Safety control system for implantable neural stimulator

Abstract

A neural stimulation system includes a safety control system that prevents delivery of neural stimulation pulses from causing potentially harmful effects. The neural stimulation pulses are delivered to one or more nerves to control the physiological functions regulated by the one or more nerves. Examples of such harmful effects include unintended effects in physiological functions associated with autonomic neural stimulation and nerve injuries caused by excessive delivery of the neural stimulation pulses.

1 - 20 . (canceled) 
     
     
         21 . A neural stimulation system, comprising:
 a stimulation output circuit configured to deliver neural stimulation pulses;   a stimulation controller coupled to the stimulation output circuit, the stimulation controller configured to control the delivery of the neural stimulation pulses using stimulation parameters; and   a safety controller coupled to the stimulation controller, the safety controller including:
 a safety-control event detection module including an unintended effect detection module and a stimulation parameter detection module, the unintended effect detection module configured to detect an unintended effect associated with the delivery of the neural stimulation pulses, the stimulation parameter detection module configured to detect at least a first parameter value being a value of a first parameter of the stimulation parameters, the safety-control event detection module configured to indicate a detection of a safety-control event in response to a detection of the unintended effect and in response to the value of the first parameter exceeding a threshold; and 
 a safety response module configured to adjust one or more parameters of the stimulation parameters in response to the detection of the safety-control event. 
   
     
     
         22 . The neural stimulation system of  claim 21 , further comprising an implantable housing containing the stimulation output circuit, the stimulation controller, and the safety controller. 
     
     
         23 . The neural stimulation system of  claim 22 , wherein the safety response module comprises a stimulation switching module configured to suspend the delivery of the neural stimulation pulses in response to the detection of the safety-control event being indicated. 
     
     
         24 . The neural stimulation system of  claim 22 , wherein the safety response module comprises a parameter limiting module configured to adjust one or more parameters of the stimulation parameters to reduce the intensity of the delivery of the neural stimulation pulses in response to the detection of the safety-control event being indicated. 
     
     
         25 . The neural stimulation system of claim  1 , wherein the unintended effect detection module comprises a physiological parameter detection module configured to sense a value of a physiological parameter, compare the sensed value to a normal value range including one or more threshold values, and indicate the detection of the unintended effect in response to the sensed value falling out of the normal value range. 
     
     
         26 . The neural stimulation system of  claim 25 , wherein the unintended effect detector comprises an unintended cardiac event detector configured to detect an unintended cardiac event. 
     
     
         27 . The neural stimulation system of  claim 26 , wherein the unintended cardiac event detector configured to detect arrhythmia. 
     
     
         28 . The neural stimulation system of  claim 26 , wherein the unintended cardiac event detector configured to detect hypotension. 
     
     
         29 . The neural stimulation system of  claim 25 , wherein the unintended effect detector further comprises an unintended pulmonary event detector configured to detect an unintended pulmonary event. 
     
     
         30 . The neural stimulation system of  claim 29 , wherein the unintended pulmonary event detector is configured to detect dyspnea, apnea, or hypopnea. 
     
     
         31 . The neural stimulation system of  claim 29 , wherein the unintended pulmonary event detector is configured to detect coughing. 
     
     
         32 . The neural stimulation system of  claim 21 , wherein the stimulation parameter detection module is further configured to detect a second parameter value being a value of a second parameter of the stimulation parameters and dynamically adjust the first threshold value using the second parameter value. 
     
     
         33 . A method for operating a neural stimulation system including a stimulation output circuit, a stimulation controller, and a safety controller, comprising:
 delivering neural stimulation pulses from the stimulation output circuit;   controlling the delivery of the neural stimulation pulses using stimulation parameters using the stimulation controller;   detecting a safety-control event using the safety controller, including detecting an unintended effect associated with the delivery of the neural stimulation pulses and detecting a first parameter value being a value of a first parameter of the stimulation parameters;   indicating a detection of the safety-control event in response to a detection of the unintended effect;   indicating a detection of the safety-control event in response to the first parameter value exceeding a first threshold value; and   adjusting one or more parameters of the stimulation parameters, using the safety controller, in response to the detection of the safety-control event.   
     
     
         34 . The method of  claim 33 , wherein adjusting the one or more parameters comprises adjusting the one or more stimulation parameters to suspend the delivery of the neural stimulation pulses. 
     
     
         35 . The method of  claim 33 , wherein adjusting the one or more parameters comprises adjusting the one or more stimulation parameters to reduce an intensity of the delivery of the neural stimulation pulses. 
     
     
         36 . The method of  claim 33 , wherein adjusting the one or more parameters comprises setting the first parameter to the first threshold value in response to the first parameter value exceeding the first threshold value. 
     
     
         37 . The method of  claim 33 , wherein detecting the unintended effect comprises:
 sensing a value of a physiological parameter;   comparing the sensed value to a normal value range including one or more threshold values; and   indicating the detection of the unintended effect in response to the sensed value falling out of the normal value range.   
     
     
         38 . The method of  claim 37 , wherein detecting the unintended effect comprises detecting an unintended cardiac event. 
     
     
         39 . The method of  claim 37 , wherein detecting the unintended effect comprises detecting an unintended pulmonary event. 
     
     
         40 . The method of  claim 33 , further comprising:
 detecting a second. parameter value being a value of a second parameter of the stimulation parameters; and   
       dynamically adjusting the first threshold value using the second parameter value.