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Central sleep apnoea is a serious breathing disorder associated with poor outcomes. The remedé system (Respicardia Inc, Minnetonka, MN, USA) is an implantable device which transvenously stimulates a nerve causing diaphragmatic contraction similar to normal breathing. We evaluated the safety and effectiveness of unilateral neurostimulation in patients with central sleep apnoea. We recruited patients from 31 hospital-based centres in Germany, Poland, and the USA in this prospective, multicentre, randomised trial. Participants had to have been medically stable for at least 30 days and have received appropriate guideline recommended therapy, be aged at least 18 years, be expected to tolerate study procedures, and willing and able to comply with study requirements. Eligible patients with an apnoea-hypopnoea index (AHI) of at least 20 events per h, tested by a polysomnography, underwent device implantation and were randomly assigned (1:1) by a computer-generated method stratified by site to either stimulation (treatment) or no stimulation (control) for 6 months. The primary effectiveness endpoint in the intention-to-treat population was the comparison of the proportions of patients in the treatment versus control groups achieving a 50% or greater AHI reduction from baseline to 6 months, measured by a full-night polysomnography assessed by masked investigators in a core laboratory. The primary safety endpoint of 12-month freedom from serious adverse events related to the procedure, system, or therapy was evaluated in all patients. This trial is active, but not recruiting, and is registered with ClinicalTrials.gov (NCT01816776). Between April 17, 2013, and May 28, 2015, we randomly assigned 151 eligible patients to the treatment (n=73) or control (n=78) groups. In the analysis of the intention-to-treat population, significantly more patients in the treatment group (35 [51%] of 68) had an AHI reduction from baseline of 50% or greater at 6 months than had those in the control group (eight [11%] of 73; difference between groups 41%, 95% CI 25–54, p<0·0001). 138 (91%) of 151 patients had no serious-related adverse events at 12 months. Seven (9%) cases of related-serious adverse events occurred in the control group and six (8%) cases were reported in the treatment group. Seven patients died (unrelated to implant, system, or therapy), four deaths (two in treatment group and two in control group) during the 6-month randomisation period when neurostimulation was delivered to only the treatment group and was off in the control group, and three deaths between 6 months and 12 months of follow-up when all patients received neurostimulation. 27 (37%) of 73 patients in the treatment group reported non-serious therapy-related discomfort that was resolved with simple system reprogramming in 26 (36%) patients, but was unresolved in one (1%) patient. Transvenous neurostimulation significantly reduced the severity of central sleep apnoea, including improvements in sleep metrics, and was well tolerated. The clinically meaningful effects of the therapy are supported by the concordant improvements in oxygenation and quality of life, making transvenous neurostimulation a promising therapeutic approach for central sleep apnoea. Respicardia Inc.

To evaluate long-term efficacy and safety of phrenic nerve stimulation (PNS) in patients with moderate-to-severe central sleep apnea (CSA) through 3 years of therapy. Patients in the remedē System Pivotal Trial were observed every 3 months after implant until US Food and Drug Administration approval. At the time of approval and study closure, all patients completed 24 months of follow-up; 33 patients had not reached the 36-month visit. Sleep metrics (polysomnography) and echocardiographic parameters are reported at baseline, 12, 18, and 24 months, in addition to available 36-month sleep results from polygraphy. Safety was assessed through 36 months; however, analysis focused through 24 months and available 36-month results are provided. Patients were assessed at 24 (n = 109) and 36 (n = 60) months. Baseline characteristics included mean age 64 years, 91% male, and mean apnea-hypopnea index 47 events per hour. Sleep metrics (apnea-hypopnea index (AHI), central apnea index, arousal index, oxygen desaturation index, rapid eye movement sleep) remained improved through 24 and 36 months with continuous use of PNS therapy. At least 60% of patients in the treatment group achieved at least 50% reduction in AHI through 24 months. Serious adverse events (SAEs) related to the remedē System implant procedure, device, or therapy through 24 months were reported by 10% of patients, no unanticipated adverse device effects or deaths, and all events resolved. No additional related SAEs were reported between 24 and 36 months. These data suggest beneficial effects of long-term PNS in patients with CSA appear to sustain through 36 months with no new safety concerns. NCT01816776.

Transvenous phrenic nerve stimulation improved sleep metrics and quality of life after 6 months versus control in the remedē System Pivotal Trial. This analysis explored the effectiveness of phrenic nerve stimulation in patients with central sleep apnea after 12 months of therapy. Reproducibility of treatment effect was assessed in the former control group in whom the implanted device was initially inactive for the sixth month and subsequently activated when the randomized control assessments were complete. Patients with moderate-to-severe central sleep apnea implanted with the remedē System were randomized to therapy activation at 1 month (treatment) or after 6 months (control). Sleep indices were assessed from baseline to 12 months in the treatment group and from 6 to 12 months in former controls. In the treatment group, a ≥50% reduction in apnea-hypopnea index occurred in 60% of patients at 6 months (95% confidence interval [CI] 47% to 64%) and 67% (95% CI 53% to 78%) at 12 months. After 6 months of therapy, 55% of former controls (95% CI 43% to 67%) achieved ≥50%reduction in apnea-hypopnea index. Patient Global Assessment was markedly ormoderately improved at 6 and 12 months in 60% of treatment patients.Improvements persisted at 12 months. A serious adverse event within 12 months occurred in 13 patients (9%). Phrenic nerve stimulation produced sustained improvements in sleep indices and quality of life to at least 12 months in patients with central sleep apnea. The similar improvement of former controls after 6 months of active therapy confirms benefits are reproducible and reliable.

The remedē System Pivotal Trial was a prospective, multi-center, randomized trial demonstrating transvenous phrenic nerve stimulation (TPNS) therapy is safe and effectively treats central sleep apnea (CSA) and improves sleep architecture and daytime sleepiness. Subsequently, the remedē System was approved by FDA in 2017. As a condition of approval, the Post Approval Study (PAS) collected clinical evidence regarding long-term safety and effectiveness in adults with moderate to severe CSA through five years post implant. Patients remaining in the Pivotal Trial at the time of FDA approval were invited to enroll in the PAS and consented to undergo sleep studies (scored by a central laboratory), complete the Epworth Sleepiness Scale (ESS) questionnaire to assess daytime sleepiness, and safety assessment. All subjects (treatment and former control group) receiving active therapy were pooled; data from both trials were combined for analysis. Fifty-three of the original 151 Pivotal Trial patients consented to participate in the PAS and 52 completed the 5-year visit. Following TPNS therapy, the apnea-hypopnea index (AHI), central-apnea index (CAI), arousal index, oxygen desaturation index, and sleep architecture showed sustained improvements. Comparing 5 years to baseline, AHI and CAI decreased significantly (AHI baseline median 46 events/hour vs 17 at 5 years; CAI baseline median 23 events/hour vs 1 at 5 years), though residual hypopneas were present. In parallel, the arousal index, oxygen desaturation index and sleep architecture improved. The ESS improved by a statistically significant median reduction of 3 points at 5 years. Serious adverse events related to implant procedure, device or delivered therapy were reported by 14% of patients which include 16 (9%) patients who underwent a pulse generator reposition or lead revision (primarily in the first year). None of the events caused long-term harm. No unanticipated adverse device effects or related deaths occurred through 5 years. Long-term TPNS safely improves CSA, sleep architecture and daytime sleepiness through 5 years post implant. ClinicalTrials.gov Identifier: NCT01816776.

Obstructive sleep apnea (OSA) is highly prevalent among patients with asymptomatic left ventricular systolic and diastolic dysfunction and congestive heart failure, and if untreated may contribute to the clinical progression of heart failure (HF). Given the health and economic burden of HF, identifying potential modifiable risk factors such as OSA and whether appropriate treatment improves outcomes is of critical importance. Identifying the subgroups of patients with OSA and HF who would benefit most from OSA treatment is another important point. This focused review surveys current knowledge of OSA and HF in order to provide: (1) a better understanding of the pathophysiologic mechanisms that may increase morbidity among individuals with HF and comorbid OSA, (2) a summary of current observational data and small randomized trials, (3) an understanding of the limitations of current larger randomized controlled trials, and (4) future needs to more accurately determine the efficacy of OSA treatment among individuals with HF.

Abstract Central sleep apnea is not a single disorder; it can present as an isolated disorder or as a part of other clinical syndromes. In some conditions, such as heart failure, central apneic events are due to transient inhibition of ventilatory motor output during sleep, owing to the overlapping influences of sleep and hypocapnia. Specifically, the sleep state is associated with removal of wakefulness drive to breathe; thus, rendering ventilatory motor output dependent on the metabolic ventilatory control system, principally PaCO2. Accordingly, central apnea occurs when PaCO2 is reduced below the “apneic threshold”. Our understanding of the pathophysiology of central sleep apnea has evolved appreciably over the past decade; accordingly, in disorders such as heart failure, central apnea is viewed as a form of breathing instability, manifesting as recurrent cycles of apnea/hypopnea, alternating with hyperpnea. In other words, ventilatory control operates as a negative—feedback closed-loop system to maintain homeostasis of blood gas tensions within a relatively narrow physiologic range, principally PaCO2. Therefore, many authors have adopted the engineering concept of “loop gain” (LG) as a measure of ventilatory instability and susceptibility to central apnea. Increased LG promotes breathing instabilities in a number of medical disorders. In some other conditions, such as with use of opioids, central apnea occurs due to inhibition of rhythm generation within the brainstem. This review will address the pathogenesis, pathophysiologic classification, and the multitude of clinical conditions that are associated with central apnea, and highlight areas of uncertainty.

Acetazolamide is a mild diuretic and a respiratory stimulant. It is used to treat periodic breathing at high altitude. To determine the therapeutic efficacy of acetazolamide on central sleep apnea associated with heart failure. Twelve male patients with stable systolic heart failure whose initial polysomnograms showed more than 15 episodes per hour of apnea and hypopnea participated in the study. The patients were randomized to a double-blind cross-over protocol with acetazolamide or placebo, taken 1 h before bedtime for six nights with 2 wk of washout. Polysomnography, pulmonary function tests, arterial blood gases, and left ventricular ejection fraction were obtained initially along with a sleep questionnaire, history, and physical examination. Baseline measurements were repeated at the end of each arm. There were no significant differences between parameters at baseline and placebo. In comparing placebo with acetazolamide, the hourly number of episodes of central apnea (49 +/- 28 vs. 23 +/- 21 [mean +/- SD]; p = 0.004) and the percentage of total sleep time spent below an arterial oxyhemoglobin saturation of 90% (19 +/- 32 vs. 6 +/- 13%; p = 0.01) decreased significantly. Acetazolamide improved subjective perception of overall sleep quality (p = 0.003), feeling rested on awakening (p = 0.007), daytime fatigue (p = 0.02), and falling asleep unintentionally during daytime (p = 0.002). In patients with heart failure, administration of a single dose of acetazolamide before sleep improves central sleep apnea and related daytime symptoms.

Normally, the rate and depth of breathing are regulated by a negative-feedback system that maintains the partial pressure of arterial carbon dioxide within a narrow range throughout life. Changes in the partial pressure of carbon dioxide lead to changes in ventilation, so that the greater the sensitivity to carbon dioxide, the greater the ventilatory response. Among normal persons there is considerable variation in sensitivity to carbon dioxide, which may in part be related to familial (genetic) influences. 1 – 4 In a study of patients with chronic obstructive pulmonary disease, Mountain and associates 1 found that diminished sensitivity to carbon dioxide, which presumably . . .

Abstract Medication-induced central sleep apnea (CSA) is one of the eight categories of causes of CSA but in the absence of awareness and careful history may be misclassified as primary CSA. While opioids are a well-known cause of respiratory depression and CSA, non-opioid medications including sodium oxybate, baclofen, valproic acid, gabapentin, and ticagrelor are less well-recognized. Opioids-induced respiratory depression and CSA are mediated primarily by µ-opioid receptors, which are abundant in the pontomedullary centers involved in breathing. The non-opioid medications, sodium oxybate, baclofen, valproic acid, and gabapentin, act upon brainstem gamma-aminobutyric acid (GABA) receptors, which co-colonize with µ-opioid receptors and mediate CSA. The pattern of ataxic breathing associated with these medications is like that induced by opioids on polysomnogram. Finally, ticagrelor also causes periodic breathing and CSA by increasing central chemosensitivity and ventilatory response to carbon dioxide. Given the potential consequences of CSA and the association between some of these medications with mortality, it is critical to recognize these adverse drug reactions, particularly because discontinuation of the offending agents has been shown to eliminate CSA.

Purpose of Review Central sleep apnea (CSA) is associated with increased mortality, particularly in heart failure. This review discusses current treatment options with a focus on different positive airway pressure (PAP) modalities, the clinical implication of continuous PAP (CPAP) failure, and key advancements in adaptive servo-ventilation (ASV). Recent Findings CPAP reduces CSA by about 50% in patients with heart failure with reduced ejection fraction. The remaining patients are considered non-responsive and chronic use of CPAP has been associated with excess mortality. ASV is effective in several forms of CSA. While secondary analyses of the SERVE-HF trial limited its use in patients with predominant CSA and left ventricular ejection fraction < 45%, more recent data from ADVENT-HF using a newer ASV generation targeting peak flow has shown promising results. Summary Physicians should consider the underlying pathophysiology, overall prognosis, and evidence base prior to selecting CSA treatment with CPAP or ASV. Promising pharmaceutical and novel device options require more studies and long-term evidence.