Clausen, Jack L.

Gardner, Reed M.

English

The University of Utah: J. Willard Marriott Digital Library

Computer Guidelines for Pulmonary Laboratories This paper has been prepared by rhe Commi rree on Proficiency Standards for Clinical Pulmonary Fu~crio n Labo-rarories for MEMBERSHIP REVIEW AND COMMENT. Please send your wrirren comments to rhe ATS no later than January 4, 1984. Members of the Committee: REED M. G ARDNER, PH.D., Chair JACK L. CLAUSE"', M.D. DAVID). COTIDN, M.D. ROB ERT 0. CRAPO, M.D. GARY R. EPLER. M.D. JOHN L. HANK I:\iSON, PH.D. Inrroduction With the decrease tn size and cost of microprocessors and rhe increase in th eir speed and reliabilit y, most future p ulmonary function instrumentation will probably con-tain some type of digi tal computer. New quality assu rance problems will occur as pul-monary function labo rato ries become more reliant on dig ital computers and assoc iated auromatt on. Whi le ir is important to address these new problems, the advantages offered by digital computers far outweigh the disadvantages. Some typical advantages are: (J) complete automation of a procedure. resulting in sig-n ificant ly red uced rim e and cost, and in increased accuracy; (2) assurance that stan-dard ized p rocedures a re fo llowed; (3) signif-icant reduction in major measurement erro rs (1); (4) srorage and retrieval of information quickly and efficient ly; (5) implementation of automated calibrat ion and system check proced ures within rhe instrum ent; and (6) standardi zed and consistent interpretation of results. When a microprocessor or com purer is added ro instrumentation , rhe performance of rhe entire sys tem must be considered. With ana-log sys tems, rhe concept of accuracy is eas il y understood. Howeve r, when a microprocessor is added to an instrument, software may be-come an important component of overall sys-tem accuracy. For examp le, an ext rem ely ac-curate spirometer has linle advantage if ir is con nected to a microprocesso r wirh a low resolution analog-to-d igital conven er o r if a low sampling rare is used. Likewise, if only eight-bi t signed intege r arithm etic is used , ac-curacy wi ll be compromised . With rhe increase in compl exi ty of software and hardware. ir is ofren difficult for any one indi vidua l to comp letely und erstand all aspects of a computerized sys tem , and erro rs may go und etected for months. In addition , arremprs to correct programs and software problems are ofren complicated by the un -availability of the origi nal software designer or lack of documentation. The improved soft-ware may correct a problem, bur ir may also introduce new problems. Because of the increased utilization of com -puters, comprehensi ve quality assurance guidelines musr cover rhe use of digi tal com-puters. The followi ng minim al guidelines for use of computers in the pulmonary labo ratory are suggested : l. Comprehensive pe rfo rm ance resting is genera lly beyo nd rhe capab ility of most pul-monary function laboratories, and this respo nsibi lity must reside with the m anufac-turer. However, individual use rs should un-dertake an extensive initial review of instru-ment specifications and other technical d ata prior to instrument use or procurem ent. In-deed, provision that such informat ion be provided wirh the instrument should be a condition of purchase. 2. While it may nor be feasible fo r manufac-ture rs ro provide source code listings , they should at a minimum provide flow charrs or an equivalent description of software func-tion. Every labo rato ry should be provided with complete documentation of all proce-dures and parrern recognition algorithms im-plemented within computer software. For ex-ample, with spirometry, documentation of rhe m ethod used for beginning and end of rest determinations should be provided (see DISCUSSION). 3. Every laborato ry must have readily ava il -able, complete documentation of all formu-la(s) and reference equatio ns used to calcul ate and interpret resu lts. For example, the predic-tion equations used to calcu late a patient 's predicted FVC, FEY 1 , ere. , should be provid -ed or referenced. Similarl y, the BTPS co rrec-tion calcu lation technique and the use of barometric pressure in the calculation shou ld be documented . 4. If any software mod ifications or changes . are ant icipated . a la bo rato ry should docu-ment in rhe operati ng manual the personne l auth ori zed to implement software changes and doc ument procedures for implementa-t ion and resting of new software. Software modifications should be evaluated with rhe same caution as hardware changes. 5. Since software may not always be com -plete ly free of m ajo r or minor errors, a soft-ware and hardware perform ance log should be mai ntained. In this log , a ll poss ible and definitive software and hardware errors sho uld be reco rded and repo rted to the ap-propriate personnel. In addit ion , any softwa re m odifications or updates as well as routine p reventi ve and correc ti ve maintenance sho uld be recorded . The dare the changes were im -p lem ented , the reasons for the changes , and any quality assurance resuits (calibration checks) shou ld be entered into the log . 6. Perhaps the greates t potential problem as-sociated with computers is rhe potenti al loss of large am ounts of info rmation stored on a single mass storage m ed ium . Therefore, it is essential that duplicate copies of all clara be m aintained . In addition , rhese copies should be sto red with limited access to prevent inad-vertent destruction . Schedules for developing back-up d iscs or rapes shou ld be estab lished and followed. 7. Since a computer, like any msrrument , is subjecr to malfunctions , procedures to be used in case of computer failure should be es-tablished. 8. For protection of confidentia l patient data, guidelines should be es tablished as to the personnel who have access to inform ation, ac-cess procedures , and software security codes. These computer quality assurance guidelines are minimum guidelines and are neither unique nor exhaustive. Additional guidelines may be necessary fo r som e instruments. Guidelines suggested by rhe man ufacrurer should be followed . Discussion Perhaps rhe most controversial recommenda-tions in this document are the nature and ex-rent of hardware and software documenta-tion . The user, producer, and manufacturer of software have differing and som etimes con-flicting perspectives of software documema-tion . The users need complete documenta-tion , whi le the m anufac turer needs to protect the software fro m unauthorized copying. The m ore innovat ive the software , rhe greater the need for documentation , and the less wi lling the manufacturer may be to provide complete documentation. Howeve r, a reliable method of protecting software from un authori zed copying may also be beneficial to rhe users, since without this protection, manufac turers m ay be reluctant to invest in new inn ovative software development . Regard less of the problems, software users need comple te docum entation of the soft-ware, or at a minimum, sufficient informa-tion ro determine how data are manipulated within the instrument . As with any scientific experi ment, rhe methods used to conduct the experiment must be sufficiemly documented so th at rhe experimem can be repeated else-where. There are ar least four differem methods of software doc umentation: 1. Software source code listing furnished by the manufacturer. This documentat ion meth -od should allow duplication of rhe method , bu r m ay be difficult for rhe indi vidual user to comprehend , particularly if the source code is in assembl y language or a software language (Contin11<!d on IJeXI page) FALL 1984 • ATS News I 7 -Computer Guidelines in which the user is not proficient . 2. Flow cham provided by the manufac turer instead of source code listings. This documen-tation method should be somewhat indepen-dent of software language, but has the disad-vantage of not being entirely accurate or as complete as source code lis tings. 3. A narrative provided by the manufacturer giving a brief description of software func-tion. This documentat ion method would pro-vide the least complete documentation and therefore is least desirable. 4. Software performance evaluation conducted by the manufacturer. An entirely different approach is to validate the software instead of providing complete documentation . Stan-dard raw data could be provided to the manufac turers by the ATS , and each manu-facturer could provide the user with the re-sults of the analysis of this raw data. For exam-ple, a set of 24 standard spirometric wave-forms could be provided for each spirometer manufacturer. Instead of providing source code list ings, the manufacturer could elect to provide results for FVC, FEY" peak flow, etc., using this software to analyze the standard raw data. For the single breath DLco . a set of typical volume time curves with breath-hold-ing could be provided to each manufac turer. The manufacturer could then provide the user with the corresponding breath-holding times and inspired volumes obtained when the manufacturer's software was used to ana-lyze these raw data. DLc o values could also be calculated if gas concentrations were provided . This documentation method pro-vides very little actual software documenta-tion fo r the user, but does provide some fun c-tional information of the methods used to perform various calculations and measure-ments. However, it may be difficult to pro-duce standard raw data sets in a form which can be used by all manufacturers. For exam-ple, manufacturers may use different sam-pling rates and different analog-to-digital conveners. Some spirometer manufacturers sample volume as a function of time, while others sample time as a fun ction of volume. In summary, there are obvious conflicts be-tween the needs of the user and the needs of the manufacturer to protect software . Since the results of any test are very dependent on the methods used , the user must be provided with detailed documentation of methods im-plemented within software. This documenta-tion must be sufficient for the user to under-stand software function as clearly as with manual measurements and calculations. References L Gardner RM, Crapo R, Bill ings RG , Shezeoka JW, Hankinson JL Spirometry- what paper speed. Chest 1983:84(2); 161- 65 . 8 I ATS News • FALL 1984 COURSES AND WORKSHOPS 8th Annual Infectious Diseases in Clinical Practice, January 19-26, 1985, Steamboat Springs, CO, sponsored by University of California San Francisco, School of Medicine, Division of Infectious Diseases and Extended Programs in Medical Education . The pro-gram is designated for primary care physicians, including internists, pediatricians, family and general practitioners, and emergency medicine specialists. It offers 24 credit hours in Category I of the Physicians Recognition Award of the AMA and the Certification Pro-gram of the California Medical Association . It is acceptable for 24 prescribed hours by the American Academy of Family Physicians and 24 hours in Category I by the American College of Emergency Physicians. Allied health CME credits are also available. Fees: $350 for physicians; physician's assistants, nurse practitioners, nurses and other allied health professionals, $300; interns and residents, $250. For information contact Extended Pro-grams in Medical Education, University of California San Francisco, San Francisco, CA 94143 , or phone (415} 666-4251 (program information) (415} 666-5808 (registration in-form.ation ). Postgraduate Courses on Clinical Management and Control of Tuberculosis, January 21-25, 1985, National Jewish Hospital and Research Center/National Asthma Center, 3800 E. Colfax Ave., Denver, CO, sponsored by National Jewish Hospital and Research Center, National Asthma Center. Tuition fee $325 . Reduced fee for physicians in train-ing. Program is acceptable for 38 prescribed hours by the American Academy of Family Physicians. NJHRC/NAC designates th is CME activity for 38 credit hours in Category I of the Physician's Recognition Award of the AMA. This program has also been ap-proved for 38 contact hours by the Colorado Nurses' Association. For information contact TB Course Office, Dept. of Medicine, National Jewish Hospital and Research Center, 3800 E. Colfax Ave. , Denver, CO 80206. 28th Annual Midwinter Conference on Chest Disease, January 23-28, 1985 , Snowbird Ski Resort, UT, sponsored by the Intermountain Thoracic Society. The Snowbird Meet-ing offers first rate medical education (17 hours of Category I) in an informal alpine at-mosphere with prime time skiing on the "greatest snow on earth." For information and program contact Intermountain Thoracic Society, 1930 S. 1100 East, Salt Lake City, UT 84105 or phone (801) 484-4456. Seventh Annual Pulmonary Wintercourse,January 24-27, 1985, Contemporary Hotel in the Magic Kingdom , Lake Buena Vista, FL, sponsored by the Florida Thoracic Society and cosponsored by The University of Florida College of Medicine, The University of Mi-ami School of Medicine and The University of South Florida College of Medicine. The course is designed for practicing internists, family physicians, pediatricians, thoracic sur-geons, anesthesiologists, respiratory therapists and technicians with a special interest in pulmonary disorders. This CME activity meets the criteria for 19.5 credit hours in Cate-gory I of the Physicians Recognition Award of the American Medical Association, is ac-ceptable for 19.5 prescribed hours by the American Academy of Family Physicians and 19.5 credit hours in Category 2-D by the American Osteopathic Association. For infor-mation contact Florida Thoracic Society, P.O. Box 8127 , Jacksonville, FL 32239 or phone (904} 743-2933. Winter Retreat: Update on Pulmonary Disorders, February 4-6, 1985 , The Wintergreen Resort, Wintergreen, VA. Major topics of discussion include Management of COPD, Evolving Diagnostic Techniques in Pulmonary Embolism, and Exercise Testing, and new advances in the treatment of cancer. Each morning includes didactic presentations as well as case discussions from the lectures. This program meets the criteria of 12 credit hours in Category I of the Physician's Recognition Award of the American Medical As-sociation , 12 prescribed hours by the American Academy of Family Practice and 1.2 Con-tinuing Education Units by the Virginia Commonwealth University. The course fee is $250.00 for physicians and $135.00 for physicians in training and all health care profes-sionals. For further information, please contact: Beth Winn, Continuing Medical Educa-tion , .Box 48 - MCV Station, Richmond, VA 23298, or phone (804) 786-0494. 2nd International Symposium on Current Topics in Infectious Diseases, February 9- 16, 1985, Grindelwald, Switzerland, sponsored by University of California, San Francisco, School of Medicine .• Division of Infectious Diseases and Extended Programs in Medical Education, in cooperation with Division of Infectious Diseases, University of Geneva Hospital. A distinguished group of infectious disease specialists and clinical microbiolo-gists from Europe and the United States will discuss areas of infectious diseases that are controversial or have changed significantly in recent years. The emphasis will be on clini-cal problems that relate to patient care. Pathogenesis and pathophysiology will be intro-(Continued on page 10) 

Computer Guidelines for Pulmonary Laboratories

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Computer Guidelines for Pulmonary Laboratories

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