Brown R H, Herold C J, Hirshman C A, Zerhouni E A, Mitzner W
Department of Anesthesiology, Johns Hopkins Medical Institutions, Baltimore, Maryland.
Am Rev Respir Dis. 1991 Jul;144(1):208-12. doi: 10.1164/ajrccm/144.1.208.
Changes in airway resistance are reported to account for only a portion of changes in total lung resistance. The fraction of total lung resistance caused by airway resistance is difficult to quantify in vivo. High-resolution computed tomography (HRCT) has potential application for directly measuring changes in airway size in vivo. In the present investigation, we studied five anesthetized mongrel dogs using HRCT to locate and measure changes in airway area after aerosol histamine challenge in the absence and presence of deep inspiration. We also related changes in total lung resistance to changes in airway area. We found that in all dogs after histamine aerosol challenge, airway area decreased (range, 23 +/- 7 to 67 +/- 5%, mean +/- SEM), and total lung resistance increased (range, 191 to 378%). After deep inspiration (equal to three times tidal volume), four of the five dogs showed further significant decreases in airway area (range, 13 +/- 6 to 71 +/- 8%), whereas all five dogs showed decreases in RL (range, 3 to 35%). The fact that preconstricted airways constricted further after deep inspiration while the measured RL decreased suggests that RL may not always be a reliable indicator of changes in the size of conducting airways larger than 1 mm.
据报道，气道阻力的变化仅占总肺阻力变化的一部分。气道阻力在总肺阻力中所占的比例在体内难以量化。高分辨率计算机断层扫描（HRCT）在直接测量体内气道大小变化方面具有潜在应用价值。在本研究中，我们使用HRCT对五只麻醉的杂种犬进行了研究，以定位和测量在雾化组胺激发试验中，在有无深吸气情况下气道面积的变化。我们还将总肺阻力的变化与气道面积的变化联系起来。我们发现，在所有犬进行组胺雾化激发试验后，气道面积减小（范围为23±7%至67±5%，平均值±标准误），总肺阻力增加（范围为191%至378%）。深吸气（等于潮气量的三倍）后，五只犬中有四只气道面积进一步显著减小（范围为13±6%至71±8%），而所有五只犬的肺阻力（RL）均减小（范围为3%至35%）。深吸气后预先收缩的气道进一步收缩，而测量的RL却降低，这一事实表明，RL可能并不总是大于1mm的传导气道大小变化的可靠指标。
