ARDS : early diagnosis & prevention of irreversible change by surfactant therapy

(1)测定成人（急性）呼吸窘迫综合征（ARDS）的可逆性：在大鼠和家兔实验中给予内毒素、弹性蛋白酶、溶卵磷脂和抗表面活性剂蛋白B单克隆抗体，直至动脉氧压（PaO_2）开始下降6 h后，表面活性剂替代可逆转ARDS样症状。因此，出现症状后6小时被认为是可逆期。然而，即使在可逆期，肺泡内也可见透明膜的形成，提示应尽早注意防止有机改变。(2)表面活性剂的替代方法和人工表面活性剂的研制：大鼠吸入一种雾化表面活性剂（改性天然表面活性剂，表面活性剂CK）可逆转内毒素引起的ards样肺损伤症状。通过这种方法，肺组织的有机变化，一种不可逆转的损伤，可以推迟至少6小时。此外，以合成的二棕榈酰磷脂酰胆碱、磷脂酰甘油和二油基磷脂酰胆碱（60∶20∶20）与表面活性剂蛋白B（0.7%）和C（1.4%）为原料制备的人工表面活性剂具有与表面活性剂CK相同的效果。(3)肺表面活性物质状况与血管阻力的关系：我们发现肺表面活性物质失活可引起肺泡毛细血管扩张。我们认为这是解释ARDS低氧血症机制的重要发现。(4) ARDS的早期诊断：气管吸出液的表面张力值可用于ARDS的早期诊断。

(1) Determination of the reversible period in adult (acute) respiratory distress syndrome (ARDS) : In experiment to administrate endotoxin, elastase, lysolecithin, and anti-surfactant protein B monoclonal antibody in rats and rabbits, the ARDS-like symptom could be reversed by surfactant replacement until 6 hours after the arterial oxygen pressure (PaO_2) started to decrease. Therefore, 6 hours after the onset of the symptom was thought to be the reversible period. Formation of hyaline membrane, however, was noted in the alveoli even at the reversible period, uggesting that some cares should be taken to prevent the organic changes as early as possible.(2) Replacement method of surfactant and development of artificial surfactant : In rats, inhalation of an aerosolized surfactant (modified natural surfactant, Surfactant CK) reversed symptoms of ARDS-like lung injury which was induced by administration of endotoxin. By this procedure, the organic change of the lung tissue, an irreversible damage, could be postponed at least for 6 hours. In addition, an artificial surfactant which was prepared with synthetic dipalmitoyl-phosphatidylcholine, phosphatidylglycerol and dioleoylphosphatidylcholine (60 : 20 : 20) plus surfactant protein B (0.7%) and C (1.4%) exhibited the same effects with Surfactant CK.(3) Relation between condition of pulmonary surfactant and vascular resistance : We found that inactivation of pulmonary surfactant induces dilatation of the capillary vessels of the alveoli. We think that this is an important finding to explain the mechanism of hypoxemia in ARDS.(4) Early diagnosis of ARDS : We have obtained some findings that surface tension values of the liquid aspirated from the trachea may by useful for early diagnosis of ARDS.