Abstract
This investigation was concerned with extracorporeal oxygenators used to support the pulmonary function of patients undergoing open heart surgery. Of the two problems investigated, the first was a biological study of blood damage. For many years the advantages of membrane oxygenators as against direct contact oxygenators have been postulated. A review of past work shows that many of the physical and chemical factors known to cause changes in the blood are not properly understood. A study of red blood cells using the scanning electron microscope was conducted to obtain greater understanding of the changes that occur during clinical bypass. This investigation was carried out with blood taken during open heart surgery from extracorporeal circuits which losed different types of oxygenator. The results demonstrated changes in red blood cell shape and size under different conditions and in particular, they were found to undergo the echinocyte transformation. The second part of the investigation was aimed at providing an analytical description of the mechanics of mass transfer in a flat plate membrane oxygenator. In order to highlight the general characteristics of such a device, the analysis includes consideration of non-reactive fluids (e.g. water, saline) as well as reactive fluids (e.g. blood). Data obtained from a series of tests on an experimental oxygenator agreed well with the analytic solution derived for both blood and water. This solution illustrated the importance of various parameters and non-dimensional groups in die process of gas transfer in an oxygenator. In particular, the transfer rate was found to be less sensitive to variations in membrane thickness than was at first suspected. Furthermore, it was discovered that water may be used as a satisfactory substitute for blood in order to predict and test the performance of membrane oxygenators.