Obviousness

Obviousness Analysis of US Patent 10,898,709 Under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US patent 10,898,709 obvious to a person having ordinary skill in the art (PHOSITA) at the time of the invention (priority date: March 19, 2015). The discussion will focus on the key inventive concepts as described in the patent's "Definitions," particularly the asynchronous stimulation protocol and the convertible operation between synchronous and asynchronous modes based on sensor signal quality.

Background: Known Prior Art

Prior to the priority date of US10898709, several key aspects of sleep disordered breathing treatment via nerve stimulation were well-established:

• Hypoglossal Nerve Stimulation (HGNS) for Obstructive Sleep Apnea (OSA): Direct electrical stimulation of the hypoglossal nerve to alleviate OSA by maintaining upper airway patency was known. The Inspire Medical Systems hypoglossal nerve stimulator, for instance, received FDA approval in 2014, and its operation was primarily described as being synchronized with respiration.
• Synchronous Stimulation: Methods and apparatus for closed-loop stimulation of the hypoglossal nerve, synchronized with respiration based on various physiological variables (e.g., hypopharyngeal/esophageal pressure, airflow measurements), were disclosed by patents like US 6,587,725 B1 to Christopherson et al.. This patent also describes sensing hypoglossal nerve activity to detect or predict OSA and trigger stimulation.
• Respiratory Sensing: Devices and methods for recognizing and detecting features and patterns associated with respiratory effort, flow limitations, and the beginning and end of inspiratory and expiratory phases were known, as explicitly referenced in US10898709, citing PCT Publication WO/2010/059839 and US 5,944,680 to Christopherson.
• Adaptive Neurostimulation: The concept of automatically adjusting neurostimulation parameters based on sensed physiological inputs, such as body position or activity (e.g., using accelerometers), was known in other neurostimulation contexts, as shown in "Automatic Adaptation of Neurostimulation Therapy in Response to Changes in Patient Position" (2008).

Obviousness Argument 1: Asynchronous Stimulation Protocol

US10898709 claims a method of applying nerve stimulation according to a "first stimulation protocol not synchronized relative to sensed respiratory information" where each stimulation cycle includes a stimulation period and a non-stimulation period, with the stimulation period having a minimum duration equal to or greater than an inspiratory reference derived from a reference respiratory cycle.

Combination of Prior Art:

1. US 6,587,725 B1 (Christopherson et al.): This patent establishes the core technology of implantable systems for hypoglossal nerve stimulation to treat OSA, including the use of respiratory sensing to trigger synchronous stimulation.
2. "The 5 faces of flow in asynchronous hypoglossal nerve stimulation - PMC - NIH": This article, describing the behavior of an HGNS system approved in 2014, explicitly states that "If the sensing lead cannot adequately detect thoracic pressure changes, it will revert to a pacer-like mode (4 seconds on, 1 second off) which can produce periods of asynchronous stimulation".

Motivation to Combine:
A person having ordinary skill in the art (PHOSITA) in 2015 would be aware of the benefits of synchronous HGNS (US 6,587,725 B1) for OSA, as well as the practical challenges of maintaining reliable real-time respiratory sensing, which could lead to a loss of synchronization. The "The 5 faces of flow..." article describes a known fallback mechanism in commercial systems where asynchronous stimulation (e.g., "4 seconds on, 1 second off") occurs when sensing is inadequate.

A PHOSITA would be motivated to formalize and optimize such an asynchronous stimulation mode to:

• Provide a robust alternative: When synchronous sensing is difficult, unreliable, or undesirable (e.g., due to power consumption or system complexity).
• Reduce system complexity and cost: By reducing or eliminating the need for real-time respiratory synchronization hardware and algorithms.
• Minimize muscle fatigue: By incorporating non-stimulation periods while still ensuring therapeutic efficacy.

Knowing that an asynchronous "4 seconds on, 1 second off" pattern could produce stimulation periods when sensing failed, a PHOSITA would find it obvious to design such an asynchronous protocol to deliberately ensure therapeutic effect. This would involve selecting stimulation period durations that are long enough to reliably overlap the inspiratory phase of a typical breath, even without real-time synchronization. The concept of using an "inspiratory reference" based on a "reference respiratory cycle" (e.g., a patient-specific or multi-patient average for stable respiration, which can be derived from existing sensing methods like those in US 5,944,680) to set these durations would be an obvious engineering choice to maximize therapeutic benefit while minimizing stimulation volume.

Therefore, implementing a stimulation protocol with alternating stimulation and non-stimulation periods, not synchronized to real-time respiration, but designed to overlap inspiration based on physiological averages to ensure efficacy and reduce fatigue, would be obvious in light of the known asynchronous fallback modes and the existing knowledge of respiratory physiology.

Obviousness Argument 2: Convertible Operation

US10898709 claims a method involving (a) an asynchronous first stimulation mode, (b) a synchronous second stimulation mode, and (c) automatically converting between these modes "upon at least one parameter of the sensed respiratory waveform meeting or failing to meet a sensor signal quality criteria."

Combination of Prior Art:

1. US 6,587,725 B1 (Christopherson et al.): This patent clearly teaches the synchronous stimulation mode for HGNS, driven by respiratory sensing.
2. "The 5 faces of flow in asynchronous hypoglossal nerve stimulation - PMC - NIH": This article explicitly describes an existing HGNS system that, "If the sensing lead cannot adequately detect thoracic pressure changes, it will revert to a pacer-like mode (4 seconds on, 1 second off) which can produce periods of asynchronous stimulation". This directly discloses the automatic conversion from a synchronous mode to an asynchronous mode when "sensor signal quality criteria" (inability to adequately detect pressure changes) are not met.
3. US 2011/0264164 (Christopherson) and "Automatic Adaptation of Neurostimulation Therapy in Response to Changes in Patient Position": These references demonstrate the general concept of automatically adjusting neurostimulation therapy based on physiological parameters or conditions.

Motivation to Combine:
A PHOSITA would be motivated to develop a system that intelligently manages therapy delivery. The "The 5 faces of flow..." article demonstrates that existing synchronous HGNS systems already incorporated a basic form of convertible operation: switching to an asynchronous mode when sensor input for synchronization became unreliable.

A PHOSITA would find it obvious to:

• Formalize the switching mechanism: Recognizing the value of both synchronous (optimal) and asynchronous (robust fallback) modes, it would be obvious to design a system that explicitly switches between them based on a defined "sensor signal quality criteria." The article's mention of "cannot adequately detect thoracic pressure changes" serves as such a criterion.
• Implement bidirectional switching: If a system reverts to asynchronous mode upon sensor failure, it is an obvious extension to revert back to synchronous mode once sensor quality improves and reliable synchronization can be re-established. This ensures that the patient benefits from the potentially more efficacious synchronous mode whenever possible, while maintaining continuous therapy during periods of sensor unreliability.
• Utilize the asynchronous mode proactively: The patent suggests using the independent mode initially to establish a stable respiratory pattern before switching to a lower-intensity, synchronized mode to minimize muscle fatigue. This is an obvious therapeutic strategy. If synchronous modes are known to be more effective but require a stable signal, and asynchronous modes can help stabilize respiration, a PHOSITA would logically combine these approaches to optimize overall therapy success and patient comfort. This reflects a common engineering principle of using a robust, less precise method to establish a baseline before transitioning to a more precise, condition-dependent method.

Therefore, the convertible operation between synchronous and asynchronous stimulation modes, triggered by sensor signal quality criteria, would be obvious to a PHOSITA given the known behavior of existing HGNS systems that already exhibit such a fallback mechanism, combined with the general understanding of adaptive neurostimulation.