Abstract:
An early warning and shutdown system that connects to a fluid loss detection device for dressings at pre-existing port sites, catheter sites, operative sites, ostomy sites, drain sites, line sites such as those utilized in hemodialysis, wound sites, or other areas for which monitoring of fluid or blood loss is medically indicated. The early warning and shutdown system sounds an alarm when the fluid loss detection device senses a loss of fluid, and then compresses a return tube carrying such fluid to stop further fluid loss if the fluid loss continues.

Description:
CROSS-REFERENCE 
     This application is a continuation-in-part patent application of U.S. patent application Ser. No. 12/607,818 filed Oct. 28, 2009, which is a continuation-in-part patent application of U.S. patent application Ser. No. 11/832,274 filed Aug. 1, 2007, which is a continuation-in-part patent application of U.S. patent application Ser. No. 11/306,947 filed Jan. 17, 2006, all incorporated in their entireties herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an early warning and shutdown system for hemodialysis, and more particularly to a system that provides a warning if a hemodialysis return line access site is leaking and will cause the hemodialysis system to shut down if the leak continues. 
     2. Prior Art 
     There are any number of situations in which the loss of blood or fluid from one or more body locations is medically significant. Hemodialysis, for example, is a known medical procedure through which a person&#39;s blood is cleansed of toxins. Hemodialysis is often prescribed when the kidneys no longer function properly for any of a number of reasons. Hemodialysis is typically performed at a hospital or dialysis center although there is interest in, and a trend toward, at-home use. In a dialysis treatment, the patient is connected to a hemodialysis machine via two tubes. The first tube is a blood intake tube and is responsible for removing blood from the patient and transferring it to the machine. When the blood enters the machine, it is cleaned via semi-permeable filters and then is pumped back to the patient through a blood return tubing. Before hemodialysis can be done, a doctor must make an entrance, often called an “access”, into the patient&#39;s blood vessels. This is sometimes done by minor surgery in the leg, arm or neck. The best access for many patients is called a “fistula”. Minor surgery may be performed to join an artery to a vein under the skin to make a larger vessel. 
     The dialysis process can take several hours for each procedure and may be done more than once per week depending on the condition. Even if done in the supervision of medical professionals, a patient cannot be monitored every minute. Additionally, a blanket or blankets will often be placed on the patient and the patient may attempt to nap or sleep during the procedure. 
     There have been reports of the return line becoming accidentally dislodged or pulled from the access site in the patient. If the dialysis machine and its accompanying pump continue to operate, blood will be drawn from the patient but will not properly be returned to the patient. If this condition continues, the patient can suffer loss of blood and even death. While the hemodialysis machines have existing pressure sensing devices, they may not sense the condition if the blood continues to pump. Additionally, if the patient is sleeping or if medical personnel are not constantly observing the entire procedure, blood loss may occur until it is discovered. 
     Several prior attempts have been made relating to various leak detection systems. For example, Van Antwerp et al. (U.S. Pat. No. 6,752,785) show a wide variety of leak detection devices including devices as shown in  FIGS. 10(   a ),  10 ( b ) and  10 ( c ). Each of these devices must be applied to the body of a user before a needle is inserted since each includes an enclosed circular opening. The Van Antwerp devices cannot be installed once the return line is attached to the patient. If the Van Antwerp device was placed on the patient first, it would involve breaking the sterile field which is created and normally desirable on the skin of the patient before insertion of the needle. If the Van Antwerp device were to be placed prior to inserting the needle into the patient, the sterile field of the access site would be compromised, possibly resulting in an infection of the patient&#39;s blood. 
     Accordingly, it would be desirable to provide for protection of hemodialysis patients from exsanguination. 
     It would be desirable to provide a blood and fluid loss detection device which might be installed, and a method for installing the device, around a pre-existing return line or needle connected to the patient, as well as a pre-existing operative site, a catheter or port site, a drain site, an ostomy site, or a wound site. 
     It would also be desirable to provide a blood loss detection device and method which is simple and modular in design which could be easily placed or replaced without interruption of treatment. 
     It would further be desirable to provide a blood loss detection device and method having a modular connection with a sensor system to confirm the modular connection. 
     It would also be desirable to provide a blood loss detection device having a radio transmission means for wireless communication of alarm information. 
     It would further be desirable to provide an alarm and a shut-down system which operates in conjunction with or separately from existing devices such as hemodialysis systems. 
     SUMMARY OF THE INVENTION 
     The present invention provides an early warning and shutdown system for hemodialysis comprising a fluid loss detection device surrounding a return access site through which a return line enters a patient&#39;s body and an automatic shutdown device connected to the fluid loss detection device. The fluid loss detection device may comprise an emergency shut-down circuit loop wherein the emergency shut-down circuit loop is activated by a fluid leak. 
     The automatic shutdown device may comprise a channel capable of receiving the return line and a clamping mechanism located adjacent the channel such that the clamping mechanism does not compress the return line when the clamping mechanism is in an open position but is capable of compressing the return line to stop fluids from flowing therethrough when the clamping mechanism is in an engaged position. The automatic shutdown device automatically moves the clamping mechanism from the open position to the engaged position when the emergency shut-down circuit loop is activated by a fluid leak. 
     The fluid loss detection device may further comprise an early warning alarm circuit loop wherein said warning alarm circuit loop is activated by a smaller fluid leak than the fluid leak that activates the emergency shut-down circuit loop. The automatic shutdown device may further comprise an alarm wherein the alarm is activated when the warning alarm circuit loop is activated. The alarm may produce sounds, lights, vibrations, or any combination thereof. The automatic shutdown device may further comprises an alarm wherein the alarm is activated when the emergency shut-down circuit loop is activated, and the alarm may produce sounds, lights, vibrations, or any combination thereof. 
     The fluid loss detection device may connect to the automatic shutdown device via a modular connector. In one embodiment, the clamping mechanism may be spring loaded. Alternatively, the clamping mechanism may be actuated by electrical, mechanical, pneumatic, electromechanical or electropneumatic force. The automatic shutdown device may further comprise a bracket or strap capable of securing the return line within the channel. The automatic shutdown device may attach to the patient&#39;s arm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simple diagrammatic view of a blood loss detection device in communication with a hemodialysis system; 
         FIG. 2  illustrates an exploded view and  FIG. 3  illustrates a top view of an alternate embodiment of the detection device; 
         FIG. 4  is a simple illustration of the modular connectors of the detection device; 
         FIG. 5  illustrates a further alternate embodiment of a blood loss detection device (double split design); 
         FIG. 6  illustrates a further alternate embodiment of a blood loss detection device with a self-monitoring plug; 
         FIG. 7  depicts a simple diagrammatic view of an alternative embodiment of the detection device; 
         FIG. 8  depicts a simple diagrammatic view of another alternative embodiment of the detection device; 
         FIG. 9  depicts a top view of an early warning and shutdown device; 
         FIG. 10  depicts a perspective view of the early warning and shutdown device; and 
         FIG. 11  depicts a circuit diagram for the early warning and shutdown device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments discussed herein are merely illustrative of specific manners in which to make and use the invention and are not to be interpreted as limiting the scope of the instant invention. 
     While the invention has been described with a certain degree of particularity, it is to be noted that many modifications may be made in the details of the invention&#39;s shape, construction and the arrangement of its components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification. 
     The disclosure herein may be applied to a number of situations in which it is medically, diagnostically or clinically advisable to monitor blood and fluid loss. The disclosure herein may be utilized at operative sites, drain sites, port sites, catheter sites, wound sites, ostomy sites, or any other bodily location where blood and fluid loss are to be monitored. 
     Referring to the drawings in detail,  FIG. 1  illustrates a simple diagrammatic view of a blood loss detection device  10  constructed in accordance with U.S. patent application Ser. No. 12/607,818 filed Oct. 28, 2009, from which the present application is a continuation-in-part, and which is itself a continuation-in-part patent application of U.S. patent application Ser. No. 11/832,274 filed Aug. 1, 2007, which is a continuation-in-part patent application of U.S. patent application Ser. No. 11/306,947 filed Jan. 17, 2006, all incorporated in their entireties herein by reference. 
     In one embodiment, the blood loss detection device  10  is utilized with and operates along with a hemodialysis system, represented by dashed lines  12 . 
     Hemodialysis machines and the hemodialysis procedure are both well-known. A patient (not shown) will have a fluid intake tube connected through an access into the blood vessels of the patient. The blood is pumped via a pump (shown diagrammatically by box  14 ) into and through the hemodialysis machine  12  where the blood is cleansed. The blood is thereafter returned via a blood return line  201  to the patient through a return access site  16 . 
     The detection device  10  includes a patch  20  having a boundary or external edge  22  extending around and circumnavigating the entire patch. The patch  20  and its boundary edge  22  may take many configurations including, as shown in  FIG. 1 , a substantially rectangular form. 
     The patch  20  also includes an opening  24  through the patch which forms a target for receipt of the return access site  16  and the return blood line  201  from the hemodialysis machine  12 . 
     A slit  30  through the patch  20  extends from the boundary edge  22  to the patch opening  24 . Accordingly, the patch forms an enclosure and surrounds the return access site  16  with the exception of the slit  30 . The ends may be overlapped to form a complete enclosure. 
     The blood access site monitor consists of a base typically with adhesive backing, would be able to substantially encircle the blood access site, and within its inner and outer boundaries contains the primary input circuit and required number of monitoring circuits. The access site monitoring device or patch should be composed of a permeable material that would facilitate transfer of any blood or fluid across the primary input conductors and monitoring circuits. 
       FIGS. 2 and 3  illustrate an alternate embodiment of the detection device  10 .  FIG. 2  shows an exploded view of an alternate embodiment  40  while  FIG. 3  illustrates a top view. The patch  40  includes a first layer  42  having an adhesive base designed to adhere to a skin of a patient. Above the first layer  42  are the electrical conductors to be described. A top layer  44  covers both the electrical conductors and the first layer  42 . The boundary edge  46  of the alternate embodiment  40  is in the form of a circle. 
     Finally, an optional transparent cover (not shown) could be adhesively secured to the top layer  44 . The cover might be transparent to allow for visual observation but retain any blood loss. 
     With reference to  FIG. 1  and continuing reference to  FIGS. 2 and 3 , a primary loop circuit  50  extends through a multi-conductor cable  52  via a primary input loop conductor to the patch (reference numeral  10  in  FIG. 1  and reference numeral  40  in  FIGS. 2 and 3 ). The primary input conductor circuit loop  50  may terminate at a pair of opposed ends at the slit  30  in the patch, as shown in  FIGS. 1 through 7 , or may form a complete loop, as shown in  FIG. 8  and described below. The multi-conductor cable  52  carries the primary loop circuit conductor to a DC voltage power supply  54  which, in turn, is connected to transformer  56  and thereafter connected to alternating current power supply  58 . The power supply is, in turn, wired to an audio alarm  60 . Accordingly, the primary loop input conductor  50  delivers and provides operational voltage to the detection device  10 . 
     An early warning alarm loop circuit  62  passes from the multi-conductor cable  52  into the patch  20 . The early warning alarm loop circuit  62  may terminate at two ends at the slit  30 , as shown in  FIGS. 1 through 7 , or may form a complete loop, as shown in  FIG. 8  and described below. The early warning alarm loop circuit  62  passes from the patch  20  through the multi-conductor cable  52  and back to the audio alarm  60 . An emergency shut-down circuit loop  64  extends from the multi-conductor cable  52  to the patch  20 . The emergency shut-down circuit loop  64  may terminate at two ends at the slit  30 , as shown in  FIGS. 1 through 7 , or may form a complete loop, as shown in  FIG. 8  and described below. The emergency shut-down circuit  64  may extend through the multi-conductor cable  52  to the dialysis machine  12  and, in particular, to the pump  14 . The emergency shut-down circuit may include a switch mechanism  66  to shut down the dialysis machine  12  and, in particular, the pump  14 . 
     As shown in  FIG. 8 , each of the primary loop circuit  50 , the early warning alarm loop circuit  62 , and the emergency shut-down circuit loop  64  may form a complete loop originating at an input and ending at an output allowing for a simple continuity check to verify each loop is complete and functioning properly. The primary loop circuit  50  has an input  150  wherein the input voltage may be applied. The input voltage may be verified at output  152 . The integrity of the early warning alarm loop circuit  62  may be verified by monitoring the continuity of the complete early warning loop between inputs  154  and  156 . The integrity of the emergency shutdown loop would be monitored in the same manner but utilizing inputs  158  and  160 . 
     This arrangement would allow a staged response to any and all loop failures. The response to the failure of either the primary input loop circuit  50  or the emergency shut-down circuit loop  64  may be termination of the treatment due to losing the critical response protocols. The response to the failure of the early warning alarm loop circuit  62  may only necessitate a low level alarm. 
     The present invention is modular in design so that the blood loss detection device  10  may be quickly installed, removed and replaced as desirable. 
     The multi-conductor cable  52  extending from the patch  40  terminates in a male modular connector  70 . The male modular connector  70  will cooperate with a female modular connector  72  connected to multi-conductor cable  52  which, in turn, may be connected to the hemodialysis machine  12  and the component elements previously discussed. Alternately, the multi-conductor cable  52  may connect via connector  202  to an early warning and shutdown device  200 , as shown in  FIGS. 9 and 10 , as discussed below. 
       FIG. 4  illustrates the modular connectors with an optional feature of an optional safety electric loop circuit. In addition to the primary loop circuit  50 , the early warning alarm circuit  62  and the emergency shut-down circuit  64 , the modular connectors include an optional safety loop circuit  74 . 
       FIGS. 5 and 6  show another embodiment of a safety loop modular connector.  FIG. 5  shows a further alternate embodiment of the present invention including a patch  80  having a boundary edge  82  and an opening  84 . Slits  86  and  88  extend through patch  80  between the boundary edge  82  and the opening  84 . 
       FIG. 5  illustrates a further alternate embodiment  80  of the invention utilizing a double split in the patch and a modular self-monitoring plug. 
       FIG. 7  depicts an alternative embodiment of the present invention. Patch  100  has a boundary edge  102  and a slit  104 , as well as a primary loop circuit  106 , an early warning alarm loop circuit  108 , and an emergency shut-down circuit  110 . Primary loop circuit  106 , early warning alarm loop circuit  108 , and emergency shut-down circuit  110  extend through a multi-conductor cable  112  to a male connector plug  114 . Male connector plug  114  is in turn connected to radio transmitter  116 . Persons skilled in the art will appreciate that radio transmitter  116  may be any suitable device capable of transmitting a radio signal, preferably a low frequency radio signal. 
     The radio transmitter  116  features adhesive bands  118  for attachment to a patient&#39;s limb. It should be appreciated that any self-adhesive or hook-and-loop adhesive may be utilized, and that radio transmitter  116  need not be attached to the patient&#39;s body but could alternatively be attached to a chair, bed rail, instrument cart, instrument stand, night stand, or other nearby furnishing or structure. 
     Still referring to  FIG. 7 , a radio receiver  120  is situated within range of radio transmitter  116 . Persons skilled in the art will appreciate that radio receiver  120  may be any suitable device that is capable of receiving a radio signal, provided that it is compatible with radio transmitter  116 . Radio receiver  120  is operably connected to a downstream device  122 . Downstream device  122  may be a medical instrument such as a dialysis machine, or an alarm device capable of activation in response to a radio signal received by radio receiver  120 . 
     The patch  100  and accompanying multi-conductor cable  112  and plug  114  could be disposed of after a single use. 
     For simple description of operation in  FIG. 1 , the illustrations will be limited to one input conductor and two return or output circuits or conductor. In the illustration, the inner  24  and outer  22  boundaries enclose three conductors—the primary input conductor circuit loop  50 , an emergency notification conductor loop  62  and an emergency shut-down conductor loop  64 . 
     As long as the dialysis machine does not sense a change or input voltage on conductor  62  or  64 , the treatment would proceed without interruption. If the machine detects a change in the status of conductor  62 , it would activate some type of notification alarm and staff could address the problem and treatment would continue uninterrupted. If at any point during treatment, the machine would detect a change in the status of conductor  64 , the machine would initiate an alarm and shut down the blood pump, preventing blood flow to the blood return access site. 
     The device shown in  FIG. 6  also includes a tubing clip  55  to retain the needle and fluid tube (not shown) in association with the patch. The clip may include a sensor circuit that is in a non-alarm state when the tubing is properly secured but if tubing is pulled, opening said clip, same said alarm circuit will be changed to an alarm state notifying patient and medical personnel that tubing is no longer retained by the patch. 
     A machine connection lead is composed of a multi-conductor cable that originates from control connections within the machine and terminates at a modular female connector. The number of conductors are variable and will depend on the monitoring configuration of the patch/access monitoring device. In the most basic design there would be at least two conductors, the first conductor would provide signal input to the monitoring device/patch and the second would provide a return path to the dialysis machine should a blood loss incident occur. In more advanced designs there would be additional conductors that would communicate other features/embodiments back to the machine for monitoring. In the enclosed details, the machine connection lead would contain four to five conductors. The first conductor  50  would be the signal input conductor or what is referred to as line voltage. The second conductor  62  would be an early warning conductor and would be activated by a small fluid leak. The third conductor  64  would be an emergency shut-down circuit and would only be activated when a larger fluid loss occurs. The fourth conductor  53  and fifth conductor  74  would be utilized in verifying that the modular connectors were properly connected. 
     As may be appreciated from the foregoing, the present invention may include optional circuits beyond the primary conductor and alarm/shut-down circuits set forth herein. 
     In an alternate embodiment, the blood loss detection device  10  may not be connected to a dialysis machine, but rather may be connected to a stand-alone early warning and shutdown device  200 , as shown in  FIGS. 9 and 10 . The device  200  may have a modular connector  202  for connecting with the blood loss detection device  10 . The device  200  may have an alarm  203  that may be triggered by the detection of fluid by the emergency notification conductor loop  62 . The alarm  203  would operate to notify the patient or the patient&#39;s care personnel of smaller, less serious fluid loss events. The alarm  203  could be accompanied by a vibration or light emitting system to increase likelihood that a small fluid leak warning is addressed. 
     The device  200  may also have a channel  204  into which a blood return line  201  may be placed and a clamping mechanism  205  located such that the clamping mechanism  205  may compress the return line  201  when triggered by the detection of fluid by the emergency shut-down conductor loop  64 , thus preventing further movement of fluid through the return line  201 . The blood return line is typically fabricated from a flexible plastic tubing. In the event of a large fluid loss situation, the clamping mechanism  205  would compress the return line  201  until flow through the tubing is stopped. The clamping mechanism  205  could be activated and operate on many different electro-mechanical, spring loaded, or motor driven principles such as singular or multiple pistons, singular or multiple offset cams, mechanically kinking or twisting of the return line  201 , or any number of other ways of arresting the fluid flow. 
       FIG. 9  shows the clamping mechanism  205  as spring loaded, with a handle  206  for engaging the clamping mechanism  205 . When the clamping mechanism is in the open/armed/cocked position, the spring is compressed. The clamping mechanism  205  may also be accompanied by a similar yet unique audible, visual, and/or vibration notification to assure patient and available staff are aware that the fluid flow has been stopped, effectively terminating the treatment. 
     The channel  204  into which a return line  201  may be placed may have a bracket or strap  207  for securing the return line  201  into position within the channel  204  such that the return line  201  will be compressed when the clamping mechanism  205  is deployed. 
     The early warning and shutdown device  200  may be small enough to be worn on a patient&#39;s arm like a watch or bracelet. Alternately, the device  200  may be made to sit near the patient on a table, chair, or bed. 
     In operation, the return line  201  is placed within the channel  204  and secured by the bracket or strap  207 . The clamping mechanism  205  is placed in an open/armed/cocked position allowing fluid to travel through the return line  201 . If the blood loss detection device  10  senses a small fluid loss event, the alarm  203  is sounded. If the blood loss detection device  10  senses a large fluid loss event, a switch will deploy the clamping mechanism  205  to deform the return line  201  until fluid flow is no longer possible, thus terminating the flow of fluids through the return line  201 . Alternately, if the blood loss detection device  10  is incapable of distinguishing between a small fluid loss event and a large fluid loss event, the clamping mechanism  205  is deployed upon the first detection of fluid loss. 
     Ideally, the device  200  would operated at three stages, assuming the blood loss detection device  10  is capable of detecting different stages of fluid loss, as is the blood loss detection device  10  described above. The first stage would be no leak, where everything is functioning normally. The device  200  may incorporate a visual display (not shown) such as a constant or green light. The second stage would be activated when a small fluid leak is detected by closing the normally open circuit between the primary input circuit loop and the early warning circuit loop, this closing of the circuit loop accomplished by a conductive fluid breaching the non-conductive absorbent/semi-permeable barrier between the primary input loop and the early warning loop. The best response to this stage two condition would be an audible alarm  203  with or without a flashing visual indicator and possible an accompanying vibratory alert. 
     The third and final stage would be the emergency shut down stage and would be initiated when the sensor detects a larger, more severe fluid loss. This more severe fluid loss detection would occur when the normally open circuit between the primary input circuit loop and the emergency shutdown circuit loop becomes closed. The closing of this circuit would be accomplished by a conductive fluid breaching the larger non-conductive absorbent/semi-permeable barrier between the primary input loop and the emergency shut down loop. Since the barrier between the primary input loop and the emergency shut down loop is larger than the barrier between the primary input loop and the early warning loop, a larger fluid loss would be required to initiate this final stage. The response to this stage would be to release or activate the clamping mechanism  205  stopping the fluid flow, possibly accompanied by a louder, more intense audible alert with or without a flashing visual indicator and an intense vibratory alert. 
     The benefit of the stand-alone early warning and shutdown device  200  is that it may be used with an existing hemodialysis machine without requiring modification to the existing hemodialysis machine. Most hemodialysis machines are programmed to stop pumping if the pressure in the return line becomes too high. Therefore, in operation, when the clamping mechanism  205  is engaged, the increased pressure in the return line  201  will cause the hemodialysis machine to shut down, even though the early warning and shutdown device  200  is not directly connected thereto. Although the device  200  may stand alone, it may also be placed in communication with a dialysis machine, infusion pump, computer, or other notification system via cord and plug or radio frequency. 
     The device  200  may operate on batteries, household power, or both. The device  200  may have a redundant back up power source or may automatically close the clamping mechanism  205  in the event of a power loss.  FIG. 11  shows a circuit diagram of the device  200 , with power source  210 , millivolt transformer  211 , 12 v comm  212 , millivolt comm  213 , primary input circuit  50 , early warning circuit  62 , and emergency shut down circuit  64 . 
     In addition to the fluid loss detection device  10 , other monitoring systems could be integrated into the device  200 . One such device could be an air bubble detection system that incorporates a photo sensor on one side of the channel  204  and an LED lamp on the opposite side of the channel  204 . The light source would emit light toward the sensor and, if the fluid in the tubing were opaque, such as blood, the light would not be able to reach the photo sensor on the opposite side. However, if a sizeable air bubble were traveling through the tubing, the photo sensor would be able to detect light from the light source and respond with either an alarm, a shutdown, or both an alarm and shutting down/clamping the line  201 . 
     Whereas, the present invention has been described in relation to the drawings attached hereto, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention.