Electrotherapy apparatus

Abstract

An electrotherapy apparatus includes a connecting mechanism coupled between an energy source and a pair of electrodes for contacting a patient. A controller coupled to the energy source configures the energy source to provide a selected one of a plurality of energy levels. The controller actuates the connecting mechanism to couple the energy source to the electrodes. A sensor coupled to the controller measures a parameter or parameters related to the energy delivered to the patient through the electrodes. The controller performs an operation using the output received from the sensor. Based upon the operation, the controller actuates the connecting mechanism to decouple the energy source from the electrodes. In an embodiment of the electrotherapy apparatus, the energy source includes a high voltage power supply for charging a capacitor to a selected one of a plurality of initial voltages. The sensor includes a voltage sensor to measure the voltage across the capacitor and a current sensor to measure the current supplied by the capacitor. The connecting mechanism includes electronic switches coupled between the capacitor and the electrodes to permit application of an electrotherapy waveform in either polarity. The controller performs the operation using the measured voltages and currents to control the electronic switches. The operation may include computing the patient impedance, determining a time constant of the voltage or current, determining a quantity of charge delivered to the patient, or determining the time required for the voltage or current to substantially equal a predetermined fraction of the voltage or current.

What is claimed is:  
     
         1 . An electrotherapy apparatus for performing electrotherapy on a patient through a first electrode and a second electrode, the electrotherapy apparatus comprising: 
 an energy source to provide energy for performing the electrotherapy;    a connecting mechanism configured for coupling and decoupling the energy source, respectively, to and from the first electrode and the second electrode;    a first sensor configured for measuring a first parameter related to the energy supplied to the patient by the energy source; and    a controller arranged to receive the first parameter from the first sensor and configured to perform an operation, using the first parameter, for actuating the connecting mechanism to decouple the energy source from the first electrode and the second electrode.    
     
     
         2 . The electrotherapy apparatus as recited in  claim 1 , further comprising: 
 a second sensor configured for measuring a second parameter related to the energy supplied to the patient by the energy source with the controller arranged to receive the second parameter and configured to perform the operation using the second parameter.    
     
     
         3 . The electrotherapy apparatus as recited in  claim 2 , wherein: 
 the first parameter includes a voltage supplied by the energy source to the patient;    the second parameter includes a current supplied by the energy source to the patient; and    the operation includes determining a patient impedance using the first parameter and the second parameter.    
     
     
         4 . The electrotherapy apparatus as recited in  claim 3 , wherein: 
 the controller includes a configuration to control the energy source to provide a selected one of a plurality of energy levels for the electrotherapy and to perform the operation using a value corresponding to the selected one of the plurality of energy levels for the electrotherapy.    
     
     
         5 . The electrotherapy apparatus as recited in  claim 4 , wherein: 
 the operation includes determining the patient impedance based upon a plurality of values of the first parameter and a plurality of values of the second parameter.    
     
     
         6 . The electrotherapy apparatus as recited in  claim 5 , wherein: 
 the controller includes a configuration to actuate the connecting mechanism to perform a first phase of the electrotherapy having a first duration based upon the operation and to actuate the connecting mechanism to perform a second phase of the electrotherapy having a second duration based upon the operation.    
     
     
         7 . The electrotherapy apparatus as recited in  claim 1 , wherein: 
 the operation includes determining a time constant based upon the first parameter.    
     
     
         8 . The electrotherapy apparatus as recited in  claim 7 , wherein: 
 the controller includes a configuration to control the energy source to provide a selected one of a plurality of energy levels for the electrotherapy and to perform the operation using a value corresponding to the selected one of the plurality of energy levels for the electrotherapy.    
     
     
         9 . The electrotherapy apparatus as recited in  claim 8 , wherein: 
 the controller includes a configuration to actuate the connecting mechanism to perform a first phase of the electrotherapy having a first duration based upon the operation and to actuate the connecting mechanism to perform a second phase of the electrotherapy having a second duration based upon the operation.    
     
     
         10 . The electrotherapy apparatus as recited in  claim 9 , wherein: 
 the first parameter includes either a current or a voltage supplied by the energy source to the patient.    
     
     
         11 . The electrotherapy apparatus as recited in  claim 1 , wherein: 
 the operation includes determining a first time interval beginning with the first sensor measuring a first value of the first parameter and ending with the first sensor measuring a second value of the first parameter substantially equal to a predetermined fraction of the first value; and    the controller includes a configuration to actuate the connecting mechanism to couple the energy source to the first electrode and the second electrode and to decouple the energy source from the first electrode and the second electrode at the end of a second time interval determined by the operation and having a first duration based upon the first time interval.    
     
     
         12 . The electrotherapy apparatus as recited in  claim 11 , wherein: 
 the controller includes a configuration to actuate the connecting mechanism to couple the energy source to the first electrode and the second electrode after the second time interval and to decouple the energy source from the first electrode and the second electrode at the end of a third time interval determined by the operation and having a second duration based upon the first time interval.    
     
     
         13 . The electrotherapy apparatus as recited in  claim 12 , wherein: 
 the controller includes a configuration to control the energy source to provide a selected one of a plurality of energy levels for the electrotherapy and to perform the operation to determine the second time interval and the third time interval using a value corresponding to the selected one of the plurality of energy levels for the electrotherapy.    
     
     
         14 . The electrotherapy apparatus as recited in  claim 13 , wherein: 
 the first parameter includes either a current or a voltage supplied by the energy source to the patient.    
     
     
         15 . The electrotherapy apparatus as recited in  claim 1 , wherein: 
 the first parameter includes a current supplied by the energy source to the patient;    the operation includes determining a charge delivered to the patient using the first parameter and determining a first time interval beginning with the coupling of the energy source to the first electrode and the second electrode and ending with the charge delivered to the patient substantially equaling a predetermined value; and    the controller includes a configuration to actuate the connecting mechanism to couple the energy source to the first electrode and the second electrode and to decouple the energy source from the first electrode and the second electrode at the end of a second time interval determined by the operation and having a first duration based upon the first time interval.    
     
     
         16 . The electrotherapy apparatus as recited in  claim 15 , wherein: 
 the controller includes a configuration to actuate the connecting mechanism to couple the energy source to the first electrode and the second electrode after the second time interval and to decouple the energy source from the first electrode and the second electrode at the end of a third time interval determined by the operation and having a second duration based upon the first time interval.    
     
     
         17 . The electrotherapy apparatus as recited in  claim 16 , wherein: 
 the controller includes a configuration to control the energy source to provide a selected one of a plurality of energy levels for the electrotherapy and to perform the operation to determine the second time interval and the third time interval using a value corresponding to the selected one of the plurality of energy levels for the electrotherapy.    
     
     
         18 . The electrotherapy apparatus as recited in  claim 17 , wherein: 
 the energy source includes a capacitor coupled to a power supply; and    the energy source includes a configuration to charge the capacitor to a selected one of a plurality of voltages corresponding to the selected one of the plurality of energy levels.    
     
     
         19 . The electrotherapy apparatus as recited in  claim 18 , wherein: 
 the operation includes determining the first time interval based upon a time required for the charge delivered to the patient to substantially equal a selected one of a plurality of predetermined values, including the predetermined value, corresponding to the selected one of the plurality of voltages.    
     
     
         20 . The electrotherapy apparatus as recited in  claim 19 , wherein: 
 the controller includes a configuration to determine a maximum allowable current and a minimum allowable current based upon the selected one of the plurality of voltages and to actuate the connecting mechanism to decouple the energy source from the first electrode and the second electrode for a value of the first parameter greater than the maximum allowable current or less than the minimum allowable current.    
     
     
         21 . In an electrotherapy apparatus including an energy source and a controller, a method for performing electrotherapy on a patient comprising: 
 coupling the energy source to the patient;    measuring a first parameter related to energy supplied to the patient;    performing an operation upon the first parameter using the controller; and    decoupling the energy source from the patient based upon the operation.    
     
     
         22 . The method as recited in  claim 21 , further comprising: 
 measuring a second parameter related to the energy supplied to the patient after coupling the energy source to the patient, where performing the operation includes using the second parameter.    
     
     
         23 . The method as recited in  claim 22 , wherein: 
 the first parameter includes a current supplied by the energy source to the patient;    the second parameter includes a voltage supplied by the energy source to the patient; and    performing the operation includes determining a patient impedance using the first parameter and the second parameter.    
     
     
         24 . The method as recited in  claim 23 , further comprising: 
 selecting one of a plurality of energy levels for performing the electrotherapy before coupling the energy source to the patient, where performing the operation includes using a value corresponding to the selected one of the plurality of energy levels.    
     
     
         25 . The method as recited in  claim 24 , further comprising: 
 measuring a plurality of values of the first parameter before determining the patient impedance; and    measuring a plurality of values of the second parameter before determining the patient impedance, where determining the patient impedance includes using the plurality of values of the first parameter and the plurality of values of the second parameter.    
     
     
         26 . The method as recited in  claim 25  further comprising: 
 coupling the energy source to the patient after decoupling the energy source from the patient; and  
 decoupling the energy source from the patient after a time interval based upon the operation.  
 
     
     
         27 . The method as recited in  claim 21 , wherein: 
 performing the operation includes determining a time constant using the first parameter.    
     
     
         28 . The method as recited in  claim 27 , further comprising: 
 selecting one of a plurality of energy levels for performing the electrotherapy before coupling the energy source to the patient, where performing the operation includes using a value corresponding to the selected one of the plurality of energy levels.    
     
     
         29 . The method as recited in  claim 28 , further comprising: 
 coupling the energy source to the patient after decoupling the energy source from the patient; and    decoupling the energy source from the patient after a time interval based upon the operation.    
     
     
         30 . The method as recited in  claim 29 , wherein: 
 the first parameter includes either a current or a voltage supplied by the energy source to the patient.    
     
     
         31 . The method as recited in  claim 21 , wherein: 
 the first parameter includes a current supplied by the energy source to the patient;    performing the operation includes determining a charge delivered to the patient using the first parameter and determining a first time interval beginning with the coupling of the energy source to the patient and ending with the charge delivered to the patient substantially equaling a predetermined value; and    decoupling the energy source includes decoupling the energy source at the end of a second time interval determined by the operation and having a first duration based upon the first time interval.    
     
     
         32 . The method as recited in  claim 31 , further comprising: 
 selecting one of a plurality of energy levels for the energy source to perform the electrotherapy before coupling the energy source to the patient, where performing the operation includes using a value corresponding to the selected one of the plurality of energy levels to determine the first time interval.    
     
     
         33 . The method as recited in  claim 32 , further comprising: 
 determining a maximum allowable current and a minimum allowable current using the value corresponding to the selected one of the plurality of energy levels;    determining a value of the first parameter after coupling the energy source to the patient; and    actuating the connecting mechanism to decouple the energy source from the first electrode and the second electrode for the value of the first parameter greater than the maximum allowable current or for the value of the first parameter less than the minimum allowable current.    
     
     
         34 . The method as recited in  claim 33 , further comprising: 
 coupling the energy source to the patient after decoupling the energy source from the patient;    decoupling the energy source from the patient after a third time interval where performing the operation includes determining the third time interval using the value corresponding to the selected one of the plurality of energy levels.    
     
     
         35 . The method as recited in  claim 21 , wherein: 
 measuring the first parameter includes measuring a first value of the first parameter and a second value of the first parameter;    performing the operation includes determining a first time interval beginning with measuring the first value of the first parameter and ending with the second value of the first parameter substantially equal to a predetermined fraction of the first value of the first parameter;    performing the operation includes determining a second time interval based upon the first time interval; and    decoupling the energy source from the patient occurs at the end of the second time interval.    
     
     
         36 . The method as recited in  claim 35 , further comprising: 
 selecting one of a plurality of energy levels for the energy source to perform the electrotherapy before coupling the energy source to the patient where performing the operation includes using a value corresponding to the selected one of the plurality of energy levels to determine the first time interval.    
     
     
         37 . The method as recited in  claim 36 , further comprising: 
 coupling the energy source to the patient after decoupling the energy source from the patient; and    decoupling the energy source from the patient after a third time interval where performing the operation includes determining the third time interval using the value corresponding to the selected one of the plurality of energy levels.    
     
     
         38 . The method as recited in  claim 37 , wherein: 
 the first parameter includes either a current or a voltage supplied by the energy source to the patient.    
     
     
         39 . A defibrillator for delivering a multi-phasic waveform to a patient through a first electrode and a second electrode, comprising: 
 a capacitor having a first terminal and having a second terminal, with the capacitor to store charge used for delivery of the multi-phasic waveform to the patient;    a first sensor configured for measuring a first parameter related to the energy supplied to the patient by the capacitor;    a connecting mechanism coupled between the first terminal and the second terminal of the capacitor and the first electrode and the second electrode to permit the first terminal of the capacitor to selectively couple to one of the first electrode and the second electrode and to permit the second terminal of the capacitor to selectively couple to one of the first electrode and the second electrode;    a controller arranged to receive the first parameter from the sensor and configured to perform an operation, using the first parameter, for actuating the connecting mechanism to decouple the capacitor from the first electrode and the second electrode; and    a power supply configured for charging the capacitor to an initial voltage determined by the controller.    
     
     
         40 . The defibrillator as recited in  claim 39 , further comprising: 
 a second sensor configured for measuring a second parameter related to the energy supplied to the patient by the capacitor with the controller arranged to receive the second parameter and configured to perform the operation using the second parameter.    
     
     
         41 . The defibrillator as recited in  claim 40 , wherein: 
 the first parameter includes a voltage supplied by the capacitor to the patient;    the second parameter includes a current supplied by the capacitor to the patient; and    the operation includes determining a patient impedance using the first parameter and the second parameter.    
     
     
         42 . The defibrillator as recited in  claim 41 , wherein: 
 the controller includes a configuration to control the power supply to charge the capacitor to a selected one of a plurality of initial voltages, including the initial voltage, and to perform the operation using a value corresponding to the selected one of the plurality of initial voltages for the multi-phasic waveform.    
     
     
         43 . The defibrillator as recited in  claim 42 , wherein: 
 the operation includes determining the patient impedance based upon a plurality of values of the first parameter and a plurality of values of the second parameter.    
     
     
         44 . The defibrillator as recited in  claim 43 , wherein: 
 the multi-phasic waveform includes a bi-phasic waveform having a first phase and a second phase each having a duration dependent upon the operation.    
     
     
         45 . The defibrillator as recited in  claim 39 , wherein: 
 the operation includes determining a time constant based upon the first parameter.    
     
     
         46 . The defibrillator as recited in  claim 45 , wherein: 
 the controller includes a configuration to control the power supply to charge the capacitor to a selected one of a plurality of initial voltages, including the initial voltage, and to perform the operation using a value corresponding to the selected one of the plurality of initial voltages for the multi-phasic waveform.    
     
     
         47 . The defibrillator as recited in  claim 46 , wherein: 
 the multi-phasic waveform includes a bi-phasic waveform having a first phase and a second phase each having a duration dependent upon the operation.    
     
     
         48 . The defibrillator as recited in  claim 47 , wherein: 
 the first parameter includes either a current or a voltage supplied by the capacitor to the patient.    
     
     
         49 . The defibrillator as recited in  claim 39 , wherein: 
 the operation includes determining a first time interval beginning with the first sensor measuring a first value of the first parameter and ending with the first sensor measuring a second value of the first parameter substantially equal to a predetermined fraction of the first value; and    the controller includes a configuration to actuate the connecting mechanism to couple the capacitor to the first electrode and the second electrode and to decouple the capacitor from the first electrode and the second electrode at the end of a second time interval determined by the operation and based upon the first time interval.    
     
     
         50 . The defibrillator as recited in  claim 49 , wherein: 
 the controller includes a configuration to actuate the connecting mechanism to couple the energy source to the first electrode and the second electrode after the second time interval and to decouple the energy source from the first electrode and the second electrode at the end of a third time interval determined by the operation and based upon the first time interval.    
     
     
         51 . The defibrillator as recited in  claim 50 , wherein: 
 the controller includes a configuration to control the power supply to charge the capacitor to a selected one of a plurality of initial voltages, including the initial voltage, and to perform the operation using a value corresponding to the selected one of the plurality of initial voltages for the multi-phasic waveform.    
     
     
         52 . The defibrillator as recited in  claim 51 , wherein: 
 the multi-phasic waveform includes a bi-phasic waveform having a first phase and a second phase each having a duration dependent upon the operation.    
     
     
         53 . The defibrillator as recited in  claim 52 , wherein: 
 the first parameter includes either a current or a voltage supplied by the capacitor to the patient.    
     
     
         54 . The defibrillator as recited in  claim 39 , wherein: 
 the first parameter includes a current supplied by the capacitor to the patient;    the operation includes determining a charge delivered to the patient using the first parameter and determining a first time interval beginning with the coupling of the capacitor to the first electrode and the second electrode and ending with the charge delivered to the patient substantially equaling a predetermined value; and    the controller includes a configuration to actuate the connecting mechanism to couple the capacitor to the first electrode and the second electrode and to decouple the capacitor from the first electrode and the second electrode at the end of a second time interval determined by the operation and based upon the first time interval.    
     
     
         55 . The defibrillator as recited in  claim 54 , wherein: 
 the controller includes a configuration to actuate the connecting mechanism to couple the capacitor to the first electrode and the second electrode after the second time interval and to decouple the capacitor from the first electrode and the second electrode at the end of a third time interval determined by the operation and based upon the first time interval.    
     
     
         56 . The defibrillator as recited in  claim 55 , wherein: 
 the controller includes a configuration to control the power supply to charge the capacitor to a selected one of a plurality of initial voltages, including the initial voltage, and to perform the operation to determine the second time interval and the third time interval using a value corresponding to the selected one of the plurality of initial voltages for the multi-phasic waveform.    
     
     
         57 . The defibrillator as recited in  claim 56 , wherein: 
 the operation includes determining the first time interval based upon a time required for the charge delivered to the patient to substantially equal a selected one of a plurality of predetermined values, including the predetermined value, corresponding to the selected one of the plurality of initial voltages.    
     
     
         58 . The defibrillator as recited in  claim 57 , wherein: 
 the controller includes a configuration to determine a maximum allowable current and a minimum allowable current based upon the selected one of the plurality of initial voltages and to actuate the connecting mechanism to decouple the energy source from the first electrode and the second electrode for a value of the first parameter greater than the maximum allowable current or less than the minimum allowable current.