Electrical stimulation for preservation and restoration of diaphragm function
Inventors
O'Mahony, John • Wethington, Patrick J.
Assignees
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Publication Number
US-10300272-B2
Publication Date
2019-05-28
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 stimulates a diaphragm to provoke motion during inspiration by stimulating the phrenic nerve with a stimulation signal at a set level during a single selected breath of a patient. For that inspiratory breath cycle, it obtains a measurement of the diaphragm work exerted by the patient and compares the measured diaphragm work to a selected range of diaphragm work values.
In response to the actual measurement of diaphragm work being outside the selected range, the invention modifies the stimulation signal. This closed-loop approach uses the actual diaphragm work value as feedback to adjust stimulation during subsequent operation of the ventilatory cycle.
The diaphragm work measurement is obtained from work-related measurements associated with airflow and pressure generated by the patient’s lungs, using lung mechanics including lung compliance and lung resistance. The work measurement can be sensed over a plurality of breaths and an average work measurement can be determined across those breaths, and the stimulation signal can be modified in a manner associated with training the patient’s diaphragm through reducing the stimulation signal.
Claims Coverage
The independent claim set includes 1 independent method claim that defines selecting a single breath, stimulating the phrenic nerve at a set level, measuring diaphragm work for that inspiratory breath cycle, and modifying the stimulation when the measured work is outside a selected range. Additional claim features refine lead-based implementation details and more specific diaphragm-work measurement approaches, including averaging across multiple breaths and diaphragm training via reduced stimulation levels.
Phrenic-nerve stimulation during a single selected breath with diaphragm-work feedback
Stimulation of the phrenic nerve with a stimulation signal at a set level during a single selected breath of the patient; obtaining a measurement of the diaphragm work exerted by the patient for an inspiratory breath cycle of the selected breath; and modifying the stimulation signal in response to the actual value of the measurement of the diaphragm work being outside of a selected range of a value of diaphragm work exerted by the patient.
Lead-type identification by resistance characteristic and stimulation configuration
Stimulating the patient’s phrenic nerve by applying an electrical stimulation signal via an electrical lead; identifying the electrical lead type from its resistance characteristic; and configuring the stimulation signal according to the identified lead type.
Diaphragm-work measurement using airflow and pressure from lung mechanics
Obtaining a measurement of the work exerted by the patient by determining work using airflow and pressure generated by the patient’s lungs based on lung mechanics, including lung compliance and resistance.
Average diaphragm-work measurement across a plurality of breaths
Sensing work characteristics over a plurality of breaths taken by the patient and determining an average work measurement across those breaths.
Training by modifying stimulation through reduced stimulation levels
Modifying the stimulation signal by training the patient’s diaphragm through reducing the stimulation signal to a reduced level determined for operating the diaphragm of the patient.
Reduced stimulation level below gross-motion threshold in a normal healthy patient
Specifying that the reduced stimulation level is below the stimulation level required to obtain gross diaphragm and lung motion in a normal healthy patient.
Overall, the claim coverage is centered on stimulating the phrenic nerve during a single selected breath at a set level, measuring diaphragm work for the corresponding inspiratory breath cycle, and modifying the stimulation signal when the measured diaphragm work falls outside a selected range. Additional claim features refine lead-type configuration via resistance characteristic, diaphragm-work estimation using airflow and pressure and lung mechanics, optional averaging across multiple breaths, and diaphragm training using reduced stimulation levels below a threshold for gross motion in a normal healthy patient.
Stated Advantages
Provides diaphragm-work feedback to modify the stimulation signal when diaphragm work is outside a selected range.
Supports lead-type robustness by identifying the electrical lead type from its resistance characteristic and configuring stimulation accordingly.
Enables diaphragm-work measurement using airflow and pressure generated by the patient’s lungs based on lung mechanics including lung compliance and resistance.
Allows measurement over multiple breaths by determining an average work measurement.
Enables diaphragm training by reducing the stimulation signal to a reduced level.
Trains using a reduced stimulation level below a stimulation level required to obtain gross diaphragm and lung motion in a normal healthy patient.
Documented Applications
Percutaneous Electrical Phrenic Nerve Stimulation (PEPNS) for patients on mechanical ventilation.
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