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

(1)成人(急性)呼吸窘迫综合征(ARDS)可逆期的确定：在大鼠和兔应用内毒素、弹力酶、溶血磷脂和抗表面活性蛋白B单抗的实验中，应用表面活性物质替代可逆转ARDS样症状，直到动脉血氧分压(PaO2)开始下降后6h。因此，症状出现后6小时被认为是可逆期。肺表面活性物质的替代方法和人工表面活性物质的研制：在大鼠吸入一种雾化表面活性物质(改良的天然表面活性物质，表面活性物质CK)，可逆转内毒素所致的ARDS样肺损伤的症状。通过这种方法，肺组织的器质性改变这一不可逆转的损伤可以推迟至少6小时。此外，人工合成的二棕榈酰磷脂酰胆碱、磷脂酰甘油和二油酰磷脂酰胆碱(60：20：20)与表面活性蛋白B(0.7%)和C(1.4%)制备的人工表面活性物质具有与表面活性物质CK相同的作用。(3)肺表面活性物质状态与血管阻力的关系：我们发现肺表面活性物质灭活可导致肺泡毛细血管扩张。我们认为这是解释ARDS低氧血症机制的一个重要发现。(4)ARDS的早期诊断：我们已经获得了一些发现，从气管抽出的液体的表面张力值可能有助于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.