Thesis (M.S.)--University of Michigan, 1994. / Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1994. / Includes bibliographical references.

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.

INTRODUÇÃO: Clonidina intratecal pode prolongar a duração da raquianestesia, possivelmente com maior duração da analgesia pós-operatória em cesáreas. Neste estudo, avaliamos o uso de clonidina como medicação adjuvante na anestesia para cesárea, pelas vias intratecal e intravenosa e seus efeitos na dor pós-operatória e repercussões neonatais. MÉTODOS: em ensaio clínico prospectivo, aleatorizado, duplo-cego, controlado por placebo, 64 mulheres submetidas à cesárea eletiva sob raquianestesia foram aleatorizadas e alocadas em três grupos, a depender de como receberiam a clonidina adjuvante: clonidina intratecal 75 mcg, clonidina intravenosa 75 mcg, e solução fisiológica 0,9% (controle). O desfecho primário foi dor pós-operatória aguda. Os desfechos secundários foram dor pós-operatória tardia (após três meses), eventos adversos maternos e neonatais. RESULTADOS: não foram encontradas diferenças nos escores de dor ou no consumo de opioides no período pós-operatório precoce. Clonidina intratecal e intravenosa causaram maiores índices de sedação intraoperatória, em comparação com o grupo controle {RASS: 0 [(-1)-(0)] vs. 0 [(-1)-(-1)] vs. 0 [(-1)-(-1)] para controle, intratecal e intravenosa, respectivamente, p < 0,001}. Não houve diferença para efeitos adversos ou desfechos neonatais entre os grupos. CONCLUSÕES: clonidina intratecal e clonidina intravenosa não tiveram efeito na dor pós-operatória pós-cesárea. Ambas causaram maior sedação intraoperatória / BACKGROUND: Intrathecal clonidine may prolong the duration of spinal anesthesia, possibly with longer duration of postoperative analgesia in cesarean sections. In this study, we evaluated the use of clonidine as an intrathecal or intravenous adjuvant medication for cesarean section anesthesia and its effects on postoperative pain and neonatal outcomes. METHODS: In a prospective, randomized, double-blind, placebo-controlled clinical trial, 64 women undergoing elective cesarean section under spinal anesthesia were randomized and allocated to three groups, depending on how they would receive adjuvant clonidine: 75 mcg intrathecal clonidine, 75 mcg intravenous clonidine, and 0.9% saline solution (control). The primary outcome was acute postoperative pain. Secondary outcomes were late postoperative pain (after three months), maternal and neonatal adverse events. RESULTS: no differences were found in pain scores or opioid use in the acute postoperative period. Intrathecal and intravenous clonidine caused higher rates of intraoperative sedation compared to the control group {RASS: 0 [(-1)-(0)] vs. 0 [(-1)-(-1)] vs. 0 [(-1)-(-1)] for control, intrathecal and intravenous, respectively, p < 0.001}. There was no difference for adverse effects or neonatal outcomes among groups. CONCLUSIONS: intrathecal clonidine and intravenous clonidine had no effect on post-cesarean postoperative pain. Both caused higher intraoperative sedation