Patent Publication Number: US-2007112262-A1

Title: Electrode holder, headwear, and wire jacket adapted for use in sleep apnea testing

Description:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION  
      This invention relates generally to sleep apnea, and more specifically to an electrode holder, headwear, and wire jacket adapted for use in sleep apnea testing.  
      Sleep apnea is a serious, potentially life-threatening breathing disorder characterized by brief interruptions of breathing during sleep. In a given night, the number of involuntary breathing pauses or “apneic events” may be as high as 20 to 30 or more per hour. These breathing pauses are almost always accompanied by snoring between apnea episodes, although not everyone who snores has this condition. Sleep apnea can also be characterized by choking sensations. The frequent interruptions of deep, restorative sleep often lead to early morning headaches and excessive daytime sleepiness.  
      Certain mechanical and structural problems in the airway cause the interruptions in breathing during sleep. In some people, apnea occurs then the tongue and throat muscles relax during sleep and partially block the opening of the airway. When the muscles of the soft palate at the base of the tongue and the uvula relax and sag, the airway becomes blocked, making breathing labored and noisy and even stopping it altogether. Sleep apnea also can occur in obese people when an excess amount of tissue in the airway causes it to be narrowed. With a narrowed airway, the person continues their efforts to breathe, but air cannot easily flow into or out of the nose or mouth. Unknown to the person, this results in heavy snoring, periods of no breathing, and frequent arousals causing abrupt changes from deep sleep to light sleep.  
      During the apneic event, the person is unable to breathe in oxygen and to exhale carbon dioxide, resulting in low levels of oxygen and increased levels of carbon dioxide in the blood. The reduction in oxygen and increase in carbon dioxide alert the brain to resume breathing and cause an arousal. With each arousal, a signal is sent from the brain to the upper airway muscles to open the airway; breathing is resumed, often with a loud snort or gasp. Frequent arousals, although necessary for breathing to restart, prevent the patient from getting enough restorative, deep sleep.  
      The present invention relates to devices intended to promote the efficiency, quality and accuracy of sleep apnea testing. Testing is performed using a number of surface electrodes applied to the skin of a patient and connected through lead wires to a polysomnograph. The polysomnograph monitors the patient&#39;s sleep by converting electrical impulses in the body to a graphical representation. Quality and accuracy of any recording are directly related to the quality and accuracy of the input signals. Factors affecting input signals include improper placement of the electrodes and failure to properly secure the electrodes throughout testing.  
      Prior to testing, the patient is prepped or “hooked up” by a polysomnographic technologist. This involves attaching a number of electrodes on the patient&#39;s scalp, face, chin, chest, and legs. The process is painless, but generally time consuming. Each electrode is attached to the skin by completely filling a cavity of the electrode with an adhesive electrolyte gel, cream or paste. Standard commercial gels and pastes include ECG2 by Grass/AstroMed, Ten20 and Nu-Prep by Weaver, and Elefix by Nihon Kohden. In some cases, double sided adhesive washers are also used to hold the electrode in place. Failure to maintain a proper and firm attachment of the electrode to the skin throughout testing generally contributes to motion artifacts which disrupt the input signal and cause bad recordings. Overspreading of the electrolyte gel can also reduce the quality and accuracy of the recording. The electrolyte gel has a bad smell, and is generally cold and uncomfortable.  
      The present invention provides an alternative means for securing electrodes to the skin of the patient. The invention substantially reduces patient prep time, requires only a very small amount of gel, and provides improved electrode attachment resulting in reduced signal interruption and more accurate recordings.  
     SUMMARY OF INVENTION  
      Therefore, it is an object of the invention to provide medical devices which promote efficient, quality and accurate testing of sleep apnea patients.  
      It is another object of the invention to provide to maintain a stable and reliable input signal throughout sleep apnea testing.  
      It is another object of the invention to provide an improved means for attaching electrodes to the skin of the patient which requires the use of substantially less electrolyte gel—90% less in many cases.  
      It is another object of the invention to substantially reduce the messiness caused by the electrolyte gel when prepping the patient.  
      It is another object of the invention to substantially reduce the patient prep time.  
      It is another object of the invention to reduce movement artifact on the polysomnogram.  
      These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing an electrode holder adapted for cooperating with a strap applied to a body part of a patient to hold a surface electrode to the skin. The term “strap” is defined broadly herein to include any strap, band, cover, belt, patch or other article applied to a body part using any self-attachment means, such as mating ends of hook and loop fasteners, a releasable adhesive, snaps, buttons, and the like. The electrode holder includes a base and a post projecting from the base. The post is adapted for extending through the strap and into a cavity formed with the electrode. Means are provided for attaching the electrode holder to the strap. Once attached, the post secures the electrode in position thereby reducing motion artifacts caused by disturbance of the electrode after placement against the skin of the patient.  
      According to another preferred embodiment, the post includes a reinforcing member formed with the base.  
      Preferably, the reinforcing member has a generally x-shaped cross-section.  
      According to another preferred embodiment, the post further includes an electrode-penetrating tip extending from the reinforcing member.  
      Preferably, the electrode-penetrating tip has a rounded end to facilitate entry into the cavity of the electrode.  
      According to another preferred embodiment, the base comprises a thin flat disk.  
      According to another preferred embodiment, the means for attaching comprises hook fasteners located on the base and adapted for releasably mating with complementary loop fasteners located on the strap.  
      According to another preferred embodiment, the base and the post are integrally formed together of a molded polymer.  
      Preferably, the polymer is ABS plastic.  
      According to another preferred embodiment, the strap defines a post-receiving slit accommodating passage of the post through the strap and into the cavity of the electrode.  
      In another embodiment, the invention is a method for holding an electrode to the skin of a patient. The method includes the step of placing the electrode against the skin of the patient. An electrode holder is then attached to a strap. The electrode holder includes a post extending through the strap. The electrode is then covered with the strap, such that the post of the electrode holder inserts into a cavity formed with the electrode. The strap is then applied to a body part, whereby the post secures the electrode in position thereby reducing motion artifacts caused by disturbance of the electrode after placement against the skin of the patient. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Some of the objects of the invention have been set forth above. Other objects and advantages of the invention will appear as the description proceeds when taken in conjunction with the following drawings, in which:  
       FIG. 1  is an isometric view of an electrode holder according to one preferred embodiment of the present invention;  
       FIG. 2  is a side view of the electrode holder;  
       FIG. 3  is a top view of the electrode holder;  
       FIG. 4  is an isometric view of a patient&#39;s head with the electrodes and headwear attached;  
       FIG. 5  is a fragmentary perspective view of the headwear with the electrode holder in place to hold the surface electrode to the skin;  
       FIG. 6  is an exploded view showing the electrode holder removed from the cavity of the surface electrode;  
       FIG. 7  is a cross-sectional view taken substantially along line  7 - 7  of  FIG. 5 ;  
       FIG. 8  is a perspective view of the head band with the top strap, chin strap and patient&#39;s head shown in phantom;  
       FIG. 9  is a view of the head band laid flat, and showing its outside major surface;  
       FIG. 10  is a view of the head band laid flat, and showing its inside major surface;  
       FIG. 11  is a perspective view of the top strap with the head band, chin strap, and patient&#39;s head shown in phantom;  
       FIG. 12  is a view of the top strap laid flat, and showing its outside major surface;  
       FIG. 13  is a view of the top strap laid flat, and showing its inside major surface;  
       FIG. 14  is perspective view of the chin strap with the head band, top strap, and patient&#39;s head shown in phantom;  
       FIG. 15  is a view of the chin strap laid flat, and showing its outside major surface;  
       FIG. 16  is a view of the chin strap laid flat, and showing its inside major surface;  
       FIG. 17  is a front view of a patient&#39;s head with the headwear and surface electrodes attached;  
       FIG. 18  is a top view of a patient&#39;s head with the headwear and surface electrodes attached;  
       FIG. 19  is a right side view of a patient&#39;s head with the headwear and surface electrodes attached;  
       FIG. 20  is an enlarged view of the portion designated at reference numeral  20  in  FIG. 19 ;  
       FIG. 21  is a left side view of a patient&#39;s head with the headwear and surface electrodes attached;  
       FIG. 22  is an enlarged view of the portion designated at reference numeral  22  in  FIG. 21 ;  
       FIG. 23  is a back view of a patient&#39;s head with the headwear and surface electrodes attached;  
       FIG. 24  is a further perspective view of a patient&#39;s head with the headwear and surface electrodes attached, and showing the lead wires bundled together in the wire jacket;  
       FIG. 25  is a view of the wire jacket laid open; and  
       FIG. 26  is a view of the wire jacket closed around the wires. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT AND BEST MODE  
      Referring now specifically to the drawings, an electrode holder according to the present invention is illustrated in  FIGS. 1-3 , and shown generally at reference numeral  10 . In sleep apnea testing, multiple electrode holders  10  are generally used on a single patient. The electrode holders  10  cooperate with various articles of headwear to hold respective surface electrodes to the skin of the patient. Preferably, the headwear comprises an assembly of fabric-covered neoprene head straps  11 ,  12 , and  14  shown in  FIG. 4  and described further below.  
      As previously discussed, sleep apnea is typically diagnosed in a polysomnography sleep test. An overnight polysomnography test involves monitoring brain waves, muscle tension, eye movement, respiration, oxygen level in the blood and audio monitoring for snoring, gasping, etc. A polysomnograph monitors the patient&#39;s sleep by converting electrical impulses in the body to a graphical representation. Many different activities are monitored by the polysomnograph during a sleep study. These include brain waves (EEG), eye movements (EOG), muscle activity (EMG), heartbeat (EKG), blood oxygen levels (SpO2) and respiration. Each of these activities is represented by graphical tracings on a polysomnogram.  
      Prior to testing, the patient is “hooked up” by a polysomnographic technologist. This involves locating the surface electrodes on the patient&#39;s scalp, face, chin, chest, and legs. The skin is first cleaned where the electrodes will be attached. Each electrode “E” has a round cup-shaped body (See  FIGS. 6 and 7 ) which defines a small cavity “C” designed for receiving an adhesive material, such as an electrolyte gel, cream, or paste. The adhesive material serves to temporarily hold the electrode “E” to the skin during application of the headwear and throughout subsequent testing. Preferably, each electrode has a plastic-encased silver/silver chloride body with low DC offset potential, limited motion artifacts, and low frequency response. According to one embodiment, the electrode body is 12 mm in diameter and has a 2 mm cavity in the top for addition of the adhesive material. A flexible, small and durable gray lead wire “W” extends from the electrode “E” and terminates in a female safety connector (not shown). The lead wire “W” is generally available in 2, 3, 4, 5, 6, 8, &amp; 10 foot load lengths.  
      After attaching the surface electrodes “E”, the technician applies the head straps  11 ,  12 , and  14  to the patient. The head straps  11 ,  12 ,  14  cooperate with the electrode holders  10  to firmly hold the electrodes “E” in place during testing. Since the quality and accuracy of any recording are directly related to the quality and accuracy of the input signals, it is important that the electrodes “E” are accurately placed and properly secured throughout the duration of the recording. Firm attachments minimize “popping” artifacts, which can easily be caused by patient movement during a sleep study.  
      Electrode Holder  
      Referring to  FIGS. 1-3  and  5 - 7 , each electrode holder  10  has a base  15  with opposing inside and outside major surfaces,  15 A and  15 B, respectively. An elongated post  16  projects from the inside surface  15 A. The base  15  comprises a thin flat polymer disk, and hook fasteners  17  carried on a substrate  18  permanently adhered to the inside surface  15 A. The outside surface  15 B of the base  15  may include any desired indicia, such as a company logo or other source-indicating marking. The post  16  has an enlarged reinforcing member  22  integrally formed with the base  15 , and an electrode-penetrating tip  23  designed for inserting into the cavity “C” of the electrode “E”. Preferably, the reinforcing member  22  has a generally x-shaped cross-section and includes a plurality of circumferentially arranged columns  24  with respective feet  25  formed with the base  15 . The base  15  and post  16  are preferably integrally formed together of a molded ABS plastic.  
      As best shown in  FIGS. 5-7 , the electrode holder  10  is applied to the head strap  12  such that the post  16  extends through a longitudinal slit  26  formed with the strap  12 . The electrode-penetrating tip  23  is then inserted into the gel-filled cavity “C” of the electrode “E”. Preferably, the tip  23  has a rounded end  23 A in order to facilitate its entry into the cavity “C”. The hook fasteners  17  of the base  15  mate with the fabric cover (loops)  28  of the head strap  12 , as shown in  FIG. 7 , to releasably secure the holder  10  to the strap  12 , while the tip  23  of the post  16  firmly holds the electrode “E” in position against the skin of the patient.  
      Head Straps  
      Referring to  FIGS. 8-16 , the head straps  11 ,  12 ,  14  comprise a head band, a top strap, and a chin strap, respectively, which are interconnected and adapted for extending around and about the head of the patient. The head band  11 , shown in  FIGS. 8, 9 , and  10 , extends across the forehead, and has opposing ends  11 A,  11 B with complementary sections mating hook “H” and loop “L” fasteners which releasably and adjustably secure the band  11  to the patient. The end  11 A has respective sections  31  and  32  of hook fasteners “H” on the outside and the inside of the band  11 . The band  11  is applied to the head such that the loop fasteners (fabric) “L” on the outside of end  11 B mate with the hook fasteners  32  on the inside of end  11 A. This leaves the hook fastener section  31  on the outside of end  11 A exposed. These fasteners  31  cooperate with a second hook fastener section  34  located on the outside of the band  11  to attach the top strap  12 , as described below.  
      The outside of the band  11  further includes a number of spaced wire-management strips  35 ,  36 ,  37 , and  38  for arranging and segregating lead wires “W” extending from the electrodes “E”. The wire-management strips  35 - 38  are sewn to the band  11  at their respective opposite ends and include elastic yarns, such as spandex. By pulling the strip  35 - 38  slightly outwardly to create sufficient through-space, one or more lead wires “W” are fed through and held between a single strip  35 - 38  and the band  11 . Longitudinal slits  41 ,  42 , and  43  are also formed with the head band  11  for accommodating interconnection of the electrode holders  10  and surface electrodes “E”, as previously described.  
       FIGS. 11, 12 , and  13  illustrate the top strap  12 . The top strap  12  extends over the head of the patient, and has opposing ends  12 A and  12 B comprising both inside and outside loop fasteners (fabric) “F”. The ends  12 A,  12 B mate with respective hook fastener sections  31 ,  34  of the head band  11  to releasably and adjustably secure the top strap  12  in position on the head. The top strap  12  has a center wire-management strip  45  located between a pair of longitudinal slits  46  and  47 . The wire-management strip  45  serves to arrange and segregate electrode wires “W”, while the slits  46 ,  47  accommodate interconnection of the electrode holders  10  and surface electrodes “E”.  
      The chin strap  14  is best shown in  FIGS. 14, 15 , and  16 . The chin strap  14  is designed to extend under the chin of the patient, and has sections  48  and  49  of hook fasteners “H” located on the inside of respective opposite ends  14 A and  14 B. These sections  48 ,  49  mate with the loop fasteners “L” located on the outside of the top strap  12  to releasably secure the chin strap  14  to the head. Pairs of lateral slits  51  and  52  are formed on opposite sides of a divided chin opening  53  with an additional slit  54  formed in the divider for accommodating interconnection of the electrode holders  10  and surface electrodes “E” attached to the chin. The chin strap  14  may also include one or more tube-retaining strips (not shown) designed for receiving and holding airway tubes used with a CPAP device.  
       FIGS. 17-22  illustrate complete assembly of the head band  11 , top strap  12 , and chin strap  14  with electrodes “E” attached to the head of the patient and wires “W” passing through respective wire-management strips  35 - 38  and  45 . The hook “H” and loop “L” fasteners cooperate to provide a “touch” fastening system which securely holds the headwear in place, and offers ready and convenient size adjustment for increased effectiveness and added comfort. The neoprene rubber is soft, resilient, and breathable. The loop fasteners (fabric) “L” preferably comprise a cotton or cotton blend material.  
      Wire Jacket  
      Referring to  FIGS. 24-26 , the lead wires “W” extending from the surface electrodes “E” pass through the wire-management strips  35 - 38  and  45 , as previously described, and are bundled together away from the patient within an elongated wire jacket  60 . As shown in  FIG. 25 , interior loops  61  and  62  are sewn at their respective opposite ends to the jacket  60 , and serve to further bundle and contain the wires “W” passing through the jacket  60 . Preferably, the wire jacket  60  comprises a convenient longitudinal closure, such as a standard zipper  64 , which closes the jacket  60  around the wires “W” as shown in  FIGS. 23 and 26 . By bundling the wires “W”, the wire jacket  60  promotes reliable and uninterrupted signal input to the polysomnograph. In alterative embodiments, the jacket  60  may utilize other closure means including snap fasteners, buttons, hook and loop, and the like. The jacket  60  is between 18-30 inches long and is constructed of a fabric material, such as nylon.  
      An electrode holder, headwear, and wirejacket are described above. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the preferred embodiment of the invention and best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation—the invention being defined by the claims.