【答案】:B
肺内动-静脉解剖分流增加是指肺动脉内的静脉血未经氧合直接流入肺静脉,导致PaO
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/d439b6003af33a87e0b97782d45c10385243b555?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
降低,是通气/血流比例失调的特例。在这种情况下,提高吸氧浓度并不能提高分流静脉血的血氧分压。分流量越大,吸氧后提高动脉血氧分压的效果越差;若分流量超过30%,吸氧并不能明显提高PaO
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/b7003af33a87e9503fc384f402385343faf2b455?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
常见于肺动-静脉瘘。正常成人静息状态下,通气/血流比值约为0.8,部分肺泡血流不足时,通气/血流比值增大,肺泡通气不能被充分利用。弥散障碍系指O
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/3bf33a87e950352acdb552904143fbf2b3118b55?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
、CO
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/3b87e950352ac65c1cd111ebe9f2b21192138a55?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
等气体通过肺泡膜进行交换的物理弥散过程发生障碍,O
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/e850352ac65c10385eaab95aa0119313b17e8955?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
的弥散能力仅为CO
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/342ac65c10385343f51bf0b98113b07ecb808855?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
的1/20,故在弥散障碍的时候,通常以低氧血症为主。发热、寒战、呼吸困难和抽搐均增加氧耗量,正常人借助增加通气量以防止缺氧,故氧耗量增加的患者,若同时伴有通气功能障碍,则会出现严重的低氧血症。