatment for CSR-CSA associated with CHF

BACKGROUND

Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) is very common in patients with chronic congestive heart failure (CHF). A current concept of the key pathophysiological mechanism leading to CSR-CSA is a fluctuation of PaCO2 below and above the apneic threshold. A number of therapeutic approaches for CSR-CSA have been proposed-all with varying success, some of which include various modes of positive airway pressure among other strategies. However, CO2 oscillations seen in CSR-CSA have yet to be looked at as a specific therapeutic target by current treatments.

DISCUSSION

Previous studies have shown that delivery of constant CO2 is efficacious in eliminating CSR-CSA by raising PaCO2, but there are serious concerns about the potential side effects, such as unwanted elevations in ventilation, work of breathing, and sympathetic nerve activity (SNA), and consequently CO2 inhalation therapy has not been recommended as a routine option for therapy. However, recent new studies into CO2 inhalation therapy have been made that may reshape its role as therapeutic. In this review, we will focus on the recent developments of administration of dynamic CO2 in the management of CSR-CSA in CHF patients.

The treatment of central sleep apnea syndromes in adults: practice parameters with an evidence-based literature review and meta-analyses

The International Classification of Sleep Disorders, Second Edition (ICSD-2) distinguishes 5 subtypes of central sleep apnea syndromes (CSAS) in adults. Review of the literature suggests that there are two basic mechanisms that trigger central respiratory events: (1) post-hyperventilation central apnea, which may be triggered by a variety of clinical conditions, and (2) central apnea secondary to hypoventilation, which has been described with opioid use. The preponderance of evidence on the treatment of CSAS supports the use of continuous positive airway pressure (CPAP). Much of the evidence comes from investigations on CSAS related to congestive heart failure (CHF), but other subtypes of CSAS appear to respond to CPAP as well. Limited evidence is available to support alternative therapies in CSAS subtypes. The recommendations for treatment of CSAS are summarized as follows: CPAP therapy targeted to normalize the apnea-hypopnea index (AHI) is indicated for the initial treatment of CSAS related to CHF. (STANDARD)Nocturnal oxygen therapy is indicated for the treatment of CSAS related to CHF. (STANDARD)Adaptive Servo-Ventilation (ASV) targeted to normalize the apnea-hypopnea index (AHI) is indicated for the treatment of CSAS related to CHF. (STANDARD)BPAP therapy in a spontaneous timed (ST) mode targeted to normalize the apnea-hypopnea index (AHI) may be considered for the treatment of CSAS related to CHF only if there is no response to adequate trials of CPAP, ASV, and oxygen therapies. (OPTION)The following therapies have limited supporting evidence but may be considered for the treatment of CSAS related to CHF after optimization of standard medical therapy, if PAP therapy is not tolerated, and if accompanied by close clinical follow-up: acetazolamide and theophylline. (OPTION)Positive airway pressure therapy may be considered for the treatment of primary CSAS. (OPTION)Acetazolamide has limited supporting evidence but may be considered for the treatment of primary CSAS. (OPTION)The use of zolpidem and triazolam may be considered for the treatment of primary CSAS only if the patient does not have underlying risk factors for respiratory depression. (OPTION)The following possible treatment options for CSAS related to end-stage renal disease may be considered: CPAP, supplemental oxygen, bicarbonate buffer use during dialysis, and nocturnal dialysis. (OPTION) .

Sleep apnea syndrome: central sleep apnea and pulmonary hypertension worsened during treatment with auto-CPAP, but improved by adaptive servo-ventilation

In this 71-year-old man diagnosed as obstructive sleep apnea syndrome initially, the apnea-hypopnea index in polysomnography was 31.3/hour. He started auto-adjusted continuous positive airway pressure (auto-CPAP) treatment in July 2005 but developed congestive heart failure in December 2007. Pulmonary arterial pressure (PAP), estimated by echocardiography, was 71 mmHg. In January 2008, during simplified sleep examination with a breath-movement sensor under auto-CPAP, many central-type apneas were recognized. After replacing auto-CPAP with adaptive servo-ventilation (ASV), the apnea-hypopnea index was 5.3/hour and PAP became 36 mmHg after 3 months. It was thought that the increase of PAP was due to long-term inadequate use of auto-CPAP.

Moving beyond empiric continuous positive airway pressure (CPAP) trials for central sleep apnea: a multi-modality titration study

There is no universally accepted method to determine effective therapy for central sleep apnea (CSA). Continuous positive airway pressure (CPAP) applied acutely most often does not eliminate apneas and hypopneas. We hypothesized that the application of two or more therapeutic modalities after the diagnostic phase of polysomnography, a multi-modality titration study (MMTS), would identify a successful CSA treatment more often than a standard split-night study (SNS) and obviate the need for additional polysomnograms to determine a successful therapy. We retrospectively analyzed polysomnograms of patients diagnosed with CSA at our Sleep Disorders Center. We defined a therapy trial that resulted in an apnea-hypopnea index < 10 with at least one treatment modality as a therapeutic success. One hundred fifteen patients with CSA were studied. Sixty-six patients (57.4%) underwent a SNS, and 49 patients (42.6%) underwent a MMTS. SNS yielded only 8/66 (12.1%) successes on the first night, whereas a MMTS yielded 19/49 (38.8%) successes (p = 0.001, two-tailed Fishers exact). Patients who underwent a SNS eventually had similar rate of success as patients studied with MMTS (60.6 vs 63.3%, NS), but required more testing. Adaptive servo-ventilation was the most successful modality tested, yielding 36/46 (78.3%) successes. Trials of additional modalities following a failed trial of CPAP often produce a successful option that may guide therapy in patients with CSA. This approach may lead to establishing the diagnosis and treatment plans faster, while reducing unnecessary testing.

Electroencephalographic arousals during sleep do not alter the pressor response to Cheyne-Stokes respiration in subjects with chronic heart failure

This study examined the influence of electroencephalographic (EEG) arousal on the magnitude and morphology of the pressor response to Cheyne-Stokes respiration (CSR) in subjects with congestive heart failure (CHF). Thirteen subjects with stable CHF (left ventricular ejection fraction, 26 +/- 7%) and CSR (apnea-hypopnea index 52 +/- 15 h(-1)) underwent overnight polysomnography with beat-to-beat measurement of systemic arterial blood pressure (BP). CSR events were divided into those with or without an EEG arousal defined according to the criteria of the American Sleep Disorders Association. The pressor response was quantified in terms of the delta BP change (difference between the minimum BP during apnea and maximum BP during hyperpnea). Changes in the morphology of the pressor response were assessed by subdividing individual respiratory events into six periods (three during apnea: A1, A2, A3; and three during hyperpnea: H1, H2, H3). Considerable fluctuations in BP and heart rate (HR) were observed across the CSR cycle (delta mean BP 20.2 +/- 6.5 mmHg). The presence of an EEG arousal did not alter the amplitude of fluctuations in BP. Mean blood pressure (MBP) increased 21.0 +/- 7.5 mmHg with arousal versus 19.3 +/- 5.8 mmHg without arousal (NS). A repeated measures ANOVA showed no significant interaction between the presence of arousal and the proportional change in mean BP across the six periods, indicating that an EEG arousal had no effect on the morphology of MBP change during CSR [F(5,60) = 1.44, P = 0.22]. This study showed that EEG-defined arousal does not amplify the pressor response to CSR in CHF.

Bi-level positive pressure ventilation and adaptive servo ventilation in patients with heart failure and Cheyne-Stokes respiration

OBJECTIVES

Nocturnal positive pressure ventilation (PPV) has been shown to be effective in patients with impaired left ventricular ejection fraction (LVEF) and Cheyne-Stokes respiration (CSR). We investigated the effect of a bi-level PPV and adaptive servo ventilation on LVEF, CSR, and quantitative sleep quality.

METHODS

Thirty-seven patients (New York heart association [NYHA] II-III) with LVEF<45% and CSR were investigated by electrocardiography (ECG), echocardiography and polysomnography. The CSR index (CSRI) was 32.3+/-16.2/h. Patients were randomly treated with bi-level PPV using the standard spontaneous/timed (S/T) mode or with adaptive servo ventilation mode (AutoSetCS). After 6 weeks, 30 patients underwent control investigations with ECG, echocardiography, and polysomnography.

RESULTS

The CSRI decreased significantly to 13.6+/-13.4/h. LVEF increased significantly after 6 weeks of ventilation (from 25.1+/-8.5 to 28.8+/-9.8%, p<0.01). The number of respiratory-related arousals decreased significantly. Other quantitative sleep parameters did not change. The Epworth sleepiness score improved slightly. Daytime blood pressure and heart rate did not change. There were some differences between bi-level PPV and adaptive servo ventilation: the CSRI decreased more in the AutoSetCS group while the LVEF increased more in the bi-level PPV group.

CONCLUSIONS

Administration of PPV can successfully attenuate CSA. Reduced CSA may be associated with improved LVEF; however, this may depend on the mode of PPV. Changed LVEF is evident even in the absence of significant changes in blood pressure.

Non-invasive positive ventilation in the treatment of sleep-related breathing disorders

This chapter addresses the use of long-term non-invasive positive pressure ventilation (NIPPV) (to the exclusion of continuous positive airway pressure) in the different clinical settings in which it is currently proposed: principally in diseases responsible for hypoventilation characterized by elevated PaCO(2). Nasal masks are predominantly used, followed by nasal pillow and facial masks. Mouthpieces are essentially indicated in case daytime ventilation is needed. Many clinicians currently prefer pressure-preset ventilator in assist mode as the first choice for the majority of the patients with the view of offering better synchronization. Nevertheless, assist-control mode with volume-preset ventilator is also efficient. The settings of the ventilator must insure adequate ventilation assessed by continuous nocturnal records of at least oxygen saturation of haemoglobin-measured by pulse oximetry. The main categories of relevant diseases include different types of neuromuscular disorders, chest-wall deformities and even lung diseases. Depending on the underlying diseases and on individual cases, two schematic situations may be individualized. Either intermittent positive pressure ventilation (IPPV) is continuously mandatory to avoid death in the case of complete or quasi-complete paralysis or is used every day for several hours, typically during sleep, producing enough improvement to allow free time during the daylight in spontaneous breathing while hypoventilation and related symptoms are improved. In case of complete or quasi-complete need of mechanical assistance, a tracheostomy may become an alternative to non-invasive access. In neuromuscular diseases, in kyphosis and in sequela of tuberculosis patients, NIPPV always significantly increases survival. Conversely, no data support a positive effect on survival in chronic obstructive pulmonary disease.

The significance and outcome of continuous positive airway pressure-related central sleep apnea during split-night sleep studies

OBJECTIVE

To determine whether central sleep apnea (CSA) occurring during continuous positive airway pressure (CPAP) titration in patients with obstructive sleep apnea (OSA) reflects subclinical congestive heart failure (CHF), and whether these events will improve with CPAP therapy.

DESIGN

Cross-sectional analysis of patients with suspected sleep-related breathing disorders referred for split-night polysomnography

PATIENTS AND METHODS

Forty-two OSA patients with and without CPAP-related CSA were analyzed. All CSA patients (n = 21) and control subjects (n = 21) underwent echocardiography, pulmonary function testing, and arterial blood gas (ABG) analysis. Repeat polysomnography with CPAP was performed 2 to 3 months after adequate CPAP therapy in CSA group patients.

RESULTS

Demographic, Epworth sleepiness scale, pulmonary function test, ABG, and baseline diagnostic polysomnography findings were similar in both groups. There was no difference in the prevalence of subclinical left ventricular systolic dysfunction in the CSA group vs the control group. CSA patients had decreased sleep efficiency (SE), increased sleep stage 1 percentage, sleep stages shift, wake time after sleep onset (WASO), and total arousals compared to control subjects. Twelve of 14 patients (92%) in the CSA group demonstrated complete or near-complete resolution of CSA events on follow-up polysomnography and showed improvement in SE, WASO, and total arousals compared to their baseline study.

CONCLUSIONS

CSA events occurring during CPAP titration are transient and self-limited. They may be precipitated by the sleep fragmentation associated with initial CPAP titration and are not associated with an increased prevalence of occult CHF compared to OSA patients without CPAP-related CSA.

Beneficial effect of bilevel positive airway pressure on left ventricular function in ambulatory patients with idiopathic dilated cardiomyopathy and central sleep apnea-hypopnea: a preliminary study

BACKGROUND

Sleep-disordered breathing is common in individuals with left ventricular (LV) dysfunction and has been treated with nocturnal positive airway pressure. We investigated whether treatment of central sleep apnea-hypopnea with bilevel positive airway pressure (BPAP) in ambulatory patients with idiopathic dilated cardiomyopathy (IDCM) might improve LV function.

METHODS

Fifty-two consecutive patients with IDCM who underwent both cardiac catheterization and standard polysomnography were enrolled in the study; individuals with obstructive sleep apnea syndrome were excluded. Subjects with an apnea-hypopnea index (AHI) >or= 20 episodes per hour were randomized to receive medical therapy either alone (n = 11) or together with BPAP (n = 10).

RESULTS

LV end-diastolic pressure, pulmonary capillary wedge pressure, and plasma concentration of brain natriuretic peptide were significantly greater, and LV ejection fraction (LVEF) was significantly lower in patients with an AHI >or= 20/h (n = 21, 40.4%) than in those with an AHI < 20/h (n = 31, 59.6%). LVEF (30.5 +/- 1.6% vs 50.8 +/- 3.5%, p < 0.001) [mean +/- SE] and plasma concentration of brain natriuretic peptide (162.8 +/- 44.5 pg/mL vs 32.7 +/- 17.6 pg/mL, p = 0.02) were significantly increased and decreased, respectively, after treatment with BPAP (daily use, 4.8 +/- 0.3 h) for 3 months, whereas these parameters remained unchanged in the control subjects.

CONCLUSIONS

Our findings suggest that treatment of coexisting central sleep apnea-hypopnea with BPAP improves LV function in ambulatory patients with IDCM. BPAP should thus be considered as a nonpharmacologic adjunct to conventional drug therapy in such patients.

"Optimal" application of ventilatory assist in Cheyne-Stokes respiration: a simulation study

Although a variety of ventilator therapies have been employed to treat Cheyne-Stokes respiration (CSR), these modalities do not completely eliminate CSR. As well, most current strategies require that ventilatory assist be provided continuously. We used a computer model of the respiratory control system to determine whether a ventilatory assist strategy could be found that would substantially reduce the severity of CSR while minimizing the application of positive airway pressure. We assessed the effects of different levels of ventilatory assist applied during breaths that fell below selected hypopneic thresholds. These could be applied during the descending, ascending, or both phases of the CSR cycle. We found that ventilatory augmentation equal to 30-40% of eupneic drive, applied whenever ventilation fell below 70% of the eupneic level during the ascending or descending-and-ascending phases of CSR led to the greatest regularization of breathing with minimal ventilator intervention. Application of ventilatory assist during the descending phase produced little effect.

Bilevel Positive Airway Pressure Worsens Central Apneas During Sleep

STUDY OBJECTIVES

While most patients with sleep-disordered breathing are treated with continuous positive airway pressure (CPAP), bilevel positive airway pressure (BLPAP) is often used. Having observed that BLPAP therapy increased central apneas in some of our patients undergoing sleep studies, we conducted this study to evaluate the effects of BLPAP.

DESIGN

Retrospective analysis of all sleep studies performed in an outpatient sleep center that used BLPAP over a 2-year period. We assessed the incidence and frequency of events during rapid eye movement (REM) sleep and non-REM sleep during baseline conditions, CPAP, and BLPAP. Desaturations, hypopneas, obstructive apneas, and central events, including periodic breathing (PB), Cheyne-Stokes respiration (CSR), and non-CSR central apneas were evaluated.

PATIENTS

Ninety-five of the 719 patients who underwent sleep studies met inclusion criteria. Eighty of the 95 patients treated with BLPAP were also treated with CPAP.

RESULTS

BLPAP was more likely to worsen than improve CSR (p = 0.002), non-CSR central apneas (p < 0.001), and CSR or PB (p < 0.001). CSR (p = 0.03) and non-CSR central apneas (p = 0.01) were more likely to worsen with BLPAP (24% and 23%, respectively) than with CPAP (11% and 8%). Central events (p = 0.04) and CSR (p = 0.009) were more likely to worsen during BLPAP in patients with baseline CSR or PB (62% and 48%, respectively) than develop in those without baseline CSR or PB (34% and 18%). Higher BLPAP differences worsened central events in 28% of patients, while 7% improved (p = 0.02). During REM sleep, central apneas improved, while hypopneas and obstructive apneas worsened (p < 0.001).

CONCLUSIONS

BLPAP often increases the frequency of CSR and non-CSR central apneas during sleep. Since CSR has adverse effects on cardiac function and sleep, it is important to consider this possible adverse effect of BLPAP.

Heart failure and sleep apnoea: to sleep perchance to dream

Heart failure and sleep apnoea are major health problems with an increasingly recognized association; evidence suggests that sleep apnoea may play a role in the progression of heart failure. However, confounding factors such as obesity, hypertension and coronary heart disease make this relationship uncertain and an independent correlation remains unproven. Diagnosis of sleep apnoea is suboptimal, as it is often asymptomatic and polysomnography is expensive and time-consuming. A simple and reliable screening protocol is required. All heart failure patients should be considered to be at high risk of sleep apnoea, as this association might be linked to adverse outcome. Continuous positive airway pressure has shown some beneficial effects, but long-term outcome and improvement in survival remains to be demonstrated. Despite recent advances in the understanding of the complex relationship between heart failure and sleep apnoea, there are a number of areas requiring further investigation, which may have important implications for the management and prognosis of a significant number of patients.

Efficacy of nasal bi-level positive airway pressure in congestive heart failure patients with cheyne-stokes respiration and central sleep apnea

BACKGROUND

Cheyne - Stokes respiration with central sleep apnea (CSR-CSA) contributes to the poor prognosis in patients with congestive heart failure (CHF). Bi-level positive airway pressure (bi-level PAP) may be an effective alternative for treating CSR-CSA and CHF.

METHODS AND RESULTS

Fourteen patients with CSR-CSA were divided into 2 groups, a control group that included 7 patients who decided to receive only conventional medications and a group of 7 patients that received bi-level PAP. Left ventricular ejection fraction (LVEF), mitral regurgitation (MR) area, plasma brain natriuretic peptide (BNP) concentration and the New York Heart Association (NYHA) functional class were evaluated initially (baseline) and 3 months later. In the control group, there were no significant changes in cardiac function during the study period. In contrast, in the group that received bi-level PAP, there were significant improvements in LVEF (from 36.3+/-2.9% to 46.0+/-4.0%, p = 0.02), MR area (from 30.4+/-7.6% to 20.0+/-5.1%, p = 0.02), BNP (from 993.6+/-332.0 pg/ml to 474.0+/-257.6 pg/ml, p = 0.02) and NYHA functional class (from 3.1+/-0.1 to 2.1+/-0.1, p = 0.03).

CONCLUSION

Treatment with bi-level PAP improved cardiac functions in CHF patients with CSR-CSA.

Sleep disruption in critically ill patients--pharmacological considerations

Sleep disturbances are common in critically ill patients and contribute to morbidity. Environmental factors, patient care activities and acute illness are all potential causes of disrupted sleep. Additionally, it is important to consider drug therapy as a contributing factor to this adverse experience, which patients perceive as particularly stressful. Sedative and analgesic combinations used to facilitate mechanical ventilation are among the most sleep disruptive drugs. Cardiovascular, gastric protection, anti-asthma, anti-infective, antidepressant and anticonvulsant drugs have also been reported to cause a variety of sleep disorders. Withdrawal reactions to prescribed and occasionally recreational drugs should also be considered as possible triggers for sleep disruption. Tricyclic antidepressants and benzodiazepines are commonly prescribed in the treatment of sleep disorders, but have problems with decreasing slow wave and rapid eye movement sleep phases. Newer non-benzodiazepine hypnotics offer little practical advantage. Melatonin and atypical antipsychotics require further investigation before their routine use can be recommended.

Improvement of Cheyne-Stokes Respiration, Central Sleep Apnea and Congestive Heart Failure by Noninvasive Bilevel Positive Pressure and Medical Treatment

A 57-year-old man was admitted with dyspnea. Clinical evaluation revealed atrial fibrillation and congestive heart failure (CHF). Standard medical therapy of CHF failed to completely improve the dyspnea and polysomnography revealed Cheyne-Stokes respiration with central sleep apnea (CSR-CSA). He was equipped with noninvasive positive pressure ventilation (NPPV) with bilevel positive airway pressure (BiPAP). The combined therapy of medical treatment of the CHF and administration of NPPV with BiPAP reduced the CSR-CSA. This regimen resulted in marked improvement of cardiac function, evaluated by echocardiography, and reduction of plasma concentration of brain natriuretic peptide. After the patient recovered from CHF and was discharged from hospital, he continued to use NPPV with BiPAP at home. In patients with CHF, it is important to be aware of sleep-related breathing disorders because treatment will not only improve the hypoxemia, but also the cardiac dysfunction.

Sleep-disordered breathing in heart failure

Sleep-related breathing disorders are common in heart failure patients and can have significant adverse impact on clinical outcomes. If sleep-disordered breathing or considerable daytime sleepiness exists, assessment and treatment recommendations include the following: 1) carefully assess and correct hemodynamic status; heart failure exacerbations can induce central sleep apneas; 2) if overweight, encourage patient weight loss; 3) elevate head of bed; 4) discourage sleeping on back; 5) order polysomnography, to assess type and extent of sleep-related breathing disorder; and 6) treat sleep-disordered breathing with nasal continuous positive airway pressure or bilevel positive airway pressure.

A comparative study of a new wireless continuous cardiorespiratory monitor for the diagnosis and management of patients with congestive heart failure at home

Congestive heart failure (CHF) is a major and increasing chronic disease in Western society, with a high mortality, morbidity and cost for unplanned hospital admissions. Continuous cardiorespiratory monitoring is required to detect Cheyne-Stokes respiration (CSR). We have tested a new wireless monitoring system and compared it with polysomnography (PSG) and respiratory inductance plethysmography (RIP) in six CHF patients with CSR in a sleep laboratory. The wireless system compared well with RIP for the detection of CSR but less well with PSG, which had unexpected but significant respiratory sensing errors that led to misclassification of the respiratory disorder present. The wireless system could be used to select CHF patients for better-customized treatment at home as part of a specialist-supported community telemedicine programme.

Management of the hospitalized patient with sleep disordered breathing

Sleep disordered breathing (SDB) frequently comes to medical attention for the first time when patients are hospitalized for diagnosis and treatment of an associated condition (eg, poorly controlled hypertension, myocardial infarction, congestive heart failure, stroke, or problems related to management of diabetes mellitus). Diagnosis of SDB is generally performed in a specialized facility, which is often inconvenient and expensive for the hospitalized patient. Expectant perioperative management of patients with sleep apnea is critical, particularly if they are previously undiagnosed. An ideal diagnostic strategy for these patients has not been defined. Continuous positive airway pressure (CPAP) is the mainstay of treatment of patients with sleep apnea. Unfortunately, it is often difficult for very ill patients to tolerate CPAP, unless it is administered with a high level of expertise.