Electrical stimulation for preservation and restoration of diaphragm function
Inventors
O'Mahony, John • Wethington, Patrick J.
Assignees
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Publication Number
US-11052250-B2
Publication Date
2021-07-06
Expiration Date
Abstract
A system and method are presented that electrically stimulates the phrenic nerve whereby said stimulation results in muscle activation of the diaphragm as observed by a measurement of work or power of breathing associated with the inspiratory portion of a stimulated breath.
Core Innovation
The invention provides a Percutaneous Electrical Phrenic Nerve Stimulation (PEPNS) system for mechanically ventilated patients in which a stimulator/controller delivers non-permanent percutaneous/subcutaneous electrical stimulation to positions proximate at least one phrenic nerve. The stimulator circuit delivers a stimulation signal at a set level during an inspiratory breath cycle and coordinates the stimulation with ventilator-measured inspiratory and expiratory phases. Multipolar electrode leads are positioned near the phrenic nerve and stimulation is managed relative to trigger events detected from the ventilator circuit.
To quantify patient effort, an instrumented wye flow/pressure sensor in the ventilator circuit provides wye flow and wye pressure measurements, which are used to compute diaphragm work or diaphragm work/work-of-breathing (WOB). The system models predicted versus measured wye pressure using lung compliance and lung resistance and determines a diaphragm work measurement for an inspiratory breath cycle. Stimulation is modified in response when the diaphragm work measurement is outside a selected range of diaphragm work.
The system also selects specific breaths and controls timing such that diaphragm work is measured for stimulated breaths only, using a predecessor/companion breath approach. Stimulation is initiated at an inspiratory trigger event and ended at an end inspiratory trigger event corresponding to specific flow conditions, while accumulating the stimulation inspiratory period in real time and using safety/alarm concepts for erroneous triggering or stimulation conditions.
Overall, the core concept is coupling phrenic nerve stimulation with ventilator-based instrumented wye sensing to measure diaphragm work and to control stimulation so it remains within a selected diaphragm-work range and is applied beginning and ending according to trigger events derived from wye flow.
Claims Coverage
Two independent claims are identified. The first claim covers modifying a set-level phrenic nerve stimulation signal based on a diaphragm-work measurement being outside a selected diaphragm-work range, while the second claim covers subcutaneous phrenic-nerve electrode stimulation coordinated with instrumented wye flow trigger events, including real-time inspiratory-period accumulation and end-of-inspiration termination.
Modify stimulation based on diaphragm work outside a selected range
A stimulator circuit stimulates the phrenic nerve with a stimulation signal at a set level during a breath, and a sensor circuit measures diaphragm work exerted for an inspiratory breath cycle; the stimulator circuit is configured to modify the stimulation signal in response to the diaphragm-work measurement being outside of a selected range of diaphragm work.
Subcutaneous phrenic-nerve electrode pair with instrumented wye trigger and real-time inspiratory-period control
A subcutaneous electrode pair positioned proximate at least one phrenic nerve; an instrumented wye sensor circuit provides wye flow and wye pressure measurements; and the stimulator circuit delivers electrical stimulation to the electrode pair at a pulse repetition rate, with a current and a waveform sufficient to at least partially activate the diaphragm at the beginning of an inspiratory event in response to an inspiratory trigger event corresponding to flow rate, accumulates the stimulation inspiratory period in real time from the beginning of the inspiration event, and ends stimulation at the end of an inspiratory event triggered by an end inspiratory trigger event corresponding to a specific flow.
Claim coverage centers on measuring diaphragm work and modifying the stimulation signal when the measurement is outside a selected diaphragm-work range, and coordinating stimulation of a subcutaneous electrode pair near the phrenic nerve with instrumented wye flow trigger events, including real-time accumulation of the stimulation inspiratory period and ending stimulation at an end-inspiratory trigger event.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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