CON: Persistent Central Sleep Apnea/Hunter-Cheyne-Stokes Breathing, Despite Best Guideline-Based Therapy of Heart Failure With Reduced Ejection Fraction, Is Not a Compensatory Mechanism and Should Be Suppressed

Transvenous Phrenic Nerve Stimulation for Central Sleep Apnea: Clinical and Billing Review

Central sleep apnea (CSA) frequently coexists with heart failure and atrial fibrillation and contributes to cardiovascular disease progression and mortality. A transvenous phrenic nerve stimulation (TPNS) system has been approved for the first time by the Food and Drug Administration for the treatment of CSA. This system, remedē® ZOLL Medical, Inc. is implanted during a minimally invasive outpatient procedure, and has shown a favorable safety and efficacy profile. Currently, patients' access to this therapy remains limited by the small number of specialized centers in the US and the absence of a standard coverage process by insurers. While a period of evaluation by insurers is expected for new therapies in their early stages, the impact on patients is particularly severe given the already limited treatment options for CSA. Implantation and management of this novel therapy requires the establishment of a specialized multidisciplinary program as part of a Sleep Medicine practice and support from health care systems and hospitals. Several centers in the US have been successful in building sustainable TPNS program offering this novel therapy to their patients by navigating the current reimbursement environment. In this article, we will review the background and efficacy data of TPNS and briefly address relevant aspects of the clinical activities involved in a TPNS program. The article will present the status of coverage and reimbursement for this novel therapy. We will also discuss the current approach to obtaining reimbursement from third party payors during this transitional period of evaluation by Medicare and other insurers.

Algorithm for automatic detection of self-similarity and prediction of residual central respiratory events during continuous positive airway pressure

Study Objectives

Sleep-disordered breathing is a significant risk factor for cardiometabolic and neurodegenerative diseases. High loop gain (HLG) is a driving mechanism of central sleep apnea or periodic breathing. This study presents a computational approach that identifies “expressed/manifest” HLG via a cyclical self-similarity feature in effort-based respiration signals.

Methods

Working under the assumption that HLG increases the risk of residual central respiratory events during continuous positive airway pressure (CPAP), the full night similarity, computed during diagnostic non-CPAP polysomnography (PSG), was used to predict residual central events during CPAP (REC), which we defined as central apnea index (CAI) higher than 10. Central apnea labels are obtained both from manual scoring by sleep technologists and from an automated algorithm developed for this study. The Massachusetts General Hospital sleep database was used, including 2466 PSG pairs of diagnostic and CPAP titration PSG recordings.

Results

Diagnostic CAI based on technologist labels predicted REC with an area under the curve (AUC) of 0.82 ± 0.03. Based on automatically generated labels, the combination of full night similarity and automatically generated CAI resulted in an AUC of 0.85 ± 0.02. A subanalysis was performed on a population with technologist-labeled diagnostic CAI higher than 5. Full night similarity predicted REC with an AUC of 0.57 ± 0.07 for manual and 0.65 ± 0.06 for automated labels.

Conclusions

The proposed self-similarity feature, as a surrogate estimate of expressed respiratory HLG and computed from easily accessible effort signals, can detect periodic breathing regardless of admixed obstructive features such as flow limitation and can aid the prediction of REC.

Patterns of adaptive servo-ventilation settings in a real-life multicenter study: pay attention to volume! : Adaptive servo-ventilation settings in real-life conditions

Backgrounds

To explain the excess cardiovascular mortality observed in the SERVE-HF study, it was hypothesized that the high-pressure ASV default settings used lead to inappropriate ventilation, cascading negative consequences (i.e. not only pro-arrythmogenic effects through metabolic/electrolyte abnormalities, but also lower cardiac output). The aims of this study are: i) to describe ASV-settings for long-term ASV-populations in real-life conditions; ii) to describe the associated minute-ventilations (MV) and therapeutic pressures for servo-controlled-flow versus servo-controlled-volume devices (ASV-F Philips®-devices versus ASV-V ResMed®-devices).

Methods

The OTRLASV-study is a cross-sectional, 5-centre study including patients who underwent ASV-treatment for at least 1 year. The eight participating clinicians were free to adjust ASV settings, which were compared among i) initial diagnosed sleep-disordered-breathing (SBD) groups (Obstructive-Sleep-Apnea (OSA), Central-Sleep-Apnea (CSA), Treatment-Emergent-Central-Sleep-Apnea (TECSA)), and ii) unsupervised groups (k-means clusters). To generate these clusters, baseline and follow-up variables were used (age, sex, body mass index (BMI), initial diagnosed Obstructive-Apnea-Index, initial diagnosed Central-Apnea-Index, Continuous-Positive-Airway-Pressure used before ASV treatment, presence of cardiopathy, and presence of a reduced left-ventricular-ejection-fraction (LVEF)). ASV-data were collected using the manufacturer’s software for 6 months.

Results

One hundred seventy-seven patients (87.57% male) were analysed with a median (IQ_25–75) initial Apnea-Hypopnea-Index of 50 (38–62)/h, an ASV-treatment duration of 2.88 (1.76–4.96) years, 61.58% treated with an ASV-V. SDB groups did not differ in ASV settings, MV or therapeutic pressures. In contrast, the five generated k-means clusters did (generally described as follows: (C1) male-TECSA-cardiopathy, (C2) male-mostly-CSA-cardiopathy, (C3) male-mostly-TECSA-no cardiopathy, (C4) female-mostly-elevated BMI-TECSA-cardiopathy, (C5) male-mostly-OSA-low-LVEF). Of note, the male-mostly-OSA-low-LVEF-cluster-5 had significantly lower fixed end-expiratory-airway-pressure (EPAP) settings versus C1 (p = 0.029) and C4 (p = 0.007). Auto-EPAP usage was higher in the male-mostly-TECSA-no cardiopathy-cluster-3 versus C1 (p = 0.006) and C2 (p < 0.001). MV differences between ASV-F (p = 0.002) and ASV-V (p < 0.001) were not homogenously distributed across clusters, suggesting specific cluster and ASV-algorithm interactions. Individual ASV-data suggest that the hyperventilation risk is not related to the cluster nor the ASV-monitoring type.

Conclusions

Real-life ASV settings are associated with combinations of baseline and follow-up variables wherein cardiological variables remain clinically meaningful. At the patient level, a hyperventilation risk exists regardless of cluster or ASV-monitoring type, spotlighting a future role of MV-telemonitoring in the interest of patient-safety.

Trial registration

The OTRLASV study was registered on ClinicalTrials.gov (Identifier: NCT02429986). 1 April 2015.

Improving Nocturnal Hypoxemic Burden with Transvenous Phrenic Nerve Stimulation for the Treatment of Central Sleep Apnea

Nocturnal hypoxemic burden is established as a robust prognostic metric of sleep-disordered breathing (SDB) to predict mortality and treating hypoxemic burden may improve prognosis. The aim of this study was to evaluate improvements in nocturnal hypoxemic burden using transvenous phrenic nerve stimulation (TPNS) to treat patients with central sleep apnea (CSA). The remedē System Pivotal Trial population was examined for nocturnal hypoxemic burden. The minutes of sleep with oxygen saturation < 90% significantly improved in Treatment compared with control (p < .001), with the median improving from 33 min at baseline to 14 min at 6 months. Statistically significant improvements were also observed for average oxygen saturation and lowest oxygen saturation. Hypoxemic burden has been demonstrated to be more predictive for mortality than apnea–hypopnea index (AHI) and should be considered a key metric for therapies used to treat CSA. Transvenous phrenic nerve stimulation is capable of delivering meaningful improvements in nocturnal hypoxemic burden. There is increasing interest in endpoints other than apnea–hypopnea index in sleep-disordered breathing. Nocturnal hypoxemia burden may be more predictive for mortality than apnea–hypopnea index in patients with poor cardiac function. Transvenous phrenic nerve stimulation is capable of improving nocturnal hypoxemic burden.

In patients with heart failure the burden of central sleep apnea increases in the late sleep hours

Study Objectives

Periodic breathing with central sleep apnea (CSA) is common in patients with left ventricular systolic dysfunction. Based on the pathophysiological mechanisms underlying CSA, we hypothesized that the frequency of CSA episodes would increase in the late hours of non-rapid eye movement (NREM) of sleep.

Methods

Forty-one patients with left ventricular ejection fraction <40% underwent full-night-attended polysomnography scored by a central core lab. Because central apneas occur primarily in NREM sleep, total NREM sleep time for each patient was divided into 8 equal duration segments. Segment event counts were normalized to an events/hour index based on sleep segment duration.

Results

Central apnea index (CAI) varied among sleep segments (p = 0.001). As expected CAI was higher in segment 1 compared to segments 2 and 3, increasing during later segments. The minimum CAI occurred in segment 2 with mean ± SD of 21 ± 3 events/hour and maximum CAI was in segment 8 with 37 ± 4 events/hour. We also determined central apnea duration which varied among segments (p = 0.005), with longer durations later in the night (segment 1: 22 ± 1 seconds; segment 8: 26 ± 1 seconds, p < 0.001). Data were also analyzed including rapid eye movement (REM) sleep, with similar results. Further, comparison of CAI between the first and second half of the night showed a significant increase in the index. Circulation time did not change across the segments (p = 0.073).

Conclusions

In patients with left ventricular dysfunction and CSA, central apnea burden (number and duration) increases during later hours of sleep. These findings have pathophysiological and therapeutic implications.

Clinical Trial Registration

NCT01124370.

Redesigning Care for OSA

Constrained by a limited supply of specialized personnel, health systems face a challenge in caring for the large number of patients with OSA. The complexity of this challenge is heightened by the varied clinical presentations of OSA and the diversity of treatment approaches. Innovations such as simplified home-based care models and the incorporation of nonspecialist providers have shown promise in the management of uncomplicated patients, producing comparable outcomes to the resource-intensive traditional approach. However, it is unclear if these innovations can meet the needs of all patients with OSA, including those with mild disease, atypical presentations, and certain comorbid medical and mental health conditions. This review discusses the diversity of needs in OSA care, the evidence base behind recent care innovations, and the potential limitations of each innovation in meeting the diversity of care needs. We propose how these innovations can fit within the stepped care and hub and spoke models in a way that addresses the full spectrum of OSA, and we discuss future research directions to assess the deployment of these innovations.

[Central sleep apnea in patients with chronic heart failure]

Cheyne-Stokes respiration (CSR) is a form of sleep-disordered breathing seen in approximately half of patients with chronic heart failure and low left ventricular ejection fraction. The authors describe clinical features of CSR, mortality rate, treatment variants. Effects of continuous positive airway pressure (CPAP), bi-level ventilation, adaptive servoventilation (ASV) in patients with CSR and chronic heart failure are discussed. Diuretic acetazolamide is one more therapeutic option for CSR. It improves central sleep apnea and related daytime symptoms in patients with heart failure.

Death in patients with adaptive servo-ventilation for sleep apnea and no specific SERVE-HF profile: A case series study

Purpose

The SERVE-HF study reported a risk of cardiovascular death associated with adaptive servo-ventilation (ASV) for central sleep apnea in patients with chronic heart failure with reduced left ventricular ejection fraction (LVEF). Therefore, we adopted in May 2015 a safety procedure in our 32 patients with ASV since 2006. It led to ASV removal in four patients due to ≤45% LVEF. At the end of the procedure we noted eight cases of death. This high 25% mortality rate led us to study these cases.

Methods

The study population was derived from our database of patient follow-up from the sleep unit of our cardiovascular department.

Results

All deceased patients but one had cardiac disorders but only one matched the SERVE-HF patient profile. ASV was due to predominant central (n = 4) or mixed (n = 4) sleep apnea. Six patients died prior to our procedure including two patients who died several months after ASV cessation, one from ventricular fibrillation and one from respiratory infection. The cases with ongoing ASV consisted in one case of end-stage heart failure with asystole, two cases of cancer and one case of suicide. Two patients died after their safety procedure with no contra-indications to ASV and before study completion in all the patients, one from cancer and one from pulmonary and renal disorders.

Conclusions

In this series, no relationship became apparent between sleep apnea or ASV and death. Cardiovascular deaths were not predominant. Further study will be required to clarify the risks associated with ASV in patients with cardiovascular disease.

Is dynamic desaturation better than a static index to quantify the mortality risk in heart failure patients with Cheyne-Stokes respiration?

Cheyne-Stokes respiration (CSR) is a periodic, highly dynamic, respiratory pattern and a known comorbidity in congestive heart failure (CHF) patients. It is generally seen as an indicator for a negative prognosis, even if no distinction in degree is known or understood. This paper aims to improve on existing attempts by creating a quantification of the behavior of the dynamic desaturation process of oxygen in the blood. We performed this work on a cohort of 11 subjects with CHF, reduced left ventricular ejection fraction, and CSR. The dynamic desaturation process was evaluated according to changes to peripheral capillary oxygenation S p O 2 resulting from highly nonlinear relationships in the ventilatory system perturbed by periodic breathing. Hypoxaemic burden expressed as a static index T 90 was compared to a novel relative desaturation index R D I , developed in this paper. While T 90 represents a single value calculated using a static cut-off value of 90 % S p O 2 , the R D I is more sensitive to dynamic influences as it uses the specific maximum change in saturation for each CSR episode. The threshold of T 90 = 22 min per night as suggested by Oldenburg et al. could not be confirmed to predict survival, but all central apneas resulting in a relative desaturation of S p O 2 above a cut-off value of 8 % were a 100 % positive predictor of mortality. The R D I proved sufficiently stable in intraindividual measurements across CSR epochs. Across the cohort, it showed a bimodal distribution for the deceased group, indicative of a possible aetiological difference. Hence, it is our conclusion that a dynamic approach to analyse desaturation of oxygen during Cheyne-Stokes respiration is to be strongly favoured over a static approach to analysis.