Patent ID: 12233191

DETAILED DESCRIPTION

Referring toFIGS.1A and1B, a support structure102is a folding article of manufacture that is configured to enclose at least portions of one or more fluid circuits101so as to contain leaks and guide fluid from a leak at any point in the fluid circuit101to one or more locations where a sensor can detect the leak. Tube segments of the circuit may be enclosed by trough channels128and recesses of other shapes configured correspondingly to enclose other features of the fluid. In the illustrated embodiment, the support structure102has a living hinge portion136and various recesses such as recess114and cutouts such as110,116. The fluid circuit101has tubing sections122and124and other components, such as a treatment component120, which are supported in respective parts of the support102by molded troughs112which surround the tubing sections122thereby containing leaks and helping to convey them. When the support102(originally in a configuration such as discussed with reference toFIG.3B) is closed in the fashion of a book about the hinge portion136, it forms a sealed container except for access windows discussed below.

Recesses114enclose opposite sides of a treatment component120, which may be, for example, a filter, a dialyzer, hemofilter, absorbent, oxygenator or other device. Cutouts110,116expose portions of the fluid circuit101such as a tubing section124for pumping, allowing it to be engaged by actuators or sensors of a machine150with which the support structure engages (seeFIG.1Cand attending discussion). Flow guides128may also be molded into support structure102to guide leaking fluid toward the hinge portion136which may further guide leaks toward a leakage sensor106or a portion132of the support structure102where a leak sensor may be disposed to detect leaks. These flow guides may be in addition, or alternatively, to the troughs that enclose tubes and other recess features that contain fluid circuit elements. In addition, or alternatively, leaking fluid may be guided by a space between the flat portions123of the support structure102such that there are seams inter-attaching the facing flat portions (as indicated at123, for example) of support structure102.

The support structure102may be configured with a leak sensor106forming part of the support structure or it may convey fluid to a portion132of the support structure102where an external leak sensor can be disposed (not shown in the present figure but see discussion ofFIG.7B, for example). As shown inFIG.1B, the support structure102may be installed on a treatment machine (not shown) having sensors and actuators as well as connectors to other fluid sources and sinks. The support structure and treatment machine may be configured to hold the support structure at an angle with respect to the direction of gravity such that leaking fluid falls toward the sensor106.

As shown inFIG.1C, a fluid handling machine150, for example, a blood treatment device, may have a fixture152configured to receive the support structure102. The arrangement of the fixture152may be such that the component parts of the support structure are oriented and aligned with sensors158,154, and actuators156and160of the machine150. In an example embodiment, the blood treatment machine may have pump and valve actuators and pressure, temperature, and leak detection sensors. The fixture152may be a recess in a face of the machine, for example, that receives the frame of the support structure102to hold it in a specific position and orientation. Actuators and sensors may move with respect to the machine150to engage the elements of the fluid circuit101held by the support structure102. In the illustrated embodiment, a leak sensor154is positioned at a lowest position in order that gravity may drive all leaking fluids toward it. In embodiments, the fixture152may include a recess that captures and guides fluids to the leak sensor154in case some breach the enclosing structure.

The machine150may be configured with a controller109and measurement indicators such as a display output for a computer display that indicates leaks when detected. Alternatively the machine150can be configured with one or more annunciators108that may be used to generate an alarm output upon detection of a leak. Alternative outputs include data signal such as a digital signal containing a message. Other alternative outputs may be employed including automated phone (e.g. cell phone) messages to a call center, data log outputs and other output signals. For a leak detector that forms part of the support structure102, the location indicated at154may represent electrical contacts or a magnetic pickup configured to receive an indication from the sensor (e.g., as indicated at106inFIGS.1A and1B) and convey a leak indication signal to the109controller of the machine150. The controller109manages these functions and which may be integrated in the machine150, and may include a digital controller employing a variety of known devices and methods. Systems and types of outputs and alarms as well as devices and systems for generating them are described in the incorporated references identified above.

Many other kinds of elements may be included in the fluid circuit101and the illustration is merely figurative to highlight certain features of the device.FIG.2shows a configuration of a support device200(essentially an embodiment more generally represented by the embodiment ofFIG.1A) made from a panel204that may be folded or cut into two halves and welded together (the precise manner of assembly is merely a peripheral incident of the embodiment and not essential to the claimed subject matter except as recited by the claims) to enclose a fluid circuit (portions of which are visible at210,214,216,252, and251, according to an embodiment of the disclosed subject matter (See alsoFIG.3B). The present example of a support device200encloses a portion of a blood handling circuit for a dialysis system. The support device200foldable panel204structure as shown in an unfolded configuration at271inFIG.3Band shown in a folded configuration inFIGS.2and3A. The general features of the present embodiment may be as described with reference to the embodiments described with reference toFIGS.1A and1B. More detailed features are shown inFIGS.4A-4D,5A-5C, which are discussed below. The treatment unit216may be, as in the present embodiment, a dialyzer filter216(but could also be a hemofilter, blood oxygenator or the like).

A venous blood line210is exposed as shown by the support device200. An arterial line as indicated at212is also exposed by the support device200. The blood lines210and212, exposed by openings211and213, respectively, are thereby enabled to engage sensors such as a pressure sensor and/or temperature sensor, or a bubble sensor on a fluid handling machine (e.g.,150). Another portion216of the fluid circuit is exposed for engagement with a blood component sensor, for example, one that detects leakage of blood into the dialysis fluid which is conveyed by the portion216. A pumping portion of the arterial line214is exposed by a window295of the support structure200to permit its engagement with a peristaltic pump actuator of the fluid handling machine150. The exposed portions may engage sensors or actuators such as blood leak detectors (optical type) or pressure sensors, or air detectors or pumps. Interfaces to pressure sensors may be provided inline to respective tubing segments for measurement of venous line pressure, and upstream and downstream of the pump tube segment214as indicated at241.

In the embodiment shown, the dialyzer filter216has an air vent206stemming from a tube202exposed by a cutout203in the support200. The exposed tube202may be clamped by an integrated automatic clamping device controlled by a controller of a compatible treatment machine with features as discussed with reference toFIG.1C. The exposed segment of tubing202may be used by the treatment machine to detect fluid as well as to permit an automatic clamp to stop the flow of fluid. Air vent206may be used to release air during priming of the blood circuit. Air collects in the header of the filter as described in U.S. Pat. No. 7,544,300, which is also hereby incorporated by reference as is fully set forth herein. As priming fluid is flowed through the blood circuit during priming, air emerges from the vent206(a hydrophobic membrane-sealed port) displaced by fluid until the fluid enters the tube segment202and is detected. Then the tube segment202is clamped. If the retreat of the fluid column occurs due to the accumulation of air in the tube segment202, and the air retreat of the fluid detected by a fluid detector, then the clamp may be released to vent the air.

Right-angle connectors220and222interface with a dialysis circuit in an embodiment of the machine150. When the support200is inserted on a treatment device (embodiment of machine150), the right-angle connectors220and222automatically connect to source and drain connectors on the machine. These types of connectors may be used to interconnect a non-disposable portion of a fluid circuit, such as the non-blood circuit of a dialysis system, with the disposable portion. In embodiments, the non-disposable portion handles fresh and spent dialysate. The connectors may be needle-less ports (blunt stubs that insert into self-healing septa in the right-angle connectors220and222).

Referring now also toFIGS.3A and4C, a curved slot208allows long stretches of blood tubing251and252to be inserted therethrough so that tubes251and252do not kink. The curved slot208has a pair of troughs265that face toward the slot208and curves up toward the viewer to allow the distal extent of the blood tubing251and252to extend toward a patient access end as shown inFIG.3A. The distal extents of the tubing251and252can then be looped and then coiled into an oval and laid over the support200as shown inFIG.3A. It can be seen inFIG.3Athat tubing252and253are also supported by a horn shaped opening262with a curved supporting surface that also helps to prevent kinks. In embodiments, the supporting curved surface262and the supporting troughs265form a single continuous surface that prevents kinks. The curved slot208is defined by overhanging portions209that retain the tubes251and252. The size of the curved slot208and the choice of materials for the overhanging portions209are such that tubes can be snapped into the troughs265one at a time and then retained by the overhanging portions209.

In an alternative embodiment, the curved support262lie adjacent a retention mechanism that allows the distal part of the tube to be released by pulling in a direction parallel to the general plane of the support device200. For example, the configuration ofFIG.15, discussed below, has a gap645or646into which the distal part of the tube can be retained within the perimeter of the support device as discussed with reference toFIG.15, below.

The openings through which tubes251and252extend have axes that are generally in a plane of the support, which is generally planar in shape. The support200defines a trough258which protects the tubing251and252when resting therein as shown inFIG.3A. The tubing may be protected by being at least partly within the perimeter when routed as shown inFIG.3Abut even if the tubing extends slightly beyond the perimeter, if an object forces the tubing, such as when the support and circuit are pushed into a tight box, the tubing will be pushed into the trough258until the object encounters the perimeter and no further so that the tubing will still be protected. Thus, the tubing may at all points reside substantially within the perimeter, though not literally, and still be protected by the support device200.

The two panels making up the support device embodiment illustrated may be of sheet material that defines a single valued surface function such that it can be formed on, and released from, a vacuum mold or other two-part mold. Features of the support200may be applied to other types of fluid circuit support structures that do not enclose the circuit to capture leaks. For example, an open panel or simple frame may provide the tubing guides and protection features described above. These features may allow compact packaging without the risk of tubes being injured or kinked as a result of being tightly fitted in packaging, containers, or confined or forced against other objects.

By packaging the support200with the blood tubing with the disclosed configuration, kinked tubing can be avoided in packaged fluid circuits which can avoid the flow restrictions created by kinks. Also, kinks can increase the risk of thrombogenesis due to turbulence induced in the wake of the flow restriction caused by them. The openings through which the blood tubes252and251emerge may be shaped as the horn-shaped opening265with the supporting curved surface262providing a smoothly curved support on both sides for the blood tubing thereby further preventing kinks. The looping is illustrated at270inFIG.3A. The coil of tubing may be restrained with a band272such as a rubber band or tape. The coil may be taped or banded to the support200by the same or another such band273. Other restraints may be used to position the coil as shown. For example, see discussion below ofFIGS.13to17. Another feature of the present and further embodiments is the distal part of the tubing may be confined within the perimeter of the support device200such that no part of it can get trapped between the support and an external object. This helps safeguard against injury to, or kinking of, the tubing during shipping, storage, or other handling.

Referring also toFIGS.3B and4A, the panel shaped structure271has recesses283(one on either side with one indicated at283) that enclose the fluid circuit as shown inFIG.2when folded. The structure271has corresponding trough-shaped recesses281for tubes, recesses284for connectors, and recesses for285for sensor elements.FIG.4Ashows a pressure pod291visible through an opening276and a connector287visible through an opening277. Also shown is an opening289for a tubing segment294. These fluid circuits are representative of elements that may interface with external devices. Corresponding elements may be provided to enclose (fully or partially) and any other elements of a fluid circuit to form the enclosed structure200. The panel shaped structure271may be formed from thermoplastic in a vacuum molding process followed by die-cutting or any suitable process. After folding seams (or other interconnections) may be welded or attached by solvent bonding or adhesive or other suitable process. Instead of folding, the structure200may be formed using separate panels or other support elements. Referring toFIG.4B, a slot shaped opening275may expose a tube segment274for engagement with an actuator or sensor parts of which lie outside the frame of the support structure.

The support device200may be configured to enclose enough of the circuit element to minimize the risk of leaks escaping while permitting circuit elements to interface with the fluid handling machine (e.g.,150) and to guide any leaking fluid to a fluid leak sensor (for example, the integrated one indicated at106inFIG.1A).FIG.5Ashows a perspective view of a window of the support device200, for example, a window213as shown inFIG.2.FIG.5Bshows section and side views of the configuration ofFIG.5A.FIG.5Cshows a window such as213in section with both the top and bottom of the frame in section view.FIG.5Dshows a window structure in which a rectangular frame is angled which may assist in the flow of leaking fluids through a support device such as200. The support device200panels432may be configured to provide channeling for leaking fluid. In one embodiment, the panels432are welded together at dimpled points433which ensure a gap434between them is provided for leaking fluid to be conveyed between the panels432to a leak sensor. The perimeter edges (indicated at430inFIG.2) may be welded or adhesively bonded to ensure fluid cannot leak from the support structure200. Extension features440span a fluid circuit feature, such as a tube442, that is open for access (access direction indicated by arrow402) by actuators or sensors of the machine150to ensure that fluid leaking from the feature is captured. In additional embodiments, channel structures may be formed into the support structure200such as channel413indicated inFIG.5A. A rectangular window440that is angled with respect to gravity may provide advantages in terms of ensuring against the escape of fluid flowing around the window440. For example, rather than dripping from an upper edge441to a lower edge443, if the window440were straight, fluid may flow along the upper edge441and down around the window440.

Referring now toFIGS.6A and6B, an enclosure300is configured as part of a fluid handling machine with actuators and sensors generally as discussed with regard to the foregoing embodiments. In the present embodiment, a fluid circuit301is encased in the enclosure300. For example the fluid circuit301may have tubing portions314and other elements, such as a cylindrical structure310, which may be a dialyzer or any of the other components described in the foregoing embodiments. The enclosure includes an access hatch302to provide access to an interior of the enclosure. The access hatch may pivot on a hinge312by which it is attached to a back panel320. The configuration is shown in a closed position for operation inFIG.6Aand a partly open position inFIG.6B. The back panel320and/or the hatch may carry sensors, actuators, and/or other devices that interconnect with the elements of the fluid circuit301. The internal surface of the enclosure has surfaces321and304that are configured to capture and convey any leaks to a leak sensor322. The surfaces304and321may be sloped so as to cause any drips of fluid (as indicated for example at316and317) to flow toward the leak detector322and accumulate there as indicated at318. In the embodiment300, the surfaces321and304are shaped such that any fluid accumulating on the hatch302drips so as to flow to the fluid sensor322. This can be accomplished without forming a seal between the panel320and the hatch302, for example, if the hatch302fits partly inside a recess307of the enclosure300. A sloping portion305may further ensure that fluid moves toward the fluid sensor322. In a similar arrangement, shown inFIG.6C, a back panel recess340receives a hatch342with an internal surface configured similarly to that of theFIG.6A,6Bembodiment. In the present embodiment, however, the hinge344is remote from the edge of the hatch342. As in the previous embodiment ofFIGS.6A and6B, containment of leaks and their conveyance to a detector is provided without a seal between the recess340and hatch342.

FIG.7Ashows the embodiment ofFIG.6Awith a fluid circuit301that is not enclosed in a support structure such as support structure200shown inFIG.2. In the embodiment ofFIG.7A, a leak sensor323employs a non-wetted type of detection sensor, such as one that employs an optical, capacitive, induction or some other non-contact mechanism for detecting fluid. In an example embodiment, the sensor323is an optical sensor that detects blood, such as the type used in blood treatment system to detect the presence of small amounts of blood in a clear fluid.FIG.7Bshows the configuration ofFIG.7Awith an enclosed fluid circuit having a support structure essentially as described above, for example with reference toFIGS.1A and2. A support enclosure328supports and encases a fluid circuit331. At360a sensor or actuator is shown with engagement portions362that engage a fluid circuit portion332, for example a tube portion. The support enclosure has a lower portion325where leaking fluid may collect which is immediately adjacent the fluid sensor323. Thus, as illustrated inFIG.7B, the same configuration can accept both enclosed an unenclosed fluid circuits and detect leaks both.

Referring now toFIG.8, an embodiment of an enclosure450for a fluid circuit453which is generally similar to the foregoing embodiment300in that it contains leaks from fluid circuit453elements and conveys any leaking fluid to a fluid sensor468. An actuator/sensor assembly455has various components to engage with components of the fluid circuit453. Specific features of the present embodiment permit ease of installation of the fluid circuit453to the components of the fluid circuit453. A pair of right angle connectors are formed as a single connector component452to facilitate connection to a dialysis circuit behind it (not shown in the figure). Elbows454help to auto-align the tubing459and the intermediate connector component452. Pressure pod456inserts directly into transducer components in a backplane471. Pressure pods458and460insert directly in respective transducers in the backplane and in doing so, align pump tube segment463with a peristaltic pump rotor465. When a door453is closed, a constant force retaining member482holds the connector component452against the hidden mating connectors in the backplane471. The door453has a spring-biased pump race462that engages the pump tube segment463between itself and the peristaltic pump rotor465. A filter451is received in a trough493and enclosed by a closely-conforming opposing shell part487of the door453. A ridge464is received into an opening469of identical shape ensuring that any fluid that strike the interior of the door453are conducted to an interior cavity464where the optical sensor468faces inwardly.

In any of the foregoing embodiments, a leak sensor may employ any suitable technology for detecting leaks, including optical detection, capacitance, conductance, or any other property may be detected.

Referring toFIG.9, a blood treatment system508has a blood treatment component510, a blood flow reversal component512, an air infiltration detection component514, and a leak detection component516connected to a patient518by arterial and venous blood lines518and520, respectively. In operation, the blood treatment component510treats blood and pumps blood in a normal direction which delivers treated blood to the patient and withdraws untreated blood through venous and arterial lines520and518, respectively. If a disconnection of the venous line occurs, air is drawn in due to the negative pumping pressure, and the infiltrated air detected by the leak detection component516. The detection of air may cause a controller506to generate a signal indicating the event, sound an alarm, and/or enable a safety mode of the treatment component510.

In a prior art system conforming to the description ofFIG.9except for the additional leak detection component516, the blood flow reversal component512regularly reverses the flow of blood so that any disconnections or leaks arising in the venous blood line520will cause air to be drawn into the venous blood line520and conveyed to the air detection component514. A problem with the prior art leak detection scheme is that the patient is subjected repeatedly to blood flow reversal which may be undesirable, for example because it creates patient discomfort or it may add time to the treatment due to the inefficiency of reversing the blood flow repeatedly.

A problem with prior art leak detection mechanisms that rely on pressure measurement of the venous blood line is that in order for them to be sensitive enough to detect nearly all possible leaks, such systems produce too many false alarms. This can lead to so-called operator alarm-fatigue. Alarm-fatigue can result in the reflexive cancellation of alarms to the point that the operator may miss a real leak causing harm to the patient.

In the present embodiment, the blood flow reversal component512instead operates in a forward direction unless a leak is indicated by the leak detection component516. When a leak is indicated by the leak detection component516, the blood flow reversal component reverses the flow of blood for an interval to determine if a leak is confirmed by the presence of air. In embodiments, the leak detection component516includes a pressure sensor that indicates the pressure in the venous line. The controller receives a signal from the pressure sensor indicating pressure of the blood in the venous line520and when the pressure signal corresponds to a characteristic signature of a leak, for example, the drop in pressure of a certain magnitude over a predefined interval of time. If the signature is detected by the controller506, a leak indication is generated by the controller506causing it to trigger the blood flow reversal component to reverse the flow of blood. The controller may further be configured such that a leak is indicated only upon the subsequent detection of air infiltration by the air infiltration detection component. That is, the controller will only generate a signal indicating the leak and thereby causing a response such as the sounding of an alarm, and/or enablement of a safety mode of the treatment component510, if the initial detection by the blood leak detection component516is confirmed by the detection of air. Otherwise, the normal flow of blood is resumed.

In general, the present system may defined as one in which:1. A first indicator of a leak is coupled with a confirmatory leak detection device. In a narrower embodiment, the confirmatory leak detection device is triggered by the sensitive indicator.2. In a variant, the first indicator is sensitive and tends to produce false positive leak indications when used for detection of leaks.3. In another variant, combinable with the first and second, the first leak detection device triggers the confirmatory leak detection device a predefined number of times in a predefined period, a leak is indicated by the controller even if the confirmatory leak detection device fails to confirm the leak.4. In another variant, the confirmatory leak detection device is one which requires a change of machine operating state.5. In another variant, the change of operating state includes the reversal of blood flow.6. In another variant, a strong indication of a leak causes the controller to indicate an alarm without confirmation by flow reversal, for example, if the magnitude of a detected change in venous pressure over the predefined interval is beyond a second threshold that exceeds the threshold that initiates the confirmatory leak detection process, the leak is automatically indicated rather than invoking the confirmation process.7. In variants, the venous pressure is measured directly by measuring pressure in the venous blood line and in another variant, the venous pressure is measured indirectly using a pressure sensor responsive to pressure in the effluent line of a dialyzer or hemofilter.

The algorithm described for detection of a pressure drop ΔP in a predefined interval Δt is illustrated inFIG.10. Other leak indicating signatures of the pressure versus time signal may also be employed. It may be noted that the present system allows a very sensitive, and potentially false-alarm-prone, indicator of leaks to be employed without the undesirable consequence of false alarms or the risk of alarm fatigue. In addition, the present system allows the robust method of leak detection by flow reversal to be employed in a minimal fashion that mitigates its undesirable consequences.

The controller506may have a user interface507that may include, for example, a display. The user interface57and controller may be configured to store a log of instances of the sensitive indicator's indications of a leak along with a record of instances of the invocation of the verification operation. These logs may be displayed on the user interface507and used for monitoring the treatment operation.

Referring now toFIG.11, a blood treatment machine has a blood treatment device556such as a dialyzer or blood oxygenator. Medicament or gas550, as applicable, may be pumped through the treatment device556by a pump558(or flow regulator as applicable). An air detector568detects the presence of air in a venous blood line562. An arterial blood line564draw blood from a patient566by means of a pump560. A controller570receives a signal indicating pressure indicated by a venous pressure sensor554. In an embodiment, the venous pressure sensor554includes multiple sensors located at various positions with respect to a venous flow path. In another embodiment, the venous pressure sensor is located near the patient access, for example, a pressure pod forming part of a disposable access blood set. When the controller identifies a predefined leak signature, such as may be caused by the accidental withdrawal of a venous access cannula, it controls the blood pump560to reverse direction for a period of time. If the controller detects air by the air detector568, an indication of a leak is generated by the controller570which may be applied to an output device555and/or initiate a safe mode response by the treatment machine552.

FIG.12shows a method for detecting a leak according to embodiments of the disclosed subject matter. At S10, a pressure signal is continuously sampled. At S12, the pressure signal samples are stored to generate a pressure versus time signal. The samples may be stored in a buffer to cover a predefined interval of time and a delay may be chosen to provide a desired temporal spacing of the samples. Criteria may be applied for rejecting samples or for filtering the buffered samples to remove ergodic or random noise, for example, pulsations of a pump, patient movement, etc. If a signature is detected in the time series of pressure data generated at step S14, at S16, it is determined if the present indication is an instance of more than a predefined number of instances of signature recognition and if so, at step S24a leak detection signal is output. If at S16, the number of instance of the signature being recognized in the predefine interval is not exceeded, then at S18it is determined if the signature exceeds are predefined magnitude or other characteristic indicating a strong probability of a leak, for example, a pressure change of a predefined high magnitude threshold. If the signature exceeds this higher probability threshold then control moves to S24, otherwise, at S20, blood flow is reversed for a predefined period. If air is detected during the predefined period, at S24a leak is indicated otherwise control reverts to S12.

A signature has been identified from logs of actual patient data which is reasonably predictive of a leak or disconnection. This signature is a pressure loss of 17 mm Hg between two pressure plateaus within a narrow interval of 10 or 15 seconds which may be chosen, for example, responsively to pump speed or nominal flow rate.

In any of the disclosed embodiments, a safe mode may be invoked by the detection and confirmation of a leak, where the safe mode may include outputting an alarm, halting the pumping of blood, generating an automated phone call to a supervising center, reducing a rate of blood flow, clamping fluid lines, taking further corrective action to restore patency to a blood line, and generating a responsive display, for example, one including instructions for correcting a leak.

FIGS.13through18show fluid circuit support embodiments and features thereof to illustrate subject matter that, among other things, protects tubing against kinking and injury to the tubing and facilitates packaging.

Referring toFIG.13, a fluid circuit support602is of a generally planar form that encloses fluid circuit components of any description, but at least including a tubular portion604that extends outside the support602. For example, the enclosed fluid circuit components may include tubular portions such as indicated at607and612or other components such as connectors or other devices indicated figuratively at617. Components may be exposed for engagement with sensors or actuators by openings such as indicated at611. The support may be formed of molded panels that are affixed to each other by standoff dimples as indicated at615or otherwise interconnected to create an internal space in which the internal fluid circuit components may be held. The standoffs may be elongate ridges with continuous attachments (e.g., adhesively bonded, welded, or attached by fasteners) to form a fluid seal as described with reference to theFIGS.2and3Aembodiments.

The features shown inFIG.13may be employed with any of the disclosed embodiments. For example, a support structure has fence618that has a shape whose radius (which may not be constant in embodiments) is selected to prevent a tube604from kinking when drawn tightly therearound as depicted. Another fence is shown at606which supports the tube604both inside and outside.FIG.16shows a structure by which the fence604or606may be created, for example, by vacuum forming. A panel666A is formed with a ridge664A to form the fence. A panel portion is shown in section view inFIG.16. Only one tube662A is shown adjacent to an outside of the fence664A. Although the fence is shown with a rectilinear shape, it may be more tapered to facilitate release from the mold.667A shows a tube portion internal to the support structure similar to200discussed above. Reference numeral660B shows a structure essentially identical structure660A with similarly referenced elements (except that the letter A is replaced with letter B in the reference numerals). The fence664B may serve as a support for stacking multiple support structures as shown in the stack portion660B and660A. This may allow the support structures to be stacked without applying pressure to the tube662A outside the enclosed part of the support structure. It may also aid in the prevention of other outside materials, such as packaging or other objects from deforming the tube662A (662B). Tubes662A and662B represent tubes that extend beyond the support structure and which are coiled, for example as discussed above and indicated inFIG.3Aat270.

Tube604is an extension from an internal portion607that extends through an opening604. Although a single tube is shown, multiple tubes may extend from a single, or from respective openings. A slot609defines flexible tab portions that overlie the tube607partly as it emerges progressively from the interior of the support602toward the outside. A support ramp (not shown inFIG.13but see discussion ofFIG.17, in particular feature679) may be provided inside the support602to guide the tube upwardly toward, and through, the opening604. The extended portion of the tube609may be routed around fences606and618as shown. Alternatively, the extended portion of the tube609may be looped and tied as illustrated inFIG.3A. Another form of tube guide has a slot608with openings610at either end. A tube on the outside of the support602can be held in place to help prevent kinking and to help confine the external portion of the tube604within the perimeter of the support602. The feature may be used with or without the fence features.

InFIG.14, an internal tube is routed around a fence of dimples624from which the tube629can be pulled in a support device622.FIG.15shows a section view of the principle where a tube653is held in recess646formed by opposing standoffs655in respective panels642and643of a support device. The section view shows internal tube651and other circuit element654of arbitrary description enclosed between the panels642and643. Tubes641and644are doubled up in a wider area648captured similarly to tube653. The dimples or standoffs may take the form of elongate features rather than low aspect ratio features shown. Standoffs may be bonded, fastened by fasteners, welded or interconnected by any suitable means. Preferably they are arranged and numbered to provide rigidity to the support structure622,602(also200and similar).

The tube653(627) end may be pulled out between the dimples655(624) that capture it until the drawing may be halted by guides621, which may be shaped to relieve strain (thereby prevent kinking) if the tube is pulled to the side. Internal guides626,632may be provided along straight and curved sections as required to permit the tube to be wrapped. These guides626may be replaced by a continuous fence that runs along major sides of the support device622in embodiments. It can be visually confirmed that the tube629is held safely within the perimeter of the support622so that it can be shipped in tight fitting container without risk of kinking or denting the tubes and also so that the extended portion of the tube is not injured or strained during other kinds of storage or handling.

Referring toFIG.17, a support structure677with attached panel portions672and681that enclose a tube683(and optionally, other elements of a fluid circuit) that extends outside the support structure677through an opening675. The opening may include a curved surface685that supports the tube683. The panel672may have a curved support feature679as well. A fence678is formed around the external face of the upper panel681which functions to help retain and protect the external portion of the tube683(the external portion being indicated at674). The lower panel672may be attached to an underside of the upper panel681by suitable standoff features such as indicated at676to create an enclosed space671for fluid circuit components.

Referring toFIG.18, although in the embodiments described above, fluid circuit supports were described in terms of examples that employed interconnected panels. However a variety of different configurations are possible which may offer the benefit of various features of the disclosed embodiments. For example, a framed structure such as indicated at682can enclose parts of a fluid circuit and provide an opening through which an external tube portion684may emerge. Other features such as guides, strain relieving features, releasable connections etc. may also be provided. The frame (or a panel) may also be provided in a fully open structure, for example, a single panel or a frame with only one side supporting the fluid circuit elements. In the latter case, the fluid circuit elements that do not extend for connection to an outside fluid source and/or sink may be mounted to the support and the extended tube or tubes can be releasably attached to the same side or the opposite side of the support.

Referring toFIGS.19-20, detection and control system features for implementing embodiments of a system and method according to alternative embodiments of leak detection in a fluid management system are now described. A controller702is connected to a user interface718configured to receive commands and output data such as error indications, alarms, treatment logs, performance logs, treatment status, etc. A fluid management device720has sensors and actuators configured for performing a process such as an extracorporeal blood treatment or other type of operation, such as infusion, plasmapheresis, or peritoneal dialysis. The device720may receive disposable components for managing the flow of fluid while ensuring sterility. The controller702, user interface718, and further components now described may be integrated in the fluid management device720or may be separate components, either connected to it or separate from it. The controller702may be one or more controllers that operate independently or are in communication with each other or to a common element.

A pressure sensor704receives pressure signals indicating fluid pressure at one or more locations of a fluid circuit engaged by device720. The pressure signal may represent pressure in a venous line of blood treatment circuit, for example, according to a principal one of the disclosed embodiments. Alternatively it may be a normally-positive pressure line of a fluid circuit such as the return flow line of a peritoneal dialysis circuit. Alternatively, it may be any fluid conveyance channel of a fluid management circuit.

One or more accelerometers706may be connected to a fluid circuit (including the peripheral lines), a patient, patient access, and/or a patient's bed or chair. Alternatively, one or more accelerometers may be connected to components of a non-treatment circuit to detect vibrations. Such accelerations may be used to detect configuration changes that might affect pressure signals and lead to misclassification. For example, a patient rolling over in bed may cause a sudden drop in pressure. By applying the accelerometer signal to the controller contemporaneously with the pressure signal from a positive pressure line, the controller may use both signals to classify a leak. In such a case, the accelerometer signal may be used to inhibit the classification of the pressure signal as indicating a leak if the acceleration is experienced contemporaneously with the pressure drop. An accelerometer signal may be classified independently as showing the signature of an event such as striking on object (e.g., an accelerometer attached to a patient access falling out and hitting the floor).

An imaging device712generates an image of a scene, for still image capture or video capture, for example. The imaging device may use thermal imaging, optical, ultraviolet, or a combination of the above. The controller may be configured for machine classification of events or configurations of the captured scene. For example, a video sequence indicating a restless patient may be classified as such and a signal output indicating the event class and the timing thereof may be applied to the controller702. The classifier may recognize a warm or colored blob as a leak of warm and/or colored fluid such as blood and similarly output an indication of an external flow or leak thereof. The image may classify a change in the configuration of a fluid line that indicates a kinked line or a change in the position of a line that may correspond to a pressure fluctuation that is detected concurrently. The indication of the change in the shape of the fluid line (for example, kinked or simply moved) may be used by the controller to aid in the machine classification of fluid line pressure data received by it from pressure sensor704.

Note as used throughout the specification herein, classifier, classification, and classify may be used to denote machine algorithms for converting one or more inputs to an indicator of a class. The terms may correspond to the simplest classification process which is comparing a raw signal to a predefined range and outputting the result of the comparison. For example, an analog comparator circuit may be a classifier as the term is used herein.

A gas detector714may be connected to the controller to detect the presence of gas or air into a fluid line. If a line is under negative pressure, a leak (a type of leak being a disconnection of a patient access) may cause the infiltration of air which may be detected when pumped to an air detector714. A pump710or flow reversing valve711may be connected to the controller to implement the flow reversal function discussed above. A wetness detector722may also apply a signal to the controller702indicating the presence of fluid outside the fluid circuit. For example, electrodes of a galvanometer may indicate the presence of external fluid thereby indicating a leak. The electrodes may be held in an absorbent material such as an absorbent pad under a patient's access so that leaking fluid can form a conductive path in the wetted pad. A microphone716may be used to detect ambient sounds that may indicate a leak and/or may disambiguate another signal (e.g. pressure, video, etc.) used by a classification algorithm.

Any and all of the sensor signals described above with reference toFIG.19(or elsewhere herein) may be combined by the controller702in an event or state classifier to identify an event or state of the system including the classification of a leak. The classification may be done by any of a variety of classifiers such as explicit rule based networks, supervised learning algorithms, unsupervised learning algorithms, neural network, etc. Back propagation classifiers may be trained using treatment log data. In any of the foregoing, the input vector that results in a particular class recognition of a classifier may be identified as a “signature,” for example an audio signature might the sound of a needle dropping or a patient rolling over in bed. A video signature might be a growing red blob (spilled blood). A combined input vector of a video sequence and contemporaneous audio sequence may provide a signature of a patient rolling over in bed. A voltage or signal source and signal receiver or galvanometer722may be used to detect continuity in a fluid circuit by applying a voltage and measuring a current or by applying a modulated electrical voltage and measuring a current signal across the fluid circuit. This may be used to detect a conductive (e.g., blood or electrolyte) fluid path's continuity. A detection or failure signal may be applied to the controller702as well.

Referring toFIG.20, a general method for detecting leaks includes a first step S102in which a first one or more signals is analyzed to determine if there is a leak. The first one or more signals may be, alone or in combination, a weak discriminator and thus, to reduce false positives, it may be used to invoke a confirmation process. If a leak is indicated (again, either by a signal or a classifier output responsive to one or more signals), a confirmation process is invoked at S104. An examples is the flow reversal process described above with reference toFIG.12. Responsively to the confirmation process a refined signal of a leak (or no leak) is generated and used in S108to invoke a warning signal output from the UI718or a recovery or safe mode process of fluid handling device720. Examples of safe mode include halting pumps and closing valves to prevent continuation of a leak, output of instructions for recovery on the UI718, and/or an alarm to alert a technician or operator. S108may be terminal or, with recovery may revert to S102.

As indicated at750, the initial one or more signals used for step S102may be, or include, as described with reference toFIG.19, an audio signature, a pressure signal edge as described with reference to S14inFIG.12, a video event signature, wetness indication, or and accelerometer signature. Any and all of these examples may be combined. As indicated at752, the confirmation process may be, or include, a flow reversal to generate an air detection (for example, as described with reference toFIG.12).

As also indicated at752, the confirmation process S104may also include an operation in which a pressure signal is monitored during operation of the fluid circuit or only at times for the present operation. The configuration or status of the fluid management system is changed to permit the pressure signal to detect a signal that is clearer or detectable only when the fluid management system acquires that status. An example, is cessation of pumping of fluid and monitoring of the pressure in the line connected to a patient for subtle pressure fluctuations indicating vital signs such as breathing and heart beats. The pressure signal may be filtered digitally to remove noise and other external influences and the result applied to a classifier.

As also indicated at752, another confirmation process includes the application of a voltage to the fluid lines and subsequent detection of continuity with a galvanometer. The technique of using continuity or passage of a modulated signal (the modulation producing a recognizable signature that can be filtered out of background noise) confirms the connection of blood or peritoneal (or other) lines to a patient, which forms a part of the electrical path of the circuit only when the patient access is properly connected. A pressure fluctuation signal, such as a pressure fluctuation in the acoustic range, may also be applied to a fluid circuit to establish continuity. The received pressure fluctuation signal may contain transmitted and/or reflected components which may be used to establish, or suggest, the status of a fluid circuit or a connection thereof.

FIG.21is a flow chart showing a procedure that may be used for a first of the two-stage leak detection system and method described with regard to other embodiments, for example, in place of S14inFIG.12. The procedure may also be used as a stand-alone method for detecting a venous line disconnect of a blood treatment system or paroxysmal leak in the venous line. At S202, a buffer is reset by clearing all values of venous pressure and arterial pressure edges stored therein if the blood treatment system is in an unsteady operating mode. The control flow resets if the machine is in unsteady operating mode as indicated by the arrow780, clearing the buffer at the same time.

At S204, a new venous pressure and arterial pressure sample are loaded into the buffer. At S206the pump speed (blood pump speed=nominal volume rate of blood flow based on pump speed) determines the type of filter to be applied to the stored stream of arterial pressure samples. At S208, the high and low samples over the previous (in time) 6 arterial samples and averaging the rest so the filter takes a four-sample average of the samples remaining after high and low samples are discarded to form a sliding window function that is applied retrospectively to generate the slow pump filter. At S210, a notch filter is applied to the samples to remove pump noise from the arterial pressure samples. Alternatively, a low pass filter may be applied with a cutoff at about, or below, the pump pulsation frequency. In embodiments, the pump is a peristaltic or reciprocating pump. The venous pressure signal is searched for a current venous pressure plateau and a prior plateau within a prior 60 samples (i.e., 60 seconds). A venous pressure plateau may be defined as one in which the pressure values lie within a predefined range for a predefined interval. At S216if a pressure change of some predefined amount, for example in the range of 12 to 25%, is identified between detected plateaus, then it is determined if the arterial pressure was stable (within a predefined range of values) during the inter-plateau interval at S218. A pressure change of 17% was found through experiment to provide an optimal discriminator for a known hemodialysis system configuration.

The inter-plateau interval (i.e. window) may be defined responsively to pump speed, with a longer interval for slower pump speeds. If the filtered arterial pressure signal was stable, the controller generates a signal indicating a leak, or possible leak, at S220. A stable filtered arterial pressure is defined as a change of less than 10 mmHg between samples during the inter-plateau interval. At all decision points S212, S214, S216, and S218, control returns to S202if the determination is negative.

FIG.22illustrates the pressure fall detection based on plateau detection and the fall in the filtered venous pressure signal. The plateau criteria are represented as a box whose height is the predefined plateau pressure range ΔP and whose width is the predefined plateau interval Δt. The window (e.g., 10 or 15 samples) over which the pressure fall is required to be found is indicated by “w” and the magnitude by “s.” The plateau value averages are indicated at788and the difference between them indicated by “s.”

In any of the foregoing embodiments, the pressure used to trigger the second stage of the two stage leak detection system may be venous line pressure of a blood treatment system. This pressure may be measured within the blood line of the fluid circuit using a drip chamber, pressure pod, or any other suitable blood line pressure measurement technique. It may be also be measured indirectly by measuring the pressure of effluent that is in contact with the venous line through a filter membrane, such as a dialyzer.

In any of the foregoing embodiments, tubular elements may be replaced with other types of flow channels suitable for conveying fluids. Examples include seam-welded panels forming fluid channels, one or more rigid vessels defining channels therein, rigid or flexible pipe networks, etc.

In any of the embodiments for a fluid circuit and/or support for the same, the portion of the tubing that extends beyond the support device (e.g.,200or602or similar) may be for an infusion line to be extended toward a patient. Also it (or they, in the case of multiple tubes) may be for one or two patient access lines of a blood treatment system. In any of the above embodiments, the fluid circuit may be a disposable unit for use with an infusion apparatus, an extracorporeal blood treatment system, transfusion or plasmapheresis system, blood oxygenator, or any type of medical device requiring connection to a patient, a source or drain, or other connection that must be extended or may be facilitated by having an elongate attachment or more than one.

It will be appreciated that the modules, processes, systems, and sections described above can be implemented in hardware, hardware programmed by software, software instruction stored on a non-transitory computer readable medium or a combination of the above. For example, a method for detecting leaks using a processor configured to execute a sequence of programmed instructions stored on a non-transitory computer readable medium. For example, the processor can include, but not be limited to, a personal computer or workstation or other such computing system that includes a processor, microprocessor, microcontroller device, or is comprised of control logic including integrated circuits such as, for example, an Application Specific Integrated Circuit (ASIC). The instructions can be compiled from source code instructions provided in accordance with a programming language such as Java, C++, C#.net or the like. The instructions can also comprise code and data objects provided in accordance with, for example, the Visual Basic™ language, LabVIEW, or another structured or object-oriented programming language. The sequence of programmed instructions and data associated therewith can be stored in a non-transitory computer-readable medium such as a computer memory or storage device which may be any suitable memory apparatus, such as, but not limited to read-only memory (ROM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), random-access memory (RAM), flash memory, disk drive and the like.

Furthermore, the modules, processes, systems, and sections can be implemented as a single processor or as a distributed processor. Further, it should be appreciated that the steps mentioned above may be performed on a single or distributed processor (single and/or multi-core). Also, the processes, modules, and sub-modules described in the various figures of and for embodiments above may be distributed across multiple computers or systems or may be co-located in a single processor or system. Exemplary structural embodiment alternatives suitable for implementing the modules, sections, systems, means, or processes described herein are provided below.

The modules, processors or systems described above can be implemented as a programmed general purpose computer, an electronic device programmed with microcode, a hard-wired analog logic circuit, software stored on a computer-readable medium or signal, an optical computing device, a networked system of electronic and/or optical devices, a special purpose computing device, an integrated circuit device, a semiconductor chip, and a software module or object stored on a computer-readable medium or signal, for example.

Embodiments of the method and system (or their sub-components or modules), may be implemented on a general-purpose computer, a special-purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit element, an ASIC or other integrated circuit, a digital signal processor, a hardwired electronic or logic circuit such as a discrete element circuit, a programmed logic circuit such as a programmable logic device (PLD), programmable logic array (PLA), field-programmable gate array (FPGA), programmable array logic (PAL) device, or the like. In general, any process capable of implementing the functions or steps described herein can be used to implement embodiments of the method, system, or a computer program product (software program stored on a non-transitory computer readable medium).

Furthermore, embodiments of the disclosed method, system, and computer program product may be readily implemented, fully or partially, in software using, for example, object or object-oriented software development environments that provide portable source code that can be used on a variety of computer platforms. Alternatively, embodiments of the disclosed method, system, and computer program product can be implemented partially or fully in hardware using, for example, standard logic circuits or a very-large-scale integration (VLSI) design. Other hardware or software can be used to implement embodiments depending on the speed and/or efficiency requirements of the systems, the particular function, and/or particular software or hardware system, microprocessor, or microcomputer being utilized. Embodiments of the method, system, and computer program product can be implemented in hardware and/or software using any known or later developed systems or structures, devices and/or software by those of ordinary skill in the applicable art from the function description provided herein and with a general basic knowledge of medical device software and/or computer programming arts.

Moreover, embodiments of the disclosed method, system, and computer program product can be implemented in software executed on a programmed general purpose computer, a special purpose computer, a microprocessor, or the like.

It is, thus, apparent that there is provided, in accordance with the present disclosure, leak detection methods, devices and systems. Many alternatives, modifications, and variations are enabled by the present disclosure. Features of the disclosed embodiments can be combined, rearranged, omitted, etc., within the scope of the invention to produce additional embodiments. Furthermore, certain features may sometimes be used to advantage without a corresponding use of other features. Accordingly, Applicants intend to embrace all such alternatives, modifications, equivalents, and variations that are within the spirit and scope of the present invention.