Bachelorarbeit - Thomas Elser (Hochschule Ulm)

Bachelorarbeit - Thomas Elser (Hochschule Ulm) Bachelorarbeit - Thomas Elser (Hochschule Ulm)

13.01.2014 Aufrufe

Bachelorarbeit Abstract This thesis describes the optimization of a laboratory experiment, which allows the continuous, noninvasive measurement of the arterial blood pressure. Thereby the disadvantages of the invasive measuring can be avoided, for example the risk of bleeding and infection. One possible use is the analysis of the blood circulation control. The used method bases upon the discharge of the arterial wall in case of constant blood flow, which can be approximately determined via the flow velocity. This measured variable is used as input for the pressure control of a wrist cuff, which affects the arterial diameter and thus the blood flow. In case of discharged vascular wall the cuff pressure and the arterial blood pressure could be treated as equivalent. While everybody knows about the blood pressure measurement with cuff and stethoscope, the servo method is rather unknown. This experiment shall help students to become familiar with this technique and to practice on their own. The existing device was built in 1996 as part of a diploma thesis at the University of Applied Sciences in Ulm. The flow velocity is determined by a pulsed ultrasound-doppler. The cuff pressure is created by a compressor, modified with a proportional valve and controlled by an analog system. While using the old device there were often delivered too high blood pressure values. These results shall be improved with the optimization of the experiment. Furthermore, the instrument should be minimized and adapted to the state of the art. First a digital controller is developed. Afterwards the hardware can be adapted on the new control. To operate the functions, to read off the blood pressure values and to reproduce old measurements an operating interface is built. Additionally the fixation of the ultrasound probe will be improved. Last there will be a lot of test measurements to check the function of all components. The optimized laboratory experiment works without errors. In contrary to the old device the new one facilitates physiological blood pressure values. This is achieved by the numerical adaption of the servo method values, which needs another blood pressure measurement with a classical technique. Beside the blood pressure chart the device can also show numerical values for the mean arterial pressure, as well as the systolic/diastolic pressure and for the heart rate. Thomas Elser VI

Bachelorarbeit Inhaltsverzeichnis Eidesstattliche Erklärung .................................................................................................. III Danksagung..................................................................................................................... IV Zusammenfassung ............................................................................................................ V Abstract .......................................................................................................................... VI 1 Einleitung ..................................................................................................................... 1 2 Grundlagen ................................................................................................................... 2 2.1 Blutdruck .................................................................................................................................... 2 2.1.1 Invasive Messung des arteriellen Drucks ......................................................................... 2 2.1.2 Nicht-invasive Messung des arteriellen Drucks ............................................................... 2 2.2 Ultraschall-Doppler-Blutflussmessung ....................................................................................... 6 2.3 Digitale Regelung ........................................................................................................................ 6 2.3.1 Grundprinzip der Regelungstechnik ................................................................................. 6 2.3.2 Besonderheiten der digitalen Regelung ........................................................................... 7 2.3.3 Der PI-Regler .................................................................................................................... 7 2.4 Programmiersprache LabVIEW .................................................................................................. 8 2.5 Valsalva-Press-Versuch ............................................................................................................... 9 3 Aufgabenstellung ........................................................................................................ 10 3.1 Bestehender Versuchsaufbau .................................................................................................. 10 3.2 Anforderungen an den neuen Versuchsaufbau ....................................................................... 11 4 Material und Methoden .............................................................................................. 12 4.1 Realisierung einer digitalen Steuerung/Regelung .................................................................... 12 4.1.1 Programmierung ............................................................................................................ 12 4.1.2 Anpassung der Hardware ............................................................................................... 16 4.2 Anpassung der Messwerte mit alternativem Verfahren .......................................................... 18 4.2.1 Oszillometrische Bestimmung des mittleren arteriellen Blutdrucks ............................. 18 4.2.2 Anpassung der Druckwerte ............................................................................................ 19 4.2.3 Manuelle Eingabe alternativer Werte ............................................................................ 20 Thomas Elser VII

<strong>Bachelorarbeit</strong><br />

Inhaltsverzeichnis<br />

Eidesstattliche Erklärung .................................................................................................. III<br />

Danksagung..................................................................................................................... IV<br />

Zusammenfassung ............................................................................................................ V<br />

Abstract .......................................................................................................................... VI<br />

1 Einleitung ..................................................................................................................... 1<br />

2 Grundlagen ................................................................................................................... 2<br />

2.1 Blutdruck .................................................................................................................................... 2<br />

2.1.1 Invasive Messung des arteriellen Drucks ......................................................................... 2<br />

2.1.2 Nicht-invasive Messung des arteriellen Drucks ............................................................... 2<br />

2.2 Ultraschall-Doppler-Blutflussmessung ....................................................................................... 6<br />

2.3 Digitale Regelung ........................................................................................................................ 6<br />

2.3.1 Grundprinzip der Regelungstechnik ................................................................................. 6<br />

2.3.2 Besonderheiten der digitalen Regelung ........................................................................... 7<br />

2.3.3 Der PI-Regler .................................................................................................................... 7<br />

2.4 Programmiersprache LabVIEW .................................................................................................. 8<br />

2.5 Valsalva-Press-Versuch ............................................................................................................... 9<br />

3 Aufgabenstellung ........................................................................................................ 10<br />

3.1 Bestehender Versuchsaufbau .................................................................................................. 10<br />

3.2 Anforderungen an den neuen Versuchsaufbau ....................................................................... 11<br />

4 Material und Methoden .............................................................................................. 12<br />

4.1 Realisierung einer digitalen Steuerung/Regelung .................................................................... 12<br />

4.1.1 Programmierung ............................................................................................................ 12<br />

4.1.2 Anpassung der Hardware ............................................................................................... 16<br />

4.2 Anpassung der Messwerte mit alternativem Verfahren .......................................................... 18<br />

4.2.1 Oszillometrische Bestimmung des mittleren arteriellen Blutdrucks ............................. 18<br />

4.2.2 Anpassung der Druckwerte ............................................................................................ 19<br />

4.2.3 Manuelle Eingabe alternativer Werte ............................................................................ 20<br />

<strong>Thomas</strong> <strong>Elser</strong><br />

VII

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