George S C, Babb A L, Hlastala M P
Department of Chemical Engineering, University of Washington, Seattle 98195, USA.
Ann Biomed Eng. 1995 Jan-Feb;23(1):48-60. doi: 10.1007/BF02368300.
A previously developed mathematical model that describes the relationship between blood alcohol (ethanol) concentration and the concentration of alcohol in the exhaled breath at end-exhalation (BrAC) has been used to quantitate the effect of pretest breathing conditions on BrAC. The model was first used to "condition" the airways with different breathing maneuvers prior to simulating a single exhalation maneuver, the maneuver used in standard breath alcohol testing. On inspiration, the alcohol in the air reaches local equilibrium with the alcohol in the bronchial capillary bed prior to entering the alveolar region. On expiration, approximately 50% of the alcohol absorbed on inspiration is desorbed back to the airways. BrAC correlates with the amount of alcohol that is desorbed to the airways. The six pretest breathing conditions and the percent change in BrAC relative to the control maneuver were: hyperventilation (-4.4%), hypoventilation (3.7%), hot-humid air (-2.9%), hot-dry air (0.66%), cold-humid air (0.13%), and cold-dry air (0.53%). The mechanism underlying these responses is not due to changes in breath temperature, but, rather to changes in the axial profile of alcohol content in the mucous lining of the airways.
一个先前开发的数学模型，用于描述血液酒精（乙醇）浓度与呼气末呼出气体中酒精浓度（BrAC）之间的关系，已被用于量化测试前呼吸条件对BrAC的影响。该模型首先用于在模拟单次呼气动作（标准呼气酒精测试中使用的动作）之前，通过不同的呼吸动作来“调节”气道。吸气时，空气中的酒精在进入肺泡区域之前，会与支气管毛细血管床中的酒精达到局部平衡。呼气时，吸气时吸收的约50%的酒精会解吸回气道。BrAC与解吸到气道中的酒精量相关。六种测试前呼吸条件以及相对于对照动作BrAC的百分比变化分别为：过度通气（-4.4%）、通气不足（3.7%）、热湿空气（-2.9%）、热干空气（0.66%）、冷湿空气（0.13%）和冷干空气（0.53%）。这些反应的潜在机制不是由于呼吸温度的变化，而是由于气道黏膜内衬中酒精含量轴向分布的变化。
