Resolving Discordant In-Lab Sleep Study Results with Home Sleep Apnea Testing to Secure Inspire® Eligibility

Kyle Schwab, M.D. ¹; Hunter Schwab ², Chelsie Rohrscheib, Ph.D. ³

Polysomnography (PSG) is the gold standard for diagnosing obstructive sleep apnea (OSA) and determining eligibility for hypoglossal nerve stimulation (Inspire®). However, equipment artifacts and night-to-night variability can sometimes compromise its accuracy. We present the case of a 59-year-old male with longstanding OSA and intolerance to continuous positive airway pressure who was initially deemed ineligible for Inspire® following a PSG that showed central apnea predominance. To clarify the diagnosis, the patient underwent home sleep apnea testing (HSAT) with the Wesper Lab system. Two HSATs revealed severe OSA with minimal central events, contradicting the PSG results. Review of the PSG recording demonstrated flat effort belt signals, which led to misclassification of obstructive events as central apneas. HSAT confirmed obstructive predominance, and with updated evidence the patient’s insurer approved Inspire® therapy. This case illustrates the potential for PSG artifacts to misclassify apnea type, with significant consequences for treatment access, and highlights the value of HSAT as a complementary diagnostic tool to ensure accurate patient selection for advanced therapies.

Sleep apnea is a common sleep disorder marked by intermittent disruptions of breathing during sleep. It generally manifests as chronic snoring, fragmented sleep due to nighttime arousals, and poor overall sleep quality [1]. Sleep apnea is classified into two main subtypes, obstructive sleep apnea (OSA) and central sleep apnea (CSA), with each possessing a unique etiology. OSA involves obstruction of the upper airway despite adequate respiratory drive, and is far more common in the general population [2]. Conversely, CSA is defined by diminished or absent respiratory drive, often caused by improper response to carbon dioxide levels with insufficient signaling to the muscles involved in respiratory effort [3]. Accurate differentiation between OSA and CSA is essential, as treatment strategies diverge significantly and a correct diagnosis is critical for optimizing patient outcomes.

Continuous positive airway pressure (CPAP) remains the gold standard treatment for OSA; however, its clinical effectiveness is often limited by suboptimal patient adherence [4,5]. Given these limitations, newer therapies such as hypoglossal nerve stimulation (HGNS) via Inspire® have shown promise as effective alternatives for patients with moderate to severe OSA who struggle with CPAP adherence [6]. Patient selection for Inspire® therapy is highly specific, requiring rigorous evaluation to determine suitability. Inspire® therapy is contraindicated in patients with central or mixed apneas, underscoring the need for comprehensive diagnostic testing, traditionally via polysomnography (PSG), to confirm OSA predominance and exclude alternative sleep-disordered breathing mechanisms [7].

PSG remains the gold standard for evaluating Inspire® candidacy, as it provides comprehensive physiologic data and standardized scoring [8]. Yet, PSG is limited by its single-night scope, potential variability across nights, and barriers related to access and insurance coverage. In contrast, home sleep apnea testing (HSAT) is increasingly common due to its convenience and lower cost [9], though it is not routinely accepted for Inspire® eligibility.

We report the case of a 59-year-old male with longstanding obstructive sleep apnea whose initial PSG suggested he was not a candidate for Inspire® therapy. Subsequent evaluation with HSAT, however, demonstrated findings that contradicted the PSG and secured his eligibility, underscoring the potential role of HSAT in clarifying misleading results from traditional testing.

Patient History

A 59-year-old male (BMI 33.6 kg/m²) was referred to the Louisiana Sleep Foundation in November 2024 for evaluation of OSA. He reported loud snoring, witnessed apneas, and excessive daytime sleepiness (Epworth Sleepiness Scale score 21). He had previously attempted CPAP therapy with multiple mask types but was unable to tolerate treatment.

Initial Polysomnography (PSG)

Diagnostic testing timelineIn November 2024, an in-lab overnight PSG was performed. Results revealed 133 apneas (34 obstructive, 46 mixed, 53 central) and no hypopneas. The apnea–hypopnea index (AHI) was 25.4 events/hour, with a central apnea index (CAI) of 10.1 events/hour. Oxygen desaturations reached a nadir of 63%, with 60 minutes spent below 88% saturation. The study was interpreted as moderate OSA with a predominance of central and mixed apneas, leading to diagnoses of OSA, CSA, and nocturnal hypoxemia (Table 1). Given the predominance of central events, the patient was deemed ineligible for Inspire® therapy at that time, as current criteria contraindicate implantation in cases of central or mixed apnea predominance.

Reevaluation with Wesper Lab

The predominance of CSA observed on PSG was unexpected given the patient’s clinical history and symptom profile, which were strongly indicative of obstructive disease. Recognizing the possibility that the PSG results might represent an artifact rather than the patient’s true phenotype, the treating physician elected to pursue additional testing to clarify the diagnosis and ensure the patient was not prematurely disqualified from Inspire® candidacy.

In February 2025, the patient underwent two consecutive nights of reevaluation with the Wesper Lab multi-channel type 3 HSAT [10]. Hypopneas were scored using the AASM 1B definition (≥4% desaturation). The first study, performed on February 17, 2025, demonstrated an AHI of 54.6 events/hour with a CAI of 9.2 events/hour. Event distribution showed 83% obstructive and 17% central apneas. The nadir SpO₂ was 70%. A second study on February 19, 2025, confirmed the findings of severe OSA, revealing an AHI of 57.1 events/hour with a CAI of 1.0 events/hour. In this test, 98% of events were obstructive and only 2% central, with a nadir SpO₂ again of 70%. Together, these HSATs demonstrated consistent severe OSA with minimal central apnea burden, in contrast to the prior PSG that had suggested central predominance (Table 1).

Table 1: Diagnostic testing timeline

Reevaluating the PSG Data

Given the marked discrepancy between the PSG and HSAT findings, the original PSG recording was reexamined. Review revealed that both the chest and abdominal effort belts produced a relatively flat baseline signal, a pattern commonly seen when patients loosen the belts due to discomfort. During oxygen desaturations, these loose belts generated nearly flat traces, mimicking absent respiratory effort. Lacking reliable effort signals, the scoring algorithm defaulted to classifying many events as central apneas. This artifact provides a likely explanation for the disproportionate number of central events reported on the initial PSG.

Resubmissions and Inspire® Approval

With this new evidence, the updated findings and clinical justification were submitted to the patient’s insurer. His Inspire® candidacy was approved, and in 2025 he successfully underwent implantation and has since entered the titration phase.

This case underscores the importance of integrating clinical judgment, raw data review, and complementary diagnostic methods when evaluating therapy eligibility. While PSG remains the gold standard, it is not infallible; equipment artifacts and night-to-night variability can significantly distort results, with potentially serious consequences for treatment access. In this patient, misclassification of respiratory events due to faulty belt signals led to an erroneous diagnosis of CSA and initial disqualification from Inspire®.

First, signal artifacts from respiratory effort belts can profoundly affect scoring. In this case, the chest and abdominal belts displayed flat baseline signals, likely due to being loosened for patient comfort. Without reliable effort traces, desaturation events were incorrectly classified as central apneas, leading to an apparent predominance of CSA. Such misclassification has been described in the literature as a significant source of diagnostic error, particularly when sensors are improperly fitted or patients move during sleep [11,12].

Second, PSG captures only a single night of data, which introduces vulnerability to night-to-night variability. Multiple studies have shown that OSA severity and event type distribution can fluctuate significantly across nights, meaning that a single PSG may not accurately represent a patient’s typical sleep physiology [13,14]. This variability can result in under- or overestimation of apnea severity and, as in this case, may mischaracterize the predominant apnea type.

Third, patient phenotype and clinical presentation must be weighed alongside objective data. The initial PSG finding of central predominance was incongruent with the patient’s history of loud snoring, witnessed apneas, and excessive daytime sleepiness, all hallmarks of obstructive disease. When objective results and clinical suspicion diverge, repeating or complementing testing is essential.

In this case, HSAT provided critical clarification. Multiple studies have highlighted HSAT’s reliability in identifying OSA [9, 10, 15]. By eliminating the artifact-prone effort belts and providing multi-night or repeatable testing opportunities, HSAT can serve as a valuable adjunct when PSG findings are questionable. The repeat HSAT studies consistently demonstrated obstructive predominance, restoring the patient’s eligibility for Inspire®.

This case underscores the importance of integrating clinical judgment, raw data review, and complementary diagnostic methods when evaluating Inspire® eligibility. While PSG remains the gold standard, it is not infallible; equipment artifacts and night-to-night variability can significantly distort results, with potentially serious consequences for treatment access. HSAT, when carefully applied, can serve as an important confirmatory tool, particularly when PSG findings conflict with clinical presentation Ultimately, this case highlights that eligibility decisions should never rest on a single flawed dataset. Aligning clinical suspicion with robust and reliable testing ensures that patients receive appropriate access to therapies capable of transforming outcomes.

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