Patent Document

RELATED APPLICATIONS 
     This application is a divisional of application Ser. No. 08/637,426 filed Apr. 25, 1996 now issued as U.S. Pat. No. 5,885,261. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to post-surgical blood collection systems and, particularly to autotransfusion systems for post-surgical collection from a patient and reinfusion of the blood into that patient. 
     BACKGROUND OF THE INVENTION 
     Blood autotransfusion involves the collection, filtration, and reinfusion of a patient&#39;s own blood. Autotransfusion is a common post-operative practice in those surgical procedures in which it can be expected that there will be post-surgical bleeding. It has become a widely accepted practice in surgical procedures because it avoids the numerous risks associated with transfusion of blood from a third party donor. It is common practice at the end of a surgical procedure to place a drainage tube within the patient at a location where fluids can be expected to pool. The drainage tube exits the surgical wound and is connected to a collection chamber where the blood is collected. Depending on the type of device used, blood may be reinfused into the patient directly from the collection chamber or can be transferred to an intermediate chamber, such as a blood bag, from which it can be reinfused into the patient. 
     Blood flow into the collection chamber can be induced either by suction developed within the chamber or by positioning the chamber below the wound site to create a gravity head. The suction source may be external, such as directly from the hospital suction system, or from a portable suction device such as that disclosed in U.S. Pat. No. 4,664,652 (Weilbacher). Typically, such autotransfusion devices can be expected to remain connected to the patient during the early part of the patient&#39;s recovery, until the surgical site has healed sufficiently so that the volume of recoverable blood is substantially reduced, preferably no more than about six hours in most cases. Depending on the rate at which the patient&#39;s fluids may become pooled, it may be necessary to repeat several cycles of collection and reinfusion. 
     Many autotransfusion devices are designed to operate in an upright position to prevent blood within the collection chamber from being ingested into the suction inlet or leaking out of the collection chamber. Such ingestion or leakage can be expected to affect proper operation of the device. For example, U.S. Pat. No. 4,850,964 (Cotter) illustrates an autotransfusion device having a collection chamber in direct communication with the suction inlet in which blood can be expected to come into direct contact with the suction inlet if the device is placed on or falls on its side. The risk of a vertically placed device being tipped on its side is increased when the patient is being moved from one location (the operating room) to another (the recovery room). It is a common practice with such devices for an attendant to manually carry the autotransfusion device, to maintain it upright while the patient is being moved. 
     Devices have been proposed and developed to reduce such difficulties. U.S. Pat. No. 5,275,585 (Olson) discloses an autotransfusion system in which the blood collection chamber and suction chamber are isolated from each other. The device has a rigid outer receptacle and a flexible blood collection chamber within the outer receptacle to define an intermediate space between the two. The collection chamber has a blood inlet for receiving blood through a drainage tube from the wound site. The outer receptacle has a port to communicate the intermediate chamber either with ambient air at atmospheric pressure or suction from a suitable suction source. Another approach is incorporated in U.S. Pat. No. 5,374,257 (Drainville) in which an autotransfusion device is provided with a hydrophobic filter between the suction port and the collection chamber to prevent blood in the chamber from being exhausted into the suction source should the container accidentally tip over. That can result in a clogged filter that may impair the efficiency of operation of the device. It is among the general objects of the invention to provide an autotransfusion device having a collection chamber and airflow system that employs a simple, inexpensive arrangement to reduce the risk of blood becoming ingested into the airflow system, not only when the device is upright, but when it is horizontal. 
     It is desirable that the patient and his surroundings be clean after the conclusion of the surgery when the patient is transferred to his hospital room, not only for aesthetic reasons, but also to avoid disease transmission. A clean appearance is desirable, not only for the patient&#39;s comfort, but also for those who visit the patient. It is expected, therefore, that surgical attendants will change the bedding and otherwise clean the patient and his surroundings before returning the patient to the hospital room. When an autotransfusion device has been connected to the patient, the handling of the device during its placement often results in bloody residual fingerprints or smears on the device. That adds to the difficulty in cleaning the patient for optimum post-surgical presentation. It also presents some risk of disease transmission should an unprotected individual come into contact with such residual blood. It would be desirable to provide a blood collection device that simplifies post-surgical presentation of a patient by preventing the unsightly and unsanitary presence of blood on the device. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention, the autotransfusion apparatus includes a collection chamber that is oversized relative to the volume of blood that the device is intended to contain. Consequently, when operated within its intended parameters, the chamber will not be filled completely with blood but, instead, will always have an exposed horizontal surface within the chamber. The device also includes an internal airflow port within the collection chamber. The internal port is configured to have an exposed orifice that is located and oriented in the collection chamber so that it will be above the exposed surface of the blood in the collection chamber when the device is upright as well as when the device is disposed on its side. The device includes an external suction port connectible to a source of suction and another external port for admission of atmospheric air into the device, both of which are communicated with the internal airflow port through a series of valves and filters. Suction may be applied from either source to facilitate drawing of blood into the collection chamber and atmospheric air may be applied to facilitate flow of blood from the chamber during the reinfusion process. A gravity head can be maintained to promote blood collection at all times, including during reinfusion. 
     In another aspect of the invention, the autotransfusion device is maintained clean and free of blood smears when it is connected to the patient by enclosing it within a transparent, flexible envelope that enables the device to be connected and set-up for proper operation while preventing blood from contacting the outer surfaces of the device. The envelope may be provided with a means to facilitate its separation from the autotransfusion device after it has been placed. 
     It is among the objects of the invention to provide a simple, inexpensive autotransfusion device in which the risk of blood leakage into the airflow system is reduced whether the device is in an upright or a horizontal attitude. 
     Another object of the invention is to provide an arrangement for an autotransfusion system that facilitates a clean presentation of the device after the device has been connected to the patient. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects and advantages of the invention will be appreciated more fully from the following further description thereof with reference to the accompanying drawings wherein: 
     FIG. 1 is a front elevation, partly broken away of the autotransfusion device; 
     FIG. 2 is a partly fragmented, oblique illustration of the collection device and an associated portable suction device; 
     FIG. 3 is a side elevation of the collection unit and portable suction device; 
     FIG. 4A is a diagrammatic illustration of the device showing the relation between the airflow port and the free liquid surface in the collection chamber when the device is in a vertical orientation and has been filled to a level not greater than its rated capacity; 
     FIG. 4B is a diagrammatic illustration of the device shown in FIG. 4A when resting on its back wall and illustrating the relation between the airflow port and the free liquid level; 
     FIG. 4C is an illustration of the device shown in FIG. 4B but resting generally horizontally with its front wall facing downwardly; 
     FIG. 5 is an illustration of the control module that defines a number of flow passages and includes several valves and filters that enable operation of the device in its intended modes; 
     FIG. 6 is a somewhat diagrammatic sectional illustration of the interior of the control module as would appear with the front wall of the control module removed, modified to shift slightly the position of several of the components for clarity of illustration and with the atmospheric vent omitted, also for clarity of illustration; 
     FIG. 7 is an illustration, partly fragmented, of the divider plate in the control module as seen along the line  7 — 7  of FIG. 6; 
     FIG. 8 is a sectional illustration of the control module illustrating the arrangement of the atmospheric vent and its relation to the control module with other components of the control module removed for clarity of illustration; and 
     FIG. 9 is an illustration of the device enclosed within a protective envelope. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 illustrate the main components of the autotransfusion system, including the collection unit, indicated generally at  10 , a manually operable portable suction evacuator  12  (FIG. 2) and a blood reinfusion bag  14  connectible by a tubing set  16  to the collection unit  10 . The collection unit  10  includes a collection chamber  18  and a control housing  20  disposed above the collection chamber  18 . Blood is directed into the collection unit  10  through a blood inlet tube  22  having a fitting  24  that is connectible to the outlet end of a patient drainage tube (not shown). The drainage tube will have been placed at the conclusion of the surgery to receive and collect internally pooled blood and other body fluids. The liquid flow path through the control housing  20  directs the blood into the interior of the collection chamber  18  through a blood filter  26  that depends from the control housing  20  into the collection chamber  18 . Blood is drawn through the system and into the collection chamber  18  by one or both of gravity and vacuum developed within the collection chamber  18 . The vacuum may be developed by connecting the device to a source of suction, such as the wall outlet of a hospital suction system (not shown) or the manually operable portable suction device  12 . To that end, the collection unit  10  has two suction fittings, including a wall suction fitting  28  and a portable suction fitting  30 , the latter being connected to a flexible tube  32  that extends from the control housing  20 . A control module, illustrated in phantom at  34 , is contained within the control housing  20  and includes an arrangement of flow passages, valves and filters through which the suction, either from fitting  28  or tube  32 , is applied to the interior of the collection chamber  18 . As will be described in further detail, the suction is communicated through an airflow port, indicated generally at  36 , that depends downwardly from the control module  34  into the collection chamber  18 . 
     The control module  34  and airflow port  36  also permit the admission of filtered ambient air into the collection chamber  18  through the airflow port  36  to enable the collected liquids to flow out of a liquid outlet port  38  at the bottom of the collection chamber  18  when the blood is to be reinfused into the patient. Ambient air is admitted into the control module  34  by manual operation of an air inlet valve  40 , actuable by a depressible button  42  accessible at the front of the device. 
     In accordance with the invention, the collection unit  10  is constructed in a manner that reduces the risk of collected liquid being ingested into the airflow port  36 . To that end, the collection chamber  18  is dimensioned to define a volume that is substantially greater than the volume of body liquid that the device is intended to hold. For example, in a collection device intended to collect up to about 500 to 600 milliliters of liquid, the total volume defined by the collection chamber may be of the order of 1200 milliliters. The airflow port  36  is arranged so that as long as the device is not filled above its rated capacity, it will be disposed above the horizontal free liquid surface of the collected blood whether the collection unit  10  is oriented vertically or horizontally on its front or back wall. As used herein, the term “rated capacity” is intended to define a predetermined subvolume of liquid such that the airflow port  36  will remain above the free horizontal liquid level of the collected blood whether the device is in a vertical or horizontal attitude. In a device with the illustrative volumetric dimensions discussed above, the device may be considered to have a rated capacity defined by a subvolume of about 500 milliliters. Suitable indicia  37  formed on the collection chamber enable an attendant to determine when the rated capacity has been reached. 
     The collection unit  10  is configured to define relatively flat front and rear walls  44 ,  46  that are connected by a continuous side wall  48 . The flat front and rear walls  44 ,  46  provide a stable base for the device when it is rested in a horizontal position. The collection chamber  18  may be considered as including a midplane  50  that extends generally parallel to and between the front and rear walls  44 ,  46 . The midplane  50  is disposed to define volumes on opposite sides of the midplane that are at least as great as the rated capacity of the device. Such volumes may be approximately equal. Thus, for the above dimensioned collection chamber, intended to contain between 500 to 600 milliliters of liquid, the oversized volume of the collection chamber  18  may be of the order of 1200 milliliters such that the midplane divides the chamber into two volumetric halves, each about 600 milliliters in volume. 
     In the illustrative embodiment, the airflow port  36  is in the form of a tube  52  that depends from the control module  34 . The tube  52  terminates in an orifice  54 , preferably planar, that lies substantially at the midplane  50 . As long as the device is not overfilled beyond its rated capacity, the orifice  54  of the airflow port  36  will be disposed above the liquid level, thus avoiding ingestion of liquid into the port  36 . The orifice  54  also is disposed sufficiently close to the control housing  20  to assure that it will be spaced from the liquid surface when the collection unit  10  is in a vertical orientation. The device, therefore, presents a reduced risk of liquid being drawn into the airflow port whether the device is oriented vertically or is resting horizontally on either of its front or rear walls. 
     FIGS. 4A,  4 B and  4 C illustrate, diagrammatically, the relation between the orifice  54  of the airflow port and the liquid level  74  within the collection chamber  12  when the device is filled below its rated capacity and is oriented in a vertical or either face-down or face-up horizontal attitudes. FIG. 4A illustrates the relation between the orifice  54  and the free surface  74  of the liquid when the device, filled to its rated capacity, is oriented in a vertical position as would be the case when the device is attached to a suitable support, as by a clip  76 , or other means. The orifice  54  is disposed above the free liquid surface  74 , thereby avoiding ingestion of liquid into the port  36 . Should the device be disposed horizontally, as on its rear wall, such as when the patient is being transported to a different location, the orifice will be disposed above the free liquid surface  74  as long as the device has not been allowed to be filled beyond its rated capacity. To that end, it is preferable that the orifice  54  be generally planar and lie substantially at the midplane  50  of the device. As shown in FIG. 4B, when the device is so oriented, the free liquid surface  74  will be disposed below the level of the orifice  54 . FIG. 4C similarly illustrates the relation between the orifice  54  and the free liquid surface  74  when the device is placed on its front wall. When the portable suction generator  12  is not attached, to the front wall  44  of the device, the relation between the orifice  54  and free liquid surface  74  will be the same as when the device is disposed horizontally on its rear wall  46 . In the event that the device is placed with its front wall  44  facing down while the suction generator  12  is attached, the device may tend to tilt somewhat. It is preferable, therefore, that the chamber  12  be configured so that even if the device tilts somewhat, as suggested in phantom in FIG. 4C, the orifice  54  still will be disposed above the free liquid surface  74  as long as the device is not filled beyond its rated capacity. The side wall  48  of the collection chamber preferably is formed to define somewhat of a rounded or beveled shape such that the device cannot readily be rested on the side wall. 
     Although the orifice  54  in the preferred embodiment is disposed at the midplane  50  so that the device can rest horizontally on either of its front or rear walls with the same effect, in some instances it may be preferable to increase the rated capacity of the device by increasing the subvolume and by moving the midplane closer to one of the walls than the other. For example, such a device may include a flat configuration only at its rear wall while the front of the device is configured so that it is not readily restable in a horizontal configuration. With that arrangement, the orifice  50  can be disposed further from the flat wall thereby defining an increased subvolume and rated capacity. 
     The portable suction evacuator  12  may be of the type described in U.S. Pat. No. 4,664,652 (Weilbacher), the entire disclosure of which is incorporated by reference herein. The portable suction evacuator  12  includes a front wall  56 , a rear wall  58  and a flexible, transparent polymeric side wall  60  connecting the front and rear walls  56 ,  58 . An arrangement of springs  62  extending between the front and rear walls  56 ,  58  continually biases the evacuator  12  in a distended configuration. The evacuator  12  can be manually compressed, in opposition to the force of the springs  62  to cause air from the evacuator  12  to be exhausted through an exhaust port  64  formed in the front wall  56 . The exhaust port can be closed by a plug  66  tethered to the evacuator  12 . Alternately, the device may be provided with a detachable one-way valve  68  that can be securely placed in the exhaust port  64  to permit air flow out of the evacuator  12  when the evacuator is compressed. The suction evacuator  12  includes a suction tube  68  that communicates with the interior of the evacuator and a fitting  70  on the end of the tube  68 . The fitting  70  is connectible to the fitting  30  on the collection unit  10  to communicate vacuum developed within the suction evacuator  12  through the control module  34  to the air flow port  36 . The portable suction evacuator  12  may be detachably secured to the front wall  44  of the collection chamber  18  by Velcro touch fasteners  72 . The portable suction evacuator enables suction to be maintained while the patient is being transported as well as when the patient is in the recovery room. 
     The control module  34  has a number of control features including a vacuum limiter to prevent development of excessive vacuum levels in the collection chamber  18  and filters to permit flow of air but to maintain isolation of liquids from the suction sources. Filtration also is provided to prevent airborne contaminants from contacting the blood when the collection chamber is vented to the atmosphere. The control module  34  is similar to that disclosed in U.S. Pat. No. 5,374,257 (Drainville). The device is illustrated in FIGS. 5-8 and may include a housing  78  arranged to define a suction chamber  80  and a fluid inlet chamber  82  separated by an internal wall  83 . A divider plate  84  separates the suction chamber  80  to define a suction source side  86  and a fluid collection side  88 . The underside of the divider plate  84  is provided with an arrangement of downwardly extending support ridges  90  that provide support for a film of hydrophobic material, indicated at  92 . Although the hydrophobic filter  92  prevents blood from exhausting into the suction source, even if the collection device is allowed to fill above its rated capacity and is accidentally tipped over, such blood contacts, however, could compromise the efficiency of the filter  92 . The support ridges are provided with interruptions  93  to facilitate airflow freely between the filter  92  and the divider plate  84 . The divider plate includes openings by which either of hospital suction or portable suction can be applied to the suction source side  86  of the suction chamber  80  and, consequently, to the airflow port  36 . A hollow projection  95  depends downwardly from the bottom of the collection site  88  and defines a passageway  97 . The airflow port  36  is connected to and extends downwardly from the projection  95  and communicates the orifice  54  with the fluid collection site  88  of the suction chamber  80 . Wall suction is connectible through the wall suction fitting  28  by a wall suction tube  94 . The wall suction fitting  28  communicates directly with the suction source side  86  of the suction chamber  80 . A one-way umbrella valve  96  is mounted to the divider plate  84  to permit airflow from the collection container side  86  of the divider plate to the suction source side  86 . The umbrella valve  96  normally maintains closed the flow passage through the flow apertures  98 . When wall suction is applied, the umbrella valve  96  will open to permit evacuation from the collection side  88  of the suction chamber  80 . When the device is disconnected from wall suction, the umbrella valve  96  will remain closed to prevent flow through the apertures  98 . In order to prevent excess suction from being applied to the collection chamber and, consequently, to the patient&#39;s drainage site, one or more suction relief valves  100  may be disposed in the top wall of the suction chamber  80 . The suction relief valve(s)  100  may be umbrella valves  102  mounted to permit flow of ambient air into the suction source side  86  of the suction chamber  80  when the level of wall suction reaches a predetermined maximum value. 
     The portable suction evacuator  12  is connectible, as described, through the flexible tube  32  that, in turn, is connected to a tube  104  that extends downwardly through the top wall of the suction chamber  80  and is connected to the divider plate  84  to communicate the passageway through the tube to the region between the divider plate and the filter  92 . The suction evacuator  12 , therefore, can be connected directly to the fluid collection side of the suction chamber without passing through any intermediate safety valves. No such intermediate valves are required because the suction levels developed by the portable suction evacuator  12  are far less than those available through the hospital suction system. The suction developed by the portable evacuator  12  communicates with the collection chamber through the filter  92 . 
     FIG. 8 illustrates the arrangement by which atmospheric air can be vented into the collection chamber to enable the collected liquids to flow out of the collection chamber either directly to the patient or to an intermediate transfer reinfusion bag. The venting system includes the air inlet valve  40  comprising a venting chamber  108  with a port  110  which is in communication with the fluid collection container side  88  of the suction chamber  80 . A valve actuator  112  having a head  114  is slidably mounted in the chamber. An O-ring  116  together with the face of the valve head  114  seals an opening  118  to the venting chamber  108  when the valve is in the normally closed position. A spring  120  biases the valve head  114  against the vent housing surrounding the opening  118 . Depression of the actuator button  42  actuates the valve to an open position to enable atmospheric air to flow through the opening  118  into the vent chamber  108 , through the vent port  110 , and into the fluid collection side  88  of the suction chamber to relieve the applied suction and facilitate blood flow from the collection chamber  18 . In order to prevent airborne contaminants from being exposed to the collected blood, a filter  122  is arranged to cover the port  110 . The filter  122  may include a mesh-like support matrix  124  to which a film  126  of hydrophobic filter material may be applied. The support matrix  124  may be supported by ultrasonically welding it to the upper edge of a support wall  128  that surrounds the port  110 . 
     FIG. 9 illustrates the arrangement by which the cleanliness of the device is maintained during connection to the patient. The device is provided with an envelope that may take the form of an elongate tubular sleeve  130  having open ends  132  through which the tubes and fittings of the device may be readily accessible. The sleeve fully encloses and extends well beyond the ends of the device. Preferably, the sleeve length is about double the length of the device so that the ends of the sleeve overhang the ends of the device by a substantial margin, of the order of half the length of the device. That assures that the device will remain protected by the sleeve even though it might shift about somewhat relative to the sleeve when the device is placed and set-up for operation. The openings  132  are large enough to permit ready accessibility to the ends of the device. The sleeve  130  is formed from a thin, flexible, substantially transparent polymeric material, such as a low density polyethylene about 0.001 inch thick. The sleeve is dimensioned so that it will maintain a snug fit about the device when the suction evacuator  12  is attached and is in its fully distended configuration. After the device has been connected to the patient, the suction evacuator  12  is compressed and will assume a reduced profile, thereby releasing the snug fit of the sleeve. The sleeve then can be removed by simply slipping it free. The flexibility and transparent nature of the polymeric film from which the sleeve is made enables operation of all the controls, devices and connections required to set up and operate the device. 
     From the foregoing, it will be appreciated that the invention provides an improved blood collection device and autotransfusion system in which the risk of collected blood being drawn into the suction pathway of the collection device is reduced and in which the ease of maintaining the device clean during its installation is facilitated.

Technology Category: 4