Abstract:
In a preferred embodiment, a percutaneous electrode remover includes a housing adapted to be held in a user&#39;s hand, the housing having an aperture at a distal end; and an actuator operable by a user to move a precutaneously inserted electrode through the aperture and completely into the housing.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to percutaneous electrical therapy systems for medical use. In particular, the invention relates to an electrode remover for removing percutaneously inserted electrodes from a patient&#39;s tissue. 
     Electrical therapy has long been used in medicine to treat pain and other conditions. For example, transcutaneous electrical nerve stimulation (TENS) systems deliver electrical energy through electrode patches placed on the surface of a patient&#39;s skin to treat pain in tissue beneath and around the location of the patches. The efficacy of TENS systems in alleviating pain is questionable at best, however. 
     More recently, a technique in which electrodes are placed through the patient&#39;s skin into the target tissue has been proposed. Percutaneous Neuromodulation Therapy (“PNT”) (also sometimes called Percutaneous Electrical Nerve Stimulation or “PENS”) using percutaneously placed electrodes achieves significantly better pain relief results than TENS treatments using skin surface electrodes. This therapy is described in Ghoname et al., “Percutaneous Electrical Nerve Stimulation for Low Back Pain,” JAMA 281:818-23 (1999); Ghoname et al, “The Effect of Stimulus Frequency on the Analgesic Response to Percutaneous Electrical Nerve Stimulation in Patients with Chronic Low Back Pain,” Anesth. Analg. 88:841-6 (1999); Ahmed et al., “Percutaneous Electrical Nerve Stimulation (PENS): A Complementary Therapy for the Management of Pain Secondary to Bony Metastasis,” Clinical Journal of Pain 14:320-3 (1998); and Ahmed et al., “Percutaneous Electrical Nerve Stimulation: An Alternative to Antiviral Drugs for Herpes Zoster,” Anesth. Analg. 87:911-4 (1998). The contents of these references are incorporated herein by reference. 
     Thus far, PNT practitioners have used percutaneously placed acupuncture needles attached to waveform generators via cables and alligator clips to deliver the therapy to the patient. This arrangement and design of electrodes and generator is far from optimal. For example, removal of percutaneous electrodes has thus far been a cumbersome operation. It has also been dangerous, since the prior art has not addressed the issue of sharps protection for the patients&#39; caregivers and other bystanders. It is therefore an object of this invention to provide a more efficient electrode remover and to reduce the exposure of electrical therapy patients&#39; caregivers to accidental exposure to bloodborne pathogens, microbes, toxins, etc., via an injury caused by unintended contact with a sharp electrode. 
     It is a further object of this invention to provide a percutaneous electrical therapy system having electrodes and electrode assemblies that are safe, efficacious, inexpensive and easy to use. 
     Other objects of the invention will be apparent from the description of the preferred embodiments. 
     SUMMARY OF THE INVENTION 
     The invention is a percutaneous electrode remover. In a preferred embodiment, the remover includes a housing adapted to be held in a user&#39;s hand, the housing having an aperture at a distal end; and an actuator operable by a user to move a percutaneously inserted electrode through the aperture and completely into the housing. 
     In some embodiments, the remover also includes an electrode engager adapted to engage an exposed portion of an electrode upon operation of the actuator. 
     In some embodiments of the remover, the actuator is further adapted to be operated by a user&#39;s thumb to move the electrode through the aperture. 
     In some embodiments, the remover also includes a used electrode holder adapted to hold a plurality of electrodes that had been moved into the housing by operation of the actuator. 
     In some embodiments of the remover, aperture is adapted to cooperate with an alignment element to align the introducer with an electrode insertion site. 
     The invention is described in more detail below with reference to the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a percutaneous electrode in place within a patient&#39;s tissue during electrical therapy. 
     FIG. 2 is an elevational view of an operator using the remover of this invention. 
     FIG. 3 is a partial sectional view of an electrode remover and sharp point protection assembly according to yet another embodiment of the invention prior to removal of an electrode. 
     FIG. 4 is a partial sectional view of the electrode remover and sharp point protection assembly of FIG. 3 partially actuated but prior to removal of an electrode. 
     FIG. 5 is a partial sectional view of the electrode remover and sharp point protection assembly of FIG. 3 partially actuated but prior to removal of an electrode. 
     FIG. 6 is a partial sectional view of the electrode remover and sharp point protection assembly of FIG. 3 partially actuated and engaged with an electrode but prior to removal of the electrode. 
     FIG. 7 is a partial sectional view of the electrode remover and sharp point protection assembly of FIG. 3 during removal of an electrode. 
     FIG. 8 is a partial sectional view of the electrode remover and sharp point protection assembly of FIG. 3 after removal of an electrode. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Percutaneous electrical therapy systems, such as PNT systems, deliver electric current to a region of a patient&#39;s tissue through electrodes that pierce the skin covering the tissue. The electric current is generated by a control unit external to the patient and typically has particular waveform characteristics such as frequency, amplitude and pulse width. Depending on the treatment or therapy being delivered, there may be one electrode containing both a cathode and an anode or a plurality of electrodes with at least one serving as a cathode and at least one serving as an anode. 
     The electrode has a sharp point to facilitate insertion through the patient&#39;s skin and to enhance local current density during treatment. Once inserted into the skin, the sharp point may become exposed to pathogens, microbes, toxins, etc. in the patient&#39;s tissue and/or blood. After removal of the electrode from the patient&#39;s tissue, a caregiver or other bystander may be stuck accidentally with the sharp point of the electrode, thereby exposing the caregiver to any pathogens that may be on the used electrode. This invention therefore provides an electrode remover having a sharp point protection assembly that is efficient and easy to use. 
     FIG. 1 shows a percutaneous electrode  102  whose sharp point  108  is in place in the tissue beneath a patient&#39;s skin  22 . During use, electrode  102  is connected to a control unit  150  via a cable  149  attached to an upper wide portion  112  of a handle portion  107  of the electrode. Insertion of the electrode and operation of the control unit and electrode to provide electrical therapy to the patient is explained in more detail in copending patent application [sharps protection], the disclosure of which is incorporated herein by reference. 
     Electrode  102  is shown deployed through a compressible annular patch  140 , which is attached to the patient&#39;s skin by adhesive or other suitable means. Patch  140  has a rigid annular member  141  disposed in its center and extending upwardly from it. Rigid member  141  has a smaller diameter opening  142  leading to a larger diameter opening  144 . The diameter of opening  142  is slightly smaller than a lower wide portion  114  of a handle portion  107  of electrode  102  and slightly larger than the diameter of a central portion  113  of electrode handle  107 . Lower wide portion  114  is preferably made of a resilient and compressible material. 
     As shown in FIGS. 3-8, remover  200  is designed to work with the electrode and electrode patch assembly of FIG.  1 . It should be understood that the remover of this invention can be used with other electrode designs and with or without electrode holding members such as patch  140 . 
     Remover  200  has a housing  202  with an aperture  204  at its distal end. A number of previously undeployed electrodes  102  are stored within housing  202 . A pair of rails  214  and  216  hold the electrodes  102  in alignment via the electrode handles  107 , as shown. While this embodiment of the remover is designed to provide sharps-safe removal and storage of a plurality of electrodes, the invention applies to removers designed to remove and store one or any number of electrodes. 
     As described above, electrodes for percutaneous electrical therapy are inserted through a patient&#39;s skin into underlying tissue with handle portions exposed above the skin. The first step in undeploying and removing an inserted electrode is to line up the exposed handle  107  of an electrode with the remover&#39;s aperture  204 , as shown in FIGS. 2 and 3, by placing the distal face  205  of remover  200  against the patient&#39;s skin or against any portion of the electrode assembly (such as an adhesive patch) surrounding the electrode. While not shown in FIGS. 3-8, aperture  204  is sized to surround an annular member holding an electrode handle of an electrode assembly, such as that shown in FIG. 1, the sharp point of which has been inserted through a patient&#39;s skin. 
     An electrode engagement fork  206  is pivotably attached to a longitudinally movable actuator  208  via an arm  209  and a hinged pivot  210 . A coil spring  212  biases actuator  208  upwards towards the actuator and fork position shown in FIG. 8. A leaf spring  218  extends from arm  209 . A cross-bar  220  at the end of leaf spring  218  slides in groove  222  and a corresponding groove (not shown) on the other side of housing  202 . Leaf spring  218  is in its relaxed state in the position shown in FIG.  3 . In this position, a cross-bar  224  extending from the distal end of arm  209  adjacent fork  206  lies at the top of a camming member  226  and a corresponding camming member (not shown) on the other side of housing  202 . 
     Downward movement of actuator  208  (in response, e.g., to pressure from a user&#39;s thumb) against the upward force of spring  212  moves cross-bar  224  against a first camming surface  228  of camming member  226 , as shown in FIG.  4 . Camming surface  228  pushes cross-bar  224  of arm  209  against the action of leaf spring  218  as actuator  208 , arm  209  and fork  206  move downward. 
     FIG. 5 shows the limit of the downward movement of fork  206 . At this point, cross-bar  224  clears the camming member  226 , and leaf spring  218  rotates fork  206  and arm  209  about pivot  210  to engage fork  206  with electrode handle  107 , as shown in FIG.  6 . The tine spacing of fork  206  is shorter than the diameter of the upper wide portion  112  of electrode handle  107  but wider than the diameter of the narrow middle portion  113  of electrode handle  107 . 
     Release of actuator  208  by the user permits spring  212  to move actuator  208 , arm  209  and fork  206  proximally. The engagement between fork  206  and electrode handle  107  causes the electrode to begin to move proximally with the fork out of the patient and into the remover housing, as shown in FIG.  7 . At this point, cross-bar  224  is now engaged with a second cramming surface  230  of camming member  226 . Camming surface  230  pushes cross-bar  224  against the action of leaf spring  218  in the other direction (to the left in the view shown in FIG. 7) as the electrode, fork and arm rise under the action of coil spring  212 . 
     The electrode and fork continue to rise until they reach the upward limit of their permitted motion, as shown in FIG.  8 . At this point, electrode handle  107  has engaged rails  214  and  216  and the most recent electrode previously stored in remover  200 . Electrode handle  107  pushes against the electrode handle of the previously stored electrode handle, which in turn pushes against any electrode handles stored above it in the stack. In this manner, the latest electrode removed by remover  200  goes into the bottom of the stack of used electrodes stored in remover  200 . Now that the sharp point  108  of electrode  102  is safely inside housing  202 , remover  200  can be withdrawn from the site on the patient&#39;s skin through which the electrode had been inserted. Once cross-bar  224  clears the top of camming member  226 , and leaf spring  218  moves arm  209  back to the center position shown in FIG.  3 . 
     It should be noted that remover  200  provides sharp point protection for the entire electrode undeployment and removal process. Once all electrodes have been removed, the used electrodes can be safely transported in the sharps-safe container provided by the housing  202  of remover  200 . 
     Modifications of the above embodiments of the invention will be apparent to those skilled in the art. For example, while the invention was described in the context of percutaneous electrical therapy in which electrodes are used to deliver electricity to a patient, the features of this remover may be used to remove electrodes designed for medical monitoring and/or diagnosis. In addition, the remover features of this invention may be used with acupuncture needles or other needles not used for conducting electricity to or from a patient.