Differences in regional wash-in and wash-out time constants for xenon-CT ventilation studies

被引:53
作者
Chon, D
Simon, BA
Beck, KC
Shikata, H
Saba, OI
Won, CH
Hoffman, EA
机构
[1] Univ Iowa, Coll Med, Dept Radiol, Iowa City, IA 52242 USA
[2] Univ Iowa, Coll Med, Dept Biomed Engn, Iowa City, IA 52242 USA
[3] Johns Hopkins Univ, Dept Anesthesiol & Crit Care Med, Baltimore, MD 21218 USA
关键词
xenon; inert gas dilution; regional lung ventilation measurements; computed tomography; pulmonary imaging; airway conductance; multi-detector row CT;
D O I
10.1016/j.resp.2005.06.003
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Xenon-enhanced computed tomography (Xe-CT) has been used to measure regional ventilation by determining the wash-in (WI) and wash-out (WO) rates of stable Xe. We tested the common assumption that WI and WO rates are equal by measuring WO-WI in different anatomic lung regions of six anesthetized, supine sheep scanned using multi-detector-row computed tomography (MDCT). We further investigated the effect of tidal volume, image gating (end-expiratory EE versus end-inspiratory EI), local perfusion, and inspired Xe concentration on this phenomenon. Results: WO time constant was greater than WI in all lung regions, with the greatest differences observed in dependent base regions. WO-WI time constant difference was greater during EE imaging, smaller tidal volumes, and with higher Xe concentrations. Regional perfusion did not correlate with WI-WO. We conclude that Xe-WI rate can be significantly different from the WO rate, and the data suggest that this effect may be due to a combination of anatomic and fluid mechanical factors such as Rayleigh-Taylor instabilities set up at interfaces between two gases of different densities. (c) 2005 Elsevier B.V. All rights reserved.
引用
收藏
页码:65 / 83
页数:19
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