Thesis (MScIng)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Conventional pulse oximetry has limited accuracy in measuring blood oxygen saturation
in low saturation and perfusion scenarios. This limits the application of
pulse oximetry in patients su ering from peripheral vascular a ictions.
A novel pulse oximetry system is presented in this study which proposes solutions
to these low saturation and perfusion issues. The presented system was
designed to overcome the low perfusion issues by inducing an arti cial pulse in the
detected photoplethysmograph. A novel arterio-venous hypothesis was formulated
to extract arterial and venous saturation data from this arti cial photoplethysmograph
using arterial-to-venous compliance ratios. Sensor wavelengths were selected
to provide high and low saturation accuracy, followed by an in vitro sensor calibration
procedure. System performance was validated by means of in vivo human
studies.
In vivo results indicate good accuracy for high saturation, with limited accuracy
in low saturation scenarios. The arterio-venous hypothesis was validated, indicating
that venous saturation information can be extracted from the arti cial PPG.
Although inconclusive, results indicate that the proposed system might be able
to accurately monitor arterial and venous saturation in severe hypoperfusion scenarios
with recommended hardware and calibration modi cations. It is recommended
that further studies into the presented system's performance are conducted. / AFRIKAANSE OPSOMMING: Konvensionele 'pulse oximetry' sisteme het beperkte akkuraatheid tydens die meting
van bloed suurstof saturasie in lae saturasie en perfusie gevalle. Dit beperk die
bruikbaarheid van 'pulse oximetry' in pasiënte wat ly aan perifere vaskulêre siektes.
'n Nuwe 'pulse oximetry' sisteem, wat oplossings vir hierdie lae saturasie en
perfusie beperkings voorstel, word in hierdie studie aangebied. Die voorgestelde
sisteem is ontwerp om die lae perfusie beperkings te oorkom deur 'n kunsmatige
polsslag in die 'photoplethysmograph' te induseer. 'n Nuwe arterio-veneuse hipotese
is geformuleer om arteriële en veneuse saturasie inligting uit hierdie kunsmatige
polsslag te onttrek deur middel van 'n arteriële-teenoor-veneuse styfheids verhouding.
Die gol engtes wat gebruik is in die sensors, is spesi ek gekies om hoë en
lae saturasie akkuraatheid te verskaf. 'n In vitro kalibrasie prosedure is gevolg om
die sensors vir hoë en lae saturasie te kalibreer, waarna die werkverrigting van die
sisteem getoets is deur middel van 'n in vivo validasie prosedure.
Die in vivo resultate toon goeie akkuraatheid vir hoë saturasie, met beperkte
akkuraatheid vir lae saturasie. Die arterio-veneuse hipotese is gevalideer, wat aandui
dat veneuse saturasie wel uit die kunsmatige 'photoplethysmograph' onttrek
kan word.
Alhoewel die resultate wat in hierdie studie aangebied word nie omvattend of
beslissend is nie, dui dit egter aan dat die voorgestelde sisteem dalk in staat kan
wees om arteriële en veneuse saturasie in uiters lae perfusie gevalle te meet. Verbeteringe
sal egter aan die sisteem aangebring moet word in terme van hardeware
en kalibrasie, om 'n meer gestandardiseerde metings metode te verseker. Verdere
navorsing oor die werkverrigting van die voorgestelde sisteem word ook voorgestel.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21460 |
| Date | 03 1900 |
| Creators | Schoevers, Jacobus Engelbertus |
| Contributors | Scheffer, C., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xiv, 133 leaves : ill. |
| Rights | Stellenbosch University |
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