Acute kidney injury colon dialysis device based on intestinal perfusion dynamics

Abstract

The invention provides an acute kidney injury colon dialysis device based on intestinal perfusion dynamics. The device comprises a multi-cavity colon dialysis catheter, a dialysate treatment and supply unit, a waste liquid discharge unit, a monitoring sensing unit and a perfusion dynamics control unit. The dialysis catheter infuses dialysate in different colon sections in a partitioned mode through the first infusion cavity and the second infusion cavity, and the dialysate is recycled at the anal proximal end in a centralized mode through the drainage cavity. The monitoring sensing unit is used for acquiring colon pressure, dialysate conductivity and flow signals; the perfusion dynamics control unit models colon compliance based on a pressure-volume relationship, controls perfusion flow on the premise of ensuring that the pressure and the compliance do not exceed safety thresholds, and constructs a propelling flow field similar to intestinal peristalsis through traveling wave control of an annular air bag; meanwhile, a toxin mass transfer model and a mixing efficiency index are utilized to adaptively adjust the perfusion amplitude, frequency and retention time, so that closed-loop optimization of toxin removal efficiency and safety in the colon dialysis process of the acute kidney injury patient is realized.

Description

Technical Field

[0001] This invention belongs to the field of colonic dialysis for kidney injury, and specifically relates to a colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics. Background Technology

[0002] Patients with acute kidney injury often require hemodialysis or continuous renal replacement therapy to maintain homeostasis due to a rapid decline in glomerular filtration rate and retention of urea nitrogen, creatinine, electrolytes, and fluids. However, hemodialysis requires vascular access and relies on complex extracorporeal circulation equipment, which presents challenges such as high equipment dependence, high costs, and heavy circulatory burden in primary hospitals and for critically ill patients in the early stages of illness. While peritoneal dialysis is relatively less invasive, it requires peritoneal catheter implantation and is not suitable for patients with pre-existing abdominal infections or postoperative conditions.

[0003] Colonic dialysis, as an alternative route for solute exchange and fluid removal through the intestinal mucosa, has been explored and applied since the last century. Currently used clinical colonic dialysis or colonic hydrotherapy equipment mostly uses single-lumen or simple double-lumen catheters. After insertion into the anus, dialysate is infused into the colon at a constant flow rate, and gravity or a simple peristaltic pump is used to complete the infusion and drainage. Such devices typically have the following characteristics: First, the infusion and drainage are mostly "proximal infusion and proximal reflux," with the dialysate flow pattern in the intestinal lumen being predominantly laminar. Dead spaces for exchange easily form in the distal colonic segment, leading to uneven mucosal contact and limited solute clearance efficiency. Second, the pressure control method is crude, relying solely on mechanical pressure limiting or simple flow rate settings without modeling individual patient colonic compliance parameters. This makes it difficult to detect excessive colonic distension or increased local rigidity in a timely manner, posing risks such as mucosal damage and perforation. Third, there is a lack of precise kinetic control over the "infusion-retention-drainage" process. Fluid changes are often performed at fixed time intervals, without considering changes in toxin concentration and mixing levels in the dialysate, easily resulting in waste from early fluid changes and low efficiency from late changes. Fourth, existing devices are mostly designed for chronic bowel treatment or patients with chronic kidney disease. There is a lack of dedicated colonic dialysis systems designed for patients with acute kidney injury requiring "short-term, high-efficiency clearance + strict safety control," especially in areas such as precise multi-segment colonic coverage, real-time pressure-volume modeling, and adaptive infusion waveform control, for which a systematic technical solution has not yet been developed.

[0004] In summary, existing colonic dialysis technologies generally have the following shortcomings:

[0005] The catheter has a simple structure, but the spatial distribution of the injection and return holes is coarse, resulting in insufficient perfusion coverage in the distal colon and different colonic segments.

[0006] There is a lack of compliance modeling based on the pressure-volume relationship, and a lack of individualized maximum perfusion volume control methods constrained by the upper limit of safe pressure and compliance threshold.

[0007] There is a lack of a unified kinetic model to support the phased perfusion flow waveform, airbag traveling wave control and solute mass transfer process, and the adjustment of perfusion kinetics mainly relies on experience.

[0008] Without incorporating information such as discharge conductivity and toxin concentration into the closed-loop control, it is difficult to dynamically adjust the residence time and fluid exchange rhythm based on the actual clearance efficiency, thus failing to meet the needs of patients with acute kidney injury to achieve high-dose, safe clearance within a limited time. Summary of the Invention

[0009] The purpose of this invention is to provide a colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics, addressing the problem that without incorporating information such as excretion conductivity and toxin concentration into closed-loop control, it is difficult to dynamically adjust residence time and fluid exchange rhythm according to actual clearance efficiency, thus failing to meet the needs of acute kidney injury patients for high-dose, safe clearance within a limited time; including:

[0010] A colonic dialysis catheter assembly is a flexible multi-lumen catheter with a multi-channel connector at the proximal end and the distal end inserted into the patient's colon via the anus. The multi-lumen catheter has a first perfusion chamber, a second perfusion chamber, a drainage chamber, and a pressure conduction chamber within its cross-section. The first perfusion chamber has a first set of side holes along the catheter's axial direction at its distal end, with multiple lateral perfusion holes for infusing dialysate into the ascending colon and proximal transverse colon. The second perfusion chamber has a second set of side holes along the middle section of the catheter, with multiple lateral perfusion holes for infusing dialysate into the distal transverse colon and descending colon. The drainage chamber has multiple reflux holes near the anus to collect dialysate flowing towards the anus from each colonic segment and drain it out of the body. The distal end of the pressure conduction chamber is connected to the colonic lumen through micropores or a breathable membrane, while the proximal end is connected to a pressure sensor. Multiple annular balloons are spaced axially around the catheter's outer periphery, each balloon connected to a gas control valve assembly via an independent inflation / deflation line.

[0011] The dialysate processing and supply unit includes a first dialysate storage tank, a second dialysate storage tank, a dialysate mixing unit, and a temperature control unit. Multiple inlets of the dialysate mixing unit are connected to the outlets of the first and second dialysate storage tanks, respectively. The outlet of the dialysate mixing unit is connected to the inlet of a first pump via the temperature control unit. The temperature control unit is used to heat the dialysate and maintain it at a constant temperature within the range of 36–38°C. The first pump is a programmable medical peristaltic pump, and its outlet is connected to the proximal ends of the first and second perfusion chambers via an inlet pipe.

[0012] The waste liquid discharge unit includes a second pump and a waste liquid collection container. The second pump is connected to the proximal end of the discharge chamber through a discharge pipeline and is used to apply negative pressure to the discharge chamber during the discharge stage to draw the dialysate and intestinal contents in the colon lumen into the waste liquid collection container.

[0013] The monitoring sensing unit includes the pressure sensor and a conductivity sensor disposed in the draining pipeline. The conductivity sensor is used to measure the conductivity value of the drained dialysate to reflect the change in solute concentration in the dialysate.

[0014] The perfusion kinetics control unit includes a processor and a memory. The processor is connected to a first pump, a second pump, a dialysate mixing unit, a gas control valve group, a pressure sensor, and a conductivity sensor via input / output interfaces. The memory stores a program that can run on the processor. The program causes the processor to perform the following steps: establish a colonic pressure-volume relationship model based on the monitored colonic pressure and perfusion volume, and set a safe pressure upper limit and a maximum perfusion volume; control the first pump to output a perfusion flow rate with predetermined time characteristics during the perfusion phase; adjust the perfusion parameters and fluid exchange timing based on pressure signals and conductivity changes during the residence and drainage phases; and simultaneously control the gas control valve group to inflate and deflate each annular balloon according to a set sequence to form a propulsive pressure wave within the colonic lumen.

[0015] Furthermore, the length of the first side hole group along the distal end of the catheter is 20-35 cm, and the length of the second side hole group along the catheter is 10-20 cm. The diameter of the lateral infusion holes in the first and second side hole groups is 0.8-1.2 mm, the hole spacing is 1.5-2.5 cm, and the lateral infusion holes of the second side hole group are offset from the lateral infusion holes of the first side hole group in the circumferential direction by 30°-90°.

[0016] Furthermore, the drainage chamber has 8 to 16 reflux holes continuously opened within a range of 10 to 15 cm along the end of the catheter near the anus. The diameter of the reflux holes is 1.2 to 1.8 mm, which are used to collect the dialysate and intestinal contents flowing towards the anus from each colonic segment.

[0017] Furthermore, the perfusion kinetic control unit is configured to, during the colonic compliance calibration phase, control the first pump to perfuse the colon with several equal volume increments ΔV at an exploratory perfusion flow rate, and record the corresponding pressure P. i and volume V i The pressure-volume relationship was obtained through fitting:

[0018] Where P is the intraluminal pressure of the colon, V is the perfusion volume, P0 is the resting pressure, and α and β are the fitted elastic parameters; and colonic compliance is calculated based on the above relationships:

[0019]

[0020] Based on this, a lower limit for compliance, C, is set. min Upper limit of safety pressure P safeand maximum perfusion volume V max Such that in V≤V max When P(V) ≤ P safe And C(V)≥Cmin.

[0021] Furthermore, the perfusion dynamics control unit is configured to control the instantaneous flow rate output of the first pump during the perfusion phase of the k-th perfusion cycle:

[0022] Among them, Q in,k (t) represents the instantaneous flow rate during the perfusion phase of the k-th cycle, in mL / min; Q0,k represents the baseline flow rate for that cycle; A k f is the amplitude of the pulse. k The pulse frequency is expressed in Hz; t is the perfusion phase time, when the perfusion volume reaches V. max Or, P(t) is detected to be close to or exceed Ps. afe The infusion phase ends at that time.

[0023] Furthermore, the perfusion dynamics control unit is configured to perform traveling wave control on N annular balloons arranged along the axial direction of the catheter, and let the state function of the i-th annular balloon be S. i (t), S i (t)=1 indicates inflation, S i (t)=0 indicates venting, and the traveling wave period T is set. wave , will T wave Divide the time into N equal sub-time periods, each with a length of ΔT = T. wave / N, during the j-th sub-period, only the j-th airbag is inflated while the remaining airbags are deflated, thus creating a pressure wave that propagates along the duct axis, in conjunction with the perfusion flow rate Q. in,k (t) propels the dialysate to flow axially along the colonic lumen.

[0024] Furthermore, the perfusion kinetic control unit is configured to calculate the mass transfer flux J of a specific toxin based on a toxin mass transfer model. s (t), the toxin mass transfer model is:

[0025]

[0026] Among them, J s (t) represents the instantaneous mass transfer flux of toxin s, in mg / min; K s C is the mass transfer coefficient of toxin s, expressed in mL / (min·cm^2); b,s (t) represents the concentration of toxin s in the blood, in mg / mL; C l,s (t) represents the concentration of toxin s in the colonic dialysis fluid, in mg / mL; A represents the effective exchange area of ​​the colon, in cm²; and is based on the average flux J during the residence phase.s,k and stay time T hold,k Estimate the clearance amount in the k-th perfusion cycle:

[0027] Used to cumulatively estimate the total amount cleared.

[0028] Furthermore, the infusion dynamics control unit is configured to calculate the mixing and cleaning efficiency index M for each infusion cycle. k And according to M k Compared with the preset target value M target The deviation adaptively adjusts the infusion parameters for the next infusion cycle, and the mixing and cleaning efficiency index Mk is defined as:

[0029]

[0030] Among them, P max,k P represents the peak pressure during the k-th period. base,k σ is the pressure baseline for this cycle. P,k Let ΔC be the standard deviation of the pressure fluctuation during the injection phase of this cycle. cond,k The discharge conductivity and the initial conductance C of the infusion fluid during this cycle are given. cond,in The difference, a1, a2, and a3 are weighting coefficients; and the injection amplitude A is adjusted using the following update relationship. k , Pulse frequency f k and stay time T hold,k :

[0031]

[0032] Among them, K A K f K T The step size coefficient is , and sat(·) is a saturation function with upper and lower limits, used to saturate A. k f k T hold,k Limited to a preset range.

[0033] Further, the method using the apparatus according to any one of claims 1 to 8 includes: inserting and positioning a colonic dialysis catheter through the anus, such that the first set of side holes corresponds to the ascending colon and proximal transverse colon, the second set of side holes corresponds to the distal transverse colon and descending colon, and the drainage hole corresponds to the sigmoid colon and rectum; inputting the patient's weight, baseline blood urea nitrogen concentration, and target toxin clearance amount into the perfusion dynamics control unit, and setting a safe pressure upper limit P. safe , lower limit of compliance C min and maximum perfusion volume V max P was determined by fitting the pressure-volume relationship through trial perfusion and calculating colonic compliance. safe and V max During each infusion cycle, according to

[0034] The first pump is controlled to infuse dialysate into the colon, and each annular balloon is sequentially inflated and deflated using traveling wave control to propel the dialysate axially along the colonic lumen. During the residence phase, the current mass transfer flux is calculated and the clearance is estimated according to the toxin mass transfer model. During the drainage phase, the colonic dialysate is aspirated into the waste collection container using the second pump. At the end of each cycle, the mixing and washing efficiency index M is calculated. k Based on this, the perfusion amplitude, pulsation frequency, and residence time for the next cycle are adjusted until the preset total clearance or total dialysis time is reached.

[0035] This invention addresses the shortcomings of the prior art by incorporating intestinal perfusion dynamics design into aspects such as catheter structure, multi-segment perfusion and reflux layout, colonic compliance modeling, and toxin mass transfer control. It proposes a colonic dialysis device specifically designed for patients with acute kidney injury, offering the following advantages:

[0036] The multi-lumen, multi-segment perfusion structure improves colonic coverage and flow field uniformity. This invention employs a flexible multi-lumen colonic dialysis catheter, with a first perfusion chamber and a second perfusion chamber at the distal and middle sections of the catheter, respectively. Two sets of side holes are positioned at corresponding locations in the ascending colon / proximal transverse colon and distal transverse colon / descending colon. The axial length, diameter, and spacing of the side holes are defined, and the two sets of side holes are staggered circumferentially, allowing dialysate to be injected into different colonic segments rather than concentrated near the rectum. Simultaneously, multiple reflux holes are centrally located near the anus, allowing for the unified recovery of dialysate from each colonic segment through the drainage chamber. This structure creates a flow field pattern within the colonic lumen where dialysate propagates from proximal to distal, is injected at multiple points, and then centrally refluxes back towards the anus. This effectively improves the local dead space problem caused by the traditional "proximal perfusion-proximal reflux" method, increasing the contact area and exchange uniformity of the entire colonic mucosa.

[0037] This invention introduces a pressure-volume model and a compliance threshold to achieve individualized safe perfusion control. It acquires pressure data under multiple volume increments during perfusion using a pressure transmission chamber and a pressure sensor, fitting the colonic pressure-volume relationship P(V) = P0 + αV + βV², and further derives the compliance threshold C(V) = 1 / (α + 2βV). The P(V) and C(V) models are then used to set the upper limit of the safe pressure P. safe , lower limit of compliance C min and maximum perfusion volume V max The control unit can calculate the pressure and compliance corresponding to the current infusion volume in real time during each infusion cycle. When it detects that P(V) is close to or exceeds P... safe Or C(V) decreases to C minThe following measures will automatically limit the perfusion flow or terminate the perfusion prematurely. This approach transforms the traditional, simple "experience-based perfusion volume setting" into a precise control based on modeling the individual patient's biomechanical characteristics, significantly reducing the risk of colonic overdistension, mucosal damage, and even perforation. It is particularly suitable for patients with acute kidney injury who have large fluctuations in their acute condition and poor tolerance.

[0038] The perfusion waveform and balloon traveling wave are coordinated for control, constructing adjustable intestinal perfusion dynamics; this invention employs Q-wave perfusion during the perfusion phase. in,k (t)=Q 0,k +A k ·sin(2πf k The pulsed flow waveform of t) controls the output of the first pump, upgrading the perfusion process from the traditional constant flow mode to a programmable pulsed mode; simultaneously, a traveling wave control strategy is adopted for the N annular airbags arranged along the axial direction of the catheter, setting S i (t) is the state function of the i-th airbag, and is periodically T. wave Each balloon is inflated and deflated sequentially at set intervals, creating a pressure wave that moves along the colonic axis. The combined effect of the pulsating perfusion flow and the balloon traveling wave pressure causes the dialysate to no longer flow slowly in a single direction within the colonic lumen, but rather exhibits propulsive and agitating characteristics both spatially and temporally. This facilitates boundary layer disruption, reduces local concentration polarization, and significantly enhances the mixing efficiency and convective mass transfer capacity of the dialysate with the mucosal surface within the intestinal lumen. This invention also utilizes the mixing / washing efficiency index M... k A comprehensive evaluation was conducted on the pressure fluctuations, mixing intensity, and solute concentration changes in each cycle, and A was also evaluated. k f k T hold,k The parameters are adaptively updated, transforming the perfusion dynamics from static settings to dynamic optimization, thereby improving overall mass transfer efficiency and treatment stability.

[0039] This invention introduces a toxin mass transfer kinetic model to guide the optimization of residence time and fluid exchange rhythm; the invention employs J... s (t)=K s ·(C b,s (t)−C l,s The (t)·A model describes the instantaneous mass transfer flux of a certain toxin component s during colonic dialysis, combined with the average flux during the residence phase and the residence time T. hold,k Estimate the amount of material removed per cycle

[0040] ΔM s,k The control unit uses monitoring methods such as drainage conductivity to estimate the toxin concentration C in the dialysate. l,s (t), during the residence process, the concentration gradient and mass transfer efficiency are evaluated in real time, and when J is detected... sWhen the concentration (t) drops below a certain percentage of the initial value, the current dialysate is determined to be saturated, triggering drainage and fluid exchange. This fluid exchange strategy, based on a mass transfer model, allows for dynamic adjustment of residence time and exchange frequency according to actual clearance effects. This avoids dialysate waste or decreased clearance efficiency caused by fixed exchange intervals, enabling greater toxin clearance within a limited time window, which is more aligned with the goal of "short-term, high-efficiency clearance" for patients with acute kidney injury.

[0041] This invention addresses parameter design for acute kidney injury (AKI) scenarios, improving efficacy and scalability. Specific embodiments of the invention provide a method for parameter selection in adult AKI patients, such as estimating the effective colonic exchange area A and mass transfer coefficient K based on patient weight and baseline blood urea nitrogen levels. s The maximum perfusion volume per cycle is set at approximately 400 mL, the upper limit of safe pressure is approximately 40–60 mmHg, and the residence time is 15–30 min. Model calculations within a 4-hour dialysis session have verified that the total clearance can reach the hundreds to thousands of milligrams level. Compared to traditional indiscriminate enema perfusion, this invention, through an integrated design of "structure + model + control," elevates colonic dialysis from an empirical method to a calculable and verifiable intestinal perfusion dynamics system. This facilitates standardized promotion in clinical practice and provides a basis for developing individualized dialysis prescriptions for different patients with acute kidney injury.

[0042] In summary, this invention constructs a complete "structure-model-algorithm-execution" closed-loop system through a multi-cavity, multi-segment perfusion structure, compliance modeling based on pressure-volume curves, coordinated control of balloon traveling waves and pulsating perfusion, and a residence and fluid exchange strategy guided by toxin mass transfer kinetics. This system significantly improves the contact efficiency between dialysate and the intestinal mucosa and the toxin clearance efficiency while ensuring colonic safety. It is particularly suitable for adjunctive intestinal dialysis treatment in patients with acute kidney injury, demonstrating significant practical value and inventiveness. Attached Figure Description

[0043] Figure 1This is a system block diagram of the colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics according to the present invention. The diagram shows the connection relationship between the colonic dialysis catheter assembly, the dialysate treatment and supply unit, the waste discharge unit, the monitoring and sensing unit, and the perfusion dynamics control unit. The dialysate treatment and supply unit is connected to the first and second perfusion chambers of the catheter assembly through the inlet pipe and the first pump, and is used to infuse the mixed and temperature-controlled dialysate into the colon; the waste discharge unit is connected to the discharge chamber through the discharge pipe and the second pump, and is used to aspirate the dialysate containing toxins and intestinal contents into the waste collection container; the monitoring and sensing unit acquires pressure signals, conductivity signals, and flow signals through the pressure transmission chamber and the discharge pipe, and sends the signals to the perfusion dynamics control unit; the perfusion dynamics control unit outputs control signals to each pump, the dialysate mixing unit, and the gas control valve group according to the sensor data, so as to achieve unified control of the perfusion waveform, the traveling wave balloon, and the fluid exchange rhythm.

[0044] Figure 2 This is a schematic diagram of the axial structure of the colonic dialysis catheter assembly of the present invention. The proximal end of the catheter is connected to an external tubing via a multi-channel connector, and the distal end is arranged along the colonic axis, placing the distal end of the catheter near the ascending colon or cecum. A first set of side holes is formed along the catheter wall within a range of 20-35 cm from the distal end of the catheter, corresponding to the outlet of the first perfusion chamber, preferably spraying dialysate towards the ascending colon and proximal transverse colon; a second set of side holes is formed within a range of 10-20 cm from the middle section of the catheter, corresponding to the outlet of the second perfusion chamber, for discharging dialysate towards the distal transverse colon and descending colon; multiple drainage return holes are continuously arranged axially within a range of 10-15 cm from the end of the catheter near the anus, corresponding to the inlet of the drainage chamber, for collecting the dialysate and intestinal contents returned from the distal end; multiple annular balloons are arranged at intervals along the axial direction around the outer periphery of the catheter, which can form a locally closed chamber in the corresponding colonic segment when inflated, and cooperate with the perfusion pump to propel the dialysate in a wave-like manner. The diagram also shows the locations of the anatomical segments of the ascending colon, transverse colon, descending colon, sigmoid colon, and rectum, illustrating the spatial correspondence between different functional areas of the duct and the segments of the colon.

[0045] Figure 3 This is a schematic cross-sectional view of the colonic dialysis catheter of the present invention. The outer circumferential cross-section of the catheter is circular, and four independent cavities are arranged radially within the cross-section: a first perfusion cavity, a second perfusion cavity, a drainage cavity, and a pressure transmission cavity. The first perfusion cavity communicates with the distal first side hole group, the second perfusion cavity communicates with the mid-section second side hole group, the drainage cavity communicates with the proximal drainage return hole, and the pressure transmission cavity communicates with the colonic lumen through a distal micropore and is connected to a pressure sensor at the proximal end. This cross-sectional view clearly shows the internal structural arrangement of the multi-cavity catheter and the mutual isolation between the cavities, ensuring that perfusion, drainage, and pressure measurement are physically independent.

[0046] Figure 4This is a block diagram of the perfusion kinetics control system of the present invention. The diagram shows the perfusion kinetics control unit as the core control module, connected via signal lines to monitoring and sensing units such as pressure sensors, conductivity sensors, and flow sensors to receive real-time colonic pressure, drainage conductivity, and flow signals. Simultaneously, it is connected via control lines to the first pump (perfusion pump), the second pump (drainage pump), the dialysate mixing unit, the gas control valve group, and the miniature air pump, for outputting perfusion flow waveform control commands, fluid exchange start / stop commands, and inflation / deflation control commands for each annular airbag. The control unit is also connected to a human-machine interface, allowing medical personnel to set target clearance volumes, safety thresholds, and dialysis prescriptions, and to view feedback information in real time. This diagram visually illustrates the closed-loop control architecture of the present invention: "sensor-algorithm-execution."

[0047] Figure 5 This is a schematic diagram of the colonic dialysis control process of the present invention. The process begins with "catheter insertion and parameter setting" and includes, in sequence, "compliance calibration and P(V), C(V) fitting", "start of the kth perfusion cycle", and "perfusion phase: according to Q". in,k (t) Output pulsed perfusion parallel wave control balloon; "Safety check: Determine if the perfusion volume and pressure have reached the upper limit"; "Retention phase: Maintain the dialysate retention in the intestinal lumen and estimate ΔM according to the mass transfer model". s,k "Drainage phase: Start the drainage pump to suck up the waste liquid." "Calculate the mixing and cleaning efficiency Mk for this cycle and adaptively adjust A." k f k T hold,k "Determine whether the preset target clearance volume or total dialysis time has been reached; if not, proceed to the next perfusion cycle; if reached, end dialysis." This flowchart clearly illustrates the timing logic of each control step in a complete dialysis treatment using the device of the present invention. Detailed Implementation

[0048] This invention discloses a colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics, comprising a colonic dialysis catheter assembly, a dialysate treatment and supply unit, a waste fluid discharge unit, a monitoring and sensing unit, and a perfusion dynamics control unit. These components are connected via fluid and electrical circuits to form a closed-loop system of "structure-sensing-algorithm-execution". The colonic dialysis catheter assembly is a flexible multi-lumen tube structure, preferably made of medical-grade silicone or polyurethane. Its proximal end is equipped with a multi-channel connector for connecting the perfusion line, drainage line, pressure conduction line, and each segment of the balloon inflation / deflation line. The distal end is inserted into the patient's rectum through the anus and advanced along the colon, positioning the distal end of the catheter near the ascending colon or cecum. The catheter cross-section is radially arranged with a first perfusion chamber, a second perfusion chamber, a drainage chamber, and a pressure conduction chamber. The first perfusion chamber has a first set of side holes within a range of 20-35 cm axially from the distal end of the catheter. The first set of side holes includes multiple lateral perfusion holes communicating with the first perfusion chamber. The diameter of the side holes is preferably 0.8-1.2 mm, the spacing between the holes is 1.5-2.5 cm, and the arrangement direction is towards the inner wall of the ascending colon and the proximal transverse colon, for perfusion of the proximal colonic segment. The second perfusion chamber has a second set of side holes within a range of 10-20 cm slightly proximal to the distal end of the catheter. The diameter and spacing of the side holes in the second set of side holes are basically the same as those in the first set of side holes, but the holes in the second set of side holes are offset by 30°-90° in the circumferential direction relative to the holes in the first set of side holes, so as to cover the distal transverse colon and related areas of the descending colon. The drainage chamber has 8-16 continuously formed collection holes (1.2-1.8 mm in diameter) within a 10-15 cm range near the anus on the catheter. These holes collect dialysate and intestinal contents flowing towards the anus from each proximal colonic segment, allowing them to drain out of the body through the drainage chamber. The distal end of the pressure transmission chamber is connected to the colonic lumen via micropores or a breathable membrane, while the proximal end is connected to a high-precision pressure sensor via a catheter connector for real-time acquisition of the colonic pressure signal P(t). Multiple annular balloons are spaced axially around the catheter's outer periphery. Each balloon surrounds the catheter's outer wall, forming a localized seal with the colonic mucosa during inflation and disappearing upon deflation. Each balloon is connected to a gas control valve assembly via a corresponding inflation / deflation tubing. This gas control valve assembly is then connected to a micro-pump and an infusion kinetics control unit to achieve independent inflation / deflation control of each balloon segment.

[0049] The dialysate processing and supply unit includes a first dialysate storage tank, a second dialysate storage tank, a dialysate mixing unit, and a temperature control unit. The first dialysate storage tank is pre-filled with near-isotonic basic dialysate, such as a solution containing 0.9% sodium chloride, an appropriate amount of sodium bicarbonate, and a certain concentration of potassium ions. The second dialysate storage tank is pre-filled with enhanced dialysate, such as a solution with a slightly higher osmotic pressure and the addition of components that specifically adsorb small molecule toxins. The dialysate mixing unit has multiple inlets, each connected to the outlet of one of the two storage tanks, and its outlet is connected to the inlet of the temperature control unit. The temperature control unit is equipped with a heating element or a constant-temperature water bath structure, and features a temperature sensor. It heats the mixed dialysate and maintains a constant temperature within the range of 36–38°C, preferably approximately 37°C. The outlet of the temperature control unit is connected to the inlet of a first pump, which is a programmable medical peristaltic pump or a plunger pump. Its outlet is connected via an inlet line to the proximal ends of the first and second perfusion chambers of the colonic dialysis catheter assembly, used to inject dialysate into the colon according to a set flow rate waveform.

[0050] The waste discharge unit includes a second pump and a waste collection container. The second pump is a peristaltic pump or a negative pressure pump, its inlet connected to the proximal end of the catheter's discharge chamber via a discharge pipeline. It generates a controllable negative pressure during the discharge phase, drawing dialysate and some intestinal contents from the colonic lumen into the waste collection container. A flow sensor and a conductivity sensor are installed on the discharge pipeline; the flow sensor measures the discharge flow rate Q. out (t), the conductivity sensor is used to measure the conductivity of the discharged fluid to estimate the changes in the concentration of small molecule solutes such as urea nitrogen and creatinine in the dialysate. l (t).

[0051] The monitoring sensing unit mainly includes the aforementioned pressure sensor, drainage conductivity sensor, and flow sensor. In addition, flexible strain sensors can be placed at specific locations around the catheter to measure the circumferential strain ε of the intestinal wall in different colonic segments. i (t), to assist in assessing local compliance. All sensor outputs are input to the perfusion kinetics control unit after passing through signal conditioning circuitry and analog-to-digital conversion module.

[0052] The perfusion kinetics control unit includes a processor, memory, and input / output interface circuitry. The memory stores program instructions for functions such as perfusion waveform control, balloon traveling wave control, colonic compliance modeling, and dialysis mass transfer optimization. The processor receives sensor data through the input interface and sends control signals to the first pump, second pump, mixing unit, and gas control valve assembly through the output interface. It also interacts with medical staff through a human-machine interface to input patient weight, baseline blood urea nitrogen concentration, target toxin clearance, and safety thresholds (such as the upper limit of safe pressure P). safe , lower limit of compliance C min Maximum infusion volume V max (etc.), and displays pressure curves, flow curves, estimated clearance volume and alarm information in real time.

[0053] In practical use, this device adopts a control process of "initialization calibration - multi-cycle perfusion dialysis - end treatment". During the initialization phase, after the catheter is inserted and positioned through the anus, the control unit first collects the baseline colonic pressure P0 at rest and performs colonic compliance calibration. During compliance calibration, a low flow rate Q is used. test (e.g., 30 mL / min) Infuse the colon with several volume increments ΔV (e.g., 50 mL each time), pausing the infusion after each infusion and recording the corresponding pressure P. i A set (V) is obtained i ,P i ) data points, where V i This represents the cumulative perfusion volume. The control unit assumes that the colonic pressure-volume relationship can be expressed as a quadratic polynomial:

[0054] Where P is the intraluminal pressure of the colon (in mmHg); V is the perfusion volume (in mL); P0 is the resting pressure; and α and β are coefficients describing the elastic properties of the colon. Substituting the measured (Vi, Pi) data into the above model, α and β are solved using the least squares method to minimize the sum of squared errors, i.e., minimizing... The fitted P-V curve is obtained. Based on this model, the instantaneous compliance C(V) of the colon can be calculated as the derivative of volume with respect to pressure:

[0055] Here, C(V) is measured in mL / mmHg and represents the colon's receptivity at the current perfusion volume. In this invention, a lower compliance limit Cmin is preset, for example, 5 mL / mmHg. When the calculated C(V) for a certain perfusion volume drops to Cmin or lower, the control unit considers that continued perfusion may lead to excessive stretching and damage to the colonic wall, and will limit subsequent perfusion parameters. Based on the P(V) curve, the control unit also sets a safe pressure upper limit P. safe For example, set it to 40 mmHg, and determine the maximum safe perfusion volume V based on the fitting results. max Such that in V≤V max Within the range, P(V) does not exceed P safe And C(V)≥C min .

[0056] After initialization, the device enters the multi-cycle perfusion dialysis phase. The entire dialysis process is divided into several perfusion cycles, with the k-th perfusion cycle including a perfusion phase, a residence phase, and a drainage phase. During the perfusion phase of the k-th perfusion cycle, the control unit drives the first pump to output a perfusion flow rate Q with pulsating characteristics. in,k (t):

[0057] Among them, Qin,k (t) represents the instantaneous flow rate (mL / min) during the perfusion phase of the k-th cycle; Q 0,k The baseline flow rate (mL / min) for this cycle; A k The pulsation amplitude (mL / min); f k T is the pulsation frequency (Hz); in,k Let be the duration of the perfusion phase (s); t is the time variable of the perfusion phase. During the perfusion phase, dialysate is infused into the proximal and mid-colon through different side holes of the first and second perfusion chambers. If the perfusion phase is discretized into small step sizes Δt, the perfusion volume of this phase is approximately ∑Q. in,k (t).Δt, the control unit ensures that the infusion volume does not exceed V by integration or accumulation. max Furthermore, real-time monitoring of P(t) ensures that the pressure does not exceed P. safe .

[0058] During the perfusion phase, to enhance the propulsion and agitation of the dialysate in the colon, this device utilizes peripheral annular balloons to simulate traveling wave-like intestinal peristalsis. Assume N annular balloons are arranged along the axial direction of the catheter, and the state function S of the i-th balloon... i (t) is defined as: S i (t)=1 indicates that the airbag is inflated, S i (t)=0 indicates that the system is in the venting state. The control unit sets the traveling wave period T. wave Divide it into N equal subintervals with length ΔT=T. wave / N. Within each sub-interval, only one airbag is inflated, while the rest are deflated, specifically:

[0059] when At that time, let S j When (t)=1, i≠j, S i (t)=0,

[0060] Where t0 is the initiation time of the traveling wave, and j = 1, 2, ..., N. This forms a balloon inflation sequence that moves from the proximal end to the distal end (or in the reverse direction if needed) over time, causing the local pressure high points in the intestinal lumen to advance segment by segment in space, thereby pushing the dialysate to move along the colonic axis, in conjunction with the perfusion waveform Q. in,k (t) Superposition forms a perfusion dynamics model with spatial propagation characteristics. In terms of specific parameter settings, for example, N=4, T wave =20s, then ΔT=5s. Airbags 1, 2, 3, and 4 inflate sequentially every 5 seconds, completing one traveling wave cycle. (As with Q) in,k f in (t) k Matching the frequency to 0.2Hz (one pulse every 5 seconds) allows for synchronization of the perfusion flow pulsation with the airbag pressure wave, ensuring that the dialysate is subjected to a local "pushing" effect at each flow peak, thus improving the propulsion effect.

[0061] During the injection phase, the control unit collects P(t) in real time and calculates the peak pressure P within this cycle. max,k Pressure baseline P base,k (e.g., the average pressure 5 seconds before the start of perfusion), pressure fluctuation standard deviation σ P,k Isostatistics were used, and the change in dialysate conductivity ΔC caused by perfusion was monitored. cond,k (Drainage conductivity and initial perfusion conductivity C) cond,in The difference (to reflect changes in toxin concentration) is used. After the conditions for ending the perfusion phase are met (perfusion volume reaches the set value or pressure reaches the limit), the residence phase begins. The first pump stops operating, and the inflation combinations of each balloon can be maintained as needed to preserve the locally sealed chamber, allowing the dialysate to remain in the colonic lumen for T seconds. hold,k The time (usually 15-30 minutes) is during which the toxins are transferred from the intestinal wall to the dialysate mainly through diffusion.

[0062] The toxin mass transfer process can be described by the following model: the instantaneous mass transfer flux J of a target toxin component s (such as urea nitrogen) from the blood into the dialysate through the colonic mucosa. s (t) is approximately:

[0063] Among them, J s (t) represents the mass transfer flux of toxin s (mg / min); K s C is the mass transfer coefficient of toxin s in the colonic wall (mL / min·cm²); b,s (t) represents the concentration of the toxin in the blood (mg / mL); C l,s (t) represents the concentration of the toxin in the colonic dialysis fluid; A represents the colonic mucosal surface area (cm²) effectively in contact with the dialysis fluid. During a single residence phase, if C is considered... b,s (t) changes relatively slowly, while C l,s (t) gradually increases over time, then the toxin clearance rate J s (t) is initially large, then gradually decreases. When the average flux J during the residence phase is large... s,k and the length of stay T hold,k Once determined, the amount of toxin s cleared in this cycle can be approximately expressed as:

[0064]

[0065] Where ΔM s,k The unit is mg. C can be estimated by monitoring the conductivity of the excreted fluid or by directly analyzing a portion of the excreted fluid. l,s (t), thereby using the above model to calculate the clearance amount per cycle and cumulatively estimate the total clearance amount of treatment.

[0066] At the end of each infusion cycle, the control unit calculates the mixing / cleaning efficiency index Mk for that cycle, which guides the adjustment of control parameters for the next cycle. Mk can be defined as a weighted combination of pressure fluctuations and toxin concentration changes, for example:

[0067]

[0068] Where a1, a2, and a3 are weighting coefficients. According to M k The deviation from the target value Mtarget determines the perfusion amplitude A for the next cycle. k+1 , Pulse frequency f k+1 Duration of stay T hold,k+1 Adjustments may be made, for example, by using the following update formula:

[0069] Where K A K f K T The step size coefficient is , and sat(·) is the saturation function used to limit the parameters within a preset safety range, such as A. k Limited to [A] min A max ], f k Limited to [f min ,f max ], T hold,k Limited to [T] hold,min ,T hold,max ]. When M k Significantly lower than M target And when pressure and compliance are safe, A k+1 and / or f k+1 Increase the size to enhance mixing and irrigation effects, while appropriately shortening T. hold,k+1 When M k More than M target Or accompanied by P max,k Approaching or exceeding P safe C(V) is close to C min When, then decrease A k+1 and / or f k+1 And extend T hold,k+1 This makes the perfusion dynamics gentler, thereby protecting the colon wall.

[0070] The feasibility of the device of the present invention is illustrated below with a numerical example. Assume the patient weighs 70 kg, is in stage II of acute kidney injury, and has a baseline blood urea nitrogen concentration C. b,urea (0) = 25 mg / dL, with the goal of reducing blood urea nitrogen by approximately 40% within 4 hours via colonic dialysis. The effective colonic exchange area A is estimated to be approximately 1500 cm² based on the patient's height and body surface area. The effective mass transfer coefficient K of urea in the colonic wall can be determined by referring to relevant literature. ureaIf the initial mass transfer flux is approximately 0.02 mL / min·cm², then the initial mass transfer flux is approximately:

[0071] In compliance calibration, assuming the perfusion test fit yields P(V) = 10 + 0.08V + 1.0 × 10⁻⁴V² (units: P is mmHg, V is mL), then when V = 400 mL, P ≈ 10 + 0.08 × 400 + 0.0001 × 400² = 10 + 3² + 16 = 58 mmHg, which is lower than the set P. safe =60 mmHg, corresponding to a compliance C(V) = 1 / (0.08 + 2 × 0.0001 × 400) = 1 / 0.16 ≈ 6.25 mL / mmHg, which is still higher than C. min =5mL / mmHg, therefore the single-cycle perfusion volume V can be safely set. max =400mL. To simplify the design, T is set for each infusion cycle. in =40s, T hold The initial perfusion time was 20 min, Tout = 5 min, using a perfusion waveform of Q0 = 100 mL / min, A1 = 50 mL / min, and f1 = 0.25 Hz. The perfusion volume per cycle was approximately 100 × (40 / 60) ≈ 66 mL, with multiple short cycles forming a total perfusion volume of 400 mL. In the first two hours, the average clearance rate, calculated based on the mass transfer model and real-time monitored conductivity changes, was approximately 5–7 mg / min, resulting in a total urea clearance of approximately 300–400 mg per hour, and a total clearance of approximately 1000–1500 mg over 4 hours. Considering the volume of distribution in the body and endogenous urea production, this colonic dialysis device can significantly reduce blood urea nitrogen levels, achieving the target reduction. During this process, the control unit adjusts the perfusion parameters according to Mk in each cycle, increasing the perfusion amplitude and frequency for rapid clearance when toxin concentration is high in the early stages, and appropriately reducing the kinetic intensity as toxin concentration decreases and compliance may decline in the later stages to protect the colonic mucosa.

[0072] As can be seen from the above structural design, control process, algorithm formula and numerical examples, this invention explicitly discloses the hardware components of the colonic dialysis device, the connection relationship of the components, the perfusion and drainage control logic, the compliance modeling process, the toxin mass transfer kinetic model and the parameter update algorithm, and provides clinically reasonable numerical parameter selection, which is sufficient to enable those skilled in the art to implement it without creative effort, and meets the requirements of sufficiency of disclosure and implementability of Chinese invention patents.

Claims

1. A colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics, characterized in that, include: A colonic dialysis catheter assembly is a flexible multi-lumen catheter with a multi-channel connector at the proximal end and the distal end inserted into the patient's colon via the anus. The multi-lumen catheter has a first perfusion chamber, a second perfusion chamber, a drainage chamber, and a pressure conduction chamber within its cross-section. The first perfusion chamber has a first set of side holes along the catheter's axial direction at its distal end, with multiple lateral perfusion holes for infusing dialysate into the ascending colon and proximal transverse colon. The second perfusion chamber has a second set of side holes along the middle section of the catheter, with multiple lateral perfusion holes for infusing dialysate into the distal transverse colon and descending colon. The drainage chamber has multiple reflux holes near the anus to collect dialysate flowing towards the anus from each colonic segment and drain it out of the body. The distal end of the pressure conduction chamber is connected to the colonic lumen through micropores or a breathable membrane, while the proximal end is connected to a pressure sensor. Multiple annular balloons are spaced axially around the catheter's outer periphery, each balloon connected to a gas control valve assembly via an independent inflation / deflation line. The dialysate processing and supply unit includes a first dialysate storage tank, a second dialysate storage tank, a dialysate mixing unit, and a temperature control unit. Multiple inlets of the dialysate mixing unit are connected to the outlets of the first and second dialysate storage tanks, respectively. The outlet of the dialysate mixing unit is connected to the inlet of a first pump via the temperature control unit. The temperature control unit is used to heat the dialysate and maintain it at a constant temperature within the range of 36–38°C. The first pump is a programmable medical peristaltic pump, and its outlet is connected to the proximal ends of the first and second perfusion chambers via an inlet pipe. The waste liquid discharge unit includes a second pump and a waste liquid collection container. The second pump is connected to the proximal end of the discharge chamber through a discharge pipeline and is used to apply negative pressure to the discharge chamber during the discharge stage to draw the dialysate and intestinal contents in the colon lumen into the waste liquid collection container. The monitoring sensing unit includes the pressure sensor and a conductivity sensor disposed in the draining pipeline. The conductivity sensor is used to measure the conductivity value of the drained dialysate to reflect the change in solute concentration in the dialysate. The perfusion kinetics control unit includes a processor and a memory. The processor is connected to a first pump, a second pump, a dialysate mixing unit, a gas control valve group, a pressure sensor, and a conductivity sensor via input / output interfaces. The memory stores a program that can run on the processor. The program causes the processor to perform the following steps: establish a colonic pressure-volume relationship model based on the monitored colonic pressure and perfusion volume, and set a safe pressure upper limit and a maximum perfusion volume; control the first pump to output a perfusion flow rate with predetermined time characteristics during the perfusion phase; adjust the perfusion parameters and fluid exchange timing based on pressure signals and conductivity changes during the residence and drainage phases; and simultaneously control the gas control valve group to inflate and deflate each annular balloon according to a set sequence to form a propulsive pressure wave within the colonic lumen.

2. The colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics according to claim 1, characterized in that, The length of the first side hole group along the distal end of the catheter is 20-35 cm, and the length of the second side hole group along the catheter is 10-20 cm. The diameter of the lateral infusion holes in the first and second side hole groups is 0.8-1.2 mm, the hole spacing is 1.5-2.5 cm, and the lateral infusion holes of the second side hole group are offset from the lateral infusion holes of the first side hole group in the circumferential direction by 30°-90°.

3. The colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics according to claim 2, characterized in that, The drainage chamber has 8 to 16 reflux holes continuously opened within a range of 10 to 15 cm from the end of the catheter near the anus. The diameter of the reflux holes is 1.2 to 1.8 mm, which are used to collect the dialysate and intestinal contents flowing towards the anus from each colonic segment.

4. The colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics according to claim 1, characterized in that, The perfusion kinetic control unit is configured to, during the colonic compliance calibration phase, control the first pump to perfuse the colon with several equal-volume increments ΔV at an exploratory perfusion flow rate, and record the corresponding pressure P. i and volume V i The pressure-volume relationship was obtained through fitting: Where P is the intraluminal pressure of the colon, V is the perfusion volume, P0 is the resting pressure, and α and β are the fitted elastic parameters; and colonic compliance is calculated based on the above relationships: Based on this, a lower limit for compliance, C, is set. min Upper limit of safety pressure P safe and maximum perfusion volume V max Such that in V≤V max When P(V) ≤ P safe And C(V)≥Cmin.

5. The colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics according to claim 4, characterized in that, The infusion dynamics control unit is configured to control the instantaneous flow rate output of the first pump during the infusion phase of the k-th infusion cycle: Among them, Q in,k (t) represents the instantaneous flow rate during the perfusion phase of the k-th cycle, in mL / min; Q0,k represents the baseline flow rate for that cycle; A k f is the amplitude of the pulse. k The pulse frequency is expressed in Hz; t is the perfusion phase time, when the perfusion volume reaches V. max Or, P(t) is detected to be close to or exceed Ps. afe The infusion phase ends at that time.

6. The colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics according to claim 5, characterized in that, The perfusion dynamics control unit is configured to perform traveling wave control on N annular balloons arranged along the axial direction of the catheter, and let the state function of the i-th annular balloon be S. i(t) S i(t) =1 indicates inflation, S i(t) =0 indicates venting, and sets the traveling wave period T. wave , will T wave Divide the time into N equal sub-time periods, each with a length of ΔT = T. wave / N, during the j-th sub-period, only the j-th airbag is inflated while the remaining airbags are deflated, thus forming a pressure wave that propagates along the duct axis, in conjunction with the perfusion flow rate Q. in,k (t) propels the dialysate to flow axially along the colonic lumen.

7. The colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics according to claim 6, characterized in that, The perfusion kinetics control unit is configured to calculate the mass transfer flux J of a specific toxin based on a toxin mass transfer model. s (t), the toxin mass transfer model is: Among them, J s (t) represents the instantaneous mass transfer flux of toxin s, in mg / min; K s C is the mass transfer coefficient of toxin s, expressed in mL / (min·cm^2); b,s (t) represents the concentration of toxin s in the blood, in mg / mL; C l,s (t) represents the concentration of toxin s in the colonic dialysis fluid, in mg / mL; A represents the effective exchange area of ​​the colon, in cm²; and is based on the average flux J during the residence phase. s,k and stay time T hold,k Estimate the clearance amount in the k-th perfusion cycle: Used to cumulatively estimate the total amount cleared.

8. The colonic dialysis device for acute kidney injury based on intestinal perfusion dynamics according to claim 7, characterized in that, The infusion dynamics control unit is configured to calculate the mixing and cleaning efficiency index M for each infusion cycle. k And according to M k Compared with the preset target value M target The deviation adaptively adjusts the infusion parameters for the next infusion cycle, and the mixing and cleaning efficiency index M... k Defined as: Among them, P max ,k is the peak pressure in the k-th period, P base,k σ is the pressure baseline for this cycle. P,k Let ΔC be the standard deviation of the pressure fluctuation during the injection phase of this cycle. cond,k The discharge conductivity and the initial conductance C of the infusion fluid during this cycle are given. cond,in The difference, a1, a2, and a3 are weighting coefficients; and the injection amplitude A is adjusted using the following update relationship. k , Pulse frequency f k and stay time T hold,k : Among them, K A K f K T Here, is the step size coefficient, and sat(·) is a saturation function with upper and lower limits, used to saturate A. k f k T hold,k Limited to a preset range.

9. A colonic dialysis method for acute kidney injury based on intestinal perfusion dynamics, characterized in that, The procedure using the apparatus according to any one of claims 1 to 8 includes: inserting and positioning a colonic dialysis catheter via the anus, such that the first set of side holes corresponds to the ascending colon and proximal transverse colon, the second set of side holes corresponds to the distal transverse colon and descending colon, and the drainage hole corresponds to the sigmoid colon and rectum; inputting the patient's weight, baseline blood urea nitrogen concentration, and target toxin clearance amount into the perfusion kinetic control unit, and setting a safe pressure upper limit P. safe , lower limit of compliance C min and maximum perfusion volume V max P was determined by fitting the pressure-volume relationship through trial perfusion and calculating colonic compliance. safe and V max During each infusion cycle, according to The first pump is controlled to infuse dialysate into the colon, and each annular balloon is sequentially inflated and deflated using traveling wave control to propel the dialysate axially along the colonic lumen. During the residence phase, the current mass transfer flux is calculated and the clearance is estimated according to the toxin mass transfer model. During the drainage phase, the colonic dialysate is aspirated into the waste collection container using the second pump. At the end of each cycle, the mixing and washing efficiency index M is calculated. k Based on this, the perfusion amplitude, pulsation frequency, and residence time for the next cycle are adjusted until the preset total clearance or total dialysis time is reached.

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