Simple contrivance "clamps" end-tidal Pco2 and Po2 despite rapid changes in ventilation
Simple contrivance "clamps" end-tidal Pco2 and Po2 despite rapid changes in ventilation
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DOI：
10.1152/jappl.2000.88.5.1597
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发表时间：
2000-05-01
影响因子：
3.3
通讯作者：
Moosavi, SH
中科院分区：
文献类型：
--
作者：
Banzett, RB;Garcia, RT;Moosavi, SH
本研究中所描述的装置使用功能可变的死腔来保持有效的肺泡通气量恒定。它能够在呼吸增加超过基线水平的情况下，将呼气末PCo(2)和Po-2保持在设定值的+/-1 Torr内。通过改变新鲜气流中的浓度，可以独立地改变呼气末PCO(2)或Po-2的设定水平。该装置包括位于口部的T形三通，其中一个入口提供有限的新鲜气流，而另一个入口在通气量超过新鲜气流时提供补充的肺泡气体。由于该设备不依赖于潮气末或动脉血气水平的测量和校正，因此该设备的响应基本上是瞬时的，从而避免了具有显著延迟的负反馈系统的不稳定性。这一发明提供了一种简单的方法，可以在呼吸自发变化(高于最低肺泡通气量)时保持动脉血气不变，这在呼吸实验和脑功能成像中都很有用，因为在脑功能成像中，血气变化可能会影响脑血流量，从而混淆解释。
The device described in this study uses functionally variable dead space to keep effective alveolar ventilation constant. It is capable of maintaining end-tidal Pco(2) and Po-2 within +/-1 Torr of the set value in the face of increases in breathing above the baseline level. The set level of end-tidal Pco(2) or Po-2 can be independently varied by altering the concentration in fresh gas flow. The device comprises a tee at the mouthpiece, with one inlet providing a limited supply of fresh gas flow and the other providing reinspired alveolar gas when ventilation exceeds fresh gas flow. Because the device does not depend on measurement and correction of end-tidal or arterial gas levels, the response of the device is essentially instantaneous, avoiding the instability of negative feedback systems having significant delay. This contrivance provides a simple means of holding arterial blood gases constant in the face of spontaneous changes in breathing (above a minimum alveolar ventilation), which is useful in respiratory experiments, as well as in functional brain imaging where blood gas changes can confound interpretation by influencing cerebral blood flow.