Electrotherapy Apparatus

Abstract

An apparatus for producing analgesia in a patient through electrical signals applied through electrodes to a patient's body, and methods of treating patients using the apparatus. The apparatus comprises a signal generator arranged to generate a biphasic waveform comprising successive cycles each containing a positive and negative pulse.

1 . An apparatus for producing analgesia in a patient through electrical signals applied by electrodes to the patient's body, the apparatus comprising electrodes for application to the patient's body and a signal generator which is connectable to the electrodes, wherein the signal generator is arranged to generate a biphasic waveform comprising successive cycles each containing a positive and negative pulse, wherein the mean pulse width P w  is 10 μs or less, and wherein V p   2 .Pw.F p  is at least 200, where V p  is the mean pulse voltage, and F p  is the number of forward and reverse pulses per second.  
     
     
         2 . The apparatus of  claim 1 , wherein the mean pulse width is 4 μs or less.  
     
     
         3 . The apparatus of  claim 1 , wherein the mean pulse width is 1.5 μs or less.  
     
     
         4 . The apparatus of  claim 1 , wherein the mean pulse width is 0.75 μs or less.  
     
     
         5 . The apparatus of  claim 1 , wherein the mean pulse voltage is at least 100V.  
     
     
         6 . The apparatus of  claim 1 , wherein the mean pulse voltage is at least 150V.  
     
     
         7 . The apparatus of  claim 1 , wherein the voltage is at least 100V and the pulse width is 6 μs or less.  
     
     
         8 . The apparatus of  claim 1 , wherein the voltage is at least 200V and the pulse width is 1.5 μs or less.  
     
     
         9 . The apparatus of  claim 1 , wherein the pulse frequency is at least 1000 Hz.  
     
     
         10 . The apparatus of  claim 1 , wherein the pulse frequency is at least 5 KHz.  
     
     
         11 . The apparatus of  claim 1 , wherein V p   2 .Pw.F p  is at least 250.  
     
     
         12 . The apparatus of  claim 1 , wherein V p   2 .Pw.F p  is at least 340.  
     
     
         13 . The apparatus of  claim 1 , wherein the biphasic wave is continuous.  
     
     
         14 . The apparatus of  claim 1 , wherein each pulse in the biphasic wave has an edge rate exceeding 250V/μs.  
     
     
         15 . The apparatus of  claim 1 , wherein each pulse in the biphasic wave has an edge rate exceeding 500V/μs.  
     
     
         16 . The apparatus of  claim 1 , wherein the signal generator is arranged to provide a biphasic waveform providing a mean modulus current flowing through the patient of at least 3 mA.  
     
     
         17 . The apparatus of  claim 1 , wherein the signal generator is arranged to provide a biphasic waveform providing a mean modulus current flowing through the patient of at least 6 mA.  
     
     
         18 . The apparatus of  claim 1 , wherein the signal generator is arranged to provide a biphasic waveform providing a mean modulus current flowing through the patient of at least 10 mA.  
     
     
         19 . The apparatus of  claim 1 , wherein the interpulse spacing is less than 4 μs.  
     
     
         20 . The apparatus of  claim 1 , wherein the interpulse spacing is less than 1 μs.  
     
     
         21 . The apparatus of  claim 1 , wherein the interpulse spacing is 0 μs.  
     
     
         22 . A method of inducing analgesia in a patient, the method comprising providing an apparatus according to  claim 1 , applying the electrodes to the patient's body, and providing a waveform as described.  
     
     
         23 . A method of inducing analgesia in a patient's body through electrical signals applied by electrodes to the patient's body, using an apparatus comprising electrodes for application to the patient's body and a signal generator which is connectable to said electrodes, wherein the signal generator is arranged to generate a biphasic waveform comprising successive cycles each containing a positive and negative pulse, the method comprising: 
 applying the electrodes to two or more locations on the patient's body such that at least one of said locations on the patient's body does not overlie the central nervous system;    providing said biphasic electrical waveform so as to induce analgesia at said site.    
     
     
         24 . The method of  claim 23 , wherein the locations span the area of pain or discomfort, and/or peripheral nerves conducting signals from said area of pain or discomfort.  
     
     
         25 . The method of  claim 23 , which relieves pain or discomfort associated with physical injury.  
     
     
         26 . The method of  claim 23 , which relieves pain or discomfort associated with inflammatory conditions.  
     
     
         27 . The method of  claim 23 , wherein the mean pulse width is 10 μs or less.  
     
     
         28 . The method of  claim 23 , wherein the mean pulse width is 4 μs or less.  
     
     
         29 . The method of  claim 23 , wherein the mean pulse width is 1.5 μs or less.  
     
     
         30 . The method of  claim 23 , wherein the mean pulse width is 0.75 μs or less.  
     
     
         31 . The method of  claim 23 , wherein the mean pulse voltage is at least 100V.  
     
     
         32 . The method of  claim 23 , wherein the mean pulse voltage is at least 150V.  
     
     
         33 . The method of  claim 23 , wherein the pulse voltage is at least 100V and the pulse width is 6 μs or less.  
     
     
         34 . The method of  claim 23 , wherein the pulse voltage is at least 200V and the pulse width is 1.5 μs or less.  
     
     
         35 . The method of  claim 23 , wherein the pulse frequency is at least 1200 Hz.  
     
     
         36 . The method of  claim 23 , wherein the pulse frequency is at least 5 kHz.  
     
     
         37 . The method of  claim 23 , wherein the signal generator is arranged to provide a biphasic waveform providing a mean modulus current flowing through the patient of at least 3 mA.  
     
     
         38 . The method of  claim 23 , wherein the signal generator is arranged to provide a biphasic waveform providing a mean modulus current flowing through the patient of at least 6 mA.  
     
     
         39 . The method of  claim 23 , wherein the signal generator is arranged to provide a biphasic waveform providing a mean modulus current flowing through the patient of at least 10 mA.  
     
     
         40 . The method of  claim 23 , wherein the interpulse spacing is less than 4 μs.  
     
     
         41 . The method of  claim 23 , wherein the interpulse spacing is less 1 μs.  
     
     
         42 . The method of  claim 23 , wherein the interpulse spacing is 0 μs.  
     
     
         43 . The method of  claim 23 , wherein the apparatus is an apparatus according  claim 1 .  
     
     
         44 . An apparatus for producing analgesia in a patient through electrical signals applied by electrodes to the patient's body, the apparatus comprising electrodes for application to the patient's body and a signal generator which is connectable to the electrodes, wherein the signal generator is arranged to generate a biphasic waveform comprising successive cycles each containing a positive and negative pulse, and wherein the apparatus comprises a control element for varying the spacing between the positive and negative pulse.  
     
     
         45 . The apparatus of  claim 44 , wherein the signal generator is arranged to generate a biphasic waveform having a mean pulse width of less than 4 μs.  
     
     
         46 . The apparatus of  claim 44 , wherein the signal generator is arranged to generate a biphasic waveform having a mean pulse width of at least 0.5 μs.  
     
     
         47 . The apparatus of  claim 44 , wherein the signal generator is arranged to generate a biphasic waveform having a voltage of at least 100V.  
     
     
         48 . The apparatus of  claim 44 , wherein the control element is operable by an operator.  
     
     
         49 . The apparatus of  claim 44 , wherein the control element provides automated variation of interpulse spacing.  
     
     
         50 . The apparatus of  claim 49 , wherein the control element provides automated variation of interpulse spacing in a series of modulation cycles.  
     
     
         51 . The apparatus of  claim 50 , wherein modulation rates are between 1200 Hz and 0.25 Hz.  
     
     
         52 . A method of inducing analgesia through electrical signals applied by electrodes to the patient's body, wherein the induction of analgesia comprises 
 providing an apparatus comprising electrodes for application to the patient's body and a signal generator connected to said electrodes, wherein the signal generator is arranged to provide a biphasic electrical waveform comprising successive cycles each having a positive and negative pulse,    applying the electrodes to two or more locations on the patient's body; and    providing said biphasic electrical waveform;    wherein the spacing between the positive and negative pulse is modulated during the treatment.    
     
     
         53 . The method of  claim 52 , wherein the spacing between the positive and negative pulse is modulated so as to alter the level of sensation experienced by the patient during the treatment.  
     
     
         54 . The method of  claim 52 , wherein the biphasic waveform has a mean pulse width of less than 4 μs.  
     
     
         55 . The method of  claim 52 , wherein the biphasic waveform has a mean pulse width of at least 0.5 μs.  
     
     
         56 . The method of  claim 52 , wherein the signal generator is arranged to generate a biphasic waveform having a voltage of at least 100V.  
     
     
         57 . The method of  claim 52 , wherein the modulation is repeated during the treatment in a series of modulation cycles.  
     
     
         58 . The method of  claim 57 , wherein modulation rates are between 1200 Hz and 0.25 Hz.  
     
     
         59 . A method for pre-setting the operating parameters of an apparatus for producing analgesia in a patient through electrical signals applied by electrodes to the patient's body, the apparatus comprising electrodes for application to the patient's body and a signal generator which is connectable to said electrodes, wherein the signal generator is arranged to provide a biphasic waveform comprising successive cycles each having a positive and negative pulse, the method comprising 
 selecting the voltage and pulse width, and    selecting the interpulse spacing with reference to a predetermined relationship between sensation and interpulse spacing at said voltage and pulse width.    
     
     
         60 . A method of selecting treatment parameters during the induction of analgesia through electrical signals applied by electrodes to the patient's body, wherein said therapy comprises: 
 providing an apparatus comprising electrodes for application to the patient's body and a signal generator connectable to said electrodes, wherein the signal generator is arranged to generate a biphasic waveform comprising a successive cycles each containing a forward and reverse pulse,    applying the electrodes to two or more locations on the patient's body;    and providing said waveform at a starting voltage and pulse width;    the method of selecting treatment parameters comprising varying the voltage and/or pulse width until the patient experiences a comfortable level of sensation, and selecting the voltage and pulse width at which comfortable sensation is felt.    
     
     
         61 . An apparatus for producing analgesia in a patient through electrical signals applied by electrodes to the patient's body, the apparatus comprising electrodes for application to the patient's body and a signal generator which is connectable to the electrodes, wherein the signal generator is arranged to generate a biphasic waveform comprising successive cycles each containing a positive and negative pulse, and comprises: 
 a converter for producing a desired voltage from a power supply;    a first capacitor which is in electrical connection with said converter and which is arranged to provide the positive pulse to one of said electrodes;    a second capacitor which is in electrical connection with said converter and which is arranged to provide the negative pulse to one of said electrodes;    wherein said first and second capacitors are respectively connected to an output by a corresponding pathway, the pathways including respective switches, and wherein the signal generator includes a controller arranged to control the operation of the switches to cause alternate discharge of the first and second capacitors through the corresponding pathway to generate said positive and negative pulses.    
     
     
         62 . The apparatus of  claim 61 , wherein the capacitance of the capacitor decreases with voltage.  
     
     
         63 . The apparatus of  claim 61 , wherein the capacitors are ceramic type capacitors.  
     
     
         64 . The apparatus of  claim 61 , wherein the first and second capacitors are connected via respective diodes to a common supply generated by the converter, and wherein the pathways corresponding to the first and second capacitors are provided respectively by two arms of an H-bridge.  
     
     
         65 . The apparatus of  claim 61 , wherein the output has a peak pulse current of greater than 1 A.  
     
     
         66 . The apparatus of  claim 65 , wherein the output has a peak pulse current of greater than 2 A.  
     
     
         67 . The apparatus of  claim 61 , wherein the apparatus comprises a control to control the operation of switches, such that during the pulse off time, the switches in the pathway connecting the first and second capacitor to the respective output are switched off, and one or more additional switches are operated to short the patient outputs.  
     
     
         68 . The apparatus of  claim 61 , wherein the signal generator is arranged to generate a biphasic waveform wherein each pulse of the biphasic waveform has an edge rate is greater than 250 V/μs.  
     
     
         69 . The apparatus of  claim 61 , wherein the signal generator is arranged to generate a biphasic waveform wherein each pulse of the biphasic waveform has an edge rate is greater than 500 V/μs.  
     
     
         70 . The apparatus according to  claim 61 , wherein the apparatus further comprises means to limit the pulse width to less than a predetermined period.  
     
     
         71 . The apparatus according to  claim 61 , wherein the apparatus further comprises means for detecting when said positive or negative pulse is of over-prolonged duration, and for limiting said duration.  
     
     
         72 . The apparatus of  claim 70 , wherein the pulse “on” time is limited by circuitry in the switch drive logic or level translation circuitry.  
     
     
         73 . The apparatus of  claim 70 , wherein the pulse length is limited by one or both of a logic circuit and output transistors, which cannot remain in the “on” state for more than a fixed period without edge transitions on the gate drives.  
     
     
         74 . The apparatus of  claim 61 , wherein the therapeutic pulse charge does not exceed a safe value in the event of software failure or single component failure.  
     
     
         75 . The apparatus of  claim 74 , wherein said safe value is 75 μC.  
     
     
         76 . The apparatus of  claim 61 , having means for earthing said electrical connection of each of said first and second capacitors, thereby to halt the provision of said pulses.  
     
     
         77 . The apparatus of  claim 76 , wherein said earthing means comprises a switch controlled by said controller.  
     
     
         78 . The apparatus of  claim 61 , wherein the apparatus further comprises one or more independent means for monitoring the signal produced by the apparatus.  
     
     
         79 . The apparatus of  claim 61 , wherein the signal generator is arranged to generate a biphasic waveform comprising successive cycles each containing a positive and negative pulse, wherein the mean pulse width P w  is 10 μs or less, and wherein V p   2 .Pw.F p  is at least 200, where V p  is the mean pulse voltage, and F p  is the number of forward and reverse pulses per second.  
     
     
         80 . (canceled)