血浆量血液量血红素红血球量.ppt

Acclimatisation to High Altitude 高地適應 Dr Jim Milledge Hon. Prof. University College London Symptoms of sudden hypoxia突然缺氧症狀 Effect of Chronic altitude exposure慢性高地暴露之效應 Respiratory Acclimatisation呼吸適應 The earliest and most important defence against altitude hypoxia is an increase in minute ventilation.增加每分鐘通氣量是人體最早也是最重要之防禦機制 There is an increase in both depth and rate of breathing. 增加通氣量亦即增加呼吸深度與呼吸率 This results in a decrease in PACO2 and an increase in PAO2 增加通氣量造成動脈血氧分壓增加，動脈血二氧化碳分壓降低 Chemoreceptors, central and peripheral 中樞與周邊之化學接受器 CO2 Response –Acclimaitzation適應－二氧化碳之反應 Effect of acclimatisation (left) on CO2 and Hypoxic Ventilatory Response二氧化碳適應之效應(左)與低氧通氣反應 Effect of acclimatisation on HVR低氧通氣效應之適應 Mechanism of Resp Acclimatization呼吸適應機制 Hypoxia – Carotid body – hyperventilation 低氧－頸動脈體－過度通氣 Hyperventilation – PCO2 down 過度通氣－二氧化碳分壓下降 PCO2 down – pH alkaline (resp) 二氧化碳分壓下降－酸鹼值上升（偏鹼性）（呼吸） Less hyperventilation 降低過度通氣 Renal excretion of HCO3 (Diamox)腎臟過濾出重碳酸根 pH returned towards normal 酸鹼值(pH) 恢復至正常 Ventilatory drive restored, further hyperventilation. 通氣驅使再次循環，回至過度通氣 Art. – vein. PO2 difference 動靜脈氧氧分壓差 Depends on 依據: -1. Cardiac output 心輸出量 2. Hb concentration 血紅素濃度 3. Position on O2 dissociation curve 氧解離曲線之位置 Increase in RBCs at altitude高地增加紅血球 Best known physiological effect of Alt. 目前最著名之高地生理效應 Paul Bert, La Pression Barometric (1878) suggested it might happenPaul Bert, La Pression Barometric (1878) 認為將會發生 Was sent samples of blood of animals from La Paz, showed O2 capacity increased La Paz分析動物血液檢體發現氧容積增加 Viault (1890) found RBC increased in man at (4372m), from 5 to 7.1 million/cu.mm