Although ACC exerted a strong effect on the haemodynamic changes after SA, SA per se did not have much influence on ACC. The incidence and severity of ACC remained unchanged compared with the pre-spinal state. As long as maternal blood pressure were well controlled, the uterine blood flow indices were not affected by ACC. / Although there are many publications on ACC, most publications have considered ACC as a single entity, or reported its effects in terms of just a few end-point measures. The information published so far on ACC remains fragmented. This will be readdressed by taking a multidisciplinary approach with input from the fields of anaesthesia, obstetrics and radiology to non-invasively assess the haemodynamic changes associated with ACC. / Aortocaval compression occurs when parturients lie in the supine position with the gravid uterus compressing the aorta and the inferior vena cava. This interferes with venous return to the heart to reduce cardiac output, resulting in hypotension, uterine hypo-perfusion and fetal acidosis. Under neuraxial anaesthesia when the compensatory mechanisms via the sympathetic nervous outflow are blocked, the effects from ACC are exaggerated and results in maternal and fetal morbidity. / Intermittent IVC compression was responsible for most of the haemodynamic effects, presenting mainly as a reduction in cardiac output. Blood pressure or heart rate changes are poor indicators for IVC compression, and most patients were asymptomatic. Patients who have moderate to severe ACC have a higher incidence of hypotension after SA and consume a higher amount of phenylephrine for maintaining BP. / The research was conducted on non-labouring term parturients presenting for elective Caesarean section under spinal anaesthesia. Measurements were performed to assess the patency of blood vessels and haemodynamic responses to lateral tilts, using ultrasound and non-invasive haemodynamic monitors. / This research has achieved the following: (1) Qualitative measurements of compression of the aorta and IVC with US imaging and Doppler US; (2) Development of a new simple bedside method for detecting ACC using US; (3) Quantitative measurements of physiological responses in the maternal and fetal circulation associated with ACC; (4) Investigation of the effects of spinal anaesthesia per se on ACC. / Lee, Wee Yee Shara. / Adviser: Khaw Kim Sun. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3446. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 234-254). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.