Patent Application
20230284613
The present disclosure relates to maintenance, assessment, maturation, and rehabilitation of a tissue for a transplant recipient. In 2020, there were about 39,000 transplants of all types of tissues performed in the United States. Every nine minutes, someone else is added to the transplant waiting list. There are a number of different types of tissues that are utilized from organ donors. Tissues, including organs, that are considered for transplantation include, but are not limited to, kidney, pancreas, liver, heart, lung, stomach, intestine, composite allografts, thymus, uterus, skin, bone, tendon, middle ear, cartilage, heart valves, trachea, nerves, veins, hands, feet, arms, adrenal tissue, fetal thymus, cornea, and composite transplantation tissue. Regarding specific organs, in the United States in 2020, there were 12,141 people on the liver transplant waiting list, while only 8,906 transplants occurred. Pancreas, heart, lung, and intestine candidates awaiting transplants numbered 14,489. Further, while there were 91,834 kidney candidates on the transplant list, only around 20,000 kidney transplants were performed.
With respect to the kidney, in 2020, over 700,000 patients per year in the United States and an estimated 2 million patients worldwide were affected by end stage renal disease (ESRD). Further, morbidity among ESRD patients increased during the early months of the COVID-19 pandemic resulting in an estimated 6,953-10,316 deaths. The primary treatments for ESRD are dialysis and kidney transplant. In the United States, an overwhelming percentage of people with ESRD are on dialysis, with a small fraction living with transplants. In general, patients on dialysis have a lower life expectancy and lower quality of life than patients receiving a kidney transplant. Most transplanted kidneys come from deceased donors, and yet a large number of these available kidneys are discarded. Deceased donor kidneys have several challenges: higher rates of delayed graft function (DGF) post-transplant, longer warm ischemic time during kidney recovery, higher degree of cold induced injury, and lower long term graft survival rates.
In collecting tissue for transplantation, supporting tissues that feed necessary life support to the tissue as well as providing necessary connective tissue during transplantation are cut in a manner that leaves intact as much of the supportive tissue as possible. During storage and transplantation, support means are often connected, removed and reconnected to the supportive tissue to facilitate feeding life supportive nutrients to the tissue to be transplanted. During such connection, removal and reconnection, often incremental portions of the supportive tissues are cut or altered thereby reducing the supportive tissue available for later attachment during transplantation.
Cold storage of tissue for transport, while logistically effective, can injure the tissue, and assessing tissue health, particularly when the tissue is cold and not metabolically active, can be a challenge. The result of the cold storage cycle (warm-cold-warm) can cause a chain reaction of oxygen deficiency that can result in ischemic injury. The initial effects of such injury can include delayed graft function, and there can be a long-term effect on kidney function.
Current methods of tissue screening can be flawed and may not provide direct measures of tissue health. When a tissue is considered possibly marginal, the tissue screening system is biased towards discard. As a result, a large fraction of donated tissue (21% or 5,051 kidneys in the United States in 2020 alone) is discarded each year. Studies have found that a sizable fraction of these discards could have been transplanted with resulting favorable outcomes for the patients. A thorough quantitative ex vivo assessment of the tissue is critical for reducing discard rate. Ex vivo tissue assessment can remove dependency upon donor scoring, and provide a real-time measurement of tissue heath, which can ease the mind of risk-averse doctors. Other future options can include immunomodulatory drugs that can make donor matching matter less, gene therapy to treat tissue in vivo, tissue engineering, and tissue transplantation.
Still further options include normothermic/subnormothermic perfusion which is likely to extend preservation time, enable real-time tissue diagnostics, and significantly reduce cold-induced injury. Extended preservation time increases the likelihood of finding a recipient for the tissue. Preservation techniques such as ex vivo normothermic machine perfusion (NMP) can be used to assess the quality of the tissue before transplantation before committing the recipient to surgery. Normothermic or subnormothermic perfusion results in a metabolically active tissue, which can enable assessment via direct measures of kidney function and through enabling laboratory analysis of tissue, perfusate and urine samples.
What is needed is a system that provide a releasable interface with a tissue, that allows the necessary nutrients to flow to the tissue to maintain its vitality before transplantation, while preserving supportive tissues in a manner that allows interfacing with the tissue of the recipient during transplantation. What is needed is a system that can allow medical personnel to observe, sample, or otherwise collect data on metabolically active tissue, to help assess tissue health and viability. Such a system could sense a sufficient range of characteristics, including but not limited to glucose and pH. A successful tissue maintenance and assessment system can provide medical personnel with quantitative measures of tissue health, enable reconditioning of the tissue to optimize its performance prior to implant, and enable ex vivo treatment of the tissue, for example, but not limited to, pharmacologic and gene therapy. What is further needed is a system that achieves low hemolysis and maintains desired characteristics of the tissue. What is needed is a normothermic/subnormothermic tissue perfusion device with onboard sensors to simulate body circulation and monitor the tissue, respectively.
In accordance with some configurations, the present teachings include a system and method for tissue perfusion in order to maintain and possibly rehabilitate the tissue. Among other features, the system of the present teachings can include a tissue enclosure having a fluid reservoir. Pumps, valves, and a controller can move perfusate through the tissue. The system can include features to assist in monitoring the health of the tissue, and a removable tray to facilitate moving the tissue from a point of origin to the tissue enclosure. The system of the present teachings is fully configured to perfuse and provide nutrition for transplant tissue such as, but not limited to, human tissue. Other features of the system of the present teachings include, but are not limited to, a urine flow rate sensor, a nutrition pump, disposable and durable parts, and non-invasive sensors.
The system of the present teachings can include at least one controller or processor that can enable valves and pumps to perfuse fluids through tissue, for example, but not limited to, a human tissue. The at least one controller/processor can be, for example, but not limited to, a general purpose processor managing several tasks, a custom processor configured to manage a specific task, a proportional controller, and integral controller, a derivative controller, a programmable logic controller, a distributed control system, a programmable automated controller, a microcontroller, a microprocessor, an embedded processor, or supervisory control and data acquisition software. The controller/processor can receive data from sensors located throughout the system and other forms of data input, and can adjust, among other things, the pumps and valves according to the data. For example, the controller/processor can receive user input, recipe input, and/or default settings that can be used, along with values of the sensor data, to adjust the flow parameters of the perfusate. In some configurations, the controller/processor can access a default method of perfusion for a specific type of tissue. The default method can supply a standard set of instructions that have been found to normally elicit a desired result for the tissue. The default method can be changed dynamically when sensor data indicates that the standard instructions may not achieve the desired result. User input can also result in changes to the default method.
In addition to controlling perfusate flow, the controller/processor can issue instructions to pumps and valves that regulate the provision of infusion/nutrition to the tissue. In some configurations, infusion/nutrition can be pumped into the perfusate in a fluid reservoir that is in fluidic communication with the tissue. The contents of possible infusion/nutrition options can be pumped into the fluid reservoir when sensors indicate a need for perfusate modification. The system of the present teachings can include a pumping cassette that can deliver, under direction from the controller/processor, the infusion/nutrition at a possibly variable rate specific to a particular tissue, and specific to the current status of the tissue. The controller can perform processing associated with the specific sensor suite. In some configurations, the controller can automatically determine which sensors are available in a particular system and execute processes associated with the identified sensors.
The system of the present teachings can include a pump subsystem that can enable tissue perfusion and perfusate recirculation. The pump subsystem can pump perfusate, for example blood and other additives, through the tissue. The blood can include whole blood or a diluted/modified/altered blood composition, for example. In some configurations, the pump subsystem can enable perfusate flow at a rate of up to 600 ml/min at a mean arterial pressure of 20-120 mmHg. Flow can optionally be pulsatile, and the flow rate and rate of the pulse can be adjustable. As an example, a low arterial pressure and flow rate can be required for cold or damaged tissue. As tissue function improves, the arterial pressure and flow rate can be adjusted to accommodate the changed conditions. Pulsatile flow or a flow rate controlled by physiological parameters can both be accommodated by the pumps of the present teachings. In some configurations, direct acting pneumatic pumps can be used in tandem to supply a continuous flow of perfusate. Direct acting pneumatic pumps can include active inlet and outlet valves so that flow in a perfusate flow circuit can be highly controlled. Kidneys, for example, can tolerate a flow rate of 200-600 mL/min flow rate. One goal of pump choice is to reduce hemolysis. Direct acting pneumatic pumps can enable minimal hemolysis and flow metering for wetted materials as discussed herein. It can be possible to modify the pumping cycle of direct acting pneumatic pumps to match physiological pulsatile pressure duty cycles.
In some configurations, a variable pressure scheme for the negative (gauge) pneumatic pressure is used when filling pumping chambers of a pumping cassette by means of suction. The overall objective is to minimize the amount of suction pressure required, since it is well known that minimizing suction minimizes the shear if the on the blood cells in the perfusate to avoid hemolysis. To this end, the minimum necessary fill pressure is identified to ensure that the end of the fill stroke for one chamber aligns with the end of the deliver stroke of the other chamber (plus a bit of buffer time). The process includes, but is not limited to, the following steps. (1) While filling the chamber, the pressure in the chamber itself and the pressure in the regulated negative tank (the negative pressure source) are monitored. The time when these pressures equalize (to within +/−5 mmHg) is noted. This equalization occurs when the chamber membrane stops moving, hence it indicates the actual end of the fill stroke. (2) The time when the chamber is disconnected from the regulated negative tank is noted. This is based on a time offset from the start of the fill stroke, and is the scheduled end of the stroke. (3) When preparing for the next stroke, the time difference between these two times is calculated. (4) If the actual end of the fill stroke occurs before the scheduled end of the fill stroke by a pre-selected amount of time, for example, but not limited to, >200 ms, the suction pressure was higher than necessary. In this case, the suction pressure is reduced by, for example, but not limited to, 1 mmHg, down to a minimum of −40 mmHg gauge pressure. (5) If the actual end of the fill stroke occurs too near in time to the scheduled end of the fill stroke, for example, but not limited to, <50 ms, or did not occur at all, the relative pressure difference was not high enough to fully fill the chamber. In this case, the suction pressure is increased by, for example, but not limited to, lmmHg, up to a maximum of −140 mmHg. (6) When preparing for the next stroke, if the fill and deliver timing was reduced (that is, if the time from the start of the fill stroke to the scheduled end of the fill stroke was reduced), then the suction pressure is increased pre-emptively to ensure the next fill stroke completes in time. For example, if the fill time is reduced by >50 ms, then the fill pressure is increased by 5 mmHg (up to a maximum of −140 mmHg). (7) In order to ensure the two pumping chambers remain in sync, the checks in the steps of this process are conducted on one of the two chambers to prevent timing mismatches or pressure oscillations. In an aspect, a visual sensor is used to detect the location of the stroke. Because blood has an IR response, or a visual response, a visual sensor detects the thickness of blood in front of the membrane to determine where the membrane is on the stroke.
In some configurations, the pump is direct acting, where compressed air (or vacuum) is used to push/pull a membrane against fluid. A set of valves controls movement of a membrane associated with one or more pumping chambers. In some configurations, there are two pumping chambers. At the start of each stroke, one fills and one delivers. A new stroke is not completed until the sequence is complete. Partial strokes are possible to, for example, mitigate hemolysis. In some configurations, a sensor including but not limited to visual, infrared, or ultrasonic may be used to identify the position of the membrane within the chambers to control delivery volumes and ensure short strokes. The pumps control the nominal pressure in the pumping chamber by throttling the supply valves. In pump pressure control mode, the fill/deliver nominal pumping chamber pressure can be adjusted. Higher relative pressures (or vacuum) will result in faster filling or delivery times. The pump can provide smooth/consistent flow, or may provide pulsatile flow. In some configurations, the system can include multiple controllers, for example a valve controller, a pumping chamber controller, and a pump controller.
The role of the perfusion loop is to replicate basic biological functions that would otherwise take place in the body. These include oxygenation, control of carbon dioxide, thermal control, and nutrient supply. Oxygenation and carbon dioxide control are conducted through the use of a membrane oxygenator. A heat exchanger is used to maintain desired perfusate temperature. The perfusion fluid leaves the tissue, is passed through an oxygenator, is passed through a heat exchanger, and is then pumped back into the tissue. Nutrients are suppled in the perfusion solution and can be added manually or through the use of automated infusion pumps. Output generated by the tissue flows out of the tissue and is available for sampling through sterile sample ports. Output can be directed back into the perfusion loop or discarded. Output flow rates and volumes are measured and stored by the system. In the event that recirculating output proves to be a challenge, the system can be modified such that the output is collected or potentially passed through a dialysis loop.
The perfusion loop acts like a maintenance loop for the system allowing for filling or draining of the fluid reservoir and recirculation of the fluid from the fluid reservoir, essentially stirring the fluid reservoir. This loop can include the infusion pumps so that infusions can be delivered, diluted, and mixed into the perfusate instead of being passed directly into the tissue. Some or all of the infusion pumps can be made part of the perfusion loop. In some configurations, the system includes a bypass valve that can be opened during priming when bubbles are detected. To introduce new perfusate components or drain the system, the system includes at least one valve associated with the infusion path. In some configurations, a pinch valve can be associated with incoming perfusate, while another pinch valve can be associated with a drain path. In an aspect, pneumatic valves can be used. Other types of valves are contemplated by the present teachings. The perfusate pump can also drain the tissue enclosure.
The system includes means for monitoring, for example, the tissue, the perfusate, and the tissue's output. The data collected during monitoring can be used to adjust, for example, the environment of the tissue and the characteristics of the perfusate. Any types and numbers of sensors can be used for monitoring, and the controller can be programmed to automatically or manually respond to a detected situation. In some configurations, the concentrations of nutrition provided, the dissolved oxygen and carbon dioxide in the perfusate, the hemoglobin oxygen saturation level, the perfusion pumping rate, the glucose and lactate concentration in the perfusate, the temperature, and/or the pH are monitored through a group of sensors strategically positioned in the perfusion loop. The system includes sensors both in and out of the fluid path to enable adequate perfusion and collect data for tissue assessment, sterile sample ports for removing output and perfusate fluids using a sterile syringe. In an aspect, the system includes pressure sensors on tubing exiting the pump and exiting the heat exchanger. In an aspect, the membrane between the heat exchanger channels and the thermal control plate includes a pressure sensor. In an aspect, the system includes a flow sensor and/or a drip sensor to measure output that is collected from the cannulated tissue. The system can optionally include a first of at least one oxygen saturation sensor monitoring oxygen saturation of the perfusate before the perfusate enters the tissue, and a second of the at least one oxygen saturation sensor monitoring the oxygen saturation of the perfusate leaving the perfusate reservoir. The system can optionally include a first of at least one dissolved oxygen sensor monitoring dissolved oxygen in the perfusate leaving the perfusate reservoir, and a second of at least one dissolved oxygen sensor monitoring dissolved oxygen in the perfusate before the perfusate enters the tissue.
The system can optionally include at least one pH sensor monitoring pH of the perfusate leavinh the fluid reservoir, and at least one means to measure oxygen levels. One possible means is to use a dissolved oxygen sensor to monitor dissolved oxygen of the perfusate in the fluid reservoir, and a second of at least one dissolved oxygen sensor monitoring dissolved oxygen of the perfusate before the perfusate enters the tissue. Another possible means is to measure hemoglobin saturation if there are red blood cells in the perfusate, or if oxygen is above 100% saturation during perfusion and need to measure the dissolved oxygen in order to calculate the total oxygen level. The system can optionally include a first of at least one pressure sensor monitoring pressure of the perfusate before the perfusate enters the gas management subsystem, and a second of the at least one pressure sensor monitoring the pressure of the perfusate before the perfusate enters the tissue. The system can optionally include a glucose sensor and a lactate sensor to monitor glucose and lactate. In an aspect, characteristics of the circulating perfusate are determined by sensors embedded in the fluid pathway. In some configurations, dissolved oxygen, pH, temperature, and oxygen saturation are measured, among other characteristics, as the perfusate circulates. The sensors, which can include low-cost, single-use spot sensors, can be chosen based on the tissue being perfused.
The tissue enclosure provides a barrier to contamination for the tissue as it is being maintained. In an aspect, the tissue enclosure includes three main parts—a fluid reservoir, a tissue platform, and a hood, all operably coupled to form an isolation environment for the tissue. The geometry of the tissue enclosure includes connectors to receive the tissue platform, connectors and seals to receive the hood, a reservoir to house the fluid, an air space above the fluid in which the tissue platform is placed, and a fluid ramp receiving at least some of the tissue output and channeling the output towards the fluid reservoir. A temperature control mechanism is positioned in the vicinity of the tissue enclosure. In an exemplary configuration, the temperature control mechanism is positioned beneath the tissue enclosure, and is fluidically coupled with the tissue enclosure.
In some configurations, the tissue enclosure is a disposable component that is configured to be securely connected and disconnected from a set of durable components described herein. In an aspect, one possible secure means to connect the tissue enclosure to the durable components is the interaction between features on the tissue enclosure that operably couple with a durable hinged component. In an aspect, the operable coupling includes pins that travel through a groove in the hinged component and rotate at least one cam. The at least one cam, when rotated, exerts pressure upon the tissue enclosure feature(s) to drive the tissue enclosure, heat exchanger side, in secure contact with the thermal control plate. The tissue enclosure coupling/decoupling means is augmented by a locking mechanism described herein that couples the disposable components of the perfusion pumping assembly with the durable interface to the pneumatic assembly.
In an aspect, the fluid reservoir receives, for example, but not limited to, output products from the tissue, venous output from the tissue, and possibly nutrition and medications. The types and amounts of components in the fluid are not limited to such additives as are listed herein, but instead include components that are appropriate for the type of tissue being maintained. The fluid reservoir sits below the tissue platform, and thus, the tissue resides in the air space above the fluid reservoir. Perfusate is pumped from the fluid reservoir and its characteristics and temperature are adjusted and monitored before it is pumped into the tissue.
The tissue platform includes a means for stable connection between the platform and the tissue enclosure. In an aspect, connections have self-mating features, snap-together features such as an annular snap lock, a torsional snap lock, and a cantilever snap lock, latched features, hooked features, mating detents, interlocking features, press-fit, interference-fit and bolting. In an aspect, connections serve multiple purposes, if necessary, possibly providing electrical and/or data interface through plugs or jacks. In an exemplary configuration, the tissue platform includes female position alignment features. The tissue platform also includes at least one handle for retracting the platform from the tissue enclosure. The at least one handle can include an unfeatured pull handle, a pull handle with ergonomic features such as grips, a recessed folding pull handle, an offset pull handle, a utility handle, recessed handle, edge pull, and extending handles. In an exemplary configuration, the at least one handle includes a fixed pull handle with ergonomic features. The at least one handle can be affixed to the tissue platform or can be attached to the tissue platform before retraction or placement of the tissue platform. Multiple handles can be affixed to the sides of the tissue platform or to the center or within the body of the tissue platform.
The tissue platform can optionally be partitioned into areas of the platform floor. One area can be configured to receive the tissue. The tissue itself can be positioned on the platform floor on which it can be cannulated or otherwise operably coupled with perfusion tubes. In some configurations, the tissue is secured to the platform by, for example, a strap, tie-down, belt, or cord anchored in depressions on the rim of the tissue platform. Part of the floor can be configured to manage the tubing or possibly cabling. Tube management can include, but is not limited to including, weld mount clamps, rail clamps, magnetic clamps, snap-in clamps, multiline clamps, connectable clamps, expansion clamps, adhesive-back clamps, lock-close strut-mount clamps, standoff clamps, low profile clamps, and loop clamps. In an exemplary configuration, tubes and cables are routed through merlons positioned on the floor of the tissue platform, spaced according to, for example, the expected sizes of tubes and cables. Other tube and cable mount points enable the tubes and cables to be raised above the floor of the platform. In an exemplary configuration, one or more standoff features is configured with tube holders such as bent finger-like projections. In an exemplary configuration, the tubing and cables are routed along the sides of the tissue platform between crenellated edges to enable tube/cable routing between the tissue platform and other parts of the tissue maintenance system. The crenellations can be spaced according to a desired or expected tube/cable size. Multiple tubes/cables can be accommodated by the spaces between the crenellations, if desired. The tubing or cabling is routed to exit the tissue platform by, for example, but not limited to, ductwork, routing tubing, routing panels, or channeling. The tubing is coupled with connectors that enable connection to further tubing in the tissue enclosure. The on-board coupling between the tissue and the perfusion tubes or other required system connections makes it possible to ready the tissue for management by the system remotely from the tissue enclosure and convenient to the location of the tissue. This can reduce the amount of manual manipulation the tissue has to endure.
In an aspect, the floor of the platform is configured to receive fluid such as output products and venous fluids from the tissue. The floor can include a drainage means so that the tissue fluids can exit the platform floor without stagnating around the tissue. In an exemplary configuration, the floor is sloped towards a drain cavity in the floor. The drain cavity allows the tissue fluid to flow from the tissue to the fluid reservoir below the platform. In an aspect, the tissue enclosure is configured to channel the fluid from the platform so that it enters the tissue reservoir in a controlled way. In an exemplary configuration, the tissue enclosure includes a ramp that ensures that the fluid enters the fluid reservoir at an angle.
Other platform configurations are contemplated by the present teachings. The platform, detachable from the fluid reservoir, can be the only part of the system that could be specific for a tissue type, although platforms are contemplated to be used for multiple tissue types. The platform described herein, used for a kidney, illustrates the features of a particular platform. The present disclosure is not limited to accommodating a kidney platform, nor to the geometry of the kidney platform.
In an aspect, the tissue enclosure includes a hood that includes a durable/disposable barrier and houses at least one sensor. The barrier and gasket fitted to the tissue enclosure protect the tissue on the tissue platform from external environmental conditions. The barrier enables manual and automatic observation of the tissue on the tissue platform, and is securely attached at the rim of the tissue enclosure to fully shelter the tissue while still providing viewing options. Observation can include providing images of the tissue, which can aid a user in assessment of the tissue. For example, the tissue can be measured, the color of the tissue can be observed to detect, for example, insufficient perfusion free hemoglobin or bacterial infection, and the size/shape over time of the tissue can be determined to detect, for example, if the tissue is undergoing edema. If the tissue performs a particular physiological function, the user and/or the controller can observe the function of the tissue over time.
In an aspect, the barrier is associated with an anti-fog means to reduce condensation, aiding in tissue visibility through a window in the barrier. The window can occupy the entire barrier, or simply a portion of the barrier. In an exemplary configuration, the anti-fog means includes a heating wire mounted adjacent to the barrier, or threaded throughout the barrier material. Typically, fogging occurs in cooler environments, possibly making insulation of the tissue enclosure and thermal control features necessary to, among other reasons, enable observation of the tissue. Anti-fog materials such as polypropylene can bead moisture build-up. Anti-fog coatings on, for example, glass and plastic surfaces, can be used as well, including, but not limited to, polyvinyl alcohol molecules, surfactants such as detergents, and hydrophilic coatings such as polymers and hydrogels. The cleared window enables the use of standardized imaging, optical measurements, and advanced images such as thermal imaging, IR imaging, and hyperspectral imaging. Through the cleared window, the user can observe the appearance of the tissue without breaking the sterile barrier. Thermal management of the walls of the tissue enclosure has an additional benefit of encouraging moisture retention on the exterior of the tissue itself, preventing the tissue from drying out, and eliminating the need for additional moisture controls such as placing wet gauze on the tissue. Additionally, the effect of thermal management on moisture reduces hemolysis by preventing gradients through removal of pure water, and reintroducing pure water when condensation drops drip back into the perfusate.
Manual observation can include viewing the tissue through the transparent barrier. In some configurations, the barrier may be opaque and manual observation may not be possible. The hood can house sensors that can enable assisted and automatic observation. The sensors can include, but are not limited to including, image sensors such as CCDs, optical sensors, X-ray devices, and ultrasonic devices, among others. In an exemplary configuration, the hood houses a camera mounting device and a camera. Data collected by the sensors can be provided to a controller, and/or a local display, and/or a handheld/wireless device, for example. Data can be stored and tracked, and automatic analysis can be conducted on, for example, the image data collected to automatically determine the status of the tissue over time. In an aspect, the image sensors are mounted either outside or inside of the barrier, while other types of sensors whose data can provide context to the image data are mounted within the hood. Such sensors can include non-contact or contact sensors, and can measure, but are not limited to measuring, temperature, pressure, pH, oxygen, carbon dioxide, and glucose data. The sensor data can be collected wirelessly or by wired connections between the sensors and the controller. In an aspect, the sensors include a camera with associated lighting. In an aspect, the camera can be disposable. The sensor data provide tissue appearance data in real-time. The user can use these data to inspect the tissue for key areas of concern such as, for example, but not limited to, color, edema, hypoxia, bleeding, and leaking. In an aspect, the sensor data are logged and can be evaluated over time to assess changes. Sensor-detectable clues to edema include a size increase over time of the tissue. Sensor-detectable clues of poor perfusion include change of color of the tissue, and bleeding/leaking. Sensor-detectable clues of kidney failure, for example, include seizures. Sensor-detectable clues of a ureter issue, for example, include absence of ureter motion. The areas of concern are based upon the type of tissue and other factors.
The system of the present teachings pumps perfusate in a closed loop through the tissue. In an aspect, the system includes one or more fluid pumps to accomplish the perfusion. Types of perfusion pumps include, but are not limited to including, axial flow pumps, peristaltic pumps, diaphragm pumps, pumping cassettes, roller pumps, centrifugal pumps, pulsatile pumps, and non-occlusive roller pumps. A pump that can enable the perfusion of the system of the present teachings can deliver physiologic blood flows against high resistance without damaging blood, provides flows that are exact and easily monitored, creates no turbulence or stagnation, and can be manually operable in the event of a power failure. In some configurations, extracorporeal membrane oxygenation (ECMO)-type devices are used to perfuse and oxygenate the blood in the system. In some configurations, the oxygenator device uses silicone membrane contactors. The perfusate is pumped through several possible modification stations and past several sensors before entering the tissue. In an exemplary configuration, a pumping cassette, at the direction of the controller, can move perfusate from the fluid reservoir into an oxygenator. An exemplary cassette pump is described in U.S. Pat. No. 9,999,717, Systems and Methods for Detecting Vascular Access Disconnection, issued Jun. 19, 2018.
In an aspect, the pumping cassette, having a first side including number of valve wells and second side having a fluid bus, is used. In an aspect, each side is covered by a flexible membrane, and a control surface having a number of valve well control stations actuatable with respect to the flexible membrane covering the first side of the cassette to open and close the valve wells when the cassette is mated against the control surface is included. In an aspect, the pumping cassette includes two chambers. Use of the chambers can alternate in order to produce continuous flow, or can be timed so as to produce a pulsatile flow. A pressure distribution assembly having a positive and negative pressure source and a number of pneumatic valves may be included. The controller is configured to selectively actuate the number of pneumatic valves to apply pressure against the valve well control stations in a valve pumping sequence until a volume is displaced through the fluid bus of the pumping cassette from a source to a destination within a range of a target volume. The flow rate and pressure of the perfusion pump as it pumps perfusate through the system are regulated so that flow rate and pressure of the perfusate going into the tissue are regulated. The resistance of the tissue may change over time, for example, with changes to physiology. The pressure of the pumped perfusate may need to change over time to accommodate the tissue's needs. Over-pressuring the fluid line can cause lysing.
Mechanical means of cell damage can be caused by, for example, mechanical trauma, extremes of temperature, sudden changes in pressure, radiation, and electricity. A possible form of mechanical trauma can be caused indirectly by a perfusate pump. To avoid this form of mechanical trauma, the system of the present teachings includes a flow sensor to measure flow rate and at least one pressure sensor to measure perfusate pressure. The flow rate and pressure of perfusate that is pumped through the system is adjusted to a desired amount. Pressure management in the system of the present teachings includes establishing a desired pressure and applying that pressure on the pneumatic side of the pumping cassette. The flow rate, as determined by a flow meter in the perfusion path is integrated over time to determine the volume of fluid perfused over an amount of time. Because the volume of the pumping chamber on the fluid side of the pumping cassette is known, and the volume of fluid over a pre-selected amount of time is known, when the volume of fluid in the pumping chamber reaches a pre-selected level, the controller switches chambers. This form of control can, for example, avoid mechanical trauma, and therefore limit hemolysis, to cells in the perfusate because the perfusate in not pressed against the bottom of the pumping chamber by the membrane. For example, when the chamber is 95% full, the controller can switch pumping chambers. The pressure that is required to reach the desired fluid pressure at the inlet to the tissue is the desired pneumatic pressure. The desired pneumatic pressure can, at least in part, control the mechanical means of cell damage explicitly to ensure that cell damage in the perfusate is limited to a desired level. In an aspect, a flow meter monitors an instantaneous flow rate and integrates the volume. As the control loop runs, the pump ensures that the membrane for the direct-acting pump does not lyse red blood cells.
The flow meter is used to adjust the pressure on tissue as the thermal profile of the tissue changes. For example, when the tissue warms, its blood vessel expand reducing fluidic resistance and the allowable perfusate flow though the tissue at a given pressure generally increases. In an aspect, the surface temperature of the tissue is used to adjust the pumping pressure of the perfusate. The resistance of the tissue to perfusion is a function of the pressure and the volume of liquid being perfused over a pre-selected amount of time. Renal resistance is defined as the pressure divided by the flow rate. If the flow is laminar, the renal resistance will nominally scale like (L/D4) where L is an average vascular length through the kidney, and D is an average vasculature diameter in the kidney, which is a function of temperature and kidney health. Renal resistance is proportional to the ratio of the pressure on the perfusate to the flow volume. In an exemplary configuration, pressure is adjusted automatically based on surface temperature of the tissue or calculated resistance.
The tissue receives perfusate into a cannulated orifice of the tissue, and produces output through another cannulated orifice of the tissue. For example, if the tissue is a kidney, at least one of the outputs is urine. At least one output from the tissue is routed from the tissue for monitoring of the output before the output is routed back into the fluid reservoir or is routed to a waste area. To enable monitoring of the output, the system includes an output flow device that includes a collector container and sensors and a means for managing the collection device accumulation. The container can take any shape and can, for example, include graduated fill marks. Convenience of mounting the container with respect to the platform and output measurement criteria can be considered when choosing a container shape and size. The container includes at least one sensor that indicates, to a controller, the level of the output in the container. In some configurations, the container is coupled with a plurality of sensors, at least one at a desired output high level, at least another at a desired output low level. When the output reaches the high level sensor, the controller directs the valve to open to release the output. When the output reaches the low level sensor, the controller directs the valve to close, thereby retaining the fluid in the container again. In an exemplary configuration, the level sensor includes an ultrasonic sensor. In an aspect, the level sensor includes at least one visual sensor that determines the level of the fluid by locating floats within the fluid. The present teachings contemplate multiple high and low levels to enable various types of measurements. The valve includes, but is not limited to including, being selected from ball, butterfly, check, gate, knife gate, globe, needle, pinch, and plug valves. In an exemplary configuration, the valve is a pinch valve. In an aspect, the valve is a pneumatic valve. In some configurations, the output flow container is configured so that visual inspection of the output is possible. For example, the output passes through a transparent or partially transparent container. The container can be fully opaque except for a window, or can be substantially transparent, or some layout in between.
Other methods to evaluate the tissue output over time are contemplated by the present teachings. Monitoring of the output can occur manually, automatically, in real-time, and through post processing. Types of sensors can include, but are not limited to including, visual, e.g. cameras, IR, X-ray, temperature, pressure, chemical, ultrasonic, humidity, color, and light. Real-time manual monitoring can be enabled by a transparent collector into which the output can flow and collect. In an exemplary configuration, the transparent collector includes graduated marks associated with a desired granularity of collection amounts. In an aspect, the collector is opaque to electromagnetic radiation to protect the output from degradation due to exposure. If the collector is opaque, sensors in addition to the fill sensor are mounted inside and outside the collector to enable manual and automatic monitoring. The sensor data can include an amount of output, characteristics of the output, and elapsed output collection time, for example. The sensor data can be wirelessly or wired transmitted to the controller, a display, or a portable device that can be manually monitored. The controller receives data associated with the output and performs real-time automatic monitoring that can include analysis of the sensor data collected while the output is collected and flowing. The controller can change at least some of the characteristics of the system based on the analysis, if necessary. The controller can control off-line automatic monitoring by collecting a sample, subjecting it to tests, possibly lengthier in duration than the real-time tests, and logging the data or using the information to manage the controllable characteristics of the system. In an exemplary configuration, the tissue is a kidney, and the output is urine output. Urine output from the kidney can be measured and compared to expected amounts to evaluate the kidney's function. Urine output color can be observed/measured, and urine can be tested for, for example, acidity, concentration of particles, protein, sugar, ketones, bilirubin, evidence of infection, and blood. Possible sensors include optical sensors to measure the color of the urine. For example, free hemoglobin in the urine, blood, or osmolality in the urine can be detected optically. Some of these tests can be performed in real-time and the amount of nutrition can be modified, or the amount of carbon dioxide can be adjusted to move the kidney to a healthy state, for example. Some of the tests can be performed through post-processing, and the results can possibly be used to manage the perfusion of the kidney. In an aspect, the output container is transparent and includes a reservoir that allows the user to visually monitor the flow rate, color, and opacity of the output in real time. A sample of the output can be removed and tested offline, and/or the output can be returned to the perfusate reservoir.
In some configurations, the output flow device is configured with a sample means. The output can be sampled as it enters or exits the container. Samples can be examined in real-time, or off-line. The output can be directed, by tubes and valves, to a sample vessel, back into the perfusate reservoir below the tissue platform, or elsewhere. The controller directs routing valve(s) to open and close depending in the desired destination of the output, or, for example, on the amount of output to sample, among other options. In some configurations, a single 3-way valve is used to receive the output, send the output to a sample vessel, or send the output into the perfusate reservoir below the platform. In some configurations, the output can be driven passively by a combination of the force of the tissue to move the output from the tissue into the output flow device, and by the force of gravity moving the output from the container for further processing. For gravity to play a role, the output container is positioned above the perfusate reservoir below the tissue platform.
In some configurations, the output is pumped from the tissue or output reservoir into the flow meter, and is pumped from the container to be sampled or to rejoin other tissue perfusates, for example. Off-line manual monitoring can be enabled by routing some of the output to a sample collector. The output flow device container output tubing can be bifurcated. One branch of the bifurcated tubing can travel through a valve controlled by the controller and back into the perfusate reservoir. Another branch can travel to a sample vessel. The controller manages which branch is taken by controlling a valve at the bifurcation. The sample can be visually inspected, for example, or can be subjected to chemical and/or biological analyses that can be manually reviewed. In an exemplary kidney process, a sample of urine is collected and disposed of at the beginning of perfusion to remove urine that contains, for example, inflammatory markers. In an aspect, the first 50 mL or whatever is collected over 1.5 hours of collection is discarded. Monitoring can lead to changes. For example, if the user observes that output is not an expected color or quantity, the user can make manual changes to the currently-executing perfusion path, or can direct the system to make a series of changes automatically. For example, if the urine is observed to be red, there is either blood or free hemoglobin in the urine. The system can automatically stop recirculating urine and start infusing amendments to the kidney such as nutrition and medication. If cloudy urine is detected, the system can automatically raise an alarm to alert the user as this observation might indicate a bacterial infection. In the system of the present teachings, observation of output color is enabled by a transparent output container, and observation of output quantity is enabled by the output measurement system of the present teachings. Likewise, if a user observes that the characteristics of the perfusate are insufficient for adequate tissue preservation, the user can override default instructions and take actions to modify the characteristics. In some configurations, the user can initiate the perfusion process and manually control the entire process. In some configurations, the user begins manual control after the system has performed a certain number of steps. In some configurations, automatic operations are so sophisticated that user input may not be needed at all, or possibly not until the end of the perfusion cycle, as possibly judged from the characteristics of the tissue, or the amount time that has elapsed, for example. Indicative kidney characteristics can be, for example, determined from inspection of concentrations of creatinine clearance, fractional excretion of creatinine, and fractional sodium excretion present in the urine. Pool et al., Prolonged ex-vivo normothermic kidney perfusion: The impact of perfusate composition, PLoS ONE 16(5): e0251595, https://doi.org/10.1371/journal.pone.0251595, May 18, 2021, p. 4 (Pool).
The system of the present teachings provides nutrition and medications, for example, to the tissue when required. The controller controls a device that accesses various infusion materials, depending on the needs of the tissue. Nutrients and medications can include, but are not limited to including, water, lipids, amino acids, glucose, vitamins, hormones, antibiotics, chemotherapy drugs, vasodilators, vasoconstrictors, diuretics, antidiuretics, anticoagulants, and insulin. In an aspect, a kidney's characteristics are controlled by regulating infused substances, monitoring the results of the infusions on the characteristics of the kidney, and then adjusting the infusion rate based on the results. Nutrients are provided by infusion pumps, devices that deliver nutrients and medications in controlled amounts. The pump is configured, either automatically or manually, to provide specific nutrients at a specific flow rate. Automatic infusion configuration occurs when the system of the present teachings determines which kind of tissue is being processed and sets the nutrition and medication regime automatically. Manual infusion configuration occurs when the system accesses, or a user provides, set-up parameters such as the components of the nutrients and/or medications, the delivery rates, and times of delivery. In any case, the controller determines when there is a potential or actual pump failure, or when there is a potential or actual drug interaction problem, among other types of alerts. In an exemplary configuration, nutrition and medication are pumped into the fluid reservoir by a infusion pumps, the possibilities of which are described herein. In an exemplary configuration, a pumping cassette pumps the nutrition and medication to the tissue, either directly into the arterial line or into the reservoir. In an aspect, the pumping cassette is sized to accommodate the requirements of supplying nutrition/medication. For example, the pumping cassette includes a single chamber that pumps a pre-selected amount of fluid at a consistent rate, such as 10 ml/hour. In an aspect, sensors measure the consumption rate of the nutrients/medications, and those sensor data are used to control the infusion of those components. For example, a glucose sensor measures how much glucose is in the perfusate exiting the tissue, and that measurement is used to adjust the amount of infused glucose based on the metabolic rate of the tissue. The nutrition pump of the present teachings is configured to pump from an intravenous bag at rates of 1-20 mL/hour, removing the need for an IV pump. In an aspect, the nutrition pump is a sterile disposable device that is integratable with the pneumatics of the present teachings. In an aspect, the nutrition pump runs closed loop glucose control.
In some configurations, a low bolus, high accuracy infusion pump is used to enable clinical infusions such as prescription vasodilators or insulin. In some configurations, multiple infusion pumps are used to enable multiple different substances to be infused, possibly simultaneously. In some configurations, the pump reservoir is 3 mL, the pump accommodates an infusion rate of 0.5-300.0 μL/hr, an infusion volume of 0.5-250.0 μL, and infuses into the perfusate reservoir.
In some configurations, when the tissue is a kidney, the replenishment ingredients can include, for example, but are not limited to, a plurality of infusion solutions. The infusion solutions can include, but are not limited to including, an isotonic crystalloid/dextran solution, and a buffer solution. The isotonic crystalloid/dextran solution can include isotonic crystalloid with 0.026 g/mL dextran, a complex polysaccharide derived from the condensation of glucose. During replenishment, the system includes a means for maintaining a target glucose range of 100-150 mg/dL, and a basal flow of 10 mL every 15 minutes. These targets, if met, deliver 25 g of Dextran/day, and 960 mL of perfusate replenishment. The time between doses can be adjusted to achieve the target. Depending upon the sensed glucose reading, insulin can be added. The buffer solution is used to regulate the pH of the perfusate. Target pH can include the range of 6.9-7.9. In some configurations, the system includes a means for flushing the kidney with a high-flow, low-potassium preservation solution. In some configurations, the system includes a means for re-perfusing the kidney and monitoring the characteristics of the kidney to determine if the infusion is maintaining the viability of the kidney. Possible kidney nutrition can include, for example, but not limited to, albumin, saline, adenine, glucose, and mannitol, creatinine, MgSO4, calcium gluconate, insulin, and dexamethasone.
The system of the present teachings includes a means for thermal control of the perfusate, and for the tissue itself. In some configurations, maintaining the tissue at a desired temperature includes selecting a temperature regulation option that meets weight, power, and size requirements. Possible options can include, but are not limited to including, thermodynamic heat engine, phase change, and thermoelectric systems. In some configurations, the heat load is 10-20 W to maintain a 20° C. difference in temperature between the environment and the tissue, and smaller if the tissue is maintained at subnormothermic temperatures. For heat loads on the higher side of the 10-20 W range, a thermodynamic heat engine can be selected. For systems in which the size of a battery, if present, could be important, thermoelectric systems can be selected because they can be scaled. When the tissue enclosure is to be placed in closed environment, phase change material systems can be selected because they can store and release heat produced and consumed within the closed environment. Maintaining the tissue at a desired temperature can include selecting appropriate insulation. In some configurations, vacuum panels, aerogels, and/or closed-cell rigid insulation systems can be selected.
In some configurations, temperature of the perfusate is controlled through a heat exchanger. The heat exchanger can optionally include a source of thermal energy, a surface having at least one channel holding the perfusate, a membrane covering the surface and conducting thermal energy from the source through the membrane to the perfusate, and a thermal transfer plate between the membrane and the source. The at least one channel can include a serpentine flow path that rests upon a thermally-conductive and reflective membrane. In some configurations, the thermal transfer plate includes cartridge elements for active control of the temperature of the perfusate. The system includes temperature sensors that sense the temperature of the perfusate as it enters and exits a serpentine fluid path. Active control of the temperature can maintain the temperature needed for tissue perfusion, for example, in the 3°−42° C. range. The number and size of the cartridge elements is based at least on the characteristics needed to maintain uniform distribution across the serpentine path. The size of the thermal control plate is dictated by, for example, but not limited to, the number and size of the cartridges and the capacity and geometry of the tissue reservoir. The width of the serpentine channels is based on the need to maintain adequate surface area inside the channels, to avoid stagnation, to avoid substantial pressure loss, and to maintain uniform heat transfer. The geometry of the serpentine channels can be important to prevent stagnation and to prevent turbulence.
The system can optionally include a first of at least one thermal sensor monitoring a perfusate temperature before the perfusate enters the thermal management subsystem, a second of the at least one thermal sensor monitoring the perfusate temperature of the perfusate after the perfusate exits the thermal management subsystem, and a third of the at least one thermal sensor monitoring the perfusate temperature of the perfusate in the fluid reservoir.
The heat exchanger can optionally include a plate having a first side etched with a fluid path and a second opposing side, the second opposing side positioned against the tissue reservoir, and a thermally-conductive membrane having a first membrane side covering the first side, the thermally-conductive membrane having a second opposing membrane side positioned against the thermal energy source.
The system of the present teachings includes a gas management subsystem adjusting gas saturation in the perfusate. The gas management subsystem can optionally include at least one oxygenator supplying oxygen to the perfusate and managing carbon dioxide levels, and at least one gas supplying device providing at least one gas to the perfusate. The at least one gas can optionally include oxygen, nitrogen, and carbon dioxide. Before the perfusate enters the oxygenator from the perfusion pump, the pressure exerted by the perfusate exiting the pump is measured. The controller adjusts the perfusion pump pressure based on the measured pressure information and on the needs of the tissue. The oxygenator adjusts the gas levels in the perfusate as the pump moves the perfusate through the oxygenator. Based on, for example, measured pH, dissolved oxygen, and blood oxygen saturation level, the controller creates a mixture of gases that can adjust characteristics such as pH and dissolved oxygen in the perfusate. The controller interfaces with a mass flow controller, for example, to direct the gas mixture to flow through the oxygenator. In an exemplary configuration, air is removed from the perfusate by an in-line air trap in which air bubbles float to the top of the incoming perfusate, and fluid exits from the non-air section of the air trap.
The method of the present teachings can include, but is not limited to including, mounting the tissue on the tissue platform, positioning it for perfusion. The method can include coupling the tissue's orifices with pre-selected locations on the platform through tubing, connectors, and the like. For example, if the platform is configured for a kidney, the platform can include a connector and tubing to transport perfusate into the kidney and another connector and tubing to transport urine out of the kidney. The method can include directing the venous output into the perfusate reservoir. The vein can be cannulated and directed by tubing to the fluid reservoir, or can simply exit the kidney and pass through a cavity in the platform to the perfusate reservoir. In an exemplary configuration, the artery and the ureter can be cannulated, and the cannulation tubing can be fed through protrusions on the platform that can prevent movement of the tubing on its way to the platform orifices and connectors.
The method can include coupling the platform connectors to the perfusion system and securing the platform into place above perfusate in the perfusate reservoir. The perfusate tank can include space for perfusate below the platform. Into this fluid can flow the output from the tissue mounted on the platform. For example, if the tissue is a kidney, the output is venous perfusate and urine.
The method can include measuring the output from the tissue. The perfusate pumped into the tissue artery can pass through the tissue and exit, at least in part, through the tissue vein and can flow into the perfusate reservoir. The method can include recirculating perfusate from the perfusate reservoir back into the tissue artery. The perfusate can include, but is not limited to including, oxygen carriers such as, for example, but not limited to, perfluorocarbons, hemoglobin-based perfusates, and sea worm hemoglobin-based perfusates. Hemoglobin-based oxygen carriers can include infusible oxygen-carrying perfusates prepared from purified human or animal hemoglobin. The perfusate can include a combination of electrolytes, carbohydrates, vitamins, proteins, prescription drugs, and pH buffer. The method can include monitoring and regulating the temperature of the perfusate prior to pumping the perfusate into the tissue. In some configurations, the temperature can be regulated to room temperature. In some configurations, the temperature can be regulated to body temperature. In some configurations, the temperature can be regulated to a range of 3-42° C. Normal tissue handling procedures in the system and through the method of the present teachings protect the tissue from extreme temperatures over an extended period of time. When maintaining the tissue at a hypothermic level, the target temperature includes the range of 3-10° C. When maintaining the tissue at a sub-normothermic level, the target temperature includes the range of 18.5-25.5° C. When maintaining the tissue at a normothermic level, the target temperature includes the range of 32-42° C.
The method can include pumping air into an oxygen concentration device to supply oxygen to the perfusate. Mass flow controllers (MFCs) establish stable gas flow by controlling mass flow and pressure for pneumatic pump control, and for supplying a gas mixture to the perfusate. In an aspect, oxygen is controlled to maintain a desired hemoglobin oxygen saturation or partial pressure of oxygen. In an aspect, carbon dioxide is controlled to maintain a desired partial pressure of carbon dioxide or pH. In an aspect, nitrogen is controlled to balance. In an aspect, target ranges for dissolved oxygen include 74-160 mmHg arterial and 30-40 mmHg venous. In an aspect, target ranges for dissolved oxygen include 74-500 mmHg arterial and 30-500 mmHg venous. In an aspect, the system can help rehabilitate tissue operation as needed, with levels up to 760 mmHg. In an aspect, the target ranges for both arterial and venous dissolved oxygen include 300-500 mmHg in the case of no additional oxygen available, or to ensure extra oxygen is available.
The target range of dissolved carbon dioxide includes 35-45 mmHg. The method can include replenishing of fluids, electrolytes, nutrients, and other biological compounds necessary to maintain tissue health. In some configurations, an infusion pump is used to provide the replenishment of fluids into perfusate reservoir at a flow rate of 1-20 mL/min. In an aspect, urine is collected from the kidney, the urine's conductivity is monitored, the conductivity is correlated to electrolyte composition, and makeup fluid is delivered via two nutrition pumps. In an aspect, various electrolytes in the urine are measured, each requiring specific adjustments. The method can include monitoring the vitality of the tissue through monitoring the status of, for example, but not limited to, tissue resistance changes (pressure/flow), oxygen consumption, and pH. Monitoring of tissue characteristics provides an indication of the health of the tissue.
The system of the present teachings includes a combination of disposable and durable materials. For example, the oxygenation means is disposable, along with the heat exchanger, while the thermal energy source is durable. The at least one perfusion pump is disposable, while the at least one pump interface coupling the at least one disposable pump with the pneumatics is durable. The at least one infusion pump is disposable. The pneumatics can optionally include at least one durable valve, at least one durable chamber, at least one durable pressure source, and at least one durable vacuum source. Durable components can include at least one sensor providing sensor data monitoring the tissue, and at least one controller receiving and processing the sensor data. Disposable components can include spot sensors, tubing, cassette pumps, tissue containers, and the oxygenator.
The foregoing features of the disclosure will be more readily understood by reference to the following description, taken with reference to the accompanying drawings, in which:
The system of the present teachings for maintaining, assessing, maturing, and rehabilitating tissue is described in detail herein. Specifically, the system and method of the present teachings is configured to allow for real-time assessment of the tissue, using that assessment to continuously maintain the health of the tissue. The system of the present teachings includes, but is not limited to including, a disposable set of components and a durable set of components. The disposable components include, but are not limited to including, a tissue container assembly holding the tissue and a reservoir of perfusate, a perfusion pump assembly pumping perfusate through the tissue, tubing connecting the tissue container assembly with the perfusion pump assembly, a tissue gas adjustment device maintaining a myriad of characteristics of the perfusate, and sensors providing data about the tissue necessary to maintain the tissue. Disposable components can also include at least one infusion pump assembly providing nutrition and medication to the tissue, and an output monitoring, measuring, and sampling assembly receiving output from the tissue, assessing the output in real-time and possibly off-line, and returning the output to the tissue container perfusate reservoir. The durable components include, but are not limited to including, a tank monitor assembly enabling protection of the tissue from environmental contamination as well as visual inspection and sensory recording of the tissue, a thermal adjustment assembly maintaining the temperature of the perfusate, a pneumatics assembly driving the perfusion pump assembly to circulate the perfusate, power, data, and control electronics energizing the components of the system and sequencing events in the system based at least on sensor data.
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Enclosure plates 30144, 30145, 30146, and 30148 form parts of surrounding shell 30169 as discussed herein, upon which accessories such as hooks 133 and USB hub mount/monitor mount 143 are mounted. Shell 30169 includes cavity 355 that admits disposable tissue container 30076 (
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Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications and variances. Additionally, while several example configurations of the present disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular configurations. In addition, those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. Other elements, steps, methods and techniques that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure.
The drawings are presented only to demonstrate certain examples of the disclosure. And, the drawings described are only illustrative and are non-limiting. In the drawings, for illustrative purposes, the size of some of the elements may be exaggerated and not drawn to a particular scale. Additionally, elements shown within the drawings that have the same numbers may be identical elements or may be similar elements, depending on the context.
Where the term “comprising” is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun, e.g. “a”, “an”, or “the”, this includes a plural of that noun unless something otherwise is specifically stated. Hence, the term “comprising” should not be interpreted as being restricted to the items listed thereafter; it does not exclude other elements or steps, and so the scope of the expression “a device comprising items A and B” should not be limited to devices consisting only of components A and B.
Furthermore, the terms “first”, “second”, “third,” and the like, whether used in the description or in the claims, are provided for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances (unless clearly disclosed otherwise) and that the example configurations of the disclosure described herein are capable of operation in other sequences and/or arrangements than are described or illustrated herein.
This application is a non-provisional of and claims priority to earlier filed U.S. Provisional Patent Application No. 63/269,505, filed Mar. 17, 2022 (AA706), the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63269505 | Mar 2022 | US |
