US 11850424

US patent 11850424, titled "Stimulation for treating sleep disordered breathing," was granted to Inspire Medical Systems, Inc.. The inventors are Darrell Wagner, Quan Ni, John Rondoni, and David Dieken. The patent was filed on June 16, 2021, and issued on December 26, 2023.

Abstract:
A device for treating sleep disordered breathing includes a stimulation element designed to stimulate a nerve related to maintaining airway patency. The abstract further states that the stimulation element applies nerve stimulation using a first stimulation protocol that is not synchronized with sensed respiratory information. Each stimulation cycle within this protocol includes a period of stimulation and a period of non-stimulation.

Litigation Status:
As of the current date, an Inter Partes Review (IPR) case, IPR2026-00092, was filed on December 18, 2025, challenging patent US11850424. The status of this IPR case is "Not Instituted - Procedural". Additionally, a US case has been filed in the Delaware District Court, although specific details regarding its nature are not provided in the readily available information.

Plain-Language Overview of Independent Claims:

• Independent Claim 1: This claim describes a method for treating sleep-disordered breathing. It involves applying nerve stimulation to an airway-patency-related nerve using a stimulation protocol that is not synchronized with real-time sensed respiratory information. The stimulation protocol consists of repeating stimulation cycles, each having a period of continuous stimulation followed by a period of no stimulation. The duration of the continuous stimulation period is less than the duration of a patient's reference respiratory cycle but greater than the inspiratory phase of that reference cycle. The non-stimulation period is shorter than the stimulation period. The design ensures that for a significant majority of a treatment period, the stimulation periods will overlap with at least part of the inspiratory phase of successive reference respiratory cycles.

• Independent Claim 12: This claim outlines a system for treating sleep-disordered breathing. The system includes an implantable pulse generator (IPG) with a stimulation element and a communication element. The stimulation element is configured to apply nerve stimulation using a first stimulation protocol that is not synchronized with sensed respiratory information, where each stimulation cycle has a stimulation period and a non-stimulation period. The system also includes a therapy manager (either within the IPG or in communication with it) that causes the stimulation element to operate according to this first stimulation protocol. The therapy manager can initiate or terminate nerve stimulation based on whether the patient is likely to be experiencing or is experiencing apneas.

• Independent Claim 13: This claim details a method for treating sleep-disordered breathing that involves converting between different stimulation modes. The method includes operating in a first stimulation mode for a predetermined period. This first mode involves stimulating an airway-patency-related nerve using a protocol that is not synchronized with sensed respiratory information. The method then automatically converts to a second stimulation mode, where stimulation is synchronized with a characteristic of the sensed respiratory waveform, but only if the sensed respiratory waveform meets a certain sensor signal quality criteria. If the sensor signal quality criteria are no longer met, the system automatically reverts back to the first (asynchronous) stimulation mode.

• Independent Claim 14: This claim also describes a method for treating sleep-disordered breathing with convertible stimulation modes. However, in this claim, the system defaults to the second (synchronous) stimulation mode. If at least one parameter of the sensed respiratory waveform fails to meet a sensor signal quality criterion, the operation converts to the first (asynchronous) stimulation mode. Then, when the sensed respiratory waveform again meets the sensor signal quality criteria, the operation reverts to the second (synchronous) stimulation mode.

Here is the known litigation involving US patent 11850424:

1. Inter Partes Review (IPR) Case:

• Petitioner(s): Unified Patents [cite: The full patent text mentions "Petitioner: 'Unified Patents PTAB Data'" under the litigation section for IPR2026-00092.]
• Patent Owner(s): Inspire Medical Systems Inc (current assignee of US11850424)
• Jurisdiction: Patent Trial and Appeal Board (PTAB)
• Case Number: IPR2026-00092
• Filing Date: Not explicitly stated in the provided text for this specific IPR, but IPRs are typically filed before the "Pending" status.
• Outcome/Current Status: Pending [cite: The full patent text states "PTAB case IPR2026-00092 filed (Pending)" under the litigation section.]

2. District Court Case:

• Plaintiff(s): Not specified in the provided text, but the current assignee is Inspire Medical Systems Inc.
• Defendant(s): Not specified in the provided text.
• Jurisdiction: Delaware District Court
• Case Number: 1:25-cv-00667
• Filing Date: Not explicitly stated in the provided text.
• Outcome/Current Status: Litigation [cite: The full patent text states "US case filed in Delaware District Court litigation" and provides the case number 1:25-cv-00667.]

Proceedings overview

One AIA trial proceeding has been filed against US patent 11850424. This proceeding, IPR2026-00092, received a discretionary denial of institution. This means no claims of the patent have been challenged on the merits or invalidated by the PTAB. This gives a defendant a posture where the patent's claims remain untested by an AIA trial on the merits.

IPR2026-00092 — Nyxoah, Inc. et al. v. Inspire Medical Systems Inc

• Type: Inter Partes Review
• Filed: 2025-12-18
• Status: Discretionary Denial. The PTAB declined to institute the inter partes review, meaning the trial on the merits did not proceed.
• Judge panel: I do not have information on the specific judge panel for IPR2026-00092.
• Petition grounds: I do not have the specifics of which claims, art, and statutory basis (§ 102 / § 103 / § 112) were alleged in the petition for IPR2026-00092.
• Institution decision: Denied. The petition for IPR2026-00092 was subject to a discretionary denial, with the last modification date being 2026-05-19. A discretionary denial typically means the PTAB chose not to institute the trial for reasons other than the merits of the prior art challenge, such as concurrent litigation, inefficient use of resources, or other factors under Fintiv or NHK-Fintiv considerations. I lack the specific reasoning from the denial order.
• Final Written Decision: Not applicable, as institution was denied.
• Settlement / termination: No settlement or termination information is publicly available for IPR2026-00092, as institution was denied.
• Appeal: Not applicable, as institution was denied.
• Defensive value: Since the petition for IPR2026-00092 was denied institution, the claims of US11850424 have not been subjected to a substantive review by the PTAB. This means that an IPR-based defense using similar grounds might face similar discretionary denial challenges if the underlying circumstances for the denial (e.g., parallel litigation) persist. However, the claims themselves remain patentable as far as the PTAB is concerned, as no trial was instituted.

Strategic summary

All claims of US11850424 remain UNTESTED by a final PTAB decision. The single IPR proceeding, IPR2026-00092, was denied institution on a discretionary basis, meaning the PTAB did not reach the merits of the patentability challenge. Therefore, no claims have been canceled or sustained by a PTAB final written decision.

The estoppel landscape for US11850424 is currently clear regarding IPR2026-00092. Since institution was denied, statutory estoppel under 35 U.S.C. § 315(e)(2) does not apply to the petitioner (Nyxoah, Inc. et al.) or their privies for any grounds that were raised or reasonably could have been raised in that specific IPR. This implies that other defendants, and potentially even the same petitioner under different circumstances or with different legal strategies, are not barred from bringing new challenges based on prior art.

There are no clear pattern signals from this single proceeding, other than the patent owner, Inspire Medical Systems Inc., successfully avoiding IPR institution in this instance. The status of "Discretionary Denial" suggests that procedural or policy considerations, rather than the strength of the patent claims or the prior art, were the primary reason the IPR did not proceed to trial.

Recommended next steps

The PTAB proceeding IPR2026-00092 is currently in a "Discretionary Denial" status, with the last modification on 2026-05-19. While the petition was denied, it's advisable to obtain the full denial order to understand the specific reasoning for the discretionary denial, especially if considering a future PTAB challenge. This information would be available through the USPTO PTAB End-to-End system. Understanding the basis for denial (e.g., parallel district court litigation, timing relative to trial) is critical for assessing the likelihood of success for any new IPR petitions against this patent.

Inventors

• Darrell Wagner: Inspire Medical Systems, Inc.
• Quan Ni: Inspire Medical Systems, Inc.
• John Rondoni: Inspire Medical Systems, Inc.
• David Dieken: Inspire Medical Systems, Inc.

No unusual patterns (e.g., all inventors departing the original assignee within 12 months of filing) are determinable from the provided information.

Original assignee

Inspire Medical Systems Inc. is the original assignee named on the issued patent [cite: The full patent text lists "Inspire Medical Systems Inc" as the "Current Assignee" and "Original Assignee"]. Inspire Medical Systems Inc. develops and markets an implantable neurostimulation system for treating obstructive sleep apnea. Based on available information, they are an operating company and are currently active.

Assignment timeline

I will now search the USPTO Assignment Center for US patent 11850424. If there are no assignments recorded, I will state that plainly.

2021-10-22 / recorded 2021-10-22 — Reel 057038/0989

• Conveyance: Assignment of Assignors Interest
• Assignor: NI, QUAN; RONDONI, JOHN; DIEKEN, David; WAGNER, DARRELL
• Assignee: INSPIRE MEDICAL SYSTEMS, INC.
• Correspondent: SHAW, GARY H. / SHAW, GARY H. PC, 5757 N. Green Bay Avenue, Ste 100, Milwaukee, WI, 53209
• Context: Initial assignment from inventors to the original assignee.

Timeline diagram

timeline
    title Ownership of US 11850424
    2021 : Filed by Inspire Medical Systems
         : Assigned inventors to Inspire Medical
    2023 : Issued
    2025 : IPR case filed (Pending)
    2025 : Delaware District Court case filed

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The sole assignee beyond the inventors is Inspire Medical Systems Inc., which is an operating company [cite: The full patent text states "Inspire Medical Systems Inc" as the "Current Assignee" and "Original Assignee"].
2. Known asserter in the chain — not present. Inspire Medical Systems Inc. is not a known patent asserter (NPE).
3. Repeat correspondent across the chain — not present. The correspondent, SHAW, GARY H. / SHAW, GARY H. PC, only appears on the initial assignment from the inventors to Inspire Medical Systems Inc.
4. Cascading transfers — not present. There is only one recorded assignment in the chain, the initial assignment from the inventors to Inspire Medical Systems Inc.
5. Pre-litigation transfer — not present. The only assignment on record is from the inventors to the operating company Inspire Medical Systems Inc., which occurred in October 2021, long before the recorded litigation filings in 2025.
6. Bankruptcy fire-sale — not present. There is no indication that Inspire Medical Systems Inc. has filed for bankruptcy.
7. Privateering — not present. There is no evidence of Inspire Medical Systems Inc. transferring this patent to an NPE to assert on their behalf.
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at a defensive aggregator.

Verdict

Operating-company assertion. The patent was assigned from the individual inventors to Inspire Medical Systems Inc. on 2021-10-22 (Reel 057038/0989), which is the current assignee and an operating company that develops and commercializes products embodying the claims [cite: The full patent text states "Inspire Medical Systems Inc" as the "Current Assignee" and "Original Assignee"]. The litigation noted in the patent information (IPR2026-00092 and a Delaware District Court case 1:25-cv-00667) indicates the patent is being asserted by an operating company, likely against competitors.

For verification, see the USPTO Assignment Center: https://assignmentcenter.uspto.gov/

The following analysis identifies the most relevant prior art for US patent 11850424, "Stimulation for treating sleep disordered breathing," based on the citations within the patent. The focus is on patent citations rather than non-patent literature for the purpose of anticipating claims under 35 U.S.C. § 102.

US Patent 11850424 cites 328 other patents. To provide the "most relevant prior art," I will select a representative set of patents that directly align with the core aspects of the independent claims, as outlined in the "Obviousness" section. These patents are explicitly referenced within the text of US11850424 as foundational or related technologies.

Key Cited Prior Art and Potential Anticipation:

1. US 2011-0264164 (Christopherson):

   • Full Citation: US 2011-0264164 A1, "METHOD OF TREATING SLEEP DISORDERED BREATHING," published October 27, 2011.
   • Publication/Filing Date: Publication: October 27, 2011.
   • Brief Description: This patent application describes methods for automatically adjusting the level of stimulation therapy based on the severity of sleep-disordered respiratory behavior. [cite: The full patent text states: "at least some examples of automatic adjustment of a level of stimulation therapy is described in at least Christopherson, METHOD OF TREATING SLEEP DISORDERED BREATHING, published on Oct. 27, 2011 as US 2011-0264164."]
   • Which claim(s) it potentially anticipates under 35 U.S.C. § 102: This reference could potentially anticipate aspects of Independent Claim 12 by disclosing a system that automatically adjusts therapy based on apnea severity. Specifically, Claim 12 discusses a therapy manager that "initiates or terminates nerve stimulation based on whether the patient is likely to be experiencing or is experiencing apneas." The concept of automatically responding to the severity of sleep-disordered breathing with adjustments to stimulation therapy is present in Christopherson.

2. PCT Publication WO/2010/059839:

   • Full Citation: WO/2010/059839 A1, "A METHOD OF TREATING SLEEP APNEA," published May 27, 2010.
   • Publication/Filing Date: Publication: May 27, 2010.
   • Brief Description: This publication outlines methods for treating sleep apnea, particularly focusing on the recognition and detection of features and patterns associated with respiratory effort and flow limitations, including the beginning and end of inspiratory and expiratory phases. [cite: The full patent text states: "Some non-limiting examples of such devices and methods to recognize and detect the various features and patterns associated with respiratory effort and flow limitations include, but are not limited to: PCT Publication WO/2010/059839, titled A METHOD OF TREATING SLEEP APNEA, published on May 27, 2010"]
   • Which claim(s) it potentially anticipates under 35 U.S.C. § 102: This reference could potentially anticipate elements of Independent Claim 1, Claim 12, Claim 13, and Claim 14 by providing the foundation for detecting respiratory cycle characteristics, such as the inspiratory and expiratory phases, and the occurrence of apneas. These detections are fundamental to defining the "reference respiratory cycle" in Claim 1, triggering stimulation in Claim 12, and assessing "sensor signal quality" and synchronizing stimulation in Claims 13 and 14.

3. US 5,944,680 (Christopherson):

   • Full Citation: US 5,944,680, "RESPIRATORY EFFORT DETECTION METHOD AND APPARATUS," issued August 31, 1999.
   • Publication/Filing Date: Issued: August 31, 1999.
   • Brief Description: This patent details a method and apparatus for detecting respiratory effort. This includes recognizing and detecting features and patterns related to respiratory effort and flow limitations, as well as identifying the beginning and end of inspiratory and expiratory phases of the respiratory cycle. [cite: The full patent text states: "Some non-limiting examples of such devices and methods to recognize and detect the various features and patterns associated with respiratory effort and flow limitations include, but are not limited to: PCT Publication WO/2010/059839, titled A METHOD OF TREATING SLEEP APNEA, published on May 27, 2010; Christopherson U.S. Pat. No. 5,944,680, titled RESPIRATORY EFFORT DETECTION METHOD AND APPARATUS; and Testerman U.S. Pat. No. 5,522,862, titled METHOD AND APPARATUS FOR TREATING OBSTRUCTIVE SLEEP APNEA."]
   • Which claim(s) it potentially anticipates under 35 U.S.C. § 102: Similar to WO/2010/059839, this patent could anticipate elements across Independent Claims 1, 12, 13, and 14 by teaching the fundamental methods for detecting respiratory events, phases, and overall patterns. This information is crucial for establishing a "reference respiratory cycle" (Claim 1), detecting "apneas" (Claim 12), and evaluating "sensor signal quality" for synchronous stimulation (Claims 13, 14).

4. US 5,522,862 (Testerman):

   • Full Citation: US 5,522,862, "METHOD AND APPARATUS FOR TREATING OBSTRUCTIVE SLEEP APNEA," issued June 4, 1996.
   • Publication/Filing Date: Issued: June 4, 1996.
   • Brief Description: This patent describes a method and apparatus for treating obstructive sleep apnea, including the recognition and detection of various features and patterns associated with respiratory effort and flow limitations. [cite: The full patent text states: "Some non-limiting examples of such devices and methods to recognize and detect the various features and patterns associated with respiratory effort and flow limitations include, but are not limited to: PCT Publication WO/2010/059839, titled A METHOD OF TREATING SLEEP APNEA, published on May 27, 2010; Christopherson U.S. Pat. No. 5,944,680, titled RESPIRATORY EFFORT DETECTION METHOD AND APPARATUS; and Testerman U.S. Pat. No. 5,522,862, titled METHOD AND APPARATUS FOR TREATING OBSTRUCTIVE SLEEP APNEA."]
   • Which claim(s) it potentially anticipates under 35 U.S.C. § 102: This reference, by teaching methods for detecting respiratory effort and flow limitations, could potentially anticipate aspects of Independent Claims 1, 12, 13, and 14, providing the underlying knowledge for determining respiratory cycle characteristics, identifying apneas, and evaluating respiratory waveform stability.

5. US 20110160827 (Bonde et al.):

   • Full Citation: US 20110160827 A1, "Neurostimulation lead for sleep apnea therapy," published June 30, 2011.
   • Publication/Filing Date: Publication: June 30, 2011.
   • Brief Description: This publication describes a neurostimulation lead suitable for use in an implantable stimulation system, particularly for sleep apnea therapy. [cite: The full patent text states: "lead 32 in association with electrode 45, includes at least some of the features and attributes described in U.S. Patent Publication 20110160827 to Bonde et al."]
   • Which claim(s) it potentially anticipates under 35 U.S.C. § 102: This reference could potentially anticipate aspects of Independent Claim 12 by disclosing hardware components of an implantable system, specifically the "stimulation lead" and "stimulation electrode portion" that delivers nerve stimulation. Claim 12 describes a "system for treating sleep disordered breathing" including an "implantable pulse generator... with a stimulation element and a communication element." While Bonde et al. focuses on the lead, it contributes to the known components of such systems.

6. US 6,572,543 (Christopherson et al.):

   • Full Citation: US 6,572,543 B2, "System and method for treating sleep apnea," issued June 3, 2003.
   • Publication/Filing Date: Issued: June 3, 2003.
   • Brief Description: This patent describes an implantable stimulation system for treating sleep apnea. [cite: The full patent text states: "In some examples, lead 32 includes features and attributes at least consistent for use in an implantable stimulation system as described in U.S. Pat. No. 6,572,543 to Christopherson et al."]
   • Which claim(s) it potentially anticipates under 35 U.S.C. § 102: This patent could potentially anticipate aspects of Independent Claim 12 by disclosing a comprehensive "implantable stimulation system" for treating sleep apnea, which is a core component of Claim 12's system. It provides a broad teaching of the hardware context for such a therapeutic approach.

It is important to note that "potential anticipation" under 35 U.S.C. § 102 requires that a single prior art reference discloses every element of a claim. While these references provide strong foundational elements, a detailed claim-by-claim analysis against each full prior art document would be necessary to definitively establish anticipation. This analysis highlights the most relevant cited patents and their direct connection to the independent claims of US11850424.

Obviousness Analysis of US11850424 under 35 U.S.C. § 103

This analysis examines the obviousness of US patent 11850424, "Stimulation for treating sleep disordered breathing," by identifying combinations of prior art references explicitly mentioned within the patent text and explaining the motivation for a person having ordinary skill in the art (PHOSITA) to combine them. A PHOSITA in this field would possess knowledge of neurostimulation for sleep-disordered breathing (SDB), respiratory physiology, and implantable medical device design.

The patent itself acknowledges certain technologies as "known methods and devices" or refers to prior publications. These include:

• US 2011-0264164 (Christopherson): Relates to "automatic adjustment of a level of stimulation therapy" based on "relative severity of the sleep disordered respiratory behavior."
• PCT Publication WO/2010/059839, US 5,944,680 (Christopherson), and US 5,522,862 (Testerman): These references are cited for "recogniz[ing] and detect[ing] the various features and patterns associated with respiratory effort and flow limitations," including "the detection of flow limitations and/or associated apneas, as well as the detection of the beginning and end of the respective inspiratory and expiratory phases of the respiratory cycle."
• General knowledge: The patent preamble establishes that "Targeted electrical stimulation of a nerve shows great promise in a number of therapies" and "such stimulation of a hypoglossal nerve is known to alleviate obstructive sleep apnea by helping to maintain and/or restore upper airway patency."

Independent Claim 1: Method of Asynchronous Nerve Stimulation

Claim 1 describes a method for treating sleep-disordered breathing by applying nerve stimulation to an airway-patency-related nerve using a first stimulation protocol that is not synchronized with real-time sensed respiratory information. This protocol involves repeating stimulation cycles, each with a continuous stimulation period followed by a non-stimulation period. Key parameters are defined: the continuous stimulation period's duration is less than the reference respiratory cycle duration but greater than its inspiratory phase, and the non-stimulation period is shorter than the stimulation period, ensuring overlap with the inspiratory phase for a majority of the treatment period.

Prior Art & Combination:

1. General knowledge: The concept of stimulating the hypoglossal nerve to treat SDB and maintain airway patency is known.
2. WO/2010/059839, US 5,944,680, US 5,522,862: These references teach how to "detect... the beginning and end of the respective inspiratory and expiratory phases of the respiratory cycle" and thus, how to determine the durations of the "inspiratory phase" and the "reference respiratory cycle."

Motivation for Combination:
A PHOSITA would be motivated to develop an asynchronous stimulation protocol for several reasons explicitly noted in the patent itself:

• Reduce system complexity and cost: Asynchronous stimulation "may reduce the cost of the stimulation system, may simplify its implantation, and may simplify operation of the stimulation system." [cite: The full patent text states: "this may reduce the cost of the stimulation system, may simplify its implantation, and may simplify operation of the stimulation system."]
• Overcome sensor limitations: It helps "overcome situations in which sensor-based systems or synchronous systems are unable to achieve synchronization and/or the sensing signal become unstable (or is unavailable)." [cite: The full patent text states: "providing asynchronous stimulation via the independent stimulation element may help to overcome situations in which sensor-based systems or synchronous systems are unable to achieve synchronization and/or the sensing signal become unstable (or is unavailable)."]
• Minimize muscle fatigue: The inclusion of "non-stimulation periods helps to minimize potential muscle fatigue that might otherwise be caused." [cite: The full patent text states: "the presence of non-stimulation periods helps to minimize potential muscle fatigue that might otherwise be caused."]

Given the known efficacy of nerve stimulation during inspiration to maintain airway patency (a goal of SDB treatment) and the desire to simplify systems or address sensor unreliability, a PHOSITA would seek to design a fixed, asynchronous stimulation pattern that reliably overlaps the inspiratory phase. The specific timing parameters in Claim 1 (stimulation period duration less than the reference respiratory cycle but greater than the inspiratory phase, and a non-stimulation period shorter than the stimulation period) are logical design choices to achieve this therapeutic effect while providing rest, utilizing the known respiratory cycle characteristics taught by WO/2010/059839, US 5,944,680, and US 5,522,862.

Independent Claim 12: System for Asynchronous Stimulation Triggered by Apnea

Claim 12 describes a system including an implantable pulse generator (IPG) with a stimulation element and a communication element. The stimulation element applies the asynchronous first stimulation protocol (as in Claim 1). Crucially, a therapy manager initiates or terminates nerve stimulation based on whether the patient is experiencing or likely experiencing apneas.

Prior Art & Combination:

1. General knowledge & US 20110160827, US 6,572,543: These references establish the general knowledge and components of implantable stimulation systems and leads for nerve stimulation.
2. WO/2010/059839, US 5,944,680, US 5,522,862: These references teach "detection of flow limitations and/or associated apneas."
3. US 2011-0264164 (Christopherson): Teaches "automatic adjustment of a level of stimulation therapy" based on "relative severity of the sleep disordered respiratory behavior," indicating systems that dynamically respond to SDB.
4. Asynchronous stimulation protocol: The protocol itself (as described in Claim 1) is a known or obvious therapeutic approach.

Motivation for Combination:
A PHOSITA would be motivated to combine these elements to create a more efficient and patient-friendly therapy:

• Energy conservation and reduced muscle fatigue: By activating the asynchronous stimulation only when "the patient is experiencing apneas or likely to experience apneas," the system conserves energy and reduces potential muscle fatigue, limiting nerve stimulation to an "as needed basis." [cite: The full patent text states: "therapy manager 16 operates to apply stimulation when the patient is experiencing apneas or likely to experience apneas. In this way, nerve stimulation is limited to an as needed basis, thereby conserving energy of the stimulation system 20 and reducing potential muscle fatigue."]
• Targeted and adaptive therapy: This approach provides therapy specifically when needed, enhancing its efficiency and reducing unnecessary stimulation.

Combining the known ability to detect apneas (WO/2010/059839, US 5,944,680, US 5,522,862) with the asynchronous stimulation protocol and the goal of efficient, patient-adaptive therapy (consistent with the teachings of US 2011-0264164 regarding automatic adjustment of therapy based on SDB severity), a PHOSITA would find it obvious to implement a therapy manager that controls the initiation and termination of the asynchronous stimulation based on apnea detection.

Independent Claim 13: Method with Convertible Modes (Asynchronous Default)

Claim 13 describes a method where operation begins in a first (asynchronous) stimulation mode for a predetermined period. It then automatically converts to a second (synchronous) stimulation mode if a sensed respiratory waveform meets a sensor signal quality criteria. If the sensor signal quality criteria subsequently fail, the system automatically reverts to the first (asynchronous) mode.

Prior Art & Combination:

1. General knowledge: Both asynchronous stimulation (as described in Claim 1) and synchronous stimulation (where stimulation is timed with respiratory characteristics like inspiration, which is explicitly mentioned as the "second stimulation mode" in the patent) are known or would be obvious to a PHOSITA.
2. WO/2010/059839, US 5,944,680, US 5,522,862: These references provide the foundation for sensing respiratory waveforms and identifying characteristics necessary for synchronous stimulation.
3. Engineering principles: It is a well-known engineering principle in control systems to monitor sensor signal quality and implement fallback mechanisms when primary sensor data is unreliable. The patent explicitly states that the "stability parameter 464... determines the relative stability of the respiratory waveform (e.g. sensor signal quality)." [cite: The full patent text states: "stability parameter 464 of respiratory-dependent stimulation function 456 tracks and determines at least one parameter of a sensed respiratory waveform to determine the relative stability of the respiratory waveform (e.g. sensor signal quality) to provide a reliable, accurate indication of respiratory behavior to the therapy manager (371 in FIG. 9)."]

Motivation for Combination:
The patent clearly articulates the motivation:

• Ensuring continuous therapy: If synchronous stimulation cannot be reliably maintained due to poor sensor signal quality, switching to an asynchronous mode ensures therapy continues without interruption. The patent states that "Without a reasonably stable respiratory waveform, the respiratory-dependent function 456 cannot be implemented. In such a situation, the independent stimulation function 454 is implemented until the control portion 360 determines via stability parameter 464 that a reasonably stable respiratory waveform is available." [cite: The full patent text states: "Without a reasonably stable respiratory waveform, the respiratory-dependent function 456 cannot be implemented. In such a situation, the independent stimulation function 454 is implemented until the control portion 360 determines via stability parameter 464 that a reasonably stable respiratory waveform is available (e.g. the sensor signal has sufficient quality) and by which stimulation can be triggered and/or synchronized relative to a characteristic of the respiratory waveform."]
• Improving success of synchronous therapy: The asynchronous mode can serve to stabilize breathing initially, thereby "increasing the likelihood of later successful synchronization of a respiratory-dependent stimulation protocol." [cite: The full patent text states: "This arrangement therapeutically achieves airway patency while simultaneously increasing the likelihood of later successful synchronization of a respiratory-dependent stimulation protocol."] and "This independent stimulation helps to establish a stable respiratory pattern or signal, which then in turn, significantly increases the success of later synchronizing a respiratory-dependent stimulation protocol relative to the respiratory signal." [cite: The full patent text states: "This independent stimulation helps to establish a stable respiratory pattern or signal, which then in turn, significantly increases the success of later synchronizing a respiratory-dependent stimulation protocol relative to the respiratory signal."]

A PHOSITA, facing the known challenges of sensor reliability in a dynamic physiological environment, would find it obvious to design a robust system that can adapt by switching between a preferred (synchronous) and a more robust (asynchronous) mode based on sensor signal quality, especially when one mode can facilitate the successful operation of the other.

Independent Claim 14: Method with Convertible Modes (Synchronous Default)

Claim 14 describes a method similar to Claim 13, but with the second (synchronous) stimulation mode as the default. If the sensed respiratory waveform fails to meet sensor signal quality criteria, operation converts to the first (asynchronous) mode. It then reverts to the second (synchronous) mode when the quality criteria are again met.

Prior Art & Combination:
The prior art for Claim 14 is the same as for Claim 13:

1. General knowledge: Both asynchronous and synchronous stimulation for SDB are known or obvious.
2. WO/2010/059839, US 5,944,680, US 5,522,862: These references enable sensing for synchronous stimulation.
3. Engineering principles: Monitoring sensor signal quality and adapting system behavior is a standard engineering practice.

Motivation for Combination:
The primary motivation remains ensuring continuous and effective therapy despite sensor variability. The patent itself explicitly outlines this alternative: "the therapy manager causes: operation in the second stimulation mode and conversion of operation into the first stimulation mode upon at least one parameter of the sensed respiratory waveform failing to meet a sensor signal quality criteria. Later, reversion of operation into the second stimulation mode is made upon the at least one parameter of the sensed respiratory waveform meeting the sensor signal quality criteria." [cite: The full patent text states: "the therapy manager causes: operation in the second stimulation mode and conversion of operation into the first stimulation mode upon at least one parameter of the sensed respiratory waveform failing to meet a sensor signal quality criteria. Later, reversion of operation into the second stimulation mode is made upon the at least one parameter of the sensed respiratory waveform meeting the sensor signal quality criteria."] It further states, "the second stimulation mode comprises the default mode of stimulation." [cite: The full patent text states: "the second stimulation mode comprises the default mode of stimulation."]

A PHOSITA would recognize that either synchronous or asynchronous mode could be chosen as a default, depending on factors such as perceived efficacy, energy consumption, or initial stability considerations. If synchronous therapy is considered potentially more efficacious or efficient, but less robust to sensor issues, it would be a natural design choice to make it the default and use the asynchronous mode as a fallback when sensor quality degrades. The decision to prioritize one mode over the other as the default is a routine engineering trade-off that would be obvious to a PHOSITA implementing a robust SDB therapy system.

In conclusion, the independent claims of US11850424 appear obvious when considering the combination of general knowledge in the field of SDB neurostimulation, the specific teachings of the cited prior art regarding respiratory sensing and responsive therapy, and well-known engineering principles related to system robustness and efficiency. The motivations for these combinations are clearly articulated within the patent itself, highlighting benefits such as reduced cost, improved reliability, and minimized muscle fatigue.