Abstract:
A system and method for collecting distending medium or other fluids discharged during surgical procedures is shown. Also shown is a method for reducing the risk of hyponatremia. The apparatus makes it practical to determine the amount of distending medium retained by a patient during hysteroscopic or other surgical procedures, particularly procedures using non-isotonic distending medium during monopolar electrosurgery. The apparatus and methods are also useful during a variety of laparoscopic, obstetric, cardiovascular, liposuction, plastic, orthopedic, restorative, and other procedures.

Description:
REFERENCE TO PREVIOUS APPLICATION 
     This application is a Continuation-in-Part of application Ser. No. 09/020,708, filed Feb. 9, 1998 now U.S. Pat. No. 6,568,419. In addition, this application is based on Provisional Patent Application No. 60/174,617, filed Jan. 5, 2000. 
    
    
     TECHNICAL FIELD 
     The present invention relates to methods and apparatus for control of fluids in work areas. More specifically, the invention relates to methods and disposable apparatus for collecting fluids emanating from a work area. In particular, the present invention provides apparatus and methods for collecting and quantifying the amount of infused and bodily fluids released during surgical procedures, for example during hysteroscopy procedures. 
     BACKGROUND 
     A problem affecting the health and safety of a variety of workers is that of providing a safe, non-slippery, dry area upon which the workers can stand. Hospital operating room personnel are routinely required to stand and work in conditions in which the floor is inundated with several liters of blood, bodily fluids, and saline or other solutions during a single procedure. The abundance of fluids released during surgery is due in part to refinements and widespread implementation of improved surgical techniques during recent years. 
     In U.S. Pat. No. 4,635,913, issued Jan. 13, 1987; U.S. Pat. No. 4,718,653, issued Jan. 12, 1988; and U.S. Pat. No. 4,811,937, issued Mar. 14, 1989, Rothman disclosed a series of Portable Surgical Drainage Platforms. The inventions he developed could assist surgeons and other surgical staff by supporting the personnel on grating and removing liquid that falls through the grating. The platforms are, however, rather heavy and are also difficult to sterilize, especially in the limited amount of time that may be available between surgeries. 
     LaRooka received U.S. Pat. No. 4,243,214 on Jan. 6, 1981, for her Irrigation-Debridement-Repair Caddy. That disclosure is directed to an apparatus that can be placed under an extremity of a person during a surgical procedure. The Irrigation-Debridement-Repair Caddy is designed to collect some of the irrigation distending medium and excised tissue that would otherwise drip onto the floor and collect the fluid in a closeable bottle for eventual disposal. 
     Other devices such as the AquaVac mat marketed by Arthroplastics of P.O. Box 332 Chagrin Falls, Ohio 44022 appear to be directed primarily toward removing water from floors rather than quantifying the amount of fluid received from a patient in order to determine whether the patient&#39;s condition is satisfactory. 
     Clear saline solution or nonelectrolytic distending medium infused into the region where surgery is being conducted allows the surgeon to see the affected tissue much more clearly than would otherwise be possible. In addition, the distending medium can separate and stabilize the tissue to improve surgical precision and reduce the time required to carry out procedures. 
     Among the problems engendered by dispersal of infused fluids and blood onto operating room tables and floors are the considerable inconvenience to workers, the increased likelihood of contamination, the potential for spread of infectious disease, More importantly, distending medium is used in hysteroscopic, urologic, and possibly other surgical procedures that, if taken up by the patient, increase risk of complications. A patient can suffer serious, or even fatal, complications by absorption of distending medium that is suffused into the area where the surgery is conducted by the hysteroscope. The amount of distending medium that a patient can absorb without intolerably dangerous adverse effects is related in non-intuitive ways to various individual physical, chemical, and other factors. The perioperative nurse will, before the patient arrives in the operating room, make a reasonable estimate of the amount of distending medium that a specific patient can tolerably absorb by factoring the person&#39;s age, weight, fitness, hormonal balance, the formulation of the distending medium, the procedure being performed, and a host of other variables. Unfortunately, the maximum usefulness of that estimate can be realized only if the amount of fluid the patient retains can be timely determined with sufficient accuracy while the procedure is carried out. 
     The quantity of infusion fluids absorbed by a patient naturally increases with the length of time required to perform the procedure. Hospitals, surgeons, and patients normally seek to conclude the surgery as quickly as possible for good reasons. Other things being equal, the less time required to perform a surgery, the better the expected outcome and the quicker the patient is expected to recover. 
     Infusion fluids are taken up by the patient more rapidly during some procedures, compared to others. Sometimes infusion fluids are absorbed so rapidly that the surgeon may not have enough time to address and correct all of the problems and complexities discovered during the surgery. In such instances, it might be necessary to terminate a procedure when only a few additional minutes of the surgeon&#39;s time would be sufficient to complete the process as desired. That is a very undesirable situation because patients in those cases must be allowed to recover in the hospital for several days and then, often in a weakened condition, again be prepared, anesthetized, and the surgery resumed. Because those additional risks are widely recognized, as is the risk of continuing a surgery when a patient may, or may not, be in danger from excessive absorption of infusion fluids, the surgeon, lacking accurate information, is forced to make a decision that can easily be criticized in hindsight. 
     Based on these factors, it is easy to understand that surgeons, hospitals, and their patients would be greatly assisted by more accurate knowledge of the amount of infusion fluids retained by surgical patients. Although infusion fluids may accumulate in the abdomen or the patients extremities, the greatest concern is for accumulation and absorption of infusion fluids during surgeries in which severed veins are exposed to infusion fluids. Hysteroscopic and, to a lesser extent, urologic procedures performed using monopolar electrosurgery inherently give rise to conditions that can quickly lead to dangerous complications if any member of the surgical team is unable to maintain a vigilant lookout for the onset of hyponatremia. 
     The hazards of hyponatremia are widely recognized by workers throughout the fields of obstetrics and gynecology. Although the medical literature has many excellent publications addressing the problem in varying breadth and depth, a good overview explaining the subject and the causation of the potential harms is presented by Donna Morrison, R.N. in her article “Management of Hysteroscopic Surgery Complications,” J. Assoc. of Operating Room Nurses, vol. 69, No. 1, Jan. 1999, pp.□194-209. Morrison explains that dilutional hyponatremia is a complication of hysteroscopic surgery that is associated with intravasation of a low viscosity nonelectrolytic distending medium. Women are more likely than men to suffer dilutional hyponatremia, and premenopausal women are 26 times more likely than postmenopausal women to encounter hyponatremia. Premenopausal women are at greatest risk, then, usually as the result of hysteroscopic procedures; the same considerations are, however, important in urologic, and perhaps other procedures that may be undertaken on either male or female patients. For the convenience of the reader, it is to be understood that references to hysteroscopy and hysteroscopic procedures are intended to include urology, urologic, and urological procedures, and any other type of surgical procedure that exposes the patient to risk of hyponatremia or in which it would be helpful to know the volume of fluid retained by a patient. 
     The distending medium, or infusion fluid used in electrosurgery has lower osmotic potential, or tonicity, than the patient&#39;s tissues, serum, and intercellular fluids. For that reason, the distending medium is absorbed fairly quickly by the tissues surrounding the surgical site. Not only is the distending medium absorbed quickly by osmosis, the fluid is supplied under pressure in order to distend the area where the surgery is being performed to enable the surgeon to repair damaged tissue with greater speed and precision. The pressure needed to distend the area can exceed the patient&#39;s blood pressure thereby actively forcing distending medium to flow into blood veins that are cut or broken in the course of the surgery. Free water can enter the vascular system through blood vessels and sinuses opened as the integrity of the endometrial lining or other tissue is interrupted during surgery. 
     Efforts to cauterize exposed vasculature are maintained throughout the surgery, however the process is not instantaneous, and some distending medium will be forced into the patient&#39;s circulatory system as a result. The duration of the surgery must be limited for that reason, even under the best of circumstances. As a practical matter, undetected damage to vessels or other tissue exposed to the pressurized distending medium will sometimes be present, vasculature thought to have been cauterized may subsequently begin to admit distending medium, or other sub-optimal conditions may develop. Any event or condition that increases the patient&#39;s uptake of distending medium necessarily shortens the permissible duration of the surgical procedure. 
     If that were the extent of the problem, a patient in that situation might merely need to endure a period of uncomfortable puffiness. However, the brain, like the rest of the patient&#39;s tissue, seeks to balance the ionic strength of the diluted blood by removing water from the blood and adding that water to the brain tissue. The skull provides scant room for the brain to expand as it swells from the added water; extreme pressure can build fairly quickly. Brain stem herniation can develop as the brain expands attempting to equalize interstitial and intervascular osmotic pressures. Morrison reports that this condition, hyponatremic encephalopathy, has high morbidity and mortality rates and may result if dilutional hyponatremia is not recognized at its onset and treated promptly. She, like many other observers of the problem, recommends that operating room personnel regularly monitor the amount of distending medium the patient receives and the amount returned because that is the quickest way to detect possible intravasation caused dilutional hyponatremia. 
     To that end, surgeons often request the operating room personnel to report the amount of fluid that has been introduced into and received from the patient. Fluid limits are normally fixed between 500 ml and 1,500 ml., and surgery time is frequently limited to one hour. Unfortunately, it is difficult to reliably measure the volume of distending medium received from the patient using traditional methods and equipment. Likewise, It is difficult to measure the volume of fluid infused with traditional methods and equipment. 
     Operating room personnel will know with certainty the number of 3 liter bags of distending medium that have been infused at any particular time. Beyond that, there has been little certainty available. To estimate the amount remaining in a partially used 3 liter container of distending medium, it is usually necessary to remove the bag from the pressurizing cuff or collar in which it is located during use. Of course, removing the pressurizing collar halts the flow of distending medium to the location of the surgery which can quickly interrupt the conduct of the procedure. Once the uncalibrated, shapeless 3 liter bag is visible, operating room personnel would then estimate (i.e. guess at) the amount remaining in it. The amount of infusion fluid discharged from the hysteroscope outflow would normally be collected, and therefore measurable. Careful draping can direct some of the returned fluid into kick buckets, but some is likely to disperse onto the operating room floor, the table, and into pads or towels. The difference between the amount of fluid introduced and the amount of fluid collected or dispersed onto the operating table and floor gives some estimation of the amount of fluids remaining in the patient. Such estimates are crude approximations at best, and generally recognized as such by the persons making and using them. 
     A cross check may be provided by measuring serum sodium concentration during the surgery both periodically and whenever intravasation is suspected. 
     If the surgical team discovers that intravasation has occurred, the situation must be treated as an emergency requiring the surgeon to halt the procedure as soon as it is safe to do so. Electrolytes, oxygen, and other treatments would be administered as quickly as possible. 
     It is readily appreciated that the consequences of underestimating the amount of infused fluid taken up by the patient can include morbidity and mortality. Underestimating the amount of fluid received from the patient can result in premature termination of surgery and can instigate an emergency response that imposes additional risk upon the patient. 
     In an effort to determine the reliability of the estimates of fluid balance that operating room personnel make, a preliminary test was conducted by one hospital to evaluate the accuracy of visual estimates of fluid volumes experimentally. Four experienced operating room nurses were each asked to visually estimate fluid volumes under nineteen different conditions: the amount of distending medium remaining in ten different 3 liter bags; the amount of fluid received in four different kick buckets; and the volume of fluid present on five different operating room floors. The results of the experiment are presented in Table 1. Although the individuals were experienced, trained, and capable in their fields, their estimates of fluid volumes deviated from the actual amounts sufficiently to risk premature cessation of a surgical procedure in most instances. Participants underestimated the amount of fluid present regularly. Out of 76 estimates 74 were less than, and only two exceeded, the actual liquid volume. The errors are additive, and effect of the cumulative errors is that, even if only the best estimate from each trial is considered, in more than 75% of the cases, a recommendation to halt the surgery is indicated by these estimates, even if absolutely no distending medium had been retained by the patient. 
     In the effort to more accurately evaluate the amount of distending medium returned by the patient, surgical drapes may be arranged to direct the returned fluid to buckets positioned on the floor. It can be necessary to halt the surgery while the unsterile contents of the buckets are measured. But, as can be seen from studying Table 1, the estimation errors for the amounts of fluid on the operating table and on the floor can be so large that there is little value in knowing the volume of fluid accumulated in the kick buckets. 
     What is needed is a practical way to collect fluids returned from a patient during hysteroscopic surgical procedures. 
     Also needed is a way to measure the volume of fluids returned from a patient during hysteroscopic surgery. 
     A further need is for apparatus whereby it is possible to determine the volume of distending medium that has been infused into a patient. 
     Yet another need is for the ability to quickly learn the difference between the amount of distending medium that has been infused into the patient and the amount of distending medium that has been returned from the patient. 
     SUMMARY 
     Previously known methods and apparatus have been unable to implement a solution to the various problems encountered by people who work in areas where wet floors are routinely encountered. In hospital operating rooms, for example, the method for controlling wet floor problems is often merely to scatter disposable absorbent blankets, pads, or mats on the floor. Following the surgery, the absorbent material may be weighed to measure the amount of fluid lost by the patient during the procedure. Typical absorbent blankets are made of materials similar to those used to make disposable diapers. It may readily be appreciated that standing, walking, and working with several pieces of that type of material disintegrating on the floor surface is difficult, at best. Unfortunately, those activities are especially difficult under actual conditions because the considerable activity during a surgical procedure tends to bunch up the absorbent materials. It can be appreciated that these circumstances are not conducive to obtaining information about the amount of distending medium that may have been introduced into the patient&#39;s vasculature. 
     What is needed, then, is a disposable fluid control island for selectably collecting, retaining and draining fluids received from hysteroscopic surgery patients comprising a generally broad, shallow, impermeable vessel having a generally horizontal, floor-contacting, bottom portion and a generally vertical peripheral portion, a foot-supporting portion disposed within and substantially filling the vessel, the splash-preventing portion having a top surface spaced apart from the vessel bottom portion by filler comprised of nonwoven, nonabsorbent polymer fiber mesh, and a liquid retaining portion comprised of fluid-permeable material, and means for allowing fluids to be removed from the apparatus for measurement and, when necessary, additional analyses. 
     It is possible to fabricate the mesh in specific colors to accomplish additional purposes. For example, using a white mesh can make it easier for operating room personnel to determine that blood is escaping from the patient. It may also be possible to coat the fibers of the non-woven mesh with indicator dyes that would alert operating room personnel to the presence of substances of concern. 
     Embodiments of the present disclosure meet these needs, and more, by solving the long-recognized problem of containing and removing fluids received from hysteroscopic surgery patients so that the volumes of the fluids can be measured. The present disclosure teaches a disposable, fluid containing and draining vessel filled with macro-porous material having substantial void space that quickly directs fluids to a receptacle for quantification. In a preferred embodiment, the porous supporting and or filler material is a stiff, hydrophobic, non-woven, polymer fiber mat that has substantial void space. Many other configurations for the supporting material may be used without departing from the scope of this disclosure. It is believed that the non-woven polymer mat has superior splash preventing properties compared to other types of matting or mesh. 
     The support material preferred, however, is lightweight so that the fluid control island may be shipped, stored, and handled easily by personnel who have no special training, physical abilities or equipment. It is also preferred that the support material be inexpensive so that the fluid control island can be disposed of destructively to reduce the potential for environmental and health hazards that might result from attempts to clean and re-use the components. It is also preferred that the support material have good shelf life. Other desirable support material characteristics include: that it is non-slippery when wet, that it remains flat on the floor surface while the fluid control island is in use, that liquids may be readily removed from the support material for recovery or analysis, that it be easily bonded to the vessel material, that it does not cause allergic reactions, that it does not create difficult disposal problems, and that it can be folded or rolled for shipping. 
     The support material is contained within a shallow vessel that prevents fluids that fall onto the support material from contacting the floor. The vessel may be formed in many different configurations, however, it may be most useful when it substantially covers the area between the surgeon and the operating table. Since the surgeon would normally be seated near the patient and observing the surgery on a video monitor, an appropriate size for the vessel is approximately 17″×34″, but could be any other size without departing from the scope of this disclosure. 
     The fluid control island vessel may have a mesh thickness of about ¼″ to ¾″ with a drainage slope of about ¾″ over the length and/or the width. The drainage slope causes the liquid to flow toward one end or region of the vessel making it possible to remove essentially all of the fluid, with very little remaining on vessel or mesh surfaces. Evacuation of the vessel can easily be accomplished with either a vacuum source and fluid collection canisters or with use of a pump capable of pumping the specific liquids that a particular vessel collects. Such a fluid control island vessel, with the support mat in place, can contain a substantial volume of fluids giving the system a surge capacity that makes it possible to use a relatively low rate of fluid removal with an inexpensive removal system, whether vacuum operated or pumped directly, yet still have sufficient capacity to collect and remove all the fluids collected in the vessel during a procedure. 
     The base of the disposable fluid control island may be furnished with sloping transition members that make the change in elevation from the fluid control island to the floor gradual. The vessel may also be made from generally pliable material such as foamed polyurethane so that the peripheral walls of the vessel could compress or bend to conform to the presence of personnel or apparatus. It is also to be understood that the vessel may be comprised of a disposable liner and mesh pad combination that can be fitted into a more substantial receiving element. Such a receiving element could be portable or, in the case of areas or rooms where the disposable fluid control island is used frequently, it could be comprised of floor Indentations sized to receive the disposable fluid control island vessel with minimal difference in the elevation of the support surface and the surrounding floor. 
     It is believed that the integration of surgical drapes with the hysteroscopy fluid control island can enable hysteroscopic surgeons to use general operating rooms to perform hysteroscopic surgeries rather than being restricted to operating rooms that are specially equipped for hysteroscopic surgery. This advantage could make it possible for patients and physicians to obtain hysteroscopic surgical services in many additional hospitals and clinics. 
     By collecting substantially all of the fluid received from a patient during hysteroscopic procedures, it is possible to know with previously unobtainable accuracy how much fluid is retained by a patient. However, it is also necessary to determine the amount of fluid introduced to the patient. In a further development of the invention, the container (usually a 3 liter flexible plastic bag) of distending medium, together with the pressure cuff that forces the fluid out of the container, is suspended from a scale that allows surgical personnel to determine the difference between the initial weight and the weight at any subsequent time. Conversion of the weight difference is straightforward since the density of the distending medium is known. The fluid received from the patient can be drawn into collection containers by house vacuum where it can be conveniently measured directly in calibrated containers. The fluid collected by the fluid control island may also be pumped to the collection containers. It would also be possible to determine the volume of collected fluid using a weighing system as described for the distending medium. It may also be possible to weigh the source fluid and the received fluid on the same scale to achieve an accurate measure of fluid remaining in the patient in real time. Another alternative method would be to measure the amounts of fluid introduced into and received from the patient with mass flow meters and compute the difference with electronic computing machinery to inform the surgical team of the amount of fluid retained by the patient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a two-section disposable fluid control island with attached surgical drape and vacuum operated fluid removal provision. 
         FIG. 2  is an exploded view of a first alternative double bi-fold embodiment of a disposable fluid control island similar to the one shown in FIG.  1 . 
         FIG. 3  is a cross-section of the embodiment of the disposable fluid control island of  FIG. 2  taken at  3 — 3 . 
         FIG. 4  is a cross-section of the embodiment of the disposable fluid control island of  FIG. 2  taken at  4 — 4  showing the fluid-removing tubular vacuum conduit in greater detail. 
         FIG. 5  is a cross-section of the embodiment of the disposable fluid control island of  FIG. 2  taken at  4 — 4  wherein the fluid-removing conduit is an open-topped channel with a terminal vacuum connection fitting superimposed. 
         FIG. 6  is a respective view of the disposable fluid control island of  FIG. 2  wherein the embodiment is shown being folded for disposal. 
         FIG. 7  is a perspective view of a second alternative embodiment of the disposable fluid control island of  FIG. 2  wherein a surgical drape is affixed to the fluid control island to direct all fluids toward the vacuum fluid collection system. 
         FIG. 8  is an exploded perspective view of a third alternative embodiment of a fluid control island that has a drain at the center of a long edge of each rectangular section of the island. 
         FIG. 9  is a perspective view according to  FIG. 8  wherein the disposable fluid control island is folded for shipping, storage, or disposal. 
         FIG. 10  is a section detail of the disposable fluid control island of  FIG. 8  taken at  10 — 10 . 
         FIG. 11  is a section detail of the disposable fluid control island of  FIG. 8  taken at  10 — 10  wherein the article is folded according to FIG.  9 . 
         FIG. 12  is an exploded perspective view of a fourth embodiment of a folding disposable fluid control island. 
         FIG. 13  is a bottom view of the disposable fluid control island base depicted in FIG.  12 . 
         FIG. 14  is a perspective view of a fifth alternative embodiment of a fluid control island. 
         FIG. 15  is a perspective view depicting the fluid control island of  FIG. 12  with vacuum-operated drain and fluid collection canisters during a surgical procedure. 
         FIG. 16  shows an exploded perspective of a sixth alternative embodiment of a fluid control island viewed from a side of an operating table wherein an extension of a surgical drape is affixed to and between the upper surface of a floor-contacting foamed polymer wedge base and the lower surface of a non-woven mesh pad. 
         FIG. 17  shows the fluid control island of  FIG. 16  fitted to an operating table viewed from a location behind the normal position of a surgeon and in which the surgical drape is configured to extend a splash barrier substantially beyond the end of the operating table. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The construction of a fluid control island for hysteroscopic procedures may be understood viewing the accompanying FIG.  1  through  FIG. 16 , particularly in view of my co-pending patent application 09/020,708, the disclosure of which is incorporated herein by reference. 
       FIG. 1  shows, in perspective, a disposable fluid control island  20  for selectably collecting, retaining and draining fluids received from patients during surgery comprising: a generally broad, shallow, impermeable vessel  21  having a generally horizontal, floor-contacting, bottom portion  22  that is shaped to direct fluids that enter the vessel toward a drain portion  24  that extends through the vessel  21 , the drain being adapted for connection to a fluid collection container. A generally vertical peripheral portion  26 , retains a non-absorbent mesh pad portion  28  fitted within the peripheral portion  26  of the vessel and overlying the bottom portion  22  of the vessel  21 . The non-absorbent mesh pad  28  may be a non-woven, textile fiber mesh, an open-cell polymer foam, or other, equivalent, structure that prevents or reduces fluid splatter, has a high ratio of void space, and that has low fluid retention. A surgical drape  29  may optionally be affixed to the fluid control island  20 . The drape  29  may be attached to the peripheral portion  26  of the vessel along the side that is positioned closest to the operating table and continue perpendicularly along the ends of the vessel  22  for several inches. This configuration can effectively channel substantially all he fluid discharged during a surgical procedure into the fluid control island  20 . 
       FIG. 2  is an exploded perspective view of an alternative double bi-fold embodiment  30  of a disposable fluid control island  20 . It can be seen that the drain portion  24  may include a tubular portion, or bulkhead feed-through fitting  31 , communicating between the vessel  22  and a means, such as a length of tubing  32 , for conveying fluids that enter the vessel to at least one collection canister for measurement of the volume of fluids that are received by the vessel. House vacuum, a separate conventional vacuum pump or a small liquid pump may be used to convey fluids through the drain  24  and into collection canisters. 
     The bottom portion  22  of the vessel  21  may be inclined toward the drain  24 . Optionally, channels  34  may be formed in the bottom portion  22  of the vessel to direct fluids toward the drain  24  and to reinforce the vessel structure. 
     In this double bi-fold embodiment  30 , the bottom portion  22  is divided into a first bottom section  36  and a second bottom section  38  by a center hinge portion  40 . Each section of the bottom portion is further divided into a distal part  42  and a medial part  44  that are connected by a bottom hinge  46 . The mesh pad  28  may be subdivided corresponding with the bottom portion  22  and optionally affixed thereto. 
       FIG. 3  is a cross-section of the disposable fluid control island  30  taken at  3 — 3  of  FIG. 2  showing the mesh  28  and vessel  21  in greater detail. The bottom  22  is shown sloping from the peripheral edge  26  to a lower region  36 , shown in the center of the bottom portion in this embodiment. The peripheral edge  26  has a floor-contacting base  48  that may include adhesives, surface treatments, materials or finishes that impart desired properties, such as limiting slip, to the fluid control island  20 . An outer wall  50  is connected by the top portion  52  to the inner wall  54  which bounds the generally planar panel  56 . 
     The panel  56  has a panel upper surface  58  that can be configured to slope to a low point  60  where fluids accumulate for removal. The low point  60  may be in the center of the panel  56 , or at any other convenient location. Spacers  62  may be situated to support areas of the panel  56  and to maintain the desired slope. 
       FIG. 4  is a cross-section of the disposable fluid control island of  FIG. 2  taken at  4 — 4  showing an optional fluid-removing tubular vacuum conduit extension  64 . When present, the vacuum conduit extension  64  may be positioned to extend to the location of a low point  60  from the bulkhead connection  31 . The extension  64  could be fitted into a pre-formed channel  34  or held in place by adhesive or mechanical fasteners. 
     Fluids may be routed to the drain  24  through open-topped pre-formed channels  34  that do not contain a vacuum conduit extensions  64 .  FIG. 5  is a cross-section of an alternative embodiment of the disposable fluid control island of  FIG. 2  taken at  4 — 4  wherein the fluid-removing conduit is an open-topped channel  34  with a terminal vacuum connection fitting  31  superimposed. 
       FIG. 6  is a perspective view of the double bi-fold embodiment of the disposable fluid control island  30  of  FIG. 2  wherein the embodiment is shown being folded for disposal. The functions of the center hinge  40  and of the bottom hinges  46  are clearly revealed in this FIG.  6 . It is to be appreciated that the fluid control island  30  can be quickly and easily folded so that the entire article will fit into a conveniently sized disposal container. 
       FIG. 7  is a perspective view of an alternative surgical drape-equipped embodiment  66  of the disposable fluid control island of  FIG. 2  wherein a surgical drape  29  is affixed to the fluid control island to direct all fluids toward the vacuum fluid collection system. An alternative drain  24  configuration is depicted wherein each medial part  44  is fitted with a bulkhead fitting  31 . A “Y” connector  68  is used to connect both of the bulkhead fittings  31  to the conduit  32  that conveys fluids to collection containers. 
       FIG. 8  is exploded perspective view of another alternative embodiment  70  of a fluid control island. An optional drain base  71  may receive a disposable fluid control insert  70  that has an extended drain inlet  72  at the center of a long edge of each rectangular bottom part  42   44  of the island. The drain base  71  may optionally be formed integrally with the disposable fluid control insert. It is to be understood that many embodiments of the subject matter disclosed herein can provide a working fluid drainage system for surgery that can enable surgeries to be performed in rooms that lack floor drains. That is particularly true in the configuration disclosed in  FIG. 8  which provides a substantial structure for securely retaining lightweight, disposable fluid control inserts  70  that may be replaced following each patient surgery. As hospitals seek to maximize utilization of their resources, this feature makes it possible to increase the versatility of existing facilities during times of increased demand for surgical services and by eliminating the restriction on operating room design that may be imposed by the necessity of positioning apparatus with respect to floor drains. It is also possible that the article disclosed herein, in any of the disclosed embodiments and their equivalents, will be preferred as a fluid drainage system in place of floor drains because the disposable drain system  20  removes the fluids from the operating room for proper disposal (e.g., incineration) rather than as ordinary sanitary waste. 
     Advantages may result from using the fluid control apparatus and methods  20  disclosed here even if the availability of floor drains at desired locations in operating rooms imposes no restriction. This fluid control island is replaced anew before each surgical procedure, the used island being sealed and disposed of, together with other surgical debris. When fluids received from a surgical patient are collected with the present disposable island, there is no possibility that the drain can serve as a reservoir for pathogens, toxins, or other contaminants that might harm subsequent patients or health care professionals. An operating room floor drain, however, can be a reservoir of infectious microorganisms originating from previous surgical patients or even from sources external to the health care facility. 
     In addition his dual drain embodiment  70  shows an alternative method of construction. The bottom  22 , including the peripheral edge  26 , may be formed of solid foam material rather than from sheet foam material. Although this method of construction uses more material and is more costly as a result, it allows a steeper gradient on the upper surface  58  of the bottom panel. Extensions  64  reach the center of the junction of the distal  42  and medial  44  parts. This dual drain embodiment  70  is shown with optional solid foam dividers  74  between each rectangular distal part  42  and medial part  44 . This type of construction may be selected, among other times, when it is desired to make the outer wall  50  angle gradually from the floor surface to the top of the peripheral edge  52 . This configuration reduces the maximum distance between the peripheral edge  26  and drain to half that of the configuration depicted in  FIG. 1  while simultaneously doubling the gradient of the bottom surface  58 . These two factors hasten evacuation of fluid through the drain conduit is extension  64  and reduce the lag time between the cessation of fluid flow and the measurement of collected fluid volume. 
       FIG. 9  is a perspective view of the dual drain embodiment  70  according to  FIG. 8  wherein the disposable fluid control island is folded for shipping, storage, or disposal. The dividers  74  may include a slot  76  and a filter block  78  near the center drains  72  to permit fluids to flow from the distal side  42  and be evacuated. The filter block  78  may be made from the same mesh as the pad  28  or other materials. 
     The mating face of the distal portion  80  can be brought into contact with the mating face of the medial portion  82  if the hinge  46  is fitted with sufficient precision. However, the faces  80  and  82  need not actually touch to obtain satisfactory operation of the fluid control island  70  because the center drains  72  withdraw fluids that might flow into the gap between the faces. An overlap  84  may be included to divert fluids from the vicinity of the faces  80   82  and toward the upper surface of the bottom  58  that is sloped toward the drains  72 . 
       FIG. 10  is a section detail of the disposable fluid control island  70  of  FIG. 8  taken at  10 — 10  depicting one of the lateral, or bottom, hinges  46 , drain  72 , and filter block  78 . 
       FIG. 11  is a section detail of the disposable fluid control island  70  of  FIG. 8  taken at  10 — 10  wherein the article is folded according to FIG.  9 . The mating relationship among the slot  76 , the filter block  78  that fits into the slot, and the overlap  84  are readily seen in this figure. 
       FIG. 12  is an exploded perspective view of an alternative sheet-formed embodiment  86  of the folding disposable fluid control island. It is possible to vacuum-form the island bottom portion  22  from stock comprising ⅛″ polymer such as closed cell low density polyethylene foam. Of course, other materials may be used equivalently including most non-absorbent sheet materials, especially sheet metals, sheet plastics, and composites. Closed-cell foam has the advantages of being light-weight, non-absorbent, relatively inexpensive, and readily disposable. The technique of vacuum forming is relatively inexpensive for short production runs. However, the product might be made using injection molding, particularly if production runs are longer. 
     The sheet-formed embodiment  86  is shown fitted with an optional toe-board  88  that allows a surgeon to re-position the fluid control island effortlessly during a procedure. Insets  90  stiffen the peripheral edge to better retain the pads  28 . However, the bottom  22  is sufficiently resilient to collapse under the weight of a person&#39;s foot, a chair or cart wheel, or similar items, then return to the original position when the load is removed. Since the sheet-formed fluid control island  86  is not intended to support any load when in use, it is believed advantageous to allow it to deform when a load is applied to reduce the likelihood that the load will be tipped or unbalanced. 
     It can be seen that the upper surface  58  of the bottom is inclined toward the drain  24 . The inclination may be maintained by one or more sets of ridges  92  and valleys  94 . The ridges  92  support the pad  28  above the upper surface  58  of the bottom to reduce fluid retention in the island. A center dividing ridge  96  has shoulders  98  for supporting theses of th pad  28  at the same plane as the ridges  92 . The valleys  94  make channels directed toward the drain  24  and contact the floor to support the upper surface  58  and maintain the desired inclination. 
       FIG. 13  is a bottom view of the disposable fluid control island  86  base depicted in FIG.  12 . The floor-contacting portions of the insets  90  and valleys  94  formed in the bottom  22  can be readily seen in this view. In addition, the bulkhead feed-through  31  is easily viewed. 
       FIG. 14  is a perspective view of an alternative circular embodiment  100  of a fluid control island. It is possible that such a configuration will be preferred for some procedures. 
     A surgical drape  29  may be attached proximate the periphery of any embodiments of the vessel so as to convey fluids from an operating table to the vessel. The non-woven mesh or open-cell foam pad  28  may conveniently be placed into the vessel  22  after the drape  29  has been attached. It may be advantageous to affix the lower edge of the drape to the inner vessel peripheral wall  54  on the side of the vessel that will be closest to the operating table. The drape  29  may conveniently extend several inches along the vessel ends, perpendicular to the side of the vessel closest to the operating table, so as to channel fluids that run from the operating table and patient into the fluid control island. Adhesive portions may be incorporated onto the surgical drape  29  to retain the drape on the operating table and to hold other drape elements in the desired configuration. 
       FIG. 15  is a perspective view depicting the fluid control island  20  with vacuum-operated drain lines  32  linked to cascaded fluid collection canisters  102  during a surgical procedure. A fluid source  104  provides distending medium or other fluid as needed. 
     The fluid control island  20  and all of the alternative embodiments and all of their equivalents disclosed herein comprise a component of a system for determining the fluid balance of patients, particularly with respect to distending medium, but applicable to other fluids, as well. The system for determining patient fluid balance depicted in  FIG. 15  is comprised of four main elements: means for determining the amount of fluid infused into the patient  104 , means for collecting fluids received from the patient  20 , means for determining the amount of fluid received from the patient  102 , and means for comparing the amount of fluid received from a surgical patient to the amount of fluid infused into the patient, the arithmetic difference between the amount of fluid introduced  102  and the amount of fluid In the collection canisters  104 . Present methods require Individual determinations of the volume of fluid in each container of distending medium (customarily packaged in 3 liter bags that are accurate to perhaps ±10%—far less than the accuracy needed to assure patient safety in hysteroscopic procedures). 
       FIG. 16  is an exploded perspective view of a sixth alternative embodiment  106  of a fluid control island viewed from a location at the side of an operating room table wherein an extension of an extended surgical drape  108  is affixed to and between the upper surface of a floor-contacting foamed polymer wedge base  110  and the lower surface of a non-woven mesh pad  28 . The surgical drape extension  107  thereby forms a continuous fluid-collecting surface that traverses the space from beneath the patient and the bulkhead fitting  31 . It is also possible to use adhesives, mechanical fasteners, heat sealing, or other means to shape the edges of the first end of the drape extension  107  into a structure that fulfills the fluid-retaining function of peripheral edge  26  of FIG.  1  and other embodiments. The extended edges  112  of the drape may be folded up the edges of the mesh pad  28  to prevent fluids from dispersing laterally away from the collection island  106 . The drape extension  107  and drape  108  may be any convenient polymer film such as a 2 mil polyethylene material having any convenient dimensions for the procedures conducted, typically 44″×73″ with a nylon or other polymeric feed-through fitting  31 . 
     The floor-contacting lower side of the polymer foam wedge  110  may optionally have anti-skid material  114  applied in situations where foot traffic may occur. The polymer foam wedge  110  may be any convenient material such as polyurethane or other low-cost material. Dimensions of this embodiment would be similar to those of other alternative embodiments previously described with a sufficient wedge gradient to cause fluid to flow to the feed-through  31  for collection (e.g. ½″ per foot). A depression or cut-out  115  may be included to facilitate fluid collection by allowing the bulkhead fitting  31  to rest at the lowest point of the inclines created by supporting the drape material from the foam wedge  110  and operating table. Stiffening or shaping members  116  of elastic or springy material may be applied to enhance the fluid-collection functionality and stability of the drape  108 . Heat-sealing or adhesives may be used to attach the drape extension  107  to the polymer foam wedge  110  and the mesh pad  28 . 
     Although the drape extension  107  and drape  108  are depicted as formed integrally from a single sheet of plastic film, it is to be understood that either or both may be configured differently without departing from the invention. For example, the drape extension  107  might be formed to attach to the back of a conventional surgical drape  108  or to fit to a permanent fluid-guiding sluice affixed to an operating table. Likewise, it is possible to make this embodiment using different materials for the drape extension  107  and drape  108 . 
       FIG. 17  shows the fluid control island  106  of  FIG. 16  fitted to an operating table viewed from a location behind the normal position of a surgeon and in which an integral combination drape extension  107  and surgical drape  108  is configured to extend a splash barrier substantially beyond the end of the operating table. 
     It is anticipated that the foam wedge  110  would, in most instances, have very low density such that objects such as feet or instrument stands would compress the foam sufficiently to force the drape extension  107  nearly to the elevation of the floor. It is anticipated that the incremental amount of fluid retained by the embodiment  106  due to the presence of a person standing on the mesh  28  would be negligible and would flow freely toward the drain feed-through  31  as soon as the person moved. To reduce any tendency for fluids to pool where a person may stand, it would be possible to include stiff, rod-like members disposed on the top side of the drape extension  107  below the mesh  28  perpendicular to both the narrow and the wide edges of the wedge  110  such that the weight of a person&#39;s foot would compress the foam wedge below the rod-like member, thereby forming a channel in the top side of the drape extension  107  that runs adjacent the rod-like member toward the narrow edge of the wedge  110 . 
     It is possible to make the wedge  110  from any material or with any degree of stiffness or resilience. For example, the wedge could be made of wood, fiberboard, polystyrene, metal, etc., without departing from the scope of the invention disclosed here. It would also be possible to make the wedge  110  from any density of resilient or rigid foam. For example, it would be possible to make the wedge using expanded polystyrene bead board equivalent to the low-density resilient foam believed preferable at the present time. 
     Likewise, it is possible also to form the embodiment with a drain element that extends proximate, and parallel to, the narrow edge of the wedge  110 . Such a drain component could be comprised of a vacuum drain tube affixed to the top side of the drape extension  107  and running along the length of the narrow edge of the wedge. Holes could be formed through the wall of the vacuum drain tube at intervals through which fluids could enter and then be conveyed by air moving toward the vacuum source and trapped collection canisters  104 . It is possible that such a configuration would reduce the time required to effect collection of fluids because the distance fluid would be required to flow before reaching the vacuum collection point would be minimized. A vacuum conduit extension  64  could connect at either end or along the length of such a vacuum drain tube. 
     An apparatus having the elements needed to determine fluid balance holds the packaged fluids to be dispensed and the canisters that receive returned fluids on a single load cell or weight measuring scale. Ancillary equipment for pressurizing dispensed fluid and for conveying returned fluids to collection canisters may also be mounted on the device. The scale may be set to read zero when the procedure is started and to alarm in the event of a pre-determined weight loss. If desired, the system could be rinsed before zeroing the system in order to eliminate the minor effect of fluid that accumulates on wetted system surfaces. The decrease in the weight of the assembly would be directly related to the amount of fluid retained by the patient during the surgery. The scale could be calibrated to factor the density of the fluid into the amount reported so that the system could continuously display the volume of fluid retained by the patient in milliliters or other convenient units. 
     Other methods of determining the amounts of fluids provided to the patient include the use of metering pumps to displace distending medium from packages through the hysteroscope and into the surgical site, the use of mass flow meters to measure the amount of fluid introduced into the patient, and scales for weighing the distending medium separately from the returned fluids and/or ancillary equipment. Fluids received from the patient could be quantified likewise. 
     Changes and modifications in the specifically described embodiments can be carried out without departing from the scope of the invention which is intended to be limited only by the scope of the appended claims. 
     
       
         
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 ESTIMATES OF FLUID VOLUMES-SIMULATED OPERATING ROOM CONDITIONS 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                 Mean of 
                   
                   
               
               
                 Actual 
                 Nurse 1 
                 Nurse 2 
                 Nurse 3 
                 Nurse 4 
                 Mean of 
                 estimate 
                 Largest 
                 Smallest 
               
               
                 Volume 
                 estimate 
                 estimate 
                 estimate 
                 estimate 
                 estimates 
                 errors 
                 error 
                 error 
               
             
          
           
               
                 (ml) 
                 (ml) 
                 (ml) 
                 (ml) 
                 (ml) 
                 (ml) 
                 (%) 
                 (ml) 
                 (ml) 
                 (ml) 
               
               
                   
               
             
          
           
               
                 FLUID REMAINING IN 3 LITER BAGS 
               
             
          
           
               
                 2879 
                 2460 
                 2480 
                 2500 
                 2500 
                 2485 
                 −14% 
                 −394 
                 −419 
                 −379 
               
               
                 1546 
                 1200 
                 1300 
                 1350 
                 1200 
                 1263 
                 −18% 
                 −284 
                 −346 
                 −196 
               
               
                 2244 
                 1800 
                 1950 
                 1800 
                 1900 
                 1863 
                 −17% 
                 −382 
                 −444 
                 −294 
               
               
                 1784 
                 1550 
                 1600 
                 1800 
                 1700 
                 1663 
                  −7% 
                 −122 
                 −234 
                 16 
               
               
                  843 
                 525 
                 575 
                 600 
                 500 
                 550 
                 −35% 
                 −293 
                 −343 
                 −243 
               
               
                 1714 
                 1525 
                 1500 
                 1500 
                 1500 
                 1506 
                 −12% 
                 −208 
                 −214 
                 −189 
               
               
                 1075 
                 900 
                 875 
                 900 
                 900 
                 894 
                 −17% 
                 −181 
                 −200 
                 −175 
               
               
                  597 
                 275 
                 275 
                 250 
                 300 
                 275 
                 −54% 
                 −322 
                 −347 
                 −297 
               
               
                  770 
                 450 
                 450 
                 450 
                 400 
                 438 
                 −43% 
                 −333 
                 −370 
                 −320 
               
               
                 3114 
                 2710 
                 2800 
                 3250 
                 3000 
                 2940 
                  −6% 
                 −174 
                 −404 
                 −114 
               
             
          
           
               
                 FLUID IN KICK BUCKETS 
               
             
          
           
               
                  770 
                 250 
                 400 
                 650 
                 500 
                 450 
                 −42% 
                 −320 
                 −520 
                 −120 
               
               
                 1546 
                 600 
                 1200 
                 1100 
                 1000 
                 975 
                 −37% 
                 −571 
                 −948 
                 −346 
               
               
                 1075 
                 800 
                 1000 
                 900 
                 1000 
                 925 
                 −14% 
                 −150 
                 −275 
                 −75 
               
               
                  821 
                 400 
                 500 
                 600 
                 500 
                 500 
                 −39% 
                 −321 
                 −421 
                 −221 
               
             
          
           
               
                 FLUID ON OPERATING ROOM FLOOR 
               
             
          
           
               
                  570 
                 150 
                 300 
                 200 
                 200 
                 213 
                 −63% 
                 −358 
                 −420 
                 −270 
               
               
                  282 
                 100 
                 200 
                 100 
                 100 
                 125 
                 −56% 
                 −157 
                 −182 
                 −82 
               
               
                  642 
                 150 
                 400 
                 125 
                 200 
                 219 
                 −66% 
                 −423 
                 −517 
                 −242 
               
               
                 1115 
                 300 
                 600 
                 275 
                 300 
                 369 
                 −67% 
                 −746 
                 −840 
                 −515 
               
               
                  381 
                 100 
                 250 
                 140 
                 100 
                 148 
                 −61% 
                 −234 
                 −281 
                 −131 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 DRAWING REFERENCE NUMBERS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 20 
                 disposable fluid control island 
               
               
                   
                 22 
                 impermeable vessel bottom 
               
               
                   
                   
                 portion 
               
               
                   
                 24 
                 drain portion 
               
               
                   
                 26 
                 peripheral edge 
               
               
                   
                 28 
                 mesh pad 
               
               
                   
                 29 
                 surgical drape 
               
               
                   
                 30 
                 double bi-fold fluid control 
               
               
                   
                   
                 island 
               
               
                   
                 31 
                 bulkhead feed-through 
               
               
                   
                 32 
                 conduit to collection containers 
               
               
                   
                 34 
                 drain channels 
               
               
                   
                 36 
                 first bottom section 
               
               
                   
                 38 
                 second bottom section 
               
               
                   
                 40 
                 center hinge 
               
               
                   
                 42 
                 distal part 
               
               
                   
                 44 
                 medial part 
               
               
                   
                 46 
                 bottom hinge 
               
               
                   
                 48 
                 perimeter floor-contacting 
               
               
                   
                   
                 base 
               
               
                   
                 50 
                 outer wall 
               
               
                   
                 52 
                 top surface 
               
               
                   
                 54 
                 inner wall 
               
               
                   
                 56 
                 panel 
               
               
                   
                 58 
                 upper surface of bottom 
               
               
                   
                   
                 portion 
               
               
                   
                 60 
                 low point 
               
               
                   
                 62 
                 spacer 
               
               
                   
                 64 
                 vacuum conduit extension 
               
               
                   
                 66 
                 alternative surgical drape- 
               
               
                   
                   
                 equipped embodiment 
               
               
                   
                 68 
                 “Y” connector 
               
               
                   
                 70 
                 dual drain fluid control island 
               
               
                   
                 71 
                 optional drain base 
               
               
                   
                 72 
                 center drains 
               
               
                   
                 74 
                 dividers 
               
               
                   
                 76 
                 divider slot 
               
               
                   
                 78 
                 divider filter block 
               
               
                   
                 80 
                 distal portion face 
               
               
                   
                 82 
                 medial portion face 
               
               
                   
                 84 
                 overlap 
               
               
                   
                 86 
                 alternative sheet-formed fluid 
               
               
                   
                   
                 control island 
               
               
                   
                 88 
                 optional toe board 
               
               
                   
                 90 
                 insets 
               
               
                   
                 92 
                 ridge 
               
               
                   
                 94 
                 valley 
               
               
                   
                 96 
                 center dividing ridge 
               
               
                   
                 98 
                 shoulder 
               
               
                   
                 100 
                 alternative circular fluid control 
               
               
                   
                   
                 island 
               
               
                   
                 102 
                 source of distending medium 
               
               
                   
                 104 
                 fluid collection canisters 
               
               
                   
                 106 
                 sixth alternative embodiment 
               
               
                   
                 107 
                 drape extension 
               
               
                   
                 108 
                 extended surgical drape 
               
               
                   
                 110 
                 foam wedge base 
               
               
                   
                 112 
                 rolled drape peripheral edge 
               
               
                   
                 114 
                 optional anti-skid material 
               
               
                   
                 116 
                 optional shaping element