Dupont, Robert

Pryor, T. Allan

English

The University of Utah: J. Willard Marriott Digital Library

A MLM Based Order Entry System:The Use of Knowledge in a Traditional HIS ApplicationT. Allan Pryor*, Robert Dupont** and Julie Clay*** LDS Hospital **3M CorporationAbstractA new order entry system has been developed on the HELPsystem utilizing the extensive HELP knowledge basecapabilites. Rather than use tables to control site specificcharacteristics of the ordering system, the new order entrysystem uses Medical Logic Modules (MLM's) to store andexecute site specificfeatures. Using the MLM the user is notonly able to set traditionalparameters, but enter medical logicto control patientlhospital specific requirements and executecritiquing logic on the order. Simple knowledge editors areprovided which make the creation of the order MLM's nomore difficult than those programs used to define the sitespecific parameters of traditional systems.A major requirement in the design of an order entry systemfor a Hospital Information System (HIS) is the need for thatsystem to be sufficiently robust to be installed at differentsites where each site could impose specific needs to thesystem. At a minimum these needs might include site costs,special tests, specific departmental data requirements, etc.Additional site requirements are generated when the siteattempts to incorporate medical logic in the ordering system.Traditionally, the HIS applications have been designed toprovide this site flexibility through site specific tables enterdby the user and utilized by the applications. The applicationprograms have generally been written to incorporate in theapplication code a fixed set of features and functionsrequired by the user and then programmed to access sitespecific tables for information which when used by theapplication meets the requirement needs of the site.Incorporation of new features, however, generally requires arewrite of the programs and update of the information whichis stored in the disc based tables. Use of expert knowledgein assisting/critiquing the transactions of the application havenormally not been incorporated into the functionality of theapplications since maintenance of this logic is beyond thedesign of traditional order entry applications. Thus, theprograms have concentrated on the clerical andadministrative tasks of the application and ignored themedical requirements.Using the knowledge based architecture of the HELPsystem, a new approach has been taken for the developmentof HIS applications in general and the order entry applicationin particular. This approach uses the Medical Logic Module(MLM) rather than a table as the structure for recording theparameters of an order. The MLM is a knowledgerepresentation used to represent modular expert knowledgein a standard shareable format which results in compiledexecutable code on a target system. This form of knowledgerepresentation is currently under development as a standard0195-4210/90/0000/0579$01.00 1990 SCAMC, Inc.for sharing knowledge between centers and represents thethinking of several centers in the creation of ways to sharethe research being done at those centers. Use of the MLM asthe structure for recording site specific information for theorder adds several new capabilities to the site forcreation/execution of the order. Traditional systems whichprovide tables are limited to the control of procedure codes,ranges, or special parameters which may have beenincorporated into the ordering model by the designer of thesystem. With the MLM, because of its knowledge structure,the user cannot only adjust the order parameters controlledby the basic design of the system, but add any logicstatements requested by the user. A classic example of this isillustrated in medication ordering. Under classical systemsthe user may define the site specific formulary and for eachmedication in the formulary set its appropriate dose ranges,routes, and schedules. These systems may also haveincorporated some drug - drug interactions, but the user isunable to add any other alerting/critiquing knowledge to theorder. With the MLM as the model for incorporation of sitespecific information, it naturally allows the user afterentering in the dose range, route and schedule, to easily addany alerting/critiquing logic which may be appropriate fortheir site. The logic added by the user is not restricted to onlydrug-drug interactions, but may incorporate logic using anyof the data elements stored in the patient record. Because ofknowledge editors provided for creation of order specificMLM's, the user in creation of the MLM's enters the logicand parameters using a program of no more complexity thanthat provided by traditional table based systems in the settingof the order parameters. A second advantage of the MLMapproach is the run time execution of relatively simplecompiled code rather than execution of a more complexprogram which must at run time read the appropriate tablesand from those tables decide at run time the appropriate logicto be executed. Finally, because the system is executingMLM's, it may invoke MLM's which have been developedfor other applications and reside in the MLM knowledgebase. Likewise, the MLM's created for this application maybe used by other applications where appropriate. Forexample, the check of the medication order againstlaboratory values may be used in the background to monitorlaboratory values as well as critique the medication order.Figure 1 outlines the basic BELP system architecture used toexecute the MLM's. As seen in the flgure the HELP systemconsists of a patient database, a knowledge base consistingof MLM's and application specific managers which serve asexpert inference engines which access MLM's in theknowledge base. Under this architecture an applicationmanager can access anyMLM which exists in the knowledgebase and any MLM can access any other MLM. The mainpurpose of the application manager is to control thenavigation to the appropriate MLM's and serve as a global579Figure 1Architecture of HELP Application Programsmemory for the application. In so doing, its memory servesas the blackboard for the MLM's accessed during atransaction. The MLM's in the knowledge base areaccessible by any application manager and therefore existindependent of any particular application. With themodularization of the application, the expert can easilymanage the knowledge(MLM's) through knowledge editorsprovided by HELP. MLM's have traditionally been availablein HELP to provide alerting, critiquing and managementdecisions. These decisions, both data driven and userinteractive, have been one of the important features ofHELP.In development of the MLM based order entry application,extensive use of the HELP architecture was required. Themajor use was to model each type of order as a knowledgeframe. That is, it was necessary to design for clinicallaboratory tests a MLM structure, for xray orders a separateMLM structure, etc. Within each MLM structure slots weredefined to incorporate the necessary knowledge for the typeof order. While structures are different for each type of test itis easier to illustrate the system by considering a single classof orders. Figure 2 illustrates the MLM structure used indefining a clinical laboratory test order. The first slot Testholds the name of the test actually being ordered. The next 9slots describe the information needed to complete alaboratory test order. These slots include the order priority,specimen type, order start and discontinue time, etc. Whenthese slots are instantiated they will contain defaultinformation that will serve as the initial suggestions to theparameters needed to complete the order. The next slotPatient Specific Knowledge is used to store a referenceto another MLM where logic would exist to modify thedefault parameters of the test order. Execution of this MLMmay result in modification of the order based on logicevaluated from data in the patient record. Logic within thisframe can additionally perform administrative and/or clinicalchecks. This slot is optional if no patient specific frame hasbeen developed for this order.The final slot Critiquing Knowledge contains a referenceto a MLM used to critique the order. This frame is executedafter the user has reviewed and accepted the order.Following the execution of the critique a message/alert couldbe transmitted to the user indicating need for modification ofthe order. The message/alert may also be sent to anotherapplication on HELP. Again, this slot is optional in theframe and is included only when a critiquing MLM has beenwritten for the specific order.580L iTest: <The test to be ordered>Department: <The department receiving the order>Priority: <The priority of the test>Frequency: <Number of times order is to be repeated>Start Time: <Date when series order is to begin>Stop Time: <Date when series order is to be discontinued>Available: <Availability of specimen>Specimen: <Specimen type on which test is to be performed>Location: <Location where report is to be sent>Comments: <Comments>Patient Specific: <MLM containing patient specific knowledge>Critique: <MLM containing critiquing knowledge>Figure 2Definition of the MLM forFor otier classes of orders different slots would be required.Common, however, to all models are the Patient SpecificKnowledge slot and the Critiquing Knowledge slot.For example, the xray order may require a Transportationslot and a Special Handling slot as a part of the model forordering the xray, but would still have available the PatientSpecific Knowledge and Critiquing Knowledgeslot. Design of the system is really design therefore of themodels for each class of order.Using this MLM model, an MLM is instantiated for everypossible order which could be made by the system. Figure 3represents an instantiated MLM for a PTT order. Theinstantiated MLM contains information which might havebeen included in tables used in traditional design and thereferences to the expert logic modules which will beprocessed at the time of execution of the order. The figureillustrates logic that might be contained in the Patient Specificand Critiquing MLM's for that order. To create the set ofinstantiated MLM's an order knowledge editor has beenwritten. The editor allows the expert/nowledge engineer tocreate an order MLM. In creating/editing the MLM the usersets the default slots and enters the references to the PatientSpecific MLM and the Critiquing MLM. On completion ofthe editing, theMLM is compiled for use in the system. Thishas the effect of creation of a small compiled program whichis designed to have the functionality necessary for theordering application. That is, it will include within thecompiled MLM data presentation logic, data entry logic andprocedural logic necessary for execution of the MLM on theHELP system. If any of the procedural presentation logicrequirements change, each of the MLM's are recompiled bythe modified knowledge editor to incorporate the currentrequirements. Since the expert defined knowledge iscontained in the MLM it need not be reentered at the time ofrecompilation. The addition of the presentation, data entry,Clinical Laboratory Ordersand procedural knowledge to the compiled MLM ensuresthat each MLM will be implemented in a common mannerthroughout the system. This knowledge is contained in theknowledge editor and is key to the success of the system.This knowledge determines how the MLM is presented tothe user and controls the performance of the system. Theprocedural knowledge entered by the editor will interface theexecution of the MLM to the architecture of HELP. We arecurrently exploring the use of a commercial applicationgenerator to assist in the creation of the knowledge editor.The fimal MLM needed for implementation of the system isthe order manager module. This module is written using theHELP PAL language rather than the knowledge editors dueto the extensive use of procedural information contained inthe application manager. It controls the use of the testspecific order MLM's and permits easy navigation tosupporting functionality. Control of the test specific orderMLM's occurs upon entry into the order manager. The useris asked to enter a mnemonic identifying the test to beordered. This mnemonic is used as a key to link to theappropriate order MLM. The order manager is responsiblefor transmitting to the order MLM any globalinformation/parameters necessary for proper execution of theorder frame. Navigation to supporting functionality, such aschanging patient id, review of patient orders, or review ofpatient data is facilitated in the order manager. At any pointin the ordering process the user can request, via a functionkey, to be transferred to a supporting function. Thesesupporting functions are in fact other MLM's which havebeen written to support that particular function. The ordermanager is responsible for transmitting relevant information,such as the patient's name, to the MLM responsible for thesupporting function. The manager will also retrieve relevantinformation from the MLM executing the supporting581Test: PTTDepartment: Clinical LaboratoryFrequency: 1Priority: RoutineAvailable: Lab GetsSpecimen: BloodLocation: Nursing DivisionPatient Specific: MLM 20:13:3iCritiquing: MLM 20:13:36Figure 3Example of an OrderMLM andits Associated Logic MLM'sfunction. In the case of reviewing patient orders, thoseorders chosen by the user forreorder would be retrieved andused to establish initial defaults as well as provide the link tothe appropriate order MLM. The manager holds all ordersfor a user session. It permits modification of the orderswithin a session and allows storage of the orders at anytimewithin the session. Once the orders are stored, the interfaceprograms of HELP transmit the orders to the appropriatedepartments for execution and generation of the billingtransactions for use by the financial system.Because of this unique architecture, the ordering system caneasily invoke the logic MLM's which contain both patientspecific, critiquing, and alerting knowledge. Since the MLMcan contain logic covering all aspects of the HELP systemthe knowledge incorporated into the MLM can containknowledge/rules specific to the patient, the test or the doctorwho requested the order. Specific site controlledadministrative logic could be just as easily incorporated intothe MLM as patient specific knowledge. A simple exampleof patient specific logic would be changing the priority of theorder from routine to stat when the patient was located in theemergency room. In this example the Patient Specific MLMchecks the room location and if the patient is in anemergency room, it changes the priority of the order to statand returns to the order frame. An example of administrativeknowledge which could be easily entered could betransmission of the blood sample to the appropriate locationfor analysis dependent on patient location, time of day, etc.An example of knowledge in a Critiquing MLM for orderinga laboratory test would be to check the medications whichthe patient is taking and alert the user if one of themedications could interfere with the results of a laboratorytest. If such an interference was noted a message could besent to the user suggesting discontinuance of the drug orawareness of the potential interference which could cause inthe results of the test. If the drug were not discontinued, theinterference alert could then also be displayed at the time ofreview of the results of the laboratory test. Other examplesinclude knowledge of adverse reactions to some dyes used inxray procedures, awareness of patient data which may becrucial to the ordering process, suggestions of more costeffective tests to accomplish the same function, etc. Thepower of the system really comes in the use of theknowledge which could be written and evaluated at the timeof execution of the order.Currently the system as described here works only withsingle orders. Modeling is now underway to extend theMLM structures to include order sets. Order set models arebeing developed based on both ordering physician andpatient problem. Models involving order sets will beextended to include set logic which can determinedynamically which orders in the set are approprate at a givenorder session. By incorporating into an ordering system thetype of knowledge discussed here, we feel that the systemwill have greater benefit to the physician. Traditionalordering systems have not been well accepted by thephysician since they primarily are only clerical in theirfunctionality. We believe that through the introduction ofknowledge in the ordering process, we will provide to thephysician a tool to enhance his management of the patient.This process linked to the other decision modules of HELPshould provide us with a system which is perceived by thephysician as a tool which assists him/her in the care of thepatient rather than require him/her to become a clericalperson.582Author: PryorMessage: Emergent PriorityVariables: Room, PriorityLogic: If Room EQ Emergency thenPriority := Stat;Author: PryorMessage: Prothrombin Time may be decreaseddue to concurrent use of DiureticsVariables: Diuretics, OrderLogic: If Diurectics and Order EQ PTTthan Conclude TrueV'ReferencesPryor TA, Warer HR, Gardner RM, Clayton PD, Haug PJ.The HELP System Development Tools. In: ImplementingHealth Care Information Systems, Orthner and Blumeditors, pp 365-383, 1989Pryor TA, Gardner RM, Clayton PD, Warner HR. TheHELP system. Journal of Medical Systems, Vol. 7 No.2 pp87-102, 1983.Ostler MR, Stansfield JD, Pryor TA. A new, efficientversion of HELP. Proc of the Ninth Annual Symposium onComputer Applications in Medical Care, pp 296-297,November 1985.Pryor TA, Clayton PD, Haug PJ, Wigertz O. Design of aKnowledge Driven HIS. Proc of the Eleventh AnnualSymposium on Computer Applications in Medical Care, pp60-63, 1987.Clayton PD, Pryor TA, Wigertz OB, Hripcsak G. Issuesand Structures for Sharing Medical Knowledge AmongDecision-Making Systems: The 1989 Arden HomesteadRetreat. Thirteenth Annual Symposium on ComputerApplications in Medical Care, pp 116-121, 1989.583

A MLM-Based Order Entry System: The Use of Knowledge in a Traditional HIS Application

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A MLM-Based Order Entry System: The Use of Knowledge in a Traditional HIS Application

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