Hansen T N, Gest A L, Landers S
J Appl Physiol (1985). 1985 Apr;58(4):1314-8. doi: 10.1152/jappl.1985.58.4.1314.
The purpose of this study was to examine the effects of inspiratory airway obstruction on lung fluid balance in newborn lambs. We studied seven 2- to 4-wk-old lambs that were sedated with chloral hydrate and allowed to breathe 30-40% O2 spontaneously through an endotracheal tube. We measured lung lymph flow, lymph and plasma protein concentrations, pulmonary arterial and left atrial pressures, mean and phasic pleural pressures and airway pressures, and cardiac output during a 2-h base-line period and then during a 2- to 3-h period of inspiratory airway obstruction produced by partially occluding the inspiratory limb of a nonrebreathing valve attached to the endotracheal tube. During inspiratory airway obstruction, both pleural and airway pressures decreased 5 Torr, whereas pulmonary arterial and left atrial pressures each decreased 4 Torr. As a result, calculated filtration pressure remained unchanged. Inspiratory airway obstruction had no effect on steady-state lung lymph flow or the lymph protein concentration relative to that of plasma. We conclude that in the spontaneously breathing lamb, any decrease in interstitial pressure resulting from inspiratory airway obstruction is offset by a decrease in microvascular hydrostatic pressure so that net fluid filtration remains unchanged.
本研究的目的是检测吸气气道阻塞对新生羔羊肺液体平衡的影响。我们研究了7只2至4周龄的羔羊，用氯水合醛使其镇静，并让它们通过气管插管自主呼吸30%至40%的氧气。在2小时的基线期以及随后通过部分阻塞连接到气管插管的非重复呼吸阀的吸气支产生2至3小时吸气气道阻塞期间，我们测量了肺淋巴流量、淋巴和血浆蛋白浓度、肺动脉和左心房压力、平均和相位胸膜压力以及气道压力，还有心输出量。在吸气气道阻塞期间，胸膜和气道压力均降低5托，而肺动脉和左心房压力各降低4托。结果，计算出的滤过压保持不变。吸气气道阻塞对稳态肺淋巴流量或相对于血浆的淋巴蛋白浓度没有影响。我们得出结论，在自主呼吸的羔羊中，吸气气道阻塞导致的间质压力的任何降低都被微血管静水压力的降低所抵消，从而使净液体滤过保持不变。
