MXPA06005022A - Syringe pump rapid occlusion detection system - Google Patents

Abstract

An apparatus, method and program product detects an occlusion in a fluid line (22) by determining if arelationship between force measurements departs from an expected relationship.

Description

For two-letter codes and olher abbreviations, refer to the "Guidance Notes on Codes and Abbreviations" appearing at the beginning-ning ofeach regular issue of the PCT Gazette.

SYSTEM OF DETECTION OF QUICK OCCLUSION OF SYRINGE PUMP TECHNICAL FIELD OF THE INVENTION The present invention relates to drug infusion pumps and, more particularly, to the detection of an occlusion in the fluid path of said pumps.

BACKGROUND OF THE INVENTION The administration of many medications requires specific dosage regimens that occur over a relatively long period of time. To this end, the development of syringe pumps has dramatically benefited patients who require a volumetrically proportioned administration of their medication. Syringe pumps generally comprise a reservoir or syringe and are mounted on a cover. The syringe is usually filled with one or more chemical, nutritive or biological substances that are mixed in a uniform solution. An impeller associated with the pump forces a plunger through the syringe. As the impeller travels through the syringe, the medication is forced out into hoses and / or catheters, toward the patient.

During the development of the administration of the medication to the patient, it is possible that an occlusion occurs in the administration path. Examples of occlusions may include a closed stopcock, sliding valve or contracted line. If this condition is not detected, it can cause injury to the patient. That is, when an occlusion occurs along the administration path, medication is not administered to the patient, even if the pump continues to operate. Therefore, an occlusion prevents the infusion pump from supplying medication to the patient until the occlusion can be detected and eliminated from the infusion path. For this reason, the rapid detection of occlusions along the administration path is key to reliable operation of the pump. An occlusion in the infusion line will cause the force or pressure in the syringe to increase. In turn, the force between the syringe pump impeller and the syringe plunger will increase. Conventional pump systems employ a transducer to monitor the force between the syringe pump impeller and the syringe plunger, or the pressure in the syringe. Other more expensive pumping systems place a disposable detector within the actual administration line. In said prior art pumps, an alarm is generated when the force between the impeller and the plunger or the pressure in the syringe increases above a predetermined threshold. As such, the alarm is either "on" or "off", depending on whether the threshold has been reached. As a consequence, the user has no way of knowing if the pressure in the syringe is accumulated to an unacceptable level that precedes the threshold. The user only knows when the alarm has been reached. Therefore, corrective actions can only be taken once an infusion protocol has already been potentially compromised. This circumstance is aggravated when the threshold is determined at a relatively high value, in order to avoid false occlusion alarms. With low administration rates, it can take hours for a conventional pump to reach line pressure high enough to trigger conventional alarm systems. This delay of the detection period would ideally be around five minutes or less, to avoid having a negative impact on the patient's care. Another obstacle for the detection of an occlusion occurs in the context of bolus injections, where a relatively large volume of medication is delivered in a relatively short period of time. In such bolus applications, the pump pressure will easily exceed the threshold alarm level, regardless of the presence or absence of a real occlusion. Similarly, pressures that vary widely and occur during the initial elevation stage of a non-bolus administration make conventional detection methods unreliable given the caudal variables. Therefore, it is extremely difficult to detect if the administration line presents an occlusion during the stages of both bolus and non-bolus pumping applications. As a consequence, there is a need for a better way to automatically detect an occlusion within a fluid line with a medical infusion system.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides an improved apparatus, program product and method for automatically detecting an occlusion in a fluid line of a medical infusion system, so as to overcome the problems of conventional pumps. In a sense, the invention detects a tendency to indicate an occlusion much earlier than is possible with known practices. For example, the methods of the present invention typically allow the detection of closed stopcocks, slide valves, contracted lines and other occlusions in approximately five minutes or less (based on a rate of administration of 1 ml / hr with a syringe of 60 mi). Such occlusion detection results are possible using the existing transducers present in most pumps and, therefore, do not require additional hardware. In addition, occlusions are detected under a wide variety of circumstances and without a propensity for false occlusions. For this purpose, the pressure values of a force sensor are monitored over intervals spaced in time. The pressure values can be processed to generate a slope, which is compared with a value comprising an expected relationship. If the comparison is unfavorable, an occlusion alarm is initiated. In the most particular determination of the presence of an occlusion, a first and a second pressure values are obtained at times T1 and T2, respectively. A relationship between the pressure values is determined. This relationship generally comprises a slope. An occlusion is indicated if this relationship between the first and second pressure values starts from an expected relationship. For example, the test slope determined from the pressure values may be greater than a remembered memory occlusion slope. The remembered slope is optimized for the purpose of detecting an occlusion as a product of the size and type of the syringe, as well as the flow rate of the fluid administration, among other clinically established factors. In accordance with a further aspect of the invention, a steady state condition of the infusion system is determined to improve the reliability of the system. Stable state procedures consistent with the principles of the present invention adapt the pressure variance that occurs during the initial lift. In doing so, the steady-state procedures account for a period of system operation ranging from the start of an infusion application to a certain determinable point at which the initial operation stage of the application will have been completed normally. If an occlusion occurs after a steady state has been reached, the slope determined from the pressure values increases with respect to time. If this rise in pressure continues for a minimum duration to the point where it deviates from the expected ratio, the system determines that an occlusion has occurred. Another or the same embodiment that is consistent with the principles of the present invention allows an occlusion to be detected during a bolus injection, despite the high and widely varying pressure levels associated with said applications. In one sense, the movement of the plunger is stopped during a bolus infusion, whenever a detected value deviates from an expected ratio. When so desired, the movement of the plunger may continue after a certain delay time and / or at a reduced infusion rate. Allowing the pressure in the system to relax for a period equal to a delay time limit, together with the reduced rate, enables a bolus infusion so that it does not exceed the limit of the occlusion and / or initiates a false alarm of occlusion. That is, the intermittent infusion bolus (on / off) feature reduces the incidence of a false occlusion, while allowing bolus applications at the highest infusion rates. By virtue of the foregoing, there is therefore provided an improved mechanism for automatically detecting an occlusion in a fluid line of an injection system pump adapted to transport fluid under pressure to a patient. This and other purposes and advantages of the present invention will be apparent from the accompanying drawings and the description thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description of the invention provided above and the detailed description of the modalities provided below, serve to explain the principles of the invention. present invention. Figure 1 is a block diagram of a syringe pump system configured to automatically detect an occlusion in a fluid line of the system. Fig. 2 is a block diagram of an example hardware and software environment for a pump component of the system of Fig. 1. Fig. 3 is a flow diagram having suitable method steps for rapidly detecting an occlusion within the Figure 1 system. Figure 4 is a graph representing pressure values provided by a force sensor of Figure 1.

Figure 5 is a graphical illustration of a chart showing examples of content of a database having application within a memory component of Figure 2. Figure 6 is a flow chart having method steps adapted to detect a stable state of the system of Figure 1. Figure 7 is a flow chart having method steps for determining whether an occlusion alarm step of Figure 3 should be canceled. Fig. 8 is a flow diagram having method steps suitable for administering a bolus by means of the syringe pump system of Fig. 1.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows an example of a syringe pump system 10 configured to automatically detect an occlusion. The system 10 shown in Figure 1 includes a pharmaceutical cartridge or syringe 13, which is held and fixed by a cover 14 and clamp 15, respectively. The syringe 13 includes a plunger 16 that regulates the flow of fluid to a patient 24 through the infusion line 22. That is, the plunger 16 comprises a piston-type drive mechanism that is internal to the cover 14 and drives the contents of fluid out of an outlet of the syringe 13 along the infusion line to the patient 24.

To this end, an internal motor to the cover 14 drives an impeller or plunger drive mechanism 17, to move the plunger 16. A sensor, which is generally internal to the plunger drive mechanism 17, monitors the fluid force that is desired according to the system specifications. The pump cover 14 may further include a display 19 and a communication port 20. A typical display 19 may include operator interface input mechanisms, such as a keyboard, touch-sensitive display features, switches, a microphone, tones and others similar. The communication port 20 may include a communication interface for additional equipment, including laptops, portable programming devices and / or network connection equipment. For example, the communication port 20 of the pump cover 14 can be adapted to RS-232 cabling. Although not generally shown in Figure 1, the person skilled in the art will recognize that system example 10 may include additional infusion lines, as well as valve mechanisms, clamps, caps, stopcocks, connectors and additional compliance sensors. with the specifications of the system. The syringe 13 carries the medication to the infusion line downstream 22 at a controlled rate. The head of the plunger 16 is generally such that it allows the plunger 16 to be pushed, but prevents the plunger 16 from moving spontaneously as a result of passing the fluid through a siphon from the reservoir of the syringe. For example, the plunger 16 can be retained by wedge-shaped limbs that move along the front surface of the head of the plunger 16 and force the back surface of the plunger head against a forward facing surface. of the piston head retainer, so as to fix it formally against the surface. Deployment 19 may include options for a user to make introductions. Said introduction may include data corresponding to the concentration of the drug, patient weight, as well as desired dose and dose rates. The digital communication port 20 provides an external control mechanism, where desired. For example, the pump cover 14 can be wired continuously with a separate remote personal computing device. The person skilled in the art will notice that wireless communications can be used alternatively. In any case, this personal computing device can then operate a particular customized program to provide the desired pattern of drug administration appropriate for the specific circumstance. Regardless of the input source, the processor 31 contained within the pump cover 14 can initiate the volume and flow rate of the fluid to be delivered to the patient. Figure 2 illustrates a hardware and software environment for a system 30 having said processor 31 configured to detect an occlusion. As described herein, the processor 31 may monitor an occlusion using the input of a sensor 33. For the purposes of this description, a sensor may include any device configured to detect a value indicating a force. A suitable processor can include any device configured to process an electronic signal. The processor 31 of the system 30 is generally coupled to a memory 32. As described herein, the processor 31 may represent one or more processors (eg, microprocessors), while the memory 32 may represent the random access memory devices (RAM) that comprise the main storage of the system 30, as well as any supplementary level of memory, eg hidden memory, non-volatile memory or backup memory (e.g., programmable or snapshot memories), read-only memories, and so on. In addition, the memory 32 may be considered to include memory storage physically located elsewhere in the system 30, e.g. any hidden memory in a processor 31, as well as any storage capacity used as a virtual memory, e.g. as stored within a mass storage or in a computer coupled with the system 30 through a network 38. As described below in greater detail, the stored data may include information on the type and size of syringe, infusion rate and pending, as well as on force values. The processor 31 can execute various software applications, components, programs, objects, modules, etc. of the computer (e.g., rapid detection program 42, cancellation program 43, steady state program 44 and bolus program 45, among others). In general, the routines executed to implement the embodiments of the invention, whether implemented as part of an operating system or of a specific application, component, program, object, module or sequence of instructions, will be referred to herein as "programs " The programs generally comprise one or more instructions residing at different times of the system 30. When a program is read and executed by a processor 31, the program causes the system 30 to execute steps or elements that implement the different aspects of the invention. In addition, although the invention has been described and will be described hereinafter in the context of a complete operating system 30, the skilled person will realize that the various embodiments of the invention can be distributed as a program product throughout. a series of forms, as well as that the invention applies equally regardless of the particular type of signal carrier medium used to actually transmit the distribution. Examples of signal carrying media include, although not limited to, recordable media such as volatile and non-volatile memory devices, floppy disks and other removable disks, hard disk drives, optical disks (eg, CD-ROM's, DVD's, etc.), among others, as well as transmission type means such as digital and analog communication links.

In addition, various programs described hereinafter can be identified based on the application for which they are implemented in a specific embodiment of the invention. However, it should be noted that any particular program nomenclature that follows is used merely for convenience and, therefore, the invention should not be limited to the exclusive use in any specific application identified and / or implied by said nomenclature. The person skilled in the art will recognize that the examples of environments illustrated in FIGS. 1 and 2 are not intended to limit the present invention. In fact, the person skilled in the art will recognize that other alternative hardware and / or software environments can be used without deviating from the scope of the invention. Figure 3 shows examples of method steps adapted to run within the hardware environments of Figures 1 and 2. More particularly, flow chart 200 of Figure 3 includes steps to automatically detect an occlusion within a fluid line of a medical infusion system during a pumping sequence. The system 10 is initialized in block 202 of figure 3. The initialization step of block 202 may include or be preceded by the connection of a personal computer to the communication port 20 of cover 14. Therefore, the system 10 it may include external processing devices configured to connect to port 20, as described herein.

Initialization of block 202 may include infusion protocols specified by the user, operation parameters and other data. For example, the user may select one or more fluid flow rates or sequences may be selected based on a desired pattern of drug administration that is appropriate for the patient's protocol. Alternatively or additionally, certain parameters can be set at the factory and / or automatically retrieved from the memory or previous use. For example, a prior infusion protocol can be recovered when an infusion sequence for a patient must be repeated. Initialization may include remembering or defining an expected relationship. This expected relationship may include an occlusion slope. This slope can be predetermined using clinical data. For example, force measurements can be taken under known laboratory conditions at the beginning and end of a window interval. These force measurements are divided by the window to determine the occlusion slope. Some of said slopes can be stored in an associative relationship with one or more of the known conditions that are applicable for a given pumping system scenario. For example, a slope may be stored in an associative relationship with a particular type or size of syringe and / or a given infusion index. As described in more detail in the text describing Figure 6, the occlusion slope can be determined as a function of a stable state slope detected in a given patient application.

When desired, the system parameters can be set in block 202 to tolerate "slippery" syringes and to handle defects in force caused by different conditions, including a change in force due to repositioning of the height of a pump or change in the rate of administration of another pump that is feeding the same administration path. Another scenario achieved in or prior to block 202 of figure 3 may include specifying or remembering an appropriate window size. The window size can define the interval (s) in which values or force readings must be reached. In other words, a window includes first and second force values communicated from the force sensor 33 to the processor 31. As described herein, a relationship between these force values is compared with an expected ratio to determine the presence of an occlusion. That is to say, the relationship is later compared with the expected relationship to determine whether an occlusion should be declared. Yet another example of a parameter that is set in or prior to block 202 of Figure 3 may include an occlusion detection time. The occlusion detection time can define a minimum period of time required to determine if an occlusion has occurred. For example, and as described in greater detail hereinafter, an occlusion slope or other unexpected relationship may have to be maintained for at least a period equal to the occlusion detection time before an occlusion is declared. Block 202 of Figure 3 may further include starting an infusion at a specified infusion rate. For example, a medicated fluid may begin to flow in block 202 at an infusion rate of 5 ml / hr. In block 204 of Figure 3, the system 10 obtains or otherwise determines a first force value. This first force value can be obtained in time, T1, for example. As described herein, the time T1 may be stipulated by parameters input to or prior to the block 202. Although a suitable force value may comprise any measurement indicating strength present within the system 10, a typical force value includes a result binary of a transducer in communication with the force sensor. Said transducer may comprise an analog to digital converter, for example. As such, an electronic signal from the force sensor is processed by the transducer to generate an output. Therefore, the output of the A / D converter varies in accordance with the force detected by the force sensor. For example, a force reading of two PSIs can cause the A / D converter to generate a binary value of 76 mV. This voltage output can subsequently be converted into a "counting" unit to process considerations. Either or both of the output and counting comprise force values for the purposes of this specification and may be stored in block 205 for later use.

A second subsequent force value can be obtained in block 206. This second force value can be achieved in a manner similar to that of block 204 in time, T2. As before, time T2 can be predetermined as part of an infusion application configuration. When desired, this second force value is also stored in block 205. Although the steps for determining only two force values are shown in blocks 204 and 206, one skilled in the art will note that measurements of force values can be taken. additional according to the principles of the present invention. That is, more than two force values can be used to determine a ratio that compares with the expected ratio. System 10 in block 207 of Figure 3 uses the force values obtained in blocks 204 and 206 to determine a relationship between them. For example, the system 10 can determine a slope in block 207. More particularly, the difference between the force values obtained can be divided by the difference in the times that the respective force values were obtained. One or more force values may be stored in block 205 for later use. Before proceeding to another step associated with the detection of an occlusion, the system 10 in block 208 can determine whether the steady state has been reached. Although described in more detail with respect to Figure 6, the steady state includes a status of the system 10 in which the initial conditions of an infusion application will generally have less impact on occlusion determination procedures. Said example of initial condition may include an amplified force reading attributable to the normal and relatively sudden influx of fluid in a tube 22 at the start of an infusion application. Therefore, a steady state determination may include, for example, verification that a pump has been enrolled and / or that a fluid volume limit or time has been exceeded. This step of block 208 reduces the possibility of initial conditions triggering a false occlusion. The occlusion slope specified in block 202 of Figure 3 is retrieved in block 209 by system 10. Said occlusion slope may comprise the expected ratio as described herein. In block 210 of Figure 3, the recovered occlusion slope is compared to the test slope determined in block 207. More particularly, if the determined slope is less than the occlusion slope recovered in block 209, then the system 10 may not declare an occlusion and may merely continue to monitor an occlusion. For example, system 10 can change the detection window and obtain additional force values in blocks 218, 204 and / or 206, to determine a new test slope in block 207. A mode that is consistent with the principles of the present invention can additionally reset the clock or other counter which records the time in block 211. If the detected slope or other trial slope was alternatively greater than or equal to the recovered occlusion slope / expected ratio in block 210, the system 10 could determine in block 211 if an occlusion has been canceled. Although described in more detail below as the subject of Figure 7, such cancellation could occur when, for example, an occlusion slope cancellation is determined after the slope determination of block 207. The cancellation of an occlusion can make that a clock or other counter recording the passage of time associated with an occlusion detection application be restarted in block 213. Such counting can be useful to determine when an occlusion detection time has been reached. More particularly, when no cancellation has occurred in block 21 1, it can be determined in block 212 if a period corresponding to the detection time of the occlusion has expired. As described herein, the occlusion detection time can be defined as a minimum duration in which an occlusion slope must be maintained in order to declare an occlusion. Step 212 is achieved, in part, to mitigate occurrences of false occlusions. In particular, an alarm is not generated in block 217 until the time of occlusion has expired in block 212. The application counter continues to increase in block 216 until the time of occlusion is reached or some other intervention intervenes. condition. When the detected slope is greater than or equal to the occlusion slope and the detection time of the occlusion has elapsed in block 212, system 10 will generate an occlusion alarm in block 217.

Although a typical alarm may include an audible signal and / or a flashing display 19, a suitable alarm may comprise any indicator configured to communicate an occlusion status to a user. As with the flowcharts described in this specification, the person skilled in the art will note that any of the examples of steps 202 to 218 of the flow chart 200 of Figure 3 can be omitted, reordered and / or added with steps additional according to the principles of the present invention. In addition, the person skilled in the art will notice that the functions of these steps 202 to 218 of the flow chart 200 can be performed in software and / or hardware environments different from those described in relation to figures 1 and 2. Figure 4 shows a graph 300 representing the force along its axis and 302 in relation to time along its x axis 304. The resulting graph line 306 reveals a slope indicating the pressure or force within the system 10 as a function of the weather. For the purposes of this specification, "force" and "pressure" can be used interchangeably. In the embodiment described above, the slope of line 306 can be compared to an expected slope to determine whether an occlusion alarm should be initiated. In one sense, one embodiment of the present invention takes advantage of the fact that the slope experienced by an occlusion system 10 may have stable and predictable characteristics.

As shown in Figure 4, force measurements are achieved in windows 310 through 316. A window for the purposes of this specification may comprise two or more time measurements, to include multiple minor window increments and measurements. More particularly, window 310 may start at time T1 and end at time T2. Correspondingly, window 312 starts at time T2 and ends at time T3. Although it is advantageous in certain applications, the person skilled in the art should note that said windows do not need to be consecutive and can be achieved in any pre-established and / or random interval. For example, a suitable window may additionally comprise a period between T2 and Tu. In any case, the system 10 can store or otherwise store multiple force values 308 in a window memory. The size of each of the windows 310 to 316 can be adjusted to meet any number of system requirements. For example, the size or time interval for which a window 310 can be adjusted to eliminate or otherwise account for the fractions of the counts. For example, the size of a first window 310 can be adjusted, so that its size will generally detect all the count data that occurs between T1 and T2. Such a precaution can avoid cases in which the transducer generates, for example, a sixth count at the border of window 312, where most of the force associated with the sixth count has actually been generated in the time interval of the window. window 310.

As such, the window size can be expanded or contracted to avoid fractional readings. Continuing with the previous example, the size of the windows 308 can be expanded so that the sixth count is recorded in the window 310. In any case, other processing and conversion applications, as will be noticed by the person skilled in the art, could be used for achieve the desired readings, regardless of the size of the window. As described herein, each force value may comprise a counting of the analog-digital transducer / converter over a time interval defined by the size of the window, T1-T2. For example, a window that has a time interval of one minute could generate 76 counts. Therefore, the counts indicate the force within the system 10 and can be used along the y-axis 302 of Figure 4 to be used in the plotting in relation to time 304. The resulting slope could comprise a relationship that is subsequently compared with an expected relationship, to determine the presence or absence of an occlusion. Figure 5 shows an example of database structure 380 having application with embodiments of the present invention. For example, structure 380 may comprise a search box accessible to programs 42 to 45, which is consistent with the present invention. Said search box may include fields for syringe size data 382, infusion index 384 and slope index 386, among other criteria. For example, other suitable criteria may include the nature of the substance being administered, the concentration or dissolution of the substance in the fluid, the viscosity of the fluid; the recipient, including their sex, age and physical attributes, the occurrence of a change in the measurable diagnosis in relation to the actions or effects of the substance being administered, the predictability of the concentration of the drug, as well as the practices, policies, local protocols and regulations or other considerations, including the judgment of the operator. In fact, the person skilled in the art should recognize that any criteria related to an infusion process may be additionally or alternatively included or affect the content of a memory structure that is consistent with the principles underlying the present invention. One embodiment of the present invention processes the data contained within the fields of the database 382 and 384 as input by the user to determine an expected relation or slope index 386. This slope index 386, which may comprise and / or converted to counts per minute, can be recovered from memory 32 in block 209 of Figure 3, for example. Figure 6 shows examples of method steps adapted to determine whether a stable state has been reached. At the beginning of an infusion procedure, an initial slope is generated that approaches or exceeds an occlusion slope. This high level of force can be caused by the tubes 22 and other components of the system 10 which react to a sudden influx or elevation of the pumped fluid. That is, it takes a certain time for the system 10 to adjust and achieve a relaxed flow of fluid to the patient 24. Over time, the pressure / force within the system 10 finally relaxes relatively in the absence of an occlusion. That is, the force is leveled to a more moderate slope. This leveling period generally coincides with the fact that the system 10 reaches a stable state. The procedures of flow diagram 400 of Figure 6 adjust the initial influx of fluid into system 10, while mitigating false occurrences of occlusion alarms. The system 10 generally uses the steady-state detection methods shown in Figure 6 to determine when a steady state has been achieved. For example, when a slope generated as a product of the actual force over time is below or equal to a slope of detection of stable state or expected occlusion. Some modalities may require that the detected slope last for a certain minimum occlusion time before declaring a stable state or occlusion. The same or another embodiment of a 10 that is consistent with the present invention can declare a stable state when a certain designated start time expires or in response to a volume level administered. Stable state detection is allowed in block 402.

The initialization procedures in block 402 may include parameters specified by the user and / or in the factory, such as a minimum occlusion time, a start time, a steady state slope and a start volume. The system 10 determines or otherwise obtains the force values in block 404. As described herein, an example of force value may comprise a counting output of an analog-digital converter in communication with a force sensor. . The force value can be detected by a pressure or force sensor in communication with the downstream infusion tube 22, for example. System 10 can determine if pump system 10 is enrolled in block 406. Resetting the pump can include having the user press a button on a display 19 that initializes the steady state detection procedures, along with the pressure rise within the system 10 to an acceptable level. If the pump were not enrolled as such in block 406, the steady state detection algorithm 44 could declare a steady state when the volume of fluid that has been delivered is greater than a starting volume. The volume administered and / or the start volume can be determined as a function of time and the infusion rate. When it is determined that such a condition exists in block 424, then the stable state can be declared in block 418. Otherwise, additional force values can be obtained in block 404. As described herein, said force values they can be numerous depending on the conditions and specifications of the system.

The system 10 can determine a test slope in block 410 using the force values obtained in block 404. This test slope, determined or real can be compared to a slope recovered from memory 32. Although the recovered slope can comprise the slope of occlusion in one modality, another can recover a steady state slope that has some other appropriate value. If the slope determined in block 410 is greater than or equal to the recovered slope as determined in block 412, then system 10 could determine, in block 416, whether a steady state start time has been exceeded. The steady state start time could comprise a period of time after which a stable state will be declared in block 416. This specified start time limit includes a time in which the high start slopes associated with a time frame of Previous stable state is normally leveled. That is, the start-up time may comprise a certain pre-established period in which the normal previous stable state conditions (without occlusion) should have resolved on their own. When said start time limit has been met or exceeded in block 416, the system can declare a stable state in block 418. Otherwise, in block 416, system 10 can continue to determine force values in block 416. block 404 until the start time limit or other condition has been met.

If the slope determined in block 410 fails to meet or exceed the occlusion slope in block 412, the system could depend on the temporal analysis in block 422 to determine if a certain specified start time limit has expired. When said start time limit has been met or exceeded in block 416, the system can declare a stable state in block 418. Once a stable state has been detected, system 10 can proceed to another aspect of detection of occlusion as described herein. When leaving the stable state in block 426, for example, the determined slope will then be compared with the same or another one (not in a stable state) pending of occlusion, to determine if an occlusion is present within the system 10. The diagram of flow 488 of figure 7 outlines examples of process steps 489 to 498 which are further explained with the occlusion cancellation step 215 of figure 3., the method steps shown in Figure 7 work to cancel an occlusion alarm and help mitigate the occurrence of false occlusions. In block 489 of figure 7, system 10 obtains force samples. These force samples include the force values as described above and can be recovered from the memory or from a force sensor. As throughout this specification, multiple force samples can be used to determine the presence or absence of an occlusion.

A test slope or other ratio is determined in block 490 of FIG. 7. The slope may reflect force values over time, as shown and described above in relation to FIG. 4. In block 491 it may be recovered an occlusion cancellation slope value. The occlusion cancellation slope may be predetermined and specified by a user in a manner similar to the occlusion slope described in relation to Figure 3. That is, the cancellation slope of occlusion may account for factors such as size and type of syringe, as well as the infusion index, among other factors. The slope of cancellation of occlusion is generally less than or equal to the slope of occlusion. That is, detection of the occlusion cancellation slope represents a relatively steeper slope deviation associated with an occlusion, e.g. a reduction of the force within the system 10. The system 10 can compare in block 492 the slope determined in block 490 of figure 7 with the cancellation slope of occlusion recovered in block 491. More particularly, system 10 can determine if the test slope is greater than or equal to the cancellation slope of occlusion. If this condition is satisfied in block 492, then the system may increase a record in block 493. A record for the purposes of this specification may include any counting and be performed in either a software and / or hardware environment.

Alternatively, if the determined slope was less than the cancellation slope of occlusion as determined in block 492 of Figure 7, the record is not incremented in block 494. In another or the same mode, the record may be restarted in the block 494 in response to the fact that the cancellation slope of occlusion is greater than the determined slope. The record can be compared to a threshold value in block 496 when an occlusion cancellation time expires. The threshold value and occlusion cancellation times can be preset by a user. As with all specifications described herein, these specifications may be modified in the field by users to reflect preferences. In the step example of block 496 of figure 7, when the register is greater than or equal to the threshold value, the system 10 can proceed with an occlusion alarm in block 497. Alternatively, in block 498, the alarm of Occlusion can be canceled in response to a threshold value that is equal to or greater than the current value contained within the record. Such a condition may arise, for example, when there has been a temporary increase in strength of a corresponding change in a patient's elevation, not an occlusion. Flow chart 500 of Figure 8 shows additional procedures configured to detect an occlusion within an infusion system 10. Examples of procedural steps are particularly suited to the application within the context of a bolus injection.

Bolus injections represent unique challenges with respect to occlusion detection, since the high volumes and infusion rates associated with bolus injections are conventionally difficult to discern from the occlusion conditions. The user may initialize system 10 in block 502 of FIG. 8. Initialization procedures may include specifying a bolus occlusion limit. As described below, a bolus occlusion limit may be a value that functions as a calibrator to activate characteristics of the occlusion detection methods of the present invention. Other specifications achieved in block 502 may include specifying a delay time as described below. The initialization procedures of block 502 can assume that a user has connected his or her personal computer or other processing device to a pump. This scenario may be appropriate when a desired interface hardware is not included within the pump cover, for example. Initialization in block 502 may also include initiating the medication infusion. For example, a user can instruct system 10 to pump fluid at a rate of 600 ml / hr for a given bolus injection. The system 10 obtains a force value in the block 504. The force value can comprise a counting output of an analog-digital converter. For example, the system 10 can register 112 counts within the time interval of one minute. However, the person skilled in the art will notice that any value indicating force within the system 10 can be used alternatively. The system 10 determines whether the force value obtained is greater than the limit of the occlusion in block 506. The limit of the occlusion can be specified in any value. When the force value obtained is less than the limit of the occlusion, then the system can continue to monitor force readings in block 504. In flow chart 500 of Figure 8, processor 31 of system 10 can stop, interrupt, reducing, stopping or otherwise altering the trajectory of the plunger 16 (and fluid administration) in the block 508, in response to determine that the force value obtained in block 504 is greater than the limit of the occlusion or expected value, as defined in block 502. The skilled person will note that, although it is desirable to stop by complete the plunger 16 in block 508 in most cases, another embodiment consistent with the invention may merely encourage, reduce or otherwise alter the administration in the block 508. System 10 can verify that it is operating in bolus administration mode in block 510. This step in block 510 allows bolus infusion procedures to operate within the context of normal bolus infusions. More particularly, if the system determines, in block 510, that a bolus is not being administered, then an occlusion alarm may be generated in block 512. As with other embodiments of the present invention, the detection of an occlusion in block 512 can initiate a corrective action. Said action may include verifying the function of the system 10, as well as adjusting the flow rate and other infusion parameters to compensate for a potential occlusion. However, if the user has indicated, in block 502, that a bolus is being administered, then a clock and another counter are monitored in block 514. More particularly, processor 31 may determine in block 514 whether an interval of time of when the administration stopped at block 508, now exceeds a specified period in block 502 as the established time delay limit. This delay time limit can be set to a duration that will allow the force within most systems to be reduced below the limit of the occlusion in the absence of an occlusion. In the embodiment of FIG. 8, additional force values are obtained in block 504 prior to the time delay of the clock being reached in block 514. Continuing with FIG. 8, system 10 determines, in block 516, if the current force value is less than the occlusion limit. As before, the value of the occlusion limit can be recovered from the memory 32 before or at step 516. If the current force in the system remains greater than the occlusion limit at block 516, then an occlusion alarm can be generated at block 512. Otherwise, the bolus infusion is restarted in block 520. That is, the trajectory of plunger 16 is reset and the fluid administration is reset to its previous index or to a different index. As suggested by block 518 of Figure 8, the embodiments of the present invention can reset the bolus at a reduced rate. As such, one skilled in the art should note that other modalities may restart a bolus infusion in block 520 at the previous index or at any other infusion index. Allowing the force in the system 10 to relax for a period equal to the delay time limit, together with the reduced index characteristics of block 518, makes possible a bolus infusion so that it does not exceed the occlusion limit and / or initiate a false occlusion alarm. That is, the bolus on and off characteristics of blocks 508 to 520 of FIG. 8, reduce the incidences of a false occlusion, while allowing bolus applications at the highest infusion rates. In any case, the occlusion detection procedures are finalized in block 522. The person skilled in the art will note that the sequence of the steps in all of the included flowcharts may be altered, to include omitted procedures without conflict with the principles of the present invention. Similarly, related or known methods can be incorporated to complement those described herein. In addition, it should be understood that any of the modalities and associated programs described above, is compatible with most known infusion procedures and can be fully optimized to achieve even greater efficiencies. Although the present invention has been illustrated by means of describing the embodiments thereof and although the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to said details. Additional advantages and modifications will be apparent to the person skilled in the art. For example, although this specification was generally focused on a syringe pump, the skilled artisan will recognize that the principles underlying the present invention apply equally to other medical pump systems, to include peristaltic and cassette-based pumps. Additionally, although the force transducers are described above in connection with various embodiments, the pressure transducers may have equal or greater applicability in others that are consistent with the principles of the present invention. For example, a sensor comprising a pressure transducer can be used at the outlet of a syringe or in the tubes. In addition, although the embodiments described herein generally refer to the downstream occlusion, they may equally apply to upstream occlusion detection. As such, a fluid source may comprise a syringe, as well as a bag located upstream. Additionally, the person skilled in the art will notice that the entire slope, time and other value comparisons used to determine the presence of an inclusion can be configured so that a value either higher or lower triggers a given procedure. For example, an alarm of a modality can be initiated in response to a certain slope that is lower or higher than an expected slope, depending on how the system 10 is configured. Additionally, although the slope determinations serve well for Relative comparisons, an adequate expected relationship can alternatively comprise any value that indicates strength within the system. In one modality, an adequate expected relationship can be a product of both the slope and the size of the window. As such, the system 10 can maintain a series of readings of force sensors in a memory or other device 32. A difference in the readings of a force sensor can be compared with the product of the slope and window size, to determine if There is an inequity or another relationship. For example, if the difference in strength values is greater than or equal to the product of the slope and window size, then a detection count may be increased by one. Otherwise, the detection count record may remain unchanged or reset to zero. When the content of the increased detection count record is greater than or equal to that of another occlusion detection counter, an occlusion is declared. In addition, the person skilled in the art will note that, although the methods of the present invention can achieve detection of occlusion with only a single force sensor, embodiments that are consistent with the principles of the present invention can include multiple force sensors and sensor positions. In its broader aspects, the invention is not limited, therefore, to the specific details, representative apparatus and method, as well as illustrative examples shown and described. Accordingly, deviations may be made in relation to said details, without deviating from the spirit or scope of the general concept of the invention.

Claims (61)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for automatically detecting an occlusion in a fluid line 22 of a medical pump system 10, the fluid line 22 being configured to transport a fluid under pressure between a source of fluid 13 and a patient 24, the method comprising: during a pumping sequence, determining a first force value indicating the force in the fluid line 22 at time T1; during the pumping sequence, determining a second force value indicating the force in the fluid line 22 at time T2; and provide an indication of the occlusion if a relationship between the first and second force values deviates from an expected relationship.

2. The method for automatically detecting an occlusion according to claim 1, further characterized in that the fluid source 13 is a syringe 13 and the medical pump system 10 is a syringe pump 10 having a cover 14 adapted to support the syringe 13 containing a plunger 16 movable into the syringe 13 by pushing one end of the plunger 16 with an impeller 17 to eject fluid from an outlet of the syringe to the fluid line 22 connected to the outlet, so as to transporting the fluid under pressure to a patient 24, the method further comprising: mounting the syringe 13 on the cover 14 with the end of the plunger extended; coupling the impeller 17 with the end of the plunger 16; and initiating the pumping sequence to cause the fluid to flow to the fluid line 22.

3. The method for automatically detecting an occlusion in accordance with claim 1 or claim 2, further characterized in that it comprises using a sensor 33 to determine at least one of the first and second force values.

4. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that it comprises not providing any indication of occlusion when the relationship does not deviate from the expected relationship.

5. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that it comprises determining a steady-state condition.

6. The method for automatically detecting an occlusion according to claim 5, further characterized in that determining the steady-state condition further includes determining a period of stable-state starting time.

7. The method for automatically detecting an occlusion according to claim 5 or claim 6, further characterized in that determining the steady-state condition further includes determining a start-time limit.

8. - The method for automatically detecting an occlusion according to any of claims 5 to 7, further characterized in that determining the steady state condition further includes determining a volume of start fluid.

9. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that it comprises determining a window defining at least one of the time T1 and the time T2.

10. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that providing the indication of the occlusion additionally includes at least one of the expected ratio and the relation between the first and second force values.

11. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that providing the indication of the occlusion further includes determining a trial slope using at least one of the first and second force values.

12. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that providing the indication of the occlusion further includes determining an occlusion slope.

13. - The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that providing the indication of the occlusion further includes comparing the expected relationship with the relation between the first and second force values.

14. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that providing the indication of the occlusion further includes comparing an occlusion slope with a trial slope.

15. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that it comprises changing a window to obtain an additional force value.

16. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that it comprises canceling the indication of the occlusion in response to a comparison between a test slope and a cancellation slope.

17. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that determining at least one of the first and second force values further includes determining a count indicating the least one of the first and second force values.

18. The method for automatically detecting an occlusion according to claim 17, further characterized in that it comprises adjusting at least one of the time T1 and the time T2, to avoid fractioning the count.

19. The method for automatically detecting an occlusion according to claim 17 or claim 18, further characterized in that it comprises using a transducer to generate the count.

20. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that it comprises determining a window defining at least one of the time T1 and the time T2.

21. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that providing the indication of the occlusion further includes generating an alarm.

22. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that determining the first force value further includes altering the administration of the fluid.

23. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that determining the first force value further includes altering the fluid administration in response to comparing the first force value with an occlusion limit of bolus.

24. The method for automatically detecting an occlusion according to claim 23, further characterized in that determining the first force value further includes restarting the administration of the fluid after a delay time.

25. The method for automatically detecting an occlusion according to claim 23 or claim 24, further characterized in that determining the first force value includes additionally restarting the fluid administration in response to comparing the first force value with a limit of Bolus occlusion.

26. The method for automatically detecting an occlusion according to any of the preceding claims, further characterized in that providing the indication of the occlusion further includes initiating a corrective action.

27. A method for automatically detecting an occlusion in a fluid line 22 of a medical pump system 10, the fluid line 22 being configured to transport fluid under pressure between a fluid source 13 and a patient 24, the method comprising : during a pumping sequence, determine a first force value that indicates the force in the fluid line at time T1; alter fluid administration if the first force value deviates from an expected value; and automatically restart the fluid administration after a delay period.

28. The method for automatically detecting an occlusion according to claim 27, further characterized in that the fluid source 13 is a syringe 13 and the medical pump system 10 is a syringe pump 10 having a cover 14 adapted to support the syringe 13 containing a plunger 16 movable inside the syringe 13 by pushing one end of the plunger 16 with an impeller 17, to eject the fluid from an outlet of the syringe 13 to the fluid line 22 connected to the outlet, so that the fluid under pressure is transported to a patient 24, the method further comprising: mounting the syringe 13 on the cover 14 with the end of the plunger extended; coupling the impeller 17 with the end of the plunger 16; and initiating a pumping sequence to cause the fluid to flow to the fluid line 22.

29. The method for automatically detecting an occlusion in accordance with claim 27 or claim 28, further characterized by comprising providing an indication of an occlusion. if a second force value that indicates the force in the fluid line at time T2 deviates from the expected value.

30. The method for automatically detecting an occlusion according to any of claims 27 to 29, further characterized in that restarting the fluid administration further includes restarting the administration at a reduced infusion rate.

31. - The method for automatically detecting an occlusion according to any of claims 27 to 30, further characterized in that altering the administration of the fluid further includes determining the delay period.

32. The method for automatically detecting an occlusion according to any of claims 27 to 30, further characterized in that restarting the administration of the fluid further includes determining the delay period.

33. The method for automatically detecting an occlusion according to any of claims 27 to 32, further characterized in that it comprises determining if a b infusion is indicated.

34.- A pumping system comprising: a source of fluid 13; a fluid line 22 configured to transport fluid under pressure between the fluid source 13 and a patient 24; a sensor 33 for determining the first and second force values that indicate the force between the fluid source 13 and the patient 24 taken at times T1 and T2, respectively; a pump 10 configured to generate a force between the fluid source and the patient; and a processor 31 in communication with the pump 10, the processor 31 being configured to execute the program code that determines whether a relation between the first and second force values deviates from an expected relationship.

35. - The pumping system according to claim 34, further characterized in that the pumping system is a syringe pump system for a syringe 13 configured to contain fluid and including an outlet, the pumping system further comprising a cover 14 adapted to hold syringe 13; a plunger 16 having one end and configured to move inside the syringe 13; and an impeller 17 adapted to join with and push the end of the plunger 16, so as to cause the fluid to exit the exit of the syringe 13.

36.- The pumping system according to claim 35, further characterized in that it comprises a syringe 13 configured to contain fluid and including an outlet, the fluid line 22 being connected to the outlet of the syringe.

37.- The syringe pump system according to any of claims 34 to 36, further characterized in that the program code initiates the provision of an indication of an occlusion if the relation between the first and second force values deviates from the expected relationship.

38.- The syringe pump system according to any of claims 34 to 37, further characterized in that the program code initiates the determination of a window defining at least one of the time T1 and the time T2.

39.- The syringe pump system according to any of claims 34 to 38, further characterized in that the program code initiates the determination of at least one of the expected ratio and the relationship between the first and second force values .

40.- The syringe pump system according to any of claims 34 to 39, further characterized in that the expected ratio includes an occlusion slope.

41.- The syringe pump system according to any of claims 34 to 40, further characterized in that the program code starts the comparison of the expected ratio with the relation between the first and second force values.

42.- The syringe pump system according to any of claims 34 to 41, further characterized in that the program code starts the comparison of an occlusion slope with a trial slope.

43.- The syringe pump system according to any of claims 34 to 42, further characterized in that the program code initiates the determination of a third force value that indicates the force between the source of fluid and the patient taken in the timesT2 and T3, respectively.

44.- The syringe pump system according to any of claims 34 to 43, further characterized in that the program code initiates the determination of a third force value that indicates the force between the source of fluid and the patient taken in the times T1 and T3, where T3 is subsequent to T2.

45. - The pumping system according to any of claims 34 to 44, further characterized in that the program code initiates the determination of a steady state condition.

46.- The pumping system according to any of claims 34 to 45, further characterized in that the program code initiates the determination of a count indicating at least one of the first and second force values.

47.- The pumping system according to any of claims 34 to 46, further characterized in that it comprises a transducer configured to generate a count from at least one of the first and second force values.

48. The pumping system according to any of claims 34 to 47, further characterized in that the relation between the first and second force values includes a test slope.

49.- The pump system according to any of claims 34 to 48, further characterized in that the program code initiates the change of a window to obtain an additional force value.

50.- The pump system according to any of claims 34 to 49, further characterized in that the program code initiates the cancellation of the occlusion indication in response to a comparison between a test slope and a cancellation slope.

51. - The pumping system according to any of claims 34 to 50, further characterized in that the program code initiates the alteration of the fluid administration.

52.- The pumping system according to any of claims 34 to 51, further characterized in that the program code initiates the alteration of the fluid administration in response to the comparison of the first force value with a limit of bolus occlusion .

53.- The pumping system according to any of claims 34 to 52, further characterized in that the program code initiates the restart of the fluid administration after a delay time.

54.- The pumping system according to claim 53, further characterized in that the program code initiates the restart of fluid administration in response to the comparison of the first force value with a bolus occlusion limit.

55.- A pumping system comprising: a source of fluid 13; a fluid line 22 configured to transport fluid under pressure between the fluid source 13 and a patient 24; a sensor 33 for determining the first and second force values that indicate the force between the fluid source 13 and the patient 24 taken at times T1 and T2, respectively; a pump 10 configured to generate the force between the fluid source 13 and the patient 24; and a processor 31 in communication with the pump 10, the processor 31 being configured to execute the program code that initiates the alteration of fluid administration in response to the determination that at least one of the first and second force values is move away from an expected value.

56.- The pumping system according to claim 54, further characterized in that the pumping system is a syringe pump system for a syringe 13 configured to contain fluid and that includes an outlet, the syringe pump system including a cover 14 adapted to hold syringe 13; a plunger 16 having one end and configured to move inside the syringe 13; and an impeller 17 adapted to join with and push the end of the plunger 16, so as to cause the fluid to leave the outlet of the syringe 13.

57.- The pumping system according to claim 56, further characterized in that it comprises a syringe configured to contain fluid and that includes an outlet, the line of fluid being connected to the syringe outlet.

58.- The pumping system according to any of claims 55 to 57, further characterized in that the program code initiates the determination of whether a bolus infusion is being administered.

59.- The pumping system according to any of claims 55 to 58, further characterized in that the program code initiates the restart of the fluid administration after a delay period.

60. - The pumping system according to any of claims 55 to 59, further characterized in that the program code initiates the restart of the administration of the fluid at a reduced infusion rate. 61.- A pumping system comprising: a source of fluid 13; a fluid line 22 configured to transport fluid under pressure between the fluid source 13 and a patient 24; a sensor 33 for determining the first and second force values that indicate the force between the fluid source 13 and the patient 24 taken at times T1 and T2, respectively; a pump 10 configured to generate the force between the fluid source 13 and the patient 24; and a processor 31 in communication with the pump 10, the processor 31 being configured to execute the program code that determines the steady state by determining at least one of: a slope, an enlistment status, a start time limit, a volume administered, a start volume and an occlusion time limit.