| Summary: | 碩士 === 國防醫學院 === 海底醫學研究所 === 96 === 中文摘要
低血容性休克是因為全身性有效血量降低，使得心輸出量降低，肺動脈壓降低，並且使肺血管阻力增加，進而影響了氧氣的運送。正常的生理代償機制應該是提升氧氣供應量回復組織的需氧量。 已知動脈血氧分壓間接反應氧氣含量及通氣-灌流分布，過去文獻中的結果發現休克造成動脈血氧分壓表現不一致，是否因為心輸出量的改變造成肺血流重新分布，改善肺臟氣體交換而使得動脈血氧分壓增加，提高氧氣輸送能力。為了減少活體動物心輸出量不易控制及神經反應等變數，故選用兔子離體肺模式來觀察灌流量對於肺血流重分布的影響。實驗根據灌流量的增減順序分成三組，控制組的灌流量不變，向上調控組(Upward)的灌流量先增後減，向下調控組(Downward)的灌流量先減後增，利用螢光微粒技術分析肺臟整體相對血流的改變及肺血流空間分布，各組間生理參數及動脈氧分壓並沒有差異，灌流量的增減並不影響肺部氧氣之氣體交換。當灌流量增加時，肺血管阻力會明顯降低，離體肺模式維持正常的肺生理表現。灌流量的增減，並不影響高血流，中血流，低血流肺塊佔整體肺區的比例，皆維持約1: 1: 1.2的比例；各分區單獨來看，原本屬於高血流、中血流、低血流區的肺塊，當灌流量改變時，都會有部份比例的血流有增減的表現，但是沒有統計上的一致性。配合座標值觀察肺相對血流的空間分布，灌流量的改變對於左-右(Left- Right)平面及背-腹(Dorsal- Ventral)平面相對血流的分布沒有影響，但是在底-頂(Caudal-Cranial)的平面可以發現，當灌流量增加時，肺血流的空間分布會往頂部(Cranial)偏移， 肺底部減少的血流比例較大，相對血流斜率會明顯增加。當灌流量降低量較大時，底部(Caudal)的肺血流會有增加的趨勢，但可能增減變異性過大，無統計上的意義。結合立體空間發現，當灌流量不變時，肺血流的增減改變並沒有特定方向性；而灌流量增加時，肺頂部(Cranial)的相對血流有增加，而底部(Caudal)的肺血流是減少的；灌流量降低時，增加的血流分布到肺底部(Caudal)，而頂部(Cranial)的相對血流是減少的趨勢。從實驗結果得知，灌流量的改變並不會影響高、中、低血流佔整體肺區的比例，但是會使得肺血流的重新分布，使血流往特定空間偏移，且此一趨勢與重力相關。
關鍵字: 低血容性休克、離體肺、螢光微粒分析技術、灌流量、肺血流分布、動脈氧分壓
Abstract
Hypovolemic shock is a particular form of shock in which the heart is unable to supply enough blood to the body. It is caused by blood loss or inadequate blood volume, increase the pulmonary vascular resistance, and hider the delivery of oxygen, it may stop the tissue functioning. We expect a physiological compensatory mechanism would recover the tissue oxygen by elevation of the oxygen content. VA/Q match or not is an important determinant of arterial partial pressure. It’s difficult to control the cardiac output and neural reaction during the in vivo experiments, and the isolated lung model can prevent the problems. It’s the suitable model for investigate the effect of perfusion rate on pulmonary blood flow distribution. Animals have been separate 3 groups depend on the perfusion rate sequence. The perfusion rate is consistent on control group, and is raise first then reduce on upward group, downward group is opposite. Fluorescent Microsphere Technique (FMS) is used to analysis the change of relative blood flow in total lung and the redistribution. We observe there is no difference on physiological parameters and the blood gas data, the gas exchange remain saturation even the perfusion rate has been change. Fall in pulmonary vascular resistance as the perfusion rate is raised, and the isolated lung model can imitate normal pulmonary physiological. When the perfusion rate increase, the ratio of total lung region and the lung pieces of high、middle、and low region is remain consistent, the ratio is always keep 1:1:1.2. If we separate the region, the blood flow of each region increase and decrease both, but no prominent difference. The spatial distribution of pulmonary blood flow is observed, and there is no difference in left-right plane and dorsal-ventral plane. The pulmonary relative blood flow would shift to the cranial side during the perfusion rate increase on caudal-cranial plane. The relative blood flow trend toward the caudal side during the perfusion rate decrease, but no difference in statistics. Combine the spatial coordinate, the change of relative blood flow is scattered during the perfusion rate consistent. The relative blood flow of the lung pieces at cranial region is almost increased, and at caudal region is decreased during the perfusion rate raised. And during the perfusion rate reduced, there is a tendency to the relative blood flow of the lung pieces at caudal region is increased. We conclude that if the perfusion rate is change or not don’t affect the ratio of the blood flow of each region and the total lung. The redistribution of pulmonary relative blood flow would happen and there is a correction with the tendency and gravity.
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