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Entwicklung eines prototypen zur prognose von frühgeburten ein biomedizintechnischer ansatz

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  1. Tez No: 400013
  2. Yazar: HAKAN OFLAZ
  3. Danışmanlar: P. MALLMANN
  4. Tez Türü: Doktora
  5. Konular: Tıbbi Biyoloji, Medical Biology
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 2012
  8. Dil: İngilizce
  9. Üniversite: Universität zu Köln
  10. Enstitü: Yurtdışı Enstitü
  11. Ana Bilim Dalı: Belirtilmemiş.
  12. Bilim Dalı: Belirtilmemiş.
  13. Sayfa Sayısı: 133

Özet

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Özet (Çeviri)

Newborns are defined as a ?preterm? if the gestational age is younger than 37 weeks, and ?fullterm? stands for births taking place between 37-42 weeks of gestation. Prelabour rupture of membrane (PROM) can occur in both at fullterm and preterm births. When birth occurs at fullterm without any PROM is called normal birth (NB). Similarly, if the birth occurs at preterm without any PROM is called preterm birth (PRB). However, if PROM occurs at fullterm, it is called prelabour rupture of membrane birth (PROMB), and if the PROM occurs at preterm then it is called preterm prelabour rupture of membrane birth (PPROMB).PRBs are one of the most frequent causes of mortality during or after birth. The etiology of PRB is inadequately understood and many biochemical investigations have been undertaken in an attempt to find the cause, or causes. In most pregnancies, labor begins at full term with intact fetal membranes. However, PROM occurs in 10% of pregnancies at full term and exceed 40% of pregnancies at preterm.The fetal membranes, chorion and amnion, form together a ~0.5 mm thin bi-layer that serves as a barrier and a container throughout gestation. The mechanical integrity of the fetal tissue is crucial for maintaining a healthy gestation. Altered tissue biomechanics can cause drastic changes in the labor type by contributing to premature cervical dilation and delivery.Mechanical rupture of membranes is a part of the natural sequence for full term delivery. However, serious complications can arise if the membrane is ruptured prior to proper term length. In surviving infants, morbidity is often severe and includes chronic lung disease, neurologic sequela such as blindness, white matter damage and periventricular leukomalacia. Understanding the mechanical behavior of fetal membranes is a necessary issue for attempting to prognoses or even prevent prelabour ruptures in both full-term and pre-term. Significant information exists on the mechanical structure of amnion and chorion and their general relation to membrane strength.Reduction of the collagen in tissue, affects the tensile strength of the membrane. Changes in the viscoelastic properties are affecting the tissue?s ability to adjust to stretch forces caused by mechanical tissue damage (perhaps by realignment or disruption of interconnections of collagen fibers). Viscoelasticity is also an important factor in predicting the rupture of membranes. A lower Stress-Strain ratio as well as membrane stretching may cause the membrane to rupture.The identification of mechanical characteristics of fetal membrane may help in understanding the mechanisms involved in rupture before the onset of labor. This knowledge is also essential in order to understand the role of fetal membrane changes associated with prelabour rupture. The purpose of this study was to examine the mechanical properties of the fetal membrane in order to interpret the causality of prelabour ruptures and preterm births. Furthermore, the results of this study were used to design a risk assessment profile and diagnostic tool, capable of prognosticating prelabour ruptures and preterm delivery.A device (DIMPAST) capable of making in-vitro measurements was designed in three steps, and has become the basis for further potential projects. The DIMPAST uses different measurement techniques such as laser triangulation, air pressure measurement, and optical coherence tomography. A total of 87 fetal membranes were collected and analyzed before designing a new probe in this study. Samples from the 45 FMs used for comparing the thickness between histologic and OCT methods to prove the OCT?s reliability, were fixed with a formaldehyde solution (3.7 %) and stored at 4 oC until they were tested later that day. Then the other 42 FM samples used for the evaluation of mechanical properties were prepared and stored at 4 oC before being tested.The significance of the differences between the groups was calculated using Mann-Whitney rank sum test. The results of the study showed three important characteristics and are outlined as: Membranes do get thicker as the gestational time increases however, it should not be interpreted that thicker membranes are stronger. Stronger membranes do not rupture before labor begins. The average stress-strain ratio and the bursting pressure of PRB?s fetal membranes are significantly higher than those for of other types of membranes. Results from the three different measurement methods for each type of birth were summarized to draw conclusions. The three primary interests of this part of the study were the total thickness, the bursting pressure, and the average Stress-strain ratio for each type of fetal membrane.According to these hopeful results, a new OCT probe was designed and manufactured. Preliminary data that was observed with a new OCT probe is willing hope for the future and its results are in correlation with the results which were taken with the DIMPAST, so the new probe can be used in clinical researches after improving its reliability.In conclusion, this study provides an understanding of the complex relationship between the biomechanical structure of the fetal membrane and the prelabour rupture of the fetal membrane, which is the first step when predicting the likelihood of a preterm birth. The study also offers a new diagnostic probe for clinical praxis.

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