Paloski W H, Slosberg R B, Kamm R D
J Appl Physiol (1985). 1987 Mar;62(3):892-901. doi: 10.1152/jappl.1987.62.3.892.
Local gas transport coefficients, quantifying longitudinal dispersion through a symmetrical constant-diameter tube network, have been measured during oscillation with both symmetrical and nonsymmetrical waveforms. Experiments were carried out over a range of conditions that would prevail in the central to lower airways during high-frequency ventilation at moderate frequency (5 Hz) and tidal volume (15-80 ml). Gas transport coefficients resulting from oscillation of three different resident-trace gas pairs were measured using a new analytic technique. This technique allowed rapid determination of the transport coefficient distribution along the entire network. Results demonstrate a small but significant influence attributable to changes in gas properties that is similar to that found in a straight tube and indicate that augmented dispersion is an important mechanism of axial transport. Gas transport coefficients were found to be unaffected by changes in flow waveform symmetry, suggesting that previously reported improvements in gas exchange associated with decreasing inspiratory to expiratory time ratios are not due to a change in local conditions such as asymmetry in the velocity profile.
在使用对称和非对称波形进行振荡期间，已经测量了通过对称等直径管网的纵向扩散的局部气体传输系数。实验是在一系列条件下进行的，这些条件在中频（5Hz）和潮气量（15 - 80ml）的高频通气过程中会在中央气道至下气道中普遍存在。使用一种新的分析技术测量了由三种不同的驻留 - 痕量气体对振荡产生的气体传输系数。该技术允许快速确定沿整个网络的传输系数分布。结果表明，气体性质变化产生的影响虽小但显著，这与直管中的情况类似，并表明增强扩散是轴向传输的重要机制。发现气体传输系数不受流动波形对称性变化的影响，这表明先前报道的与吸气与呼气时间比降低相关的气体交换改善并非由于局部条件的变化，如速度分布的不对称性。
