Müller-Esch, G.

Peters, A.

Scriba, Peter Christian

English

Peters, Achim

Open Access LMU

Band 31 • Heft 1-2 Januar/Februar 1986 Biomed ica l Engineer ing Hcmediziiiisdie Technik Gemeinschaftsorgan der Deutschen*, der österreichischen und der Schweizerischen Gesellschaft für Biomedizinische Technik Publication of the German, Austrian and Swiss Association on Biomedical Engineering Herausgeber/Editors: Prof. Dr.-lng. U. Boenick, Fachgebiet Biomedizinische Technik, Technische Universität Berlin, Dovestraße 6, D-1000 Berlin 10 Prof. Dr. M. Schaldach, Zentralinstitut für Biomedizinische Technik der Universität Erlangen-Nürnberg, Turnstraße 5, D-8520 Erlangen Redaktion/Editorial Staff: Prof. Dr.-lng. U. Boenick, Fachgebiet Biomedizinische Technik, Technische Universität Berlin, Dovestraße 6, D-1000 Berlin 10, Tel. 030/3145112 (Deutschland) Prof. Dr. techn. S. Schuy, Institut für Elektro- und Biomedi-zinische Technik der Universität Graz, Inffeldgasse 18, A-8010 Graz, Tel. 0043316/77511/7390-92 (Österreich) Prof. Dr. sc. nat. M. Anliker, Institut für Biomedizinische Technik der Universität Zürich und ETHZ, Mousson-straße 18, CH-8044 Zürich, Tel. 00411/2564582 (Schweiz) Wissenschaftlicher Beirat/Editorial Board: Prof. Dr.-lng. O. Anna, Hannover Prof. Dr. med. K. Hammacher, Tübingen Prof. Dr. med. P. Heintzen, Kiel Prof. Dr. med. F. Heuck, Stuttgart Prof. Dr. med. D. Hohmann, Erlangen Prof. Dr.-lng. W. Irnich, Gießen Prof. Dr. med. H. Just, Freiburg Prof. Dr. med. H. Keller, St. Gallen Prof. Dr. rer. nat. H. Kresse, Erlangen Prof. Dr. med. H. Lutzeyer, Aachen Prof. Dr. med. J. D. Meyer-Erkelenz, Aachen Prof. Dr. rer. nat. H. Pfeift, Gießen Prof. Dr. med. G. Vossius, Karlsruhe Inhalt/Contents: Seite/Page A. Peters, G. Müller-Esch, P. C. Scriba: Simplified Evaluation and Documentation of Data from Glucose-Controlled Insulin Infusion Systems, Part II: Artefact Handling 2 Computerunterstützte Datenauswertung und Doku-mentation beim Einsatz glukosekontrollierter Insulin-Infusionssysteme, Teil II: Artefaktbehandlung H. J. Marsoner: Elektroanalyse in Körperflüssigkeiten mit ionen-sensitiven Sensoren (Teil II) 5 Electrolyte Analysis in Body Fluids with Ion Selective Electrodes (Part II) P. Eyerer, R. Jin: Einfluß der Anrührbedingungen von PMMA-Knochen-zementen auf deren Eigenschaften, Teil 2: Analyse des Anrührvorganges 11 Influence of the Mixing Technique on the Properties of PMMA Bone Cement, Part 2: Analysis of the Mixing Procedure B. Kurz, W. Diebschlag, F. Stumbaum: Portables Druckverteilungsmeßsystem für biomecha-nische Gangspuranalysen 19 Portable Device for the Measurement of Pressure Distribution for Use in Biomechanical Gaitanalysis Mitteilungen der Deutschen, der österreichischen und der Schweizerischen Gesellschaft für Biomedizi-nische Technik 25 Dissertationen /Habilitationen 27 Kongresse/Veranstaltungen 28 Buchbesprechungen 29 Neues aus Forschung und Industrie 30 Verlag/Publishing Company: Fachverlag Schiele & Schön GmbH Postfach 610280, Markgrafenstraße 11, D-1000 Berlin 61 Telefon-Sammei-Nr. 030/2516029 Telex 181470 sundsd Die Geschäftsstelle der Deutschen Gesellschaft für Biomedizini-sche Technik e.V. befindet sich beim Fachverlag Schiele & Schön GmbH (Anschrift siehe oben) Hinweise für Autoren/Hints for Authors: Eine Kurzfassung der Hinweise für Autoren befindet sich auf der 3. Umschlagseite dieses Heftes. Die ausführliche Fassung kann beim geschäftsführenden Redak-teur oder beim Verlag angefordert werden. 2 Glucose Controlled Insulin Infusion Systems Biomedizinische Technik Band 31 Heft 1-2/1986 Biomed. Technik 31 (1986), 2 - 5 A.. Peters G. Müller-Esch P. C. Scriba Simplified Evaluation and Documentation of Data from Glucose-Controlled Insulin Infusion Systems Part II: Artefact Handling Computerunterstützte Datenauswertung und Dokumentation beim Einsatz glucosekontrollierter Insulin-Infusionssysteme Teil II: Artefaktbehandlung Klinik für Innere Medizin (Prof. Dr. P. C. Scriba) Medical University of Lübeck I Federal Republic of Germany Key-words: Glucose-controlled insulin infusion, artificial beta cell, data processing, artefact handling A computerized method for handling artefacts occurring during recording and evaluation of data with glucose-controlled insulin infusion systems (GCIIS) is demonstrated: 1) Recording phase: - »Interrupt«-Mode: Maintenance of the original l inear data- t ime relation is achieved by using an additional time channel. Analogous structuring of t ime- and parameter data files permits correct correlation. - »Communication I/O error«: An error-handling subroutine prevents the interruption of the program caused by lead characters which occur when restarting the GCIIS thereby disturbing GCIIS-microcomputer communication. - Risk of data loss caused by power failure is minimized by an appropriate interaction between intermediate store and floppy disk. 2) Evaluation phase: - Implausible data: Obstruction of double lumen catheter as well as loss of glucose sensor sensitivity result in inappropriate data with consecutive incorrect computation of glycemic indices such as MAGE and M-value. - Zero-values: In the »HOLD«-mode, all blood glucose values are set to zero by the GCIIS causing forbidden arithmetic operations. These artefact periods are marked in the prepared time-file, deleted and interpolated subsequently. In conclusion, our method permits automatic artefact handling during the recording phase and complete correct data processing during the evaluation phase. Schlüsselwörter: Glucosegesteuerte Insulin-Infusion, künstliche Beta-Zelle, Meßdatenver-arbeitung, Artefaktbehandlung Eine computerunterstützte Methode zur Behandlung von Artefakten bei der Aufzeichnung und Auswertung von Daten glucosegesteuerter Insulin-Infusions-Systeme (GCIIS) wird vor-gestellt: 1. Aufzeichnungsphase: - »INTERRUPT«-Mode: Ein zusätzlicher Zeitkanal ermöglicht die Aufrechterhaltung der originalen Zeit-Daten-Relation. Die analoge St ruktur der Zeit- und Parameterdateien erlaubt es, den jeweiligen Meßwerten den Zeitpunkt der Messung zuzuordnen. - »Communication I/O error«: Ein übergeordnetes Fehlerprogramm verhindert den Pro-grammabbruch durch steuerzeichenbedingte Störung der Datenübertragung vom GCIIS zum Mikrocomputer. - Das Risiko des Datenverlustes durch Stromausfall wird durch geeignete Wechselbezie-hungen zwischen Floppy-Disk und Zwischenspeicher reduziert. 2. Aus wert ungsphase: - Nicht plausible Daten: Verstopfung des Doppellumenkatheters sowie Defekt der Glu-coseoxidasemembran führen zu Falschbestimmungen der Blutglucose und damit zu falsch berechneten descriptiven Parametern wie MAGE und M-Value. - Null-Werte: Im »HOLD«-Mode werden alle Blutglucosewerte vom GCIIS gleich Null gesetzt. Bei der Berechnung der glycämischen Parameter treten nicht definierte ar i th-metische Ausdrücke auf. Diese Artefaktperioden werden in der Zeitdatei gekennzeichnet, ausgeschlossen, und nachträglich werden die fehlenden Werte interpoliert. Die Methode erlaubt die automatische Behebung von Störungen während der Datenaufzeich-nung und vollständige, korrekte Auswertung von GCIIS-Daten. Biomedizinische Technik Band 31 Heft 1-2/1986 Glucose Controlled Insulin Infusion Systems 3 Introduction Recently we have published a method which permits complete processing of data from glucose-controlled insulin infusion systems (GCIIS) [1]. Our device has proved to be particularly useful in the improvement of conventional subcutaneous insulin therapy in diabetes mellitus, as well as in the treatment of acute myocardial infarction with feedback controlled glucose-insulin-potassium therapy [2]. However, data handling is often disturbed by several undesired events: - Interruption of the GCIIS control period because of technical or clinical problems or break of electric current results in stop of data flow from the GCIIS to the microcomputer. - Obstruction of the doublelumen catheter or defect of the glucose sensor produce implausible data, which have to be excluded subsequently (fig. 1). Therefore, we developed a BASIC computer-program for the detection, evaluation and exclusion of artefacts from the GCIIS. TIME 10:00 -BLOOD GLUCOSE (mg/d l ) 0 100 200 300 400 500 11 00 -• 12:00 -13:00 u.-oo INTERRUPT HOLD - Sensor p r o b l e m s O b s t r u c t i o n of c a t h e t e r 0 100 200 300 400 500 INSULIN INFUSION RATE (mU/min) Fig. 1. Original plot of blood glucose (BG) and insulin infusion rate (IR) obtained from the GCIIS during an insulin hypogly-caemia test demonstrat ing common problems of data re-cording: 1. At 10.50 »INTERRUPT«-Mode is started and results in stop of data flow for 6 minutes. 2. After restart ing GCIIS at 10.56 communication 1/0 error occurs, which would lead to program break. 3. »HOLD«-Mode from 10.58 to 11.00 sets blood glucose levels to zero. 4. Obstruction of doublelumen catheter produces implau-sible value at 13.25. Methods: I. Artefact handling during the recording phase 1. »INTERRUPT«-Mode: Technical and clinical problems sometimes make it necessary to stop feedback controlled insulin/dextrose infusion by »INTERRUPT«-Mode. During this mode blood glucose is no longer measured by the GCIIS and neither insulin/dextrose infusion nor transmission of data to the microcomputer takes place. As a result, GCIIS data do no longer appear in their time related position in the computer-plot. Therefore a major goal of data processing must be to restore the original linear data-time relation. This implies simul-taneous transmission and recording of parameters (fig. 2) [blood glucose (BG), insulin infusion rate (IR), dextrose infusion rate (DR)] and time by two seperated analogous files. Parameters from the intermediate store are transmitted to the floppy disk in 30-minute inter-vals. Identical structure of time file and parameter file allows analogous treatment. Thus, correct correlation between parameters and time is possible. In case of »INTERRUPT«-Mode or break of current the missing interval is replaced by line feed in the plot. TIME PARAMETERS BG DR IR GCIIS 11:17:271 1080 000 2501 COMMENTS [DRIFTCHECKl KEYBOARD INTERFACE MICRO -COMPUTER FLOPPY- ^ INTERMEDIATE STORE COMPUTER MODULE DISK 1 17 \2U BG.DR.IR DR 1 FTC 1 1 7 . 2 5 H E C K . . 1 1 7 : 2 4 TIME FILE PARAMETER FILE TEXT FILE Fig. 2. 1. Input parameter data contain of 9 bits (3x3 bits), which are reduced by storage procedure to 6 bits (3x2 bits) using special characters. 2. During storage procedure one redundant bit (first colon) is omitted to achieve analogous structure of time and para-meter file. The remaining colon later on is used for marking artefacts. 3. Any comment entered via keyboard is stored in its time related position with a maximum of 24 bits. A further problem concerning »INTERRUPT«-Mode is »Communication 1/0 error« which occurs after restart-ing the GCIIS. In these cases specific constants (body weight, basal insulin infusion rate, etc.) are printed by the GCIIS and transferred by the interface to the microcomputer. This data sequence contains lead-characters disturbing GCIIS-microcomputer commu-nication, which results in break of the program. This problem is dealt with by means of an error handling subroutine: If such lead characters occur, input and output chan-nels are closed. A loop proves if utilizable data are received. Not until information without disturbing lead 4 Glucose Controlled Insulin Infusion Systems Biomedizinische Technik Band 31 Heft 1-2/1986 characters is transmitted, all channels are reopened and recording continues. This kind of interruption effects only a one-minute pause. 2. Break of electric circuit Two technical problems result from breakdown of electric circuit: - Although it lasts only a few seconds until the emer-gency current is started, parameters from the inter-mediate store are cleared. - Files are not regularly finished by »CLOSE «-demand. Such incomplete files cannot be recalled from floppy-disk. Break of current may occur at any program-step regardless whether channels are still open or already closed. Thus, it is necessary to coordinate input and output channels by time sharing to keep the storage procedure-implying open channels - in comparison to the storage interval as short as possible. A long storage interval increases the risk of data-loss from the intermediate store; a short one that of com-plete data-loss from floppy disk as a result of circuit-breakdown occuring during the storage procedure. Further, mechanical overload of disks is more likely to occur with a short storage-interval. As a compromise we choose a 30-minute storage interval, so that a maximum of 30 triplets (G, DR, IR) is lost and the risk of interruption during the vulnerable storage phase is about 1:1000. II. Artefact handling during the evaluation phase There are several reasons for recording false values: - Obstruction of the doublelumen catheter results in an inappropriate decrease of blood glucose levels. - Defect of the glucose sensor produces implausible data. - During »HOLD«-Mode all blood glucose values are set to zero. Therefore an additional channel is applied: Comments concerning these different artefacts may be entered via keybord, stored on floppy disk (fig. 2) and finally printed in their time related position (fig. 1). However, all these artefacts cannot definitely be dealt with, until the original GCIIS control period is finished, because the identification of implausible or systematic errors requires experience in GCIIS-handling. Exclu-sion of these artefacts is especially important for the calculation of descriptive parameters such as MAGE [3], M-value [4], MBG etc. and calculation of infinite-zimal parameters as slopes and areas under the curve (AUC). Zero values of blood glucose (»HOLD«-Mode) cause forbidden arithmetic operations as division by zero. Sudden decrease of blood glucose (defect of the glucose sensor) falsifies the determination of MAGE, slopes and AUC. Subsequent deletion of these artefacts is managed by a subroutine reduplicating the original time-file and marking those time-points where artefacts are identified (fig. 3). In the printer-plot the missing values of an artefact interval are, interpolated linearly. The excluded period is marked on the time scale (fig. 4). Thus, step wiese exclusion of artefacts with subsequent time scale marking is achieved and maintenance of the original documentation is guaranteed. ORIGINAL FILE ARTEFACT FILE 1 1 7 : 2 8 1 1 7 : 2 8 1 1 7 : 2 9 1 1 7 : 2 9 1 1 7 : 3 0 1 1 7 * 3 0 1 1 7 : 3 1 —* 1 1 7 * 3 1 1 1 7 : 3 2 1 1 7 : 3 2 -ARTEFACT -ARTEFACT Fig. 3. For exclusion of artefacts the original time file is re-duplicated. The position of the remaining colon (fig. 2) is used to mark the t ime-point where artefacts are identified. BLOOD GLUCOSE (mg/d l ) 0 100 200 300 400 500 11:00 12:00 -13:00 -u.-oo 0 100 200 300 400 INSULIN INFUSION RATE (mU/min ) 500 Fig. 4. Original data plot from fig. 1 after exclusion of ar te-facts during the evaluation phase. Missing data during »INTERRUPT«-Mode are interpolated. Inappropriate low (obstruction of double catheter) or zero blood glucose values (»HOLD«-Mode) have been marked on the time scale (black bars) and linearly interpolated, too. Results: Fig. (1) and fig. (4) show as an example the stepwise handling of artefacts during a GCIIS guided insulin hypoglycaemia test. During the recording phase (fig. 1) an error handling subroutine prevents break of programm, which would have taken place after restarting the GCIIS at 10.56 as Biomedizinische Technik Band 31 Heft 1-2/1986 Elektroanalyse mit ionensensitiven Sensoren 5 a result of »Communication I/O error«. Data transmis-sion continues after having only paused for a one minute interval. Automatic interpolation of the missing recording periods during »INTERRUPT«-Mode and »Communication I/O error« maintains linear time-scale. During the evaluation phase (fig. 4) implausible BG data, i.e. zero during »HOLD«-Mode, inappropriately low during obstruction of the doublelumen catheter, are deleted and interpolated subsequently. In conclusion our method sucessfully deals with the various problems which may occur during the record-ing of GCIIS data. It permits complete and correct data processing during the recording and the evaluation phase. Only by this, further computing, e.g. calculation of descriptive glycaemic parameters, slopes and areas under the curve, is possible. R e f e r e n c e s : [1] Müller-Esch, G., A. Peters, M. Göhl, K. Heidbüchel, P. C. Scriba: Simplified evaluation and documentation of data from glucose controlled insulin infusion systems (GCIIS). Biomedizinische Technik 4 (1984), 6 2 - 6 6 [2] Müller-Esch, G , P : Ball, U. Bekemeyer, H. Djonlagic, A. Hauptmann, K. Heidbüchel, A. Peters, R. Tybussek, W. G. Wood, P. C. Scriba: Glucose-insulin-potassium therapy guided by a glucose-controlled insulin infusion system in acute myocardial infarction. In: Osswald, P. M. (editor): Computers in critical care and pulmonary medicine. Springer-Verlag Berlin, Heidelberg, New York, Tokyo (1985), 252-258 [3] Service, F. J., G. D. Molnar, J. W. Rosevear, E. Ackermann, L. C. Gatewood, W. F. Taylor: Mean ampli tude of glycemic excursions, a measure of diabetic instability. Diabetes 19 (1979), 644-6.55 [4] Schlichtkrull, J., O. Munck, M. Jersild: The M-value, an index of blood sugar control in diabetics. Acta. Med. Scand. 177 (1965), 95 -102 2 6 8 Anschrift des Verfassers: Dr. med. Achim Peters Klinik für Innere Medizin Medizinische Universität zu Lübeck Ratzeburger Allee 160 D-2400 Lübeck 1 

Mean amplitude of glycemic excursions, a measure of diabetic instability.

Scriba: Glucose-insulin-potassium therapy guided by a glucose-controlled insulin infusion system in acute myocardial infarction.

Simplified evaluation and documentation of data from glucose controlled insulin infusion systems (GCIIS).

The M-value, an index of blood sugar control in diabetics.

Simplified evaluation and documentaion of data from glucose-controlled insulin infusion Systems: Part. II: Artefact handling

Universität München: Elektronischen Publikationen

Band 31 • Heft 1-2 Januar/Februar 1986 
Biomed ica l Engineer ing 
Hcmediziiiisdie Technik 
Gemeinschaftsorgan der Deutschen*, der österreichischen und der Schweizerischen Gesellschaft 
für Biomedizinische Technik 
Publication of the German, Austrian and Swiss Association on Biomedical Engineering 
Herausgeber/Editors: 
Prof. Dr.-lng. U. Boenick, Fachgebiet Biomedizinische 
Technik, Technische Universität Berlin, Dovestraße 6, 
D-1000 Berlin 10 
Prof. Dr. M. Schaldach, Zentralinstitut für Biomedizinische 
Technik der Universität Erlangen-Nürnberg, Turnstraße 5, 
D-8520 Erlangen 
Redaktion/Editorial Staff: 
Prof. Dr.-lng. U. Boenick, Fachgebiet Biomedizinische 
Technik, Technische Universität Berlin, Dovestraße 6, 
D-1000 Berlin 10, Tel. 030/3145112 (Deutschland) 
Prof. Dr. techn. S. Schuy, Institut für Elektro- und Biomedi-
zinische Technik der Universität Graz, Inffeldgasse 18, 
A-8010 Graz, Tel. 0043316/77511/7390-92 (Österreich) 
Prof. Dr. sc. nat. M. Anliker, Institut für Biomedizinische 
Technik der Universität Zürich und ETHZ, Mousson-
straße 18, CH-8044 Zürich, Tel. 00411/2564582 (Schweiz) 
Wissenschaftlicher Beirat/Editorial Board: 
Prof. Dr.-lng. O. Anna, Hannover 
Prof. Dr. med. K. Hammacher, Tübingen 
Prof. Dr. med. P. Heintzen, Kiel 
Prof. Dr. med. F. Heuck, Stuttgart 
Prof. Dr. med. D. Hohmann, Erlangen 
Prof. Dr.-lng. W. Irnich, Gießen 
Prof. Dr. med. H. Just, Freiburg 
Prof. Dr. med. H. Keller, St. Gallen 
Prof. Dr. rer. nat. H. Kresse, Erlangen 
Prof. Dr. med. H. Lutzeyer, Aachen 
Prof. Dr. med. J. D. Meyer-Erkelenz, Aachen 
Prof. Dr. rer. nat. H. Pfeift, Gießen 
Prof. Dr. med. G. Vossius, Karlsruhe 
Inhalt/Contents: Seite/Page 
A. Peters, G. Müller-Esch, P. C. Scriba: 
Simplified Evaluation and Documentation of Data from 
Glucose-Controlled Insulin Infusion Systems, Part II: 
Artefact Handling 2 
Computerunterstützte Datenauswertung und Doku-
mentation beim Einsatz glukosekontrollierter Insulin-
Infusionssysteme, Teil II: Artefaktbehandlung 
H. J. Marsoner: 
Elektroanalyse in Körperflüssigkeiten mit ionen-
sensitiven Sensoren (Teil II) 5 
Electrolyte Analysis in Body Fluids with Ion Selective 
Electrodes (Part II) 
P. Eyerer, R. Jin: 
Einfluß der Anrührbedingungen von PMMA-Knochen-
zementen auf deren Eigenschaften, Teil 2: Analyse 
des Anrührvorganges 11 
Influence of the Mixing Technique on the Properties of 
PMMA Bone Cement, Part 2: Analysis of the Mixing 
Procedure 
B. Kurz, W. Diebschlag, F. Stumbaum: 
Portables Druckverteilungsmeßsystem für biomecha-
nische Gangspuranalysen 19 
Portable Device for the Measurement of Pressure 
Distribution for Use in Biomechanical Gaitanalysis 
Mitteilungen der Deutschen, der österreichischen und 
der Schweizerischen Gesellschaft für Biomedizi-
nische Technik 25 
Dissertationen /Habilitationen 27 
Kongresse/Veranstaltungen 28 
Buchbesprechungen 29 
Neues aus Forschung und Industrie 30 
Verlag/Publishing Company: 
Fachverlag Schiele & Schön GmbH 
Postfach 610280, Markgrafenstraße 11, D-1000 Berlin 61 
Telefon-Sammei-Nr. 030/2516029 
Telex 181470 sundsd 
Die Geschäftsstelle der Deutschen Gesellschaft für Biomedizini-
sche Technik e.V. befindet sich beim Fachverlag Schiele & Schön 
GmbH (Anschrift siehe oben) 
Hinweise für Autoren/Hints for Authors: 
Eine Kurzfassung der Hinweise für Autoren befindet sich auf 
der 3. Umschlagseite dieses Heftes. 
Die ausführliche Fassung kann beim geschäftsführenden Redak-
teur oder beim Verlag angefordert werden. 
2 Glucose Controlled Insulin Infusion Systems 
Biomedizinische Technik 
Band 31 Heft 1-2/1986 
Biomed. Technik 
31 (1986), 2 - 5 
A.. Peters 
G. Müller-Esch 
P. C. Scriba 
Simplified Evaluation and Documentation of Data from Glucose-
Controlled Insulin Infusion Systems 
Part II: Artefact Handling 
Computerunterstützte Datenauswertung und Dokumentation beim Einsatz 
glucosekontrollierter Insulin-Infusionssysteme 
Teil II: Artefaktbehandlung 
Klinik für Innere Medizin (Prof. Dr. P. C. Scriba) 
Medical University of Lübeck I Federal Republic of Germany 
Key-words: Glucose-controlled insulin infusion, artificial beta cell, data processing, artefact 
handling 
A computerized method for handling artefacts occurring during recording and evaluation of 
data with glucose-controlled insulin infusion systems (GCIIS) is demonstrated: 
1) Recording phase: 
- »Interrupt«-Mode: Maintenance of the original l inear data- t ime relation is achieved by 
using an additional time channel. Analogous structuring of t ime- and parameter data files 
permits correct correlation. 
- »Communication I/O error«: An error-handling subroutine prevents the interruption of 
the program caused by lead characters which occur when restarting the GCIIS thereby 
disturbing GCIIS-microcomputer communication. 
- Risk of data loss caused by power failure is minimized by an appropriate interaction 
between intermediate store and floppy disk. 
2) Evaluation phase: 
- Implausible data: Obstruction of double lumen catheter as well as loss of glucose sensor 
sensitivity result in inappropriate data with consecutive incorrect computation of glycemic 
indices such as MAGE and M-value. 
- Zero-values: In the »HOLD«-mode, all blood glucose values are set to zero by the GCIIS 
causing forbidden arithmetic operations. These artefact periods are marked in the 
prepared time-file, deleted and interpolated subsequently. 
In conclusion, our method permits automatic artefact handling during the recording phase and 
complete correct data processing during the evaluation phase. 
Schlüsselwörter: Glucosegesteuerte Insulin-Infusion, künstliche Beta-Zelle, Meßdatenver-
arbeitung, Artefaktbehandlung 
Eine computerunterstützte Methode zur Behandlung von Artefakten bei der Aufzeichnung 
und Auswertung von Daten glucosegesteuerter Insulin-Infusions-Systeme (GCIIS) wird vor-
gestellt: 
1. Aufzeichnungsphase: 
- »INTERRUPT«-Mode: Ein zusätzlicher Zeitkanal ermöglicht die Aufrechterhaltung der 
originalen Zeit-Daten-Relation. Die analoge St ruktur der Zeit- und Parameterdateien 
erlaubt es, den jeweiligen Meßwerten den Zeitpunkt der Messung zuzuordnen. 
- »Communication I/O error«: Ein übergeordnetes Fehlerprogramm verhindert den Pro-
grammabbruch durch steuerzeichenbedingte Störung der Datenübertragung vom GCIIS 
zum Mikrocomputer. 
- Das Risiko des Datenverlustes durch Stromausfall wird durch geeignete Wechselbezie-
hungen zwischen Floppy-Disk und Zwischenspeicher reduziert. 
2. Aus wert ungsphase: 
- Nicht plausible Daten: Verstopfung des Doppellumenkatheters sowie Defekt der Glu-
coseoxidasemembran führen zu Falschbestimmungen der Blutglucose und damit zu falsch 
berechneten descriptiven Parametern wie MAGE und M-Value. 
- Null-Werte: Im »HOLD«-Mode werden alle Blutglucosewerte vom GCIIS gleich Null 
gesetzt. Bei der Berechnung der glycämischen Parameter treten nicht definierte ar i th-
metische Ausdrücke auf. Diese Artefaktperioden werden in der Zeitdatei gekennzeichnet, 
ausgeschlossen, und nachträglich werden die fehlenden Werte interpoliert. 
Die Methode erlaubt die automatische Behebung von Störungen während der Datenaufzeich-
nung und vollständige, korrekte Auswertung von GCIIS-Daten. 
Biomedizinische Technik 
Band 31 Heft 1-2/1986 Glucose Controlled Insulin Infusion Systems 3 
Introduction 
Recently we have published a method which permits 
complete processing of data from glucose-controlled 
insulin infusion systems (GCIIS) [1]. Our device has 
proved to be particularly useful in the improvement of 
conventional subcutaneous insulin therapy in diabetes 
mellitus, as well as in the treatment of acute myocardial 
infarction with feedback controlled glucose-insulin-
potassium therapy [2]. However, data handling is often 
disturbed by several undesired events: 
- Interruption of the GCIIS control period because of 
technical or clinical problems or break of electric 
current results in stop of data flow from the GCIIS to 
the microcomputer. 
- Obstruction of the doublelumen catheter or defect of 
the glucose sensor produce implausible data, which 
have to be excluded subsequently (fig. 1). 
Therefore, we developed a BASIC computer-program 
for the detection, evaluation and exclusion of artefacts 
from the GCIIS. 
TIME 
10:00 -
BLOOD GLUCOSE (mg/d l ) 
0 100 200 300 400 500 
11 00 -• 
12:00 -
13:00 
u.-oo 
INTERRUPT 
HOLD - Sensor p r o b l e m s 
O b s t r u c t i o n of c a t h e t e r 
0 100 200 300 400 500 
INSULIN INFUSION RATE (mU/min) 
Fig. 1. Original plot of blood glucose (BG) and insulin infusion 
rate (IR) obtained from the GCIIS during an insulin hypogly-
caemia test demonstrat ing common problems of data re-
cording: 
1. At 10.50 »INTERRUPT«-Mode is started and results in 
stop of data flow for 6 minutes. 
2. After restart ing GCIIS at 10.56 communication 1/0 error 
occurs, which would lead to program break. 
3. »HOLD«-Mode from 10.58 to 11.00 sets blood glucose 
levels to zero. 
4. Obstruction of doublelumen catheter produces implau-
sible value at 13.25. 
Methods: 
I. Artefact handling during the recording phase 
1. »INTERRUPT«-Mode: 
Technical and clinical problems sometimes make it 
necessary to stop feedback controlled insulin/dextrose 
infusion by »INTERRUPT«-Mode. 
During this mode blood glucose is no longer measured 
by the GCIIS and neither insulin/dextrose infusion nor 
transmission of data to the microcomputer takes place. 
As a result, GCIIS data do no longer appear in their 
time related position in the computer-plot. Therefore a 
major goal of data processing must be to restore the 
original linear data-time relation. This implies simul-
taneous transmission and recording of parameters 
(fig. 2) [blood glucose (BG), insulin infusion rate (IR), 
dextrose infusion rate (DR)] and time by two seperated 
analogous files. Parameters from the intermediate store 
are transmitted to the floppy disk in 30-minute inter-
vals. Identical structure of time file and parameter file 
allows analogous treatment. Thus, correct correlation 
between parameters and time is possible. In case of 
»INTERRUPT«-Mode or break of current the missing 
interval is replaced by line feed in the plot. 
TIME PARAMETERS 
BG DR IR 
GCIIS 11:17:271 1080 000 2501 
COMMENTS 
[DRIFTCHECKl KEYBOARD 
INTERFACE 
MICRO -
COMPUTER 
FLOPPY- ^ 
INTERMEDIATE STORE 
COMPUTER MODULE 
DISK 
1 17 \2U BG.DR.IR DR 1 FTC 
1 1 7 . 2 5 H E C K . . 
1 1 7 : 2 4 
TIME FILE PARAMETER 
FILE 
TEXT FILE 
Fig. 2. 
1. Input parameter data contain of 9 bits (3x3 bits), which are 
reduced by storage procedure to 6 bits (3x2 bits) using 
special characters. 
2. During storage procedure one redundant bit (first colon) is 
omitted to achieve analogous structure of time and para-
meter file. The remaining colon later on is used for marking 
artefacts. 
3. Any comment entered via keyboard is stored in its time 
related position with a maximum of 24 bits. 
A further problem concerning »INTERRUPT«-Mode is 
»Communication 1/0 error« which occurs after restart-
ing the GCIIS. In these cases specific constants (body 
weight, basal insulin infusion rate, etc.) are printed by 
the GCIIS and transferred by the interface to the 
microcomputer. This data sequence contains lead-
characters disturbing GCIIS-microcomputer commu-
nication, which results in break of the program. This 
problem is dealt with by means of an error handling 
subroutine: 
If such lead characters occur, input and output chan-
nels are closed. A loop proves if utilizable data are 
received. Not until information without disturbing lead 
4 Glucose Controlled Insulin Infusion Systems 
Biomedizinische Technik 
Band 31 Heft 1-2/1986 
characters is transmitted, all channels are reopened 
and recording continues. This kind of interruption 
effects only a one-minute pause. 
2. Break of electric circuit 
Two technical problems result from breakdown of 
electric circuit: 
- Although it lasts only a few seconds until the emer-
gency current is started, parameters from the inter-
mediate store are cleared. 
- Files are not regularly finished by »CLOSE «-
demand. 
Such incomplete files cannot be recalled from floppy-
disk. Break of current may occur at any program-step 
regardless whether channels are still open or already 
closed. Thus, it is necessary to coordinate input and 
output channels by time sharing to keep the storage 
procedure-implying open channels - in comparison to 
the storage interval as short as possible. 
A long storage interval increases the risk of data-loss 
from the intermediate store; a short one that of com-
plete data-loss from floppy disk as a result of circuit-
breakdown occuring during the storage procedure. 
Further, mechanical overload of disks is more likely to 
occur with a short storage-interval. As a compromise 
we choose a 30-minute storage interval, so that a 
maximum of 30 triplets (G, DR, IR) is lost and the risk of 
interruption during the vulnerable storage phase is 
about 1:1000. 
II. Artefact handling during the evaluation phase 
There are several reasons for recording false values: 
- Obstruction of the doublelumen catheter results in 
an inappropriate decrease of blood glucose levels. 
- Defect of the glucose sensor produces implausible 
data. 
- During »HOLD«-Mode all blood glucose values are 
set to zero. 
Therefore an additional channel is applied: Comments 
concerning these different artefacts may be entered via 
keybord, stored on floppy disk (fig. 2) and finally 
printed in their time related position (fig. 1). 
However, all these artefacts cannot definitely be dealt 
with, until the original GCIIS control period is finished, 
because the identification of implausible or systematic 
errors requires experience in GCIIS-handling. Exclu-
sion of these artefacts is especially important for the 
calculation of descriptive parameters such as MAGE 
[3], M-value [4], MBG etc. and calculation of infinite-
zimal parameters as slopes and areas under the curve 
(AUC). Zero values of blood glucose (»HOLD«-Mode) 
cause forbidden arithmetic operations as division by 
zero. Sudden decrease of blood glucose (defect of the 
glucose sensor) falsifies the determination of MAGE, 
slopes and AUC. Subsequent deletion of these artefacts 
is managed by a subroutine reduplicating the original 
time-file and marking those time-points where 
artefacts are identified (fig. 3). In the printer-plot the 
missing values of an artefact interval are, interpolated 
linearly. The excluded period is marked on the time 
scale (fig. 4). Thus, step wiese exclusion of artefacts 
with subsequent time scale marking is achieved 
and maintenance of the original documentation is 
guaranteed. 
ORIGINAL FILE ARTEFACT FILE 
1 1 7 : 2 8 1 1 7 : 2 8 
1 1 7 : 2 9 1 1 7 : 2 9 
1 1 7 : 3 0 1 1 7 * 3 0 
1 1 7 : 3 1 —* 1 1 7 * 3 1 
1 1 7 : 3 2 1 1 7 : 3 2 
-ARTEFACT 
-ARTEFACT 
Fig. 3. For exclusion of artefacts the original time file is re-
duplicated. The position of the remaining colon (fig. 2) is used 
to mark the t ime-point where artefacts are identified. 
BLOOD GLUCOSE (mg/d l ) 
0 100 200 300 400 500 
11:00 
12:00 -
13:00 -
u.-oo 0 100 200 300 400 
INSULIN INFUSION RATE (mU/min ) 
500 
Fig. 4. Original data plot from fig. 1 after exclusion of ar te-
facts during the evaluation phase. Missing data during 
»INTERRUPT«-Mode are interpolated. Inappropriate low 
(obstruction of double catheter) or zero blood glucose values 
(»HOLD«-Mode) have been marked on the time scale (black 
bars) and linearly interpolated, too. 
Results: 
Fig. (1) and fig. (4) show as an example the stepwise 
handling of artefacts during a GCIIS guided insulin 
hypoglycaemia test. 
During the recording phase (fig. 1) an error handling 
subroutine prevents break of programm, which would 
have taken place after restarting the GCIIS at 10.56 as 
Biomedizinische Technik 
Band 31 Heft 1-2/1986 Elektroanalyse mit ionensensitiven Sensoren 5 
a result of »Communication I/O error«. Data transmis-
sion continues after having only paused for a one 
minute interval. Automatic interpolation of the missing 
recording periods during »INTERRUPT«-Mode and 
»Communication I/O error« maintains linear time-
scale. 
During the evaluation phase (fig. 4) implausible BG 
data, i.e. zero during »HOLD«-Mode, inappropriately 
low during obstruction of the doublelumen catheter, 
are deleted and interpolated subsequently. 
In conclusion our method sucessfully deals with the 
various problems which may occur during the record-
ing of GCIIS data. It permits complete and correct data 
processing during the recording and the evaluation 
phase. 
Only by this, further computing, e.g. calculation of 
descriptive glycaemic parameters, slopes and areas 
under the curve, is possible. 
R e f e r e n c e s : 
[1] Müller-Esch, G., A. Peters, M. Göhl, K. Heidbüchel, P. C. 
Scriba: Simplified evaluation and documentation of data 
from glucose controlled insulin infusion systems (GCIIS). 
Biomedizinische Technik 4 (1984), 6 2 - 6 6 
[2] Müller-Esch, G , P : Ball, U. Bekemeyer, H. Djonlagic, A. Hauptmann, K. Heidbüchel, A. Peters, R. Tybussek, W. 
G. Wood, P. C. Scriba: Glucose-insulin-potassium therapy 
guided by a glucose-controlled insulin infusion system in 
acute myocardial infarction. In: Osswald, P. M. (editor): 
Computers in critical care and pulmonary medicine. 
Springer-Verlag Berlin, Heidelberg, New York, Tokyo 
(1985), 252-258 
[3] Service, F. J., G. D. Molnar, J. W. Rosevear, E. Ackermann, 
L. C. Gatewood, W. F. Taylor: Mean ampli tude of glycemic 
excursions, a measure of diabetic instability. Diabetes 19 
(1979), 644-6.55 
[4] Schlichtkrull, J., O. Munck, M. Jersild: The M-value, an 
index of blood sugar control in diabetics. Acta. Med. 
Scand. 177 (1965), 95 -102 
2 6 8 
Anschrift des Verfassers: 
Dr. med. Achim Peters 
Klinik für Innere Medizin 
Medizinische Universität zu Lübeck 
Ratzeburger Allee 160 
D-2400 Lübeck 1 


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Simplified evaluation and documentaion of data from glucose-controlled insulin infusion Systems: Part. II: Artefact handling

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