US20060030894A1 - Breathing disorder detection and therapy device for providing intrinsic breathing - Google Patents

Abstract

A device and method are provided for managing the treatment of a patient with respiratory disorders or symptoms. Respiratory parameters are sensed and recorded and communicated to an external device to provide information to a patient and/or provider for further treatment or diagnosis. Also respiratory disorders such as apnea or hypoventilation may be treated by electrically stimulating the diaphragm muscle or phrenic nerve in response to a sensed respiratory parameter or characteristic.

Description

FIELD OF THE INVENTION
• The invention relates to a device and method for detection, diagnosis and treatment of breathing insufficiencies or irregularities and to the management of pulmonary rhythm. Such irregularities may include, for example, hyperventilation, hypoventilation and apnea. The invention also relates to stimulating respiration in response to detecting hypoventilation or apnea.
BACKGROUND OF THE INVENTION
• Breathing insufficiencies and irregularities may occur in conjunction with or as a result of a variety health related disorders and may further cause or exacerbate health disorders. Such breathing insufficiencies and irregularities may include, for example, hyperventilation, hypoventilation, apnea, and other related breathing disorders. Hyperventilation, which results in hyperoxia, is a condition in which the respiratory rate is pathologically high or is above a desired rate. Hyperventilation may occur due to pulmonary edema or excess fluid built up in the lungs and may ultimately result in apnea episodes. Hypoventilation is a condition in which the respiratory rate is pathologically low or below a desired rate. Apnea (absence of breathing) is a breathing disorder most typically occurring during sleep that can result from a variety of conditions. Sleep apnea typically results in some sort of arousal or wakefulness following cessation of breathing.
• Sleep disordered breathing disorders include two types of sleep apnea: obstructive sleep apnea (partial apnea or obstructive apnea) and central sleep apnea. Obstructive sleep apneas result from narrowing of the pharynx with out-of-phase breathing in an effort to create airflow, whereas central sleep apnea arises from reductions in central respiratory drive. During obstructive sleep apnea, respiratory effort increases. In central sleep apnea, respiratory movements are absent or attenuated but in phase.
• Disordered breathing may contribute to a number of adverse cardiovascular outcomes such as hypertension, stroke, congestive heart failure, and myocardial infarction. Sleep-related breathing disorders, especially central sleep apnea, have been found to have a relatively high prevalence in patients with heart failure and may have a causative or influencing effect on heart failure. In about 50% of patients with stable congestive heart failure, there is an associated sleep disordered breathing, predominantly central sleep apnea with a minority having obstructive sleep apnea. Furthermore, sleep related breathing disorders are believed to be physiologically linked with heart failure. Central sleep apnea is a known risk factor for diminished life expectancy in heart failure. It is also believed that in view of this link, treatment aimed at relieving sleep related breathing disorders may improve cardiovascular outcomes in patients with heart failure.
• Pulmonary edema, a condition in which there is excess fluid in the lungs and often found in heart failure patients, is believed in some circumstances to lead to hyperventilation and hyperoxia or apnea. Most heart failure patients with central sleep apnea, when lying flat, tend to have central fluid accumulation and pulmonary congestion, which stimulates vagal irritant receptors in the lungs to cause reflex hyperventilation. Central Sleep Apneas usually are initiated by reduction in PCO₂resulting from the increase in ventilation. When PCO₂falls below the threshold level required to stimulate breathing, the central drive to respiratory muscles and airflow cease or diminish significantly and apnea (or attenuated breathing) ensues until the PCO₂rises again above the threshold required to stimulate ventilation. Often spontaneous arousal occurs with apnea.
• Currently a number of methods are used to treat sleep apnea. For example, supplemental oxygen such as, e.g., with a nasal ventilator, has been used to relieve symptoms of sleep apnea. Non-invasive airway pressure including continuous positive airway pressure (CPAP), bivalve and adaptive pressure support servo-ventilation have been used to treat central sleep apnea and obstructive sleep apnea with varying results. Another method to treat central sleep apnea is using aggressive diuresis to lower cardiac filling and beta-blocker and angiotensin-converting enzymes. However, this treatment does not lead to an optimum therapy since excessive use of diuretics leads to renal complications and patient discomfort.
• A method and apparatus for treatment of obstructive sleep apnea has been proposed where an implantable pulse generator stimulates a nerve in the upper airway tract of a patient to elicit a contraction by an innervated muscle through the provision of electrical stimuli. The stimulator is intended to treat the obstructed airway passage to permit breathing. The pulse generator is attached to electrodes placed on the patient's diaphragm for sensing the respiratory effort of a patient whereupon the stimulation is adjusted. The method and apparatus do not provide a satisfactory treatment or central sleep apnea.
• Phrenic nerve stimulation has been used to stimulate the diaphragm throughout an overnight period to treat sleep apnea. The device used was turned on at night to stimulate the nerve continuously and then turned off during the day. However, this device was not adapted for situations where patients would breath spontaneously.
• Accordingly it would be desirable to provide a method and apparatus for treating breathing disorders such as apnea, and hypoventilation, and especially central sleep apnea. Furthermore it would be desirable to provide treatments for breathing related disorders related pulmonary edema and conditions in heart failure patients.
SUMMARY OF THE INVENTION
• The present invention provides a method and apparatus for treating breathing disorders by sensing the respiratory parameters of the diaphragm and stimulating an associated body organ or tissue to control movement of the diaphragm and thus manage respiration. In a variation the method and apparatus provide stimulation to the diaphragm to elicit diaphragm movement to cause respiration when respiration ceases or falls below a threshold level.
• One embodiment is a device comprising: a sensor for sensing information corresponding to respiratory effort of the diaphragm and a processor for processing the sensed information and delivering electrical stimulating pulses to the associated body organ or tissue based on sensed information. The processor may further determine stimulation parameters based at least in part on sensed information. Also, the processor may determine when to cease stimulation by determining when the body resumes normal respiratory function.
• The respiratory effort may be sensed, for example, by sensing the phrenic nerve activity and/or the EMG of the diaphragm, or by detecting movement of the diaphragm or chest. Respiration by, the diaphragm may be stimulated by electrically stimulating the phrenic nerve and/or by stimulating the diaphragm muscle.
• A number of different parameters may be programmed into the processor to determine if certain breathing disorders are present, and when and how to stimulate respiration, and when to stop or modify stimulation.
• Phrenic nerve or EMG activity sensed may include, for example, amplitude, frequency, and waveform to determine central respiratory efforts, the absence, a decrease in amplitude, abnormalities in frequency and/or amplitude, or waveform morphology of which may indicate the onset of apnea, hyperventilation, or hypoventilation. The nerve activity may be compared to predetermined activity levels or patient historical activity. Similarly, diaphragm EMG amplitude, frequency, waveform morphology and history may be used to determine apnea, hyperventilation and hypoventilation. For example, the nerve activity at the onset of sleep or after a given time in a reclining position, may be used as a baseline or comparison.
• An awake sinus zone may be defined as a respiratory rate or range of races programmed into the device for a specific patient when awake, where the respiratory race is considered normal and intrinsic. A preprogrammed EMG amplitude or range may define a normal rance in this state. A sleep sinus may be defined as a respiratory rate or range of rates programmed into the device for a specific patient when asleep where the respiratory rate is considered normal and intrinsic. A preprogrammed EMG amplitude or range may define a normal range in this state. The device may be programmed to match the EMG rate and amplitude to a normal rate and amplitude by auto adjusting the pace output.
• Hypoventilation may be detected where the respiratory rate or frequency falls below a programmed rate. Hyperventilation may be detected when the respiratory rate or frequency is above a programmed rate. Complete apnea or central apnea is defined as a condition where there is no effective EMG signal or phrenic nerve signal, i.e. where there is no effective or significant physiological response. Frequently, a hyperventilation episode is followed by loss of diaphragm EMG or phrenic nerve activity. The device may be programmed to first detect the hyperventilation and wait for a preprogrammed time to be considered apnea. For example the time may be set to 10-20 seconds of lost EMG after a hyperventilation episode to detect complete apnea. Partial apnea or obstructive sleep apnea is defined to be present when the EMG or phrenic nerve activity is attenuated and may be detected when the amplitude drops below a programmed amount. For example such amount may be based on the EMG or phrenic nerve amplitude dropping a percentage, e.g. 50% of the Sleep Sinus EMG amplitude. Also the phase of the respiratory cycles in partial apnea may be determined or compared to an in phase cycle. An cut of phase or arrhythmic cycle may also be used to detect partial apnea.
• In addition, position sensors may be used to determine degree of patient reclining or standing, e.g., in increments of degrees. Information from the position sensor mart be used as a tool to match respiratory activities and patterns to the position of the patient. Accelerometer information may be used to determine information regarding patient's physical activity, e.g., to match/compare to the respiratory patterns and activities and collect data on related patient activities, respiratory activities, and create or adjust a treatment plan based thereon, (e.g., modification of diuretics or ACE inhibitors). Accelerometer sensors may also be used to determine information regarding movement pattern of the diaphragm muscles, intercostal muscles, and rib movement and thus determine overall respiratory activity and patterns.
• According to an embodiment, a stimulator includes an implantable controller coupled through leads to electrodes to be implanted on the diaphragm in the vicinity of the phrenic nerve branches. The electrodes may sense either nerve activity or EMG signals of the diaphragm. The stimulator may further include a pulse generator configured to deliver stimulating pulses, either to the same electrodes used for sensing or to additional stimulation electrodes. The stimulation electrodes may also be placed adjacent the phrenic nerve at some point along its length to provide stimulation pulse to the nerves, which in turn enervate the diaphragm muscle causing contractions and resulting respiration. Alternatively the electrodes may be placed on the phrenic nerve for both sensing and stimulation.
• Stimulation of respiration may be initiated when “no” or “attenuated” respiratory activity has been present or detected for a time period (when apnea is detected). The time period may be pre-programmed for a specific patient by the physician, as otherwise preset, or as determined a program in the treatment device. The device may be programmable for other breathing disorders, allowing slow or fast inspiration and visa versa allowing slow or fast expiration. For example, based on programmed parameters of the activity sensor, for patients suffering from hypoventilation, the inspiration rate may be increased or decreased based on the level of activity.
• Pacing starts at given intervals. In one embodiment the interval time is initially about 10 seconds. The interval is slowly increased from 11 seconds to about 15 seconds. If the patient does not breath on their own, the pacing begins again at 10-second intervals and this is repeated. If the patient begins breathing on their own, typically where the PO₂and PCO₂levels are normalized and the brain resumes sending nerve stimulation. The system then returns to the mode where it is sensing respiratory effort.
• An additional feature of the invention may include a patient self-management module. The module can be an external device configured to telemetrically communicate with the implanted device. The module is configured to communicate information with the patient based on what is received from the implantable device. The information may also be communicated with a provider who can upload information regarding the status of the patient including urgent interventions. The device may include, paging, e-mail, fax or other communication capabilities that can send information to a clinician. The device can be worn or carried with the patient while the patient is away from home. The device may be used to prompt the patient to comply with life-style and medication based on programmed parameters by the provider. The device may require the patient to interact with the device confirming compliance. The provider may receive information on patient compliance.
• The information that may be downloaded for sleep apnea treatment may include, e.g., detection rate, detection amplitude, pacing therapy amplitude, pacing pulse width, pacing frequency or other stimulation waveform morphology. This information may be used to calibrate device detection and therapy parameters.
• The information that may be downloaded for pulmonary edema management (e.g., of hyperventilation rate and frequency of occurrence) may include the detections rate, detection amplitude, ventilation waveform morphology including slopes and surface of inspiration waveform, slopes and surface area of exhalation waveform, recorded respiratory waveform information in conjunction with activity and position sensors information. A provider may use the information in developing an optimum treatment plan for the patient including drug titrations for diuretic management as well as if patient is in need of urgent attention leading to hospitalization, which is a frequent occurrence with heart failure patients dealing with pulmonary edema. The patient compliance information may also be used for understanding the drug regimen effectiveness if patient complies or educate the patient when there is lack of compliance with the therapy plan.
DETAILED DESCRIPTION OF THE DRAWINGS
• FIG. 1 illustrates a sleet breathing disorder treatment device in accordance with the invention placed on the diaphragm.
• FIG. 5 illustrates an electrode assembly in accordance with the invention implanted on the abdominal side of the diaphragm.
• FIG. 3 illustrates a sleep breathing disorder treatment device in accordance with the invention placed on the phrenic nerves.
• FIG. 4 illustrates a sleep breathing disorder treatment device in accordance with the invention placed on the diaphragm and phrenic nerves.
• FIG. 5 illustrates a sleep breathing disorder treatment device in accordance with the invention placed on the phrenic nerves.
• FIG. 6 illustrates a processor unit of a sleep breathing disorder treatment device in accordance with the invention.
• FIG. 7A is a schematic of a signal processor of the processor unit in accordance with the invention.
• FIG. 7B is an example of a waveform of an integrated signal processed by the signal processor ofFIG. 7A.
• FIG. 8 is a schematic of an external device of a stimulator in accordance with the invention.
• FIGS. 9A-9D are flow diagrams of the operation of a stimulator in accordance with the invention.
• FIG. 9B is a flow diagram of sleep apnea treatment with a stimulator in accordance with the invention.
• FIG. 9C is a flow diagram of hypoventilation treatment with a stimulator in accordance with the invention.
• FIG. 9D is a flow diagram of hyperventilation treatment with a stimulator in accordance with the invention.
• FIG. 10A-10B are an illustration of a variety of stimulation bursts with different parameters (FIG. 10B) corresponding to different resulting EMG signals (FIG. 10A).
DETAILED DESCRIPTION OF THE INVENTION
• FIG. 1 illustrates astimulator20 comprisingelectrode assemblies21,22, each comprising a plurality ofelectrodes21a-dand22a-drespectively. Theelectrode assemblies21,22 are implanted in the diaphragm muscle so that one or more ofelectrodes21a-dand toelectrodes22a-dare approximately adjacent to one or more junctions of thephrenic nerves15,16, respectively, with thediaphragm18 muscle. Theelectrode assemblies21,22 sense and pace at the diaphragm muscle. They are implanted laparoscopically through the abdomen and into the muscle of thediaphragm18 with needles or other similar devices. Theelectrode assemblies21,22 may be anchored with sutures, staples, or other anchoring mechanisms typically used with implantable EMG electrodes. The leads23,24 coupling theelectrode assemblies21,22 to thecontrol unit100 are then routed subcutaneously to the side of the abdomen where a subcutaneous pocket is created for thecontrol unit100. Theelectrode assemblies21,22 are each flexible members (such as neurostimulation leads) withelectrodes21a-d, assembled about 5-20 mm apart from one another andelectrodes22a-dassembled about 5-20 mm apart from one another. Theelectrode assemblies21,22 are coupled via leads23,24 to controlunit100. Thecontrol unit100 is configured to receive and process signals corresponding to sensed nerve activity, and/or EMG of thediaphragm18, to determine the respiratory parameters of thediaphragm18 as described in more detail herein with reference to FIGS.6,7A-7B and9A-9D.
• Theelectrodes assemblies21,22 are coupled via leads23,24 to input/output terminals101,102 of acontrol unit100. The leads23,24 comprise a plurality of electrical connectors and corresponding lead wires, each coupled individually to one of theelectrodes21a-d,22a-d. Thecontrol unit100 is implanted subcutaneously within the patient, for example in the chest region on top of the pectoral muscle. Thecontrol unit100 is configured to receive sensed nerve electrical activity from theelectrode assemblies21,22, corresponding to respiratory effort of a patient. Thecontrol unit100 includes a processor105 (FIG. 6) that delivers stimulation to thenerves15,16 ordiaphragm18 in response to a sensed degree or absence of diaphragm respiratory effort as determined and processed by theprocessor105 andcontrol unit100 as described in more detail herein with reference to FIGS.6,7A-7B and9A-9D.
• Thestimulator20 also comprisesmovement detectors25,26, in this example, strain gauges included with theelectrode assemblies21,22 respectively and electrically connected through leads23,24 to thecontrol unit100. Themovement detectors25,26 detect movement of thediaphragm18 and thus the respiratory effort exerted by thediaphragm18. Themovement detectors25,26 sense mechanical movement and deliver a corresponding electrical signal to thecontrol unit100 where the information is processed by theprocessor105. The movement may be used to qualify the electrical phrenic nerve or EMG signal sensed by the device to confirm inspiration or exhalation is occurring, e.g., by matching mechanical and electrical activities of the diaphragm.
• Electrodes may be selected from the plurality ofelectrodes21a-dand22a-d(orelectrodes41a-h,42a-h,61a-d,62a-d,71a-d,72a-din the other examples described herein) once implanted, to form bipolar or multipolar electrode pairs or groups that optimize the stimulation response. Such desired response may include tidal volume, breathing rate and the slopes of the inhalation and exhalation curves. For example, a timed series of pulses may be used to create a desired respiratory inhalation and/or exhalation period. Testing the response may be done by selecting a bipolar electrode pair from two of the multiple electrodes in an assembly or any other combination of electrodes to form at least one closed loop system, by selecting sequence of firing of electrode groups and by selecting stimulation parameters. The electrodes may be selected by an algorithm programmed into the processor that determines the best location and sequence for stimulation and/or sensing nerve ard/or EMG signals, e.g., by testing the response of the electrodes by sensing respiratory effort in response to stimulation pulses. Alternatively, the selection process may occur using an external programmer that telemetrically communicates with the processor and instructs the processor to cause stimulation pulses to be delivered and the responses to be measured. From the measured responses, the external programmer may determine the optimal electrode configuration, by selecting the electrodes to have an optimal response to a bipolar or multipolar delivery of stimulation.
• FIG. 2 illustrates adiaphragm electrode assembly40 in accordance with the invention for placement on thediaphragm18 for sensing and/or stimulation of the diaphragm and/or phrenic nerve endings located in thediaphragm18. Theassembly40 comprises aright loop41 and aleft loop42, each loop comprising a plurality ofelectrodes41a-hand42a-h, each having individual connectors and leads that form leads43,44 coupled to thecontrol unit100. Theloops41,42 are similar to electrode assembles41,42 in that the electrodes are selectable by thecontrol unit100 to form electrode pairs, multiple electrode pairs, or multipolar electrode groups.FIG. 2 illustrates rightphrenic nerve endings15aand leftphrenic nerve endings16aas well as the right phrenic nerveanterior branch15b, and left phrenic nerveanterior branch16b, located on the diaphragmabdominal surface18s. Theloops41,42 are flexible and are placed on theabdominal surface18sof thediaphragm18 on theright diaphragm18rand left diaphragm18l, respectively adjacent the rightphrenic nerve endings15aand leftphrenic nerve endings16arespectively. The flexibility of theloops41,42 permits the ability to form the loops is the shape most ideally suite for a particular patient. Theloops41,42 are attached to thediaphragm18 with sutures, staples orother attachment devices19. Other shapes may be used as well, e.g. a loop with a branch that extends to the region adjacent theanterior branches15b,16bof the phrenic nerve. Thecontrol unit100 may be programmed to activate the electrodes in a sequence that is determined to elicit the desired response from thediaphragm18 as described above with reference toelectrodes21a-d,22a-dandFIG. 1.
• Referring toFIG. 3, a breathingdisorder treatment apparatus60 according to the invention is illustrated. Theapparatus60 comprises right and leftelectrode assemblies61,62 each comprising a plurality ofelectrodes61a-61dand62a-62drespectively. Theelectrodes assemblies61,62 are illustrated attached to the right and leftphrenic nerves15,16, respectively at a location in the neck17. The electrode assembly may be a curved cuff electrode that can be placed around the nerve. Procedures for accessing and attaching such electrode assemblies are generally know, for example, as described inPhrenic Nerve Stimulation For Diaphragm Pacing With a Spiral Cord Stimulator, Sur. Neurol 2003:59: 128-32.
• FIG. 4 illustrates thedevice60 of toFIG. 3 withelectrode assemblies61,62 alternatively positioned within thethorax19 on thephrenic nerves15,16. Theelectrode assemblies61,62 are placed thoracoscopically on the phrenic nerve using a procedure similar to that described inThoracoscopic Placement of Phrenic Nerve Electrodes for Diaphragmatic Pacing in Children; Journal of Pediatric Surgery, Vol. 37, into 7 (July), 2002: pp 974-978. Theelectrode assemblies61,62 are located between the third and fourth rib within thethorax19. Thestimulator60 is used in a similar manner in thisFIG. 4 as it is with reference toFIG. 3.
• FIG. 5 illustrates astimulator70 in accordance with the invention. The stimulator comprises stimulatingelectrode assemblies71,72 implanted in the diaphragm in a manner similar to that described above with reference toelectrode assemblies71,72 inFIG. 1. Theelectrode assemblies71,72 includeelectrodes71a-d,72a-d, configured to deliver stimulating pulses to the diaphragm and or phrenic nerve branches or junctions with the diaphragm to elicit a breathing response by causing the diaphragm to move. Thestimulator70 further compriseselectrode sensor assemblies75,76 placed on the phrenic nerve at the throat in a surgical procedure similar to that described above with reference toFIG. 1 andelectrode assemblies71,72. Thesensor assemblies75,76 comprise a plurality of electrodes that are positioned and configured to sense electrical activity of the phrenic nerve to determine central respiratory effort. In response to sensed respiratory effort, thecontrol unit100 supplies EMG and/or nerve stimulation to the muscles of thediaphragm18 and/or thephrenic nerve endings15,16 located in thediaphragm18.
• FIG. 6 illustrates animplantable control unit100. Thecontrol unit100 includes electronic circuitry capable of generating and/or delivering electrical stimulation pulses to the electrodes ofelectrode assemblies21,22,41,42,61,62,71,72 throughleads23,24,43,44,63,64,73,74 respectively to cause a diaphragm respiratory response in the patient. For purposes of illustration, inFIG. 6, thecontrol unit100 is illustrated coupled to throughleads23,24 toelectrode assemblies21,22 respectively. Other leads41,42,61,62,71,72 as described herein may be connected toinputs101,102.
• Thecontrol unit100 comprises aprocessor105 for controlling the operations of thecontrol unit100. Theprocessor105 and other electrical components of the control unit are coordinated by an internal clock110 and apower source111 such as, for example a battery source or an inductive coupling component configured to receive power from an inductively coupled external power source. Theprocessor105 is coupled to atelemetry circuit106 that includes atelemetry coil107, areceiver circuit108 for receiving and processing a telemetry signal that is converted to a digital signal and communicated to theprocessor105, and atransmitter circuit109 for processing and delivering a signal from theprocessor105 to thetelemetry coil107. Thetelemetry coil107 is an RF coil or alternatively may be a magnetic coil. Thetelemetry circuit106 is configured to receive externally transmitted signals, e.g., containing programming or other instructions or information, programmed stimulation rates and pulse widths, electrode configurations, and other device performance details. The telemetry circuit is also configured to transmit telemetry signals that may contain, e.g., modulated sensed and/or accumulated data such as sensed EMG activity, sensed nerve activity, sensed responses to stimulation, sensed position information, sensed movement information and episode counts or recordings.
• The leads23,24 are coupled toinputs101,102 respectively, of thecontrol unit100, with each lead23,24 comprising a plurality of electrical conductors each corresponding to one of the electrodes or sensors (e.g., strain gauge) of theelectrode assemblies23,24. Thus theinputs101,102 comprise a plurality of inputs, each input corresponding to one of the electrodes or sensors. The signals sensed by theelectrode assemblies21,22 are input into thecontrol unit100 through theinputs101,102. Each of the inputs are coupled to a separate input of a signal processing circuit116 (schematically illustrated inFIG. 6 as one input) where the signals are then amplified, filtered, and further processed, and where processed data is converted into a digital signal and input into theprocessor105. Each signal from each input is separately processed in thesignal processing circuit116.
• The EMG/Phrenic nerve sensing has a dual channel sensor. One corresponding to each lung/diaphragm side. However, sensing can be accomplished using a single channel as the brain sends signals to the right and left diaphragm simultaneously. Alternatively, the EMG or phrenic nerve collective may be sensed using a single channel. Either a dual channel or single channel setting may be used and programmed. The typical pulse width parameter will range from 0.5 ms to 10 ms in increments of 50 μs. The pulse amplitude is from about 0.1 v to 5 volts in increments of 100 μV. The refractory period is 1 to 10 seconds in increments of 1 second. As described in more detail with reference toFIGS. 10A-10B herein the system may adjust the pace, pulse, frequency and amplitude to induce or control rate of the various portions of a respiratory cycle, e.g. slope of inspiration, fast exhalation, exhalation and tidal volume. The system may also adjust the rate of the respiratory cycle.
• The system EMG memory is programmable to pre-trigger and post trigger lengths of storage for sleep apnea episodes. The pre-trigger events are the waveform signals and other sensed information observed transitioning to an event. Post-trigger events are the waveforms and other sensed information observed after an event and/or after treatment of an event, to observe how the device operated. Post-trigger recordings can confirm if the episode was successfully treated. The pre-trigger and post-trigger time periods can be preprogrammed into thecontrol unit100.
• Thecontrol unit100 includes aposition sensor121 configured to sense a relative position of the patient, e.g. angular position, and provide a digital signal corresponding to the sensed position to theprocessor105.
• Thecontrol unit100 also includes anaccelerometer122 configured to sense acceleration and movement of the patient and to provide a digital signal corresponding to the sensed movement to theprocessor105. In addition, anaccelerometer122 is positioned within thecontrol unit100. Theaccelerometer122 measures the activity levels of the patient and provides the signal to theprocessor105 for use in further analysis. Using an accelerometer in the implanted device indicates the activity level of the patient in conjunction with breathing rate. The accelerometer senses activity threshold as at rest, low medium or high depending on the programmed threshold value for a specific patient. Using the activity (accelerometer) sensor value and respiratory information, the health of the respiratory system may be evaluated and monitored. For example, if a patient's respiratory rate increases with an increase in activity and decreases with a decrease in activity, within a normal range, the patient's system will be considered functioning normally. If the patient's respiratory rate is out of range or too high while the activity sensor indicates at rest or low, then the patient may be suffering from pulmonary edema. Using this monitor, the effect of drug titrations, e.g., diuretic dosages, on a patient with pulmonary edema can be monitored. If the pulmonary edema patient's respiration is brought more towards a normal range with a drug dose, then the drug treatment would be maintained. If the drug treatment did not effect breathing sufficiently then the drug dosage may be increased. Accordingly, the drug dosage may vary with detected breathing irregularities.
• Aposition sensor121 is also located within thecontrol unit100 and has an output coupled to theprocessor105. The position sensor senses the relative angle of the patients' position. The position sensor is used to detect a patient's relative position, e.g., horizontal, supine, or standing. An available position sensor is the Spectrol601-1045 smart position sensor, self-contained device that provides an analog output over a full range of 360 degrees without requiring external components.
• Thecontrol unit100 further includes aROM memory116 coupled to theprocessor105 by way of a data bus. TheROM memory118 provides program instructions to thecontrol unit100 that direct the operation of thestimulator40.
• Thecontrol unit100 further comprises afirst RAM memory119 coupled via a data bus to theprocessor105. Thefirst RAM memory119 may be programmed to provide certain stimulation parameters such as pulse or burst morphology; frequency, pulse width, pulse amplitude, duration and a threshold or trigger to determine when to stimulate. A second RAM memory120 (event memory) is provided to store sensed data sensed, e.g., by theelectrodes21a-d22a-d,41a-h42a-h,61a-d62a-d,71a-d,72a-d(EMG or nerve activity),position sensor121, diaphragm movement sensors orstrain gauges25,26, or theaccelerometer122. These signals may be processed and used by thecontrol unit100 as programmed to determine if and when to stimulate or provide other feedback to the patient or clinician. Also stored inRAM memory120 may be the sensed waveforms for a given interval, and a count of the number of events or episodes over a given time as counted bat theprocessor105. The system's memory will be programmable to store: number of sleep apnea episodes per night; pacing stimulation and length of time; the systemic auto-correction (i.e., how stimulus was adjusted, e.g., in amplitude frequency phase or waveform, to reach a desired or intrinsic level response); body resumption of breathing; the number of apnea episodes with specific durations and averages and trending information; hyperventilation episodes during supine position; number of hyperventilation episodes during sleep position; number of hyperventilation episodes during vertical position; and patient information including the medications and dosages and dates of changes. These signals and information may also be compiled in the memory and downloaded telemetrically to anexternal device140 when prompted by theexternal device140.
• An example of the circuits of thesignal processing circuit116 corresponding to one of the EMG inputs for one of the electrodes or pairs of electrodes of theassemblies21,22 is illustrated schematically inFIG. 7A. An EMG signal is input into anamplifier130 that amplifies the signal. The signal is then filtered to remove noise byfilter131. The amplified signal is rectified by arectifier132, is converted by an A/D converter133 and then is integrated byintegrator134 to result in an integrated signal from which respiratory information can be ascertained. The signal output of theintegrator134 is then coupled to theprocessor105 and provides a digital signal corresponding to the integrated waveform to theprocessor105. The signal output of theintegrator134 is also coupled to apeak detector135 that determines when the inspiration period of a respiratory cycle has ended and an expiration cycle has begun. The signal output of theintegrator134 is further coupled to a plurality ofcomparators136,137,138,139. Thefirst comparator136 determines when respiration (EMG signal or phrenic nerve signal) has been detected based on when an integrated signal waveform amplitude has been detected that is greater than a percentage value of the peak of an intrinsic respiratory cycle or another predetermined amount (comp 1), for example between 1-25% of the intrinsic signal. In this example, the comparator is set at a value that is 10% of the waveform of an intrinsic respiratory cycle. Thesecond comparator137 determines a value of the waveform amplitude (comp 2) when an integrated signal waveform amplitude has been detected that is at a predetermined percentage value of the peak of an intrinsic respiratory cycle or another predetermined amount, for example between 75-100% of the intrinsic signal. In this example, the comparator is set at a value that is 90% of the waveform of an intrinsic respiratory cycle. From this value and thecomp 1 value, the slope of the inspiration period (between 10% and 90% in this example) may be determined. This slope may provide valuable diagnostic information as it shows how quickly a patient inhales. After (or when) the peak detector detects the end of an inhalation period and the beginning of an exhalation period, thethird comparator138 determines an upper value for the waveform amplitude during active exhalation period, for example between 100% and 75% of the peak value detected by thepeak detector135. Then a lower value (comp 4) of the waveform during the exhalation period is determined by thefourth comparator139, which compares the measured amplitude to a predetermined value, e.g. a percentage value of the peak amplitude. In this example the value is selected to be 10% of the peak value. In one embodiment this value is selected to roughly coincide with the end of a fast exhalation period. Fromcomp 3 andcomp 4 values, the slope of the exhalation period (between 10% and 90% in this example) may be determined. This slope may provide valuable diagnostic information as it shows how quickly a patient exhales.
• FIG. 7B illustrates two sequential integrated waveforms of exemplary integrated signals corresponding to two serial respiratory cycles, described in more detail herein with reference toFIGS. 9A-9D. Thewaveform170 has abaseline170b,inspiration cycle171, a measuredinspiration cycle172, a point of 10% of peak inspiration173 (comp 1), a point of 90% of peak of inspiration174 (comp 2), apeak175 where inspiration ends and exhalation begins, and exhalation cycle176afast exhalation portion177 of theexhalation cycle176, a 90% of peak exhalation point178 (comp 3), a 10% of peak exhalation point179 (comp 4), an actual respiratory cycle160 and a measuredrespiratory cycle181. Thesecond waveform182 is similarly shaped. The 10% inspiration183 of thesecond waveform182 marks the end of the measuredrespiratory cycle181, while the 10% point173 of thewaveform170 marks the beginning of the measuredrespiratory cycle181.
• The system may adjust the pace, pulse, frequency and amplitude to induce slow and elongated inspiration period; and fast and short inspiration period. The system may match the intrinsic sleep or awake time tidal volume by adjusting the output energy while sensing the EMG or nerve amplitude. This may be done gradually by frequently sensing and incrementally adjusting. The system may deliver elongated inspiration period while shortening the expiration period to control and manipulate the PO₂and PCO₂levels in the blood to overcome and treat apnea. The system may deliver time and amplitude modulation output for control of inspiration and exhalation periods. To increase the inspiration period, the system may deliver fewer bursts at lower amplitudes and higher frequencies. To create a fast, short inspiration cycle, the system may deliver more of bursts at higher amplitudes. The system may deliver sequential low energy pacing output either from one or multiple electrodes to control and manage the pulmonary stretch receptor threshold levels to avoid or prevent the collapse of the upper airways.FIG. 10 illustrates a variety of exemplary stimulation bursts and resulting effective EMG that may be used to control the various phases of the respiratory cycle, including, e.g., slope of inspiration, fast exhalation, exhalation, tidal volume, peak value, and rate of respiration.
• Referring toFIGS. 10A-10B, a firstintrinsic EMG waveform550 is illustrated inFIG. 10A. A subsequent EMG waveform551 (FIG. 10A) is illustrated in response to a burst of pulses561 (FIG. 10B) of symmetric amplitude, frequency and pulse width. Asubsequent EMG waveform552 is illustrated (FIG. 10A) in response to burst of pulses562 (FIG. 10B). The resulting EMG waveform552 (FIG. 10A) has a flatter inspiration slope and expiration slope and relatively lower peak amplitude. This particular effect may be desirable to control breathing and create a slower more gradual inspiration. The burst562 (FIG. 10B) comprises a series of pulses increasing in amplitude and of a higher frequency than burst561 (greater number of pulses). The subsequent EMG waveform551 (FIG. 10A) has a relatively sharp inspiration slope. The corresponding burst563 of pulses has fewer pulses (3) and higher amplitude pulses. The effect of thisburst563 is to increase inspiration rate. The subsequent EMG waveform554 (FIG. 10A) has a relatively slow inspiration cycle as a result of a burst564 (FIG. 10B) with both increasing amplitudes and longer pulse widths (and a greater pulse duration). These are a few examples of a multitude of possible variations of burst pulses that can be modified to control the inspiration, expiration, tidal volume (area under waveform curve) and other parameters of the respiratory cycle by modifying frequency, amplitude, pulse width of the pulses within the burst and the duration of the burst to get a desired effect. These bursts can be modified and programmed into a stimulator and may vary from patient to patient.
• InFIG. 8 a circuit for anexternal device140 is illustrated. Theexternal device140 comprises aprocessor145 for controlling the operations of the external device. Theprocessor145 and other electrical components of theexternal device140 are coordinated by aninternal clock150 and apower source151. Theprocessor145 is coupled to atelemetry circuit146 that includes atelemetry coil147, areceiver circuit148 for receiving and processing a telemetry signal that is converted to a digital signal and communicated to theprocessor145, and atransmitter circuit149 for processing and delivering a signal from theprocessor145 to thetelemetry coil146. Thetelemetry coil147 is an RF coil or alternatively may be a magnetic coil depending on what type of coil thetelemetry coil107 of the implantedcontrol unit100 is. Thetelemetry circuit146 is configured to transmit signals to the implantedcontrol unit100 containing, e.g., programming or other instructions or information, programmed stimulation rates and pulse widths, electrode configurations, and other device performance details. Thetelemetry circuit146 is also configured to receive telemetry signals from thecontrol unit100 that may contain, e.g., sensed and/or accumulated data such as sensed EMG activity, sensed nerve activity, sensed responses to stimulation, sensed position information, or sensed movement information. Other information such as frequency and time of apnea, number of apnea events detected in a time interval or during a sleep cycle, parameter relating to pulmonary edema such as frequency of hyperventilation including time and patient position. This information may be stored inRAM event memory158 or may be uploaded and through anexternal port153 to a computer, or processor, either directly or through a phone line or other communication device that may be coupled to theprocessor145 through theexternal port153. Theexternal device140 also includesROM memory157 for storing and providing operating instructions to theexternal device140 andprocessor145. The external device also includesRAM event memory158 for storing uploaded event information such as sensed information and data from the control unit, and RAM program memory159 for system operations and future upgrades. The external device also includes abuffer154 coupled to or that can be coupled through a port to a user-operateddevice155 such as a keypad input or other operation devices. Finally, theexternal device140 includes a display device156 (or a port where such device can be connected), e.g., for display visual, audible or tactile information, alarms or pages.
• Theexternal device140 may take or operate in, one of several forms, e.g. for patient use, compliance or monitoring; and for health care provider use, monitoring, diagnostic or treatment modification purposes. The information may be downloaded and analyzed by a patient home unit device such as a wearable unit like a pager, wristwatch palm sized computer. The downloaded information may present lifestyle modification, or compliance feedback. It may also alert the patient when the health care provider should be contacted, for example if there is malfunctioning of the device or worsening of the patient's condition. The system may prompt the patients with voice, music or other audible alarms regarding compliance with medication, diet and exercise. Medication compliance is a major issue with heart failure patients due to the difficulties created for the patients by some medications. The patient hand held also provides daily update regarding the status of the device and as well as whether patients need to see the physician and/or consuming more or less of a medication according to the programmed parameters by the physician inside the implantable device. The device may also manage a patient's diuretic level in relationship to breathing frequency and character. The device may monitor the response of the treatment from measured parameters provided by thecontrol unit100 in response to diuretic usage that e.g., may be input by the patient. This system may also warn the patient to check into a hospital based on physician command (programming). The system could also direct the patient to rest in different positions to alleviate the present problem until help arrives.
• Another device that interfaces with the patient's home unit may also be used to provide information to the clinicians. Such device may communicate, for example via an internet, phone or other communication device. It may download information from the patient and/or upload information form the physician. It may provide physicians with information identifying when intervention may be necessary or to further diagnose a patient's condition.
• The external device may be equipped with a palm pilot type device that connects to the phone line for downloading the patient specific information regarding patient's pulmonary status as well as of conditions including apnea, hypoventilation and hyperventilation, and whether the parameters are programmed correctly. This device may allow for remote follow-up, continuous monitoring of the patient's hemodynamic status, effectiveness of the drug regime and in particular the management of diuretics where the apnea is influenced by pulmonary edema. The information may be viewed by the clinician using a web browser anywhere in the world of the handheld can send a fax or notice to the physician's office once the parameters of interest are outside the programmed range. The physician may then request an office visit. The system also can send a summarized report on weekly, biweekly, or monthly as routine update based on the decision of the physician programmed in the handheld device. Medication adjustment/drug titration may be accomplished remotely. Hand-held communication protocol/technology may be magnetic or RF.
• FIGS. 9A-9D illustrate the operation of a stimulator in accordance with the invention. The EMG monitoring is turned on or started200. (Alternatively, or additionally, the phrenic nerve activity may be monitored in the sequences described inFIGS. 9A-9D). As illustrated inFIG. 9A-9B, the system is turned on and begins sensing respiratory effort. It determines the intrinsic rates of breathing cycles including respiratory period, inhalation period and exhalation period, and stores the values in event memory (step200). This may be done, e.g., by sensing when a patient is in a reclining position for a predetermined period of time while their breathing normalizes to that near the breathing rate when sleeping. A threshold level is then calculated from the intrinsic rate at some level below the peak of the intrinsic respiratory effort level.
• The presence of an EMG is detected200 by detecting when the amplitude of theintegrated waveform170 reaches a predetermined level, e.g., at a percentage of the total amplitude, or the intrinsic waveform of the breathing rate when sleeping.
• If there is no EMG detected201 then the stimulator determines whether sleep apnea is present or not300 by determining a lack of EMG or phrenic nerve activity in a given period of time, e.g., 5-10 seconds, or by an attenuated EMG, e.g., not reachingcomp 1 or, e.g., not reachingcomp 2 in the case of partial apnea. If sleep apnea is present, then the stimulator goes to theapnea treatment module301 or to a program where the apnea is treated (SeeFIG. 9B). If sleep apnea is not detected, then the stimulator determines if hypoventilation is present400 by determining that the EMG is present at an intrinsic amplitude or percentage thereof, but the rate is lower than the intrinsic rate. If hypoventilation is present then the stimulator goes to thehypoventilation treatment module401 or to a program where hypoventilation is treated. (SeeFIG. 9C.) If an EMG, apnea, and hypoventilation are not detected, then presumably the patient is not breathing or there is a malfunctioning of the stimulator. If this is the case, the system may be programmed to do an emergency of the components and then communicate to the patient or health care provider that the stimulator is malfunctioning and/or the patient is not breathing250. This communication may be accomplished a number of ways via a variety of ongoing or periodic communication processes. The system may continue to listen for anEMG201 after the system does and emergency check (step250). After a given time or number of iterations of reachingstep250, the stimulator may sound an alarm.
• If an EMG is detected atstep201, then the stimulator starts arespiratory timer202 and the time and amplitude values are stored. The respiratory timer will determine the amount of time in one given breathing cycle between the detected beginning of inspiration, exhalation and the detected beginning of the inspiration of the next cycle. The inspiration timer will also be started203. The inspiration timer will time the duration of inspiration when detected, as described with respect to step201, until the peak of the inspiration or the beginning of expiration.
• The slope of the inspiration cycle is determined204 by determining the amplitude and time of that amplitude at a further point in time in the inspiration cycle (comp 2) from this information and the time and amplitude at the detection of the EMG (201).
• A peak detector monitors the integrated waveform and determines when it has peaked205, marking the end of inspiration and the beginning of expiration. When the peak is detected the time or duration of the inspiration cycle is stored along with theamplitude206. The inspiration timer is then turned off207 and the exhalation timer is started208. Instep209 the values comp3 andcomp 4 are determined as a predetermined percentage to the peak value. Instep210, a comparator will then compare the amplitude of the signal during exhalation to a predetermined value or percentage of the total amplitude as measured at the peak until that value is reached. This predetermined value is referred to herein ascomp 3. The time is stored. Instep211, a comparator will then compare the amplitude of the signal during exhalation to a predetermined lower end value or percentage of the total amplitude as measured at the peak until that value is reached. This predetermined value is referred to herein ascomp 4. The stimulator then determines the slope of the exhalation cycle based on time and amplitude values ofcomp 3 andcomp 4. The value forcomp 4 may be selected to approximately mark the end of the fast exhalation period of the exhalation cycle, which is the initial period where the exhalation is sharper. At this point, the exhalation timer is stopped and the amplitude value and time is stored212. Instep213, the stimulator may then determine the inhalation period, the exhalation period and the slope or curve characteristics of the breathing cycle during this time the slope of the waveform during either exhalation and/or inspiration may be recorded and analyzed to identify breathing irregularities. The inhalation period and exhalation period may be respectively based on the time values between the beginning of inhalation (comp 1) and the peak, and the peak (for inspiration) and the beginning of the peak and the end of the fast exhalation period. Also, the inspiration and expiration periods may also respectively include a calculation or approximation of the time between the actual beginning of inspiration to the detected beginning of inspiration and a calculation of the time between the end of the fast exhalation (comp 4) and the end of the exhalation period. The slopes of each of the inspiration periods and expiration periods may be calculated as well as the determination of other waveform characteristics that may provide useful diagnostic information. After the end of the fast exhalation period has been determined the stimulator then determines the total respirator period. After a first inhalation and exhalation cycle of a first breath, the stimulator awaits to detect a second cycle. The stimulator waits to detect the presence of acomp 1 value of anEMG215. If the EMG is present then the time is stored, the respiratory timer is stopped, and the respiratory period is stored216. The respiratory period may be a measured time from the detection of an EMG of a first waveform to the detection of an EMG of a second waveform. Alternatively, the respiratory period may be determined by adding the initial undetected period of the first waveform and subtracting the initial undetected period of the second waveform. The stimulator then determines if there ishyperventilation217 by determining if the rate is a certain value or amount above the intrinsic rate for the particular aware, sleep or other state of the patient. If hyperventilation is detected, then the stimulator goes to thehyperventilation module501 where hyperventilation is treated. If no hyperventilation is detected, the stimulator returns to itsoriginal monitoring step201 where it awaits the next EMG detection and repeats the cycle.
• FIG. 9B, illustrates thesleep apnea module301. When sleep apnea is detected300, a determination is made as to whether apnea iscomplete apnea302. Complete apnea would be determined by a complete lack in effective or detected EMG (or alternatively, phrenic nerve activity). If the apnea is not sleep apnea then a determination is made as to whether the apnea ispartial apnea320 where the EMG signal is attenuated a predetermined amount. If the apnea is obstructive apnea, an cut of chase EMG may be detected as well.
• If complete sleep apnea is detected302, then the pacing output parameters stored inRAM120 are loaded303, e.g., into a register. The pacing output is then delivered304. After delivering the pacing output to the phrenic nerve and/or diaphragm muscle, the EMG is observed305, if the EMG is not approximately at the intrinsic sleep level, then the parameters are adjusted to bring the EMG more within theappropriate range306 and elicit a response closer to intrinsic breathing. For example, if the frequency or amplitude is too low, then the frequency or amplitude of the pacing is adjusted upwards. If the frequency or amplitude is too high, then the frequency or amplitude of the pacing is adjusted downward. If the EMG is approximately at theintrinsic sleep level305, then the monitoring period is increased by one second307 (e.g., the monitoring period may start at about 10 seconds with a maximum at about 15 seconds). The EMG is then monitored again to see if apnea is present308. If it is then the pacing output is continued304. If it is then, if the monitoring period is not at a defined maximum309 then the monitoring period is increased one second and the EMG is observed again308 and as long as the EMG is present308, the stimulator will keep increasing the monitoring period by one second307 until the maximum monitoring period is reached309. When the monitoring period does reach a maximum level, the apnea is confirmed as being treated310 by observing the EMG for a given period of time, e.g. for 3 consecutive EMG's. The parameters of stimulation and information regarding the episode are stored311 inevent RAM119, and the system returns to EMG monitoring (step200 ofFIG. 9A).
• If complete sleep apnea is not detected302 then the stimulator determines if partial apnea is present320. If partial apnea is not present, the system returns to theemergency check250 to see if the system is malfunctioning. If partial apnea is present, then the existing EMG parameters are determined321 and the pacing parameters are adjusted based on the existingEMG322 and are loaded323 and are delivered324. The existing EMG parameters may be determined a number of ways. The system may attempt to match the desired EMG with the pacing output by adding on to the existing EMG. One method may involve calculating the tidal volume based on the peak value of the existing EMG voltage output, pulse width, thus area under the respiration curve; calculating the pacing energy (amplitude and frequency) required to achieve the tidal volume (of an intrinsic sleep EMG); and increasing the EMG or pacing an increased calculated amount to achieve the desired tidal volume.
• If after delivering thepacing output324, the EMG is not at theintrinsic sleep level325, then the parameters are adjusted to elicit theintrinsic response331 and the parameters are loaded3232 and delivered324 again. If the EMG is at theintrinsic sleep level325 then the monitoring period is increased by one second326, and EMG observed again to determine if the partial apnea has been treated327. If the apnea has not been treated, then the stimulator returns to delivering thepacing output324. If apnea has been treated and the monitoring period is not at the maximum328 then the monitoring time is increased by one second326, and partial apnea is detected327, etc. until the monitoring period has reached itsmaximum time328 throughout which apnea is determined to have been successfully treated after the maximum period is reached apnea treatment is confirmed329 by observing the EMG a predetermined period of time afterwards, e.g., for three consecutive EMG's. The parameters and information regarding the episode are then stored330. The system then returns to detecting the EMG (step200 ofFIG. 9A)
• FIG. 9C illustrates thehypoventilation module401. After hypoventilation is detected400 by comparing the breathing rate to a programmed low threshold breathing rate for a particular condition or state (e.g., waking, resting or sleeping), a pacing output designed to elicit the intrinsic rate is loaded and is delivered to the phrenic nerve and/ordiaphragm403. The EMG is then sensed404 and the EMG is compared to the intrinsic EMG amplitude andwaveform405. The output of the amplitude, rate and pulse width are adjusted to matchintrinsic EMG morphology406. The monitoring period is then increased by one second407. If the natural breathing rate has been restored for the maximum monitoring period, the stimulator returns to the step of detecting presence of EMG (step200,FIG. 9A). If it has not, then the EMG is sensed again404, compared to theintrinsic rate405, adjusted if necessary406, and the timer incremented again407 until the natural breathing has been restored.408.
• FIG. 9D illustrates thehyperventilation module501. If hyperventilation is present500, then the level of hyperventilation is classified as Class I (low), Class II (medium) or Class III (high) based on the rate an frequency of hyperventilation. These particular rates and classifications may vary from patient to patient and may be programmed in by the health care provider. The time date, respiratory rate, frequency or hyperventilation and activity sensor are senses and stored inevent RAM119. If class I is determined504, the patient is informed via the handheld orhome monitoring device505 and the patient is notified to further comply withdiuretic medications506. If class II is detected507, then the patient is informed and additional medication is recommended based on a prescription programmed into the hand helddevice508. The device then requests feedback by way of the hand held device, regardingcompliance509. The health care provider is notified of the status by way of the remote system, telephone connection or otherwise, and the sensed information concerning the patient's status is uploaded510. If class III is detected511, then the patient is requested to visit the physician immediately and also to consume addition medication according to the physician'srecommendation512. The health care provider is notified via theremote system512. The system then returns to detecting and EMG (step200,FIG. 9A).
• While the invention has been described with reference to particular embodiments, it will be understood to one skilled in the art that variations and modifications may be made in form and detail without departing from the spirit and scope of the invention.

Claims (13)

1-99. (canceled)

100. A device for controlling respiration of a patient comprising:

at least one electrode configured to be coupled to tissue of a patient's body wherein the at least one electrode is configured to deliver electrical stimulation to the tissue to thereby manipulate a diaphragm respiratory response;

a sensor element configured to sense information corresponding to the patient's respiration;

a breathing related disorder detector element coupled to the sensor element and configured to detect information corresponding to a breathing related disorder;

an intrinsic breathing detector element coupled to the sensor element configured to detect intrinsic breathing prior to onset of a breathing related disorder and resumption of intrinsic breathing after electrical stimulation delivered to the tissue; and

a responsive element coupled to the breathing related disorder detector element and the intrinsic breathing detector element, wherein the responsive element is configured to control electrical stimulation delivered to the tissue through the at least one electrode in response to breathing related disorder detector element detecting information corresponding to a breathing related disorder, and to modify electrical stimulation in response to the intrinsic breathing detector element detecting resumption of intrinsic breathing.

101. The device for controlling respiration of a patient ofclaim 100 wherein the breathing related disorder detector element is an apnea detector.

102. The device for controlling respiration of a patient ofclaim 100 wherein the breathing related disorder detector element is a hyperventilation detector.

103. The device for controlling respiration of a patient ofclaim 100 wherein the breathing related disorder detector element is a hyponea detector.

104. The device for controlling respiration of a patient ofclaim 100 further comprising a memory element coupled to the sensor element and configured to store information sensed by the sensor corresponding to intrinsic breathing of a patient.

105. The device for controlling respiration of a patient ofclaim 104 wherein the intrinsic breathing detector element is configured to compare sensed information corresponding to respiration of a patient to information stored in the memory corresponding to intrinsic breathing of a patient, to determine when intrinsic breathing has resumed.

106. The device for controlling respiration of a patient ofclaim 105 wherein the responsive element is configured to cease electrical stimulation in response to the intrinsic breathing detector element detecting resumption of intrinsic breathing

107. A method of controlling the respiration of a patient comprising the steps of:

sensing information corresponding to intrinsic breathing of the patient;

monitoring subsequent breathing of the patient to detect information corresponding to a breathing related disorder;

determining whether to electrically stimulate the tissue to elicit a diaphragm response in the patient, by detecting the information corresponding to a breathing related disorder;

electrically stimulating the tissue to control diaphragm movement in response to detecting apnea;

determining resumption of the intrinsic breathing in a patient after electrically stimulating the tissue to elicit the diaphragm response; and modifying electrical stimulation after determining resumption of the intrinsic breathing.

108. The method ofclaim 107 wherein the step of modifying electrical stimulation comprises ceasing electrical stimulation after determining resumption of the intrinsic breathing.

109. The method ofclaim 107 wherein the step of determining whether to stimulate comprises determining the presence of apnea.

110. The method ofclaim 107 wherein the step of determining whether to stimulate comprises determining the presence of hyperventilation.

111. The method ofclaim 107 wherein the step of determining whether to stimulate comprises determining the presence of hypopnea.

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