Obviousness

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.