The contribution of intrapulmonary shunts to the alveolar-to-arterial oxygen difference during exercise is very small.
The contribution of intrapulmonary shunts to the alveolar-to-arterial oxygen difference during exercise is very small.
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运动期间肺内分流对肺泡与动脉氧差的贡献非常小。
DOI：
10.1113/jphysiol.2007.150128
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
Wagner,PeterD
中科院分区：
文献类型：
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作者：
Vogiatzis,Ioannis;Zakynthinos,Spyros;Boushel,Robert;Athanasopoulos,Dimitris;Guenette,JordanA;Wagner,Harrieth;Roussos,Charis;Wagner,PeterD
众所周知，运动会导致动脉下降和肺泡动脉差（Aa）增加。直到最近，其生理基础被认为主要是通气/灌注/不平等和肺泡-毛细血管扩散限制。最近，已经提出通过扩张的肺血管进行动静脉分流来解释运动期间Aa的重要部分。为了验证这一假设，我们测定了7名健康的自行车运动员在同一天以平衡顺序进行的5分钟近最大恒定负荷低氧（吸入O2分数，，0.13）、常氧（，0.21）和高氧（，1.0）运动期间的静脉混合物（，61.3 ± 2.4 ml kg− 1 min −1;平均值±s.e.m.）。静脉混合反映了低氧血症的三个原因：真正的分流，扩散限制和/不平等。低氧时静脉混合液占心输出量的22.8 ± 2.5%，常氧时为3.5 ± 0.5%，高氧时为0.5 ± 0.2%。由于只有真正的分流占静脉混合物，而呼吸100%O2，本研究表明，分流只占非常小的一部分，观察到的静脉混合物，Aa和低氧血症在剧烈运动。
Exercise is well known to cause arterial to fall and the alveolar–arterial difference (Aa ) to increase. Until recently, the physiological basis for this was considered to be mostly ventilation/perfusion / inequality and alveolar–capillary diffusion limitation. Recently, arterio‐venous shunting through dilated pulmonary blood vessels has been proposed to explain a significant part of the Aa during exercise. To test this hypothesis we determined venous admixture during 5 min of near‐maximal, constant‐load, exercise in hypoxia (in inspired O2fraction, , 0.13), normoxia (, 0.21) and hyperoxia (, 1.0) undertaken in balanced order on the same day in seven fit cyclists (, 61.3 ± 2.4 ml kg−1min−1; mean ±s.e.m.). Venous admixture reflects three causes of hypoxaemia combined: true shunt, diffusion limitation and / inequality. In hypoxia, venous admixture was 22.8 ± 2.5% of the cardiac output; in normoxia it was 3.5 ± 0.5%; in hyperoxia it was 0.5 ± 0.2%. Since only true shunt accounts for venous admixture while breathing 100% O2, the present study suggests that shunt accounts for only a very small portion of the observed venous admixture, Aa and hypoxaemia during heavy exercise.