Uncovering Hidden Dangers: Central Sleep Apnea Risk Revealed in HSAT Testing

By Dr. Chelsie Rohrscheib, Ph.D. Neuroscientist and Head Sleep Expert, Wesper
August 8, 2024

Hypoglossal Nerve Stimulation (HGNS) has emerged as a promising therapeutic avenue for individuals grappling with moderate to severe obstructive sleep apnea (OSA). This condition, characterized by repeated episodes of partial or complete obstruction of the upper airway during sleep, poses significant health risks if left untreated. HGNS offers a novel approach by electrically stimulating the hypoglossal nerve to maintain airway patency during sleep, providing an alternative for patients who do not respond well to conventional treatments such as continuous positive airway pressure (CPAP). Despite the growing utilization of HGNS, concerns linger regarding the potential emergence of treatment-induced central sleep apnea (TE-CSA), a complication observed in various OSA interventions. TE-CSA involves the development of central apneas, where the brain fails to send the proper signals to the muscles that control breathing, following the initiation of a sleep apnea treatment.

The precise incidence of TE-CSA in HGNS-treated patients remains elusive due to methodological constraints in assessment. Traditional polysomnography, while comprehensive, may not capture the nuanced changes in respiratory patterns that occur during HGNS titration. This study aimed to bridge this knowledge gap by meticulously investigating the rate of TE-CSA in patients undergoing HGNS titration, leveraging frequent home sleep apnea testing (HSAT) to capture these changes in a real-world setting. By employing a strategic protocol that included regular HSAT monitoring following each adjustment in stimulation amplitude, this research provides critical insights into the prevalence of TE-CSA and highlights the importance of tailored intervention strategies to optimize treatment outcomes in OSA management.

To achieve this, researchers conducted a prospective study involving 43 adults undergoing HGNS implant titration at a sleep clinic. Patients underwent HSATs after each increase in stimulation amplitude, allowing for real-time evaluation of respiratory indices. By employing this rigorous monitoring protocol, the study sought to provide valuable insights into the prevalence of TE-CSA during HGNS therapy and its impact on treatment outcomes.

Hypoglossal Nerve Stimulation (HGNS) has emerged as a promising therapeutic avenue for individuals grappling with moderate to severe obstructive sleep apnea (OSA). Yet, concerns linger regarding the potential emergence of treatment-induced central sleep apnea (TE-CSA), a complication observed in various OSA interventions. Despite the growing utilization of HGNS, the precise incidence of TE-CSA remains elusive due to methodological constraints in assessment. This study aimed to bridge this knowledge gap by meticulously investigating the rate of TE-CSA in patients undergoing HGNS titration, leveraging frequent home sleep apnea testing (HSAT) to capture nuanced changes in respiratory patterns.

A cohort of 43 adults undergoing HGNS implant titration at a Sleep Clinic in Arizona underwent rigorous monitoring from January to November 2023. Employing a strategic protocol, HGNS activation was initiated postoperatively, with stimulation parameters systematically adjusted over time. Notably, patients underwent HSATs following each amplitude increase, enabling real-time evaluation of respiratory indices. Results unveiled a notable incidence of TE-CSA, with 30% of patients demonstrating central apnea indices (CAI) exceeding predefined thresholds during titration. Early detection, facilitated by frequent HSAT monitoring, proved pivotal in averting potential over-titration and optimizing HGNS efficacy, underscoring the importance of tailored intervention strategies for enhanced treatment outcomes in OSA management.

HGNS is an increasingly prevalent treatment for moderate-severe obstructive sleep apnea (OSA). Several OSA therapies carry a risk of treatment-emergent central sleep apnea (TE-CSA), however the rate of TE-CSA in HGNS is not well understood due to limitations in testing. The purpose of this study was to identify the rate of TE-CSA in a cohort of patients that had frequent testing with a home sleep apnea test (HSAT) during HGSN titration.

The study included 43 adults undergoing titration of an HGNS implant at a Sleep Clinic in Arizona, USA from January-November 2023. The HGNS device was activated 3-weeks post-op and the stimulation amplitude was increased by 0.1V every 4 days following device activation. Patients were advised to test their sleep with a HSAT for 1 night on the 2nd night after every amplitude increase to minimize the risk of “1st night effect” after the initial amplitude increase. Follow-up visits were scheduled every 2 weeks post-activation, where the HSAT data was reviewed. TE-CSA was defined as patients with a baseline central apnea index (CAI) of <5 events who demonstrated a CAI of >5/h during HGNS titration.

The average number of completed HSATs was 12.38 (SD 8.55) Of the patients that completed HGNS titration, 30% (n=13) had tests with a CAI of >5, 16.2% (n=7) had tests with a CAI of >15, and 4.6% (n=2) had tests with a CAI of >30. Of the patients who had Central Sleep Apnea (TE-CSA), the mean CAI point increase was 18.02 (SD 15.15). It took an average of 4.7 (SD 6.47) HSAT tests before identifying if a patient was at risk for TE-CSA, with 69.2% (9/13) patients being identified as at risk within the first 3 tests.

Frequent sleep testing with an HSAT reveals a higher incidence [RPP1] for TE-CSA during HGNS titration than previously estimated. Early detection of Central Sleep Apnea (TE-CSA) may prevent over-titration of the HGNS and triggering earlier consideration for lower amplitudes, different stimulation parameters, and electrode configurations, improving HGNS efficacy and overall treatment outcomes.