Brismar B, Hedenstierna G, Lundquist H, Strandberg A, Svensson L, Tokics L
Anesthesiology. 1985 Apr;62(4):422-8. doi: 10.1097/00000542-198504000-00009.
Twenty patients (23-76 yr) were studied with regard to lung tissue changes prior to and following induction of general anesthesia with muscular relaxation, and another four subjects were studied for a longer period awake. The transverse thoracic area and the structure of the lung tissue were determined by computerized tomography. No abnormalities in the lung tissue were noted before anesthesia. Within 5 min after induction, including muscular relaxation, all subjects had developed crest-shaped changes of increased density in the dependent regions of both lungs. They were largest in the most caudal segment (4.8 +/- 0.8% of the transverse lung area, mean +/- SE) and smaller in the cephalad exposures (3.4 +/- 0.7% of the transverse area). The size of the densities showed no correlation to age. The densities did not increase after a further 20 min of anesthesia and were not affected by the inspiratory oxygen fraction. When the subjects were moved from the supine to the lateral position, the crest-shaped densities disappeared in the nondependent lung and remained in the dorsal part of the dependent lung. The application of positive end-expiratory pressure of 10 cmH2O eliminated or reduced the densities. The four awake subjects showed no lung densities after 90 min in the supine position. It is suggested that these crest-shaped densities represent atelectases, which develop by compression of lung tissue rather than by resorption of gas.
对20名患者（23 - 76岁）进行了研究，观察全身麻醉诱导加肌肉松弛前后的肺组织变化，并对另外4名受试者进行了更长时间的清醒状态研究。通过计算机断层扫描确定胸廓横截面积和肺组织结构。麻醉前未发现肺组织异常。诱导后5分钟内，包括肌肉松弛，所有受试者双肺下垂部位均出现密度增加的嵴状改变。它们在最尾端节段最大（占肺横截面积的4.8 +/- 0.8%，均值 +/- 标准误），在头侧部位较小（占横截面积的3.4 +/- 0.7%）。密度大小与年龄无关。麻醉再持续20分钟后密度未增加，且不受吸入氧分数影响。当受试者从仰卧位转为侧卧位时，嵴状密度在非下垂肺消失，而在下垂肺的背侧部分仍存在。施加10 cmH₂O的呼气末正压可消除或降低密度。4名清醒受试者在仰卧位90分钟后未出现肺密度。提示这些嵴状密度代表肺不张，其形成是由于肺组织受压而非气体吸收。
