Detecting and treatment of sleep apnea

• US 20130197376A1
• Filed: 01/19/2013
• Published: 08/01/2013
• Est. Priority Date: 10/01/2001
• Status: Active Grant

• Current Assignee: Eckhard Alt, Maik Gollasch
• Original Assignee: Eckhard Alt, Maik Gollasch
• Inventors: Alt, Eckhard, Gollasch, Maik
• Granted Patent: US 8,781,587 B2
• Time in Patent Office: Days
• US Class Current: 600/484
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61N 1/3601 of respiratory organs
• CPC Class Codes: A61N 1/3611 Respiration control stimulating respiratory organs A61N1/3601
• CPC Class Codes: A61N 1/36128 Control systems

Abstract

A device is presented for evaluating whether an episode of sleep apnea is occurring in a patient suffering from chronic sleep apnea disorder, for delivery of appropriate therapy. The device includes circuitry adapted to respond to a cardiac signal generated by the heart. Switching circuitry diverts passage of the heart signal through both a high impedance path and a substantially lower impedance path, and a differential amplifier processes the resulting signal pairs to ascertain the difference in magnitude between the two signals of each pair. An analyzer thereof determines changes in the patient'"'"'s ventilation, from which inordinately reduced patient ventilation is detected to assess possible occurrence of an episode of sleep apnea. If the analyzer denotes change of ventilation between otherwise regular respiratory cycles, an actual episode of sleep apnea is indicated. A stimulus generator responds to such indication to generate an appropriate electrical therapy for delivery to a preselected location in the patient'"'"'s body to induce ventilation so as to terminate the apnea episode.

Claims

1. A device for detecting sleep apnea in a patient, comprising:

circuitry adapted to respond to the EKG signal generated by the patient'"'"'s heart for diverting the EKG signal in separate paths of high input impedance and of considerably lower impedance to produce two different signals, and a differential amplifier of said two signals for differential amplification thereof to detect changes in the patient'"'"'s ventilation, from which to identify inordinately reduced ventilation as a potential episode of sleep apnea.

2. The device of claim 1, including:

means for sensing consecutive respiration cycles from said detected changes of patient ventilation, and responsive thereto for establishing a predetermined escape interval of time between pairs of successive respiration cycles and for resetting said escape interval upon sensing each respiration cycle, so as to detect a sustained absence of ventilation upon expiration of a said escape interval without having detected a next following respiration cycle, as indicative of an actual episode of sleep apnea; and

a stimulator for generating electrical stimulation therapy to restore patient ventilation in response to said indication of an actual episode of sleep apnea.

3. The device of claim 1, further including:

a stimulator for generating electrical stimulation therapy to restore adequate patient ventilation in response to determination of said potential episode as being an actual episode of sleep apnea, and

an implantable electrical stimulus transmission system adapted to be coupled to said stimulator for delivering said electrical stimulation therapy to a preselected nerve of the patient in response to said actual episode of sleep apnea, for restoration of patient ventilation.

4. The device of claim 1, wherein:

said circuitry provides said separate paths by alternately shunting said high input impedance path with said considerably lower input impedance path at a relatively high switching rate selected for sufficient resolution to detect patient ventilation and changes therein.

5. The device of claim 1, including:

an electrical signal transmission system adapted to be coupled to said circuitry for delivering said EKG signal thereto from a site of the patient'"'"'s body remote from the site of the patient'"'"'s heart.

6. The device of claim 3, wherein:

an electrical signal transmission system adapted to be coupled to said circuitry for delivering said EKG signal thereto from a site of the patient'"'"'s body in the immediate vicinity of the site at which said electrical stimulation is to be delivered to said preselected nerve.

7. The device of claim 1, wherein:

said episode of sleep apnea is of a type among central sleep apnea (CSA), Cheyne-Stokes Respiration (CSR)-induced apnea, and obstructive sleep apnea (OSA),

said device includes means for distinguishing between an episode of CSA/CSR as constituting one type for treatment purposes and an episode of OSA as constituting another type for treatment purposes, and further including

an implantable electrical stimulus transmission system adapted to be coupled to said stimulator for delivering said electrical stimulation therapy in a manner according to which of said one type and said another type is present in said distinguished episode.

8. The device of claim 7, wherein:

said distinguishing means distinguishes an episode of CSA/CSR type from an episode of OSA type of sleep apnea disorder by determining whether ventilation is identified as completely absent or partly present, respectively.

9. The device of claim 7, wherein:

said distinguished episode is of CSA/CSR type, and

said stimulator is adapted to respond thereto by generating therapy for stimulating the patient'"'"'s phrenic nerve with electrical pulses in a pattern for diaphragmatic pacing to restore proper respiration.

10. The device of claim 7, wherein:

said distinguished episode is of OSA type. and

said stimulus transmission system is adapted to respond thereto by applying stimulation pulses to one of a glossopharyngeal nerve and a hypoglossus nerve whereby to move the soft palate from blockage of the patient'"'"'s airway.

11. The device of claim 6, wherein:

at least one electrode is shared by said electrical signal transmission system and said electrical stimulus transmission system for use in both said sensing and said stimulation.

20. The device of claim 3, including wherein:

said preselected nerve is one of the patient'"'"'s phrenic nerve and a nerve associated with muscle of the soft palate in the patient'"'"'s throat, according to the type of sleep apnea present in said actual episode.

21. The device of claim 3, wherein said nerve is a phrenic nerve.

22. The device of claim 3, wherein said nerve is a glossopharyngeal nerve.

23. The device of claim 3, wherein said nerve is a hypoglossus nerve.

24. The device of claim 7, wherein:

said distinguished episode is of OSA type, and said stimulus transmission system is adapted to respond by applying stimulation pulses directly to muscle of the patient'"'"'s soft palate.

12. (canceled)

13. An implantable device adapted to evaluate whether an episode of sleep apnea is occurring in a patient, comprising:

a signal processor adapted to respond to the electrical signal generated by the patient'"'"'s heart as its sole input to acquire separate high and low input impedance signals therefrom, and

a differential amplifier for differentially amplifying the high and low input impedance signals to determine ventilation of the patient and to assess therefrom whether an episode of sleep apnea has commenced.

14. The implantable device of claim 13, including:

a stimulator for generating electrical therapy adapted to stimulate a predetermined nerve of the patient when the assessment indicates an episode of sleep apnea has commenced, for restoring adequate ventilation.

15-19. -19. (canceled)

25. A device for detecting sleep apnea in a patient, comprising:

an input section adapted to receive a sensed electrical signal constituting the EKG signal generated by the patient'"'"'s heart; and

circuitry adapted for processing the sensed signal to detect changes in thoracic impedance reflecting the patient'"'"'s ventilation therefrom, and for analysis of the detected impedance changes to determine whether and when the patient is experiencing sleep apnea, whereby only electrical energy produced by the heart serves as input signal to detect said impedance changes.

26. The device of claim 25, wherein the processing of the sensed signal by said circuitry is performed to detect dynamic impedance changes for evaluation of patient ventilatory status.

27. The device of claim 25, wherein said circuitry includes means for distinguishing between sleep apnea of CSA/CSR type and sleep apnea of OSA type.

28. The device of claim 25, wherein said analysis of detected impedance changes enables determination of patient ventilatory status including number of breaths by the patient and depth of each breath corresponding with its tidal volume, whereby to enable threshold detection of ventilation and not merely detection of a total absence of breathing.

29. A device for treating sleep apnea in a patient, comprising:

an input section adapted to receive a sensed electrical signal constituting the EKG signal generated by the patient'"'"'s heart;

circuitry adapted for processing the sensed signal to detect changes in thoracic impedance reflecting the patient'"'"'s ventilation therefrom, and for analysis of the detected impedance changes to determine whether and when the patient is experiencing sleep apnea, whereby only electrical energy produced by the heart serves as input signal to detect said impedance changes; and

a stimulator responsive to a determination of sleep apnea for generating a predetermined electrical stimulus to be applied to a preselected nerve of the patient to restore an adequate breathing pattern.