Among all organs, lungs are the last ones to grow and develop fully. As a result, extreme premature neonates may suffer from respiratory failure due to their immature lungs and will require respiratory support in the form of mechanical ventilation or extracorporeal membrane oxygenation (ECMO). In addition, extreme prematurity is recognized as the primary cause of neonatal morbidity and mortality. The conventional standard of care for respiratory support of preterm neonates with respiratory failure are invasive and may lead to long-term morbidities and complications. Hence, a non-invasive respiratory support technique named “Artificial Placenta” has been developed to address the issues and challenges associated with the current technologies. An artificial placenta type device is one designed to provide required oxygenation in room air via non-invasive access to the umbilical vessels without the need of any external pump. In this thesis, microfluidic and microfabrication technologies have been employed in the development of a pumpless neonatal lung assist device (LAD) for preterm neonates in two approaches: 1) design and develop novel microfabrication techniques to fabricate advanced microfluidic blood oxygenators with high gas exchange capacity and reduced form factor and 2) design and construct several modular LADs based on the oxygenators that were developed to fulfill the required gas transfer needs for these babies. The new microfluidic blood oxygenators with double-sided gas transfer channels were found to enhance oxygenation up to 343 % in room air and be easily scaled-up to achieve higher gas exchange capacities without a noticeable increase in priming volume. Furthermore, this microfabrication method has been utilized to make the largest all PDMS ultra-thin double-sided blood oxygenator with higher gas exchange capabilities. Also, a novel composite material made of PDMS and PTFE was introduced that conferred high flexibility to the oxygenator to decrease the form factor of such devices. This device was one of the first microfluidic blood oxygenators with enough flexibility to be deformed, bent, or rolled without limitation and losing its functionality. In order to satisfy the gas transfer need of these preterm neonates, few microfluidic-based modular LADs were constructed to support different birth weights up to 2 kg. The main design criteria for such a LAD in this research was low pressure drops (capable of being operated by a baby’s heart), an oxygen transfer of 1.3 – 1.9 mL min-1 kg-1 of body weight (or an increase in oxygen saturation level from ~ 75 % to ~ 100 % and ideally in room air), and low priming volume (less than 10 % of the total blood volume of a baby). These LADs first were evaluated in vitro to measure their gas exchange capacities and those which could meet needed oxygenation would be tested in vivo. For the first time, it was shown that a pumpless microfluidic-based LAD could support a newborn piglet and provide adequate oxygenation in room air or the oxygen-rich environment. The application of these microfluidic blood oxygenators was not only limited to preterm neonates but also can be used to develop LADs for adult patients. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/25037 |
| Date | January 2019 |
| Creators | Dabaghi, Mohammadhossein |
| Contributors | Selvaganapathy, P. Ravi, Biomedical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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