Effect of blood flow rate and blood flow history on newborn pulmonary microcirculation.
Effect of blood flow rate and blood flow history on newborn pulmonary microcirculation.
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血流速率和血流史对新生儿肺微循环的影响。
DOI：
10.1152/ajpheart.1991.261.2.h271
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Kaplowitz,MR
中科院分区：
文献类型：
--
作者：
Fike,CD;Kaplowitz,MR
本研究的目的是确定肺血流量增加和/或肺血流量史是否会改变新生儿肺部微血管压力。使用直接微穿刺技术，我们测量了新生兔分离肺中20- 60微米直径的小动脉和小静脉在连续血流量为50（基线）、100和/或200 ml.min-1.kg-1时的压力。然后在一些肺中，我们将血流速率恢复到基线并重复微血管压力测量。我们保持左心房压在所有血流量下不变。当血流量增加且左房压保持不变时，肺动脉压、20- 60微米直径的小动脉压和20- 60微米直径的小静脉压均升高，导致静脉总压下降的比例增加。当我们将血流恢复到基线时，静脉压恢复到基线，但小动脉和肺动脉压恢复到低于基线的值，因此微血管发生的总压降的百分比下降。因此，血流速率和血流历史是新生儿肺血管压力纵向分布的重要决定因素。这些发现还表明，在新生儿中，直径大于60微米的肺小静脉扩张性差，因此较高的血流量导致微血管压力增加。因此，在肺血流量增加的情况下，如左向右分流，即使左房压不增加，新生儿肺部水肿形成的倾向也会增加。
The purpose of this study was to determine whether increased pulmonary blood flow and/or the history of pulmonary blood flow alters microvascular pressures in lungs of newborns. Using the direct micropuncture technique, we measured pressures in 20- to 60-microns-diameter arterioles and venules in isolated lungs of newborn rabbits at consecutive blood flow rates of 50 (baseline), 100, and/or 200 ml.min-1.kg-1. Then in some lungs we returned blood flow rate to baseline and repeated microvascular pressure measurements. We kept left atrial pressure the same at all blood flow rates. When blood flow rate increased and left atrial pressure was maintained constant, pulmonary arterial, 20- to 60-microns-diameter arteriolar, and 20- to 60-microns-diameter venular pressures increased such that the percentage of total pressure drop that occurred across veins increased. When we returned blood flow to baseline, venular pressure returned to baseline, but arteriolar and pulmonary arterial pressures returned to values less than baseline so that the percentage of the total pressure drop that occurred across microvessels decreased. Thus both blood flow rate and blood flow history are important determinants of the longitudinal distribution of pulmonary vascular pressures across newborn lungs. These findings also suggest that in newborn lungs venules greater than 60 microns diameter are poorly distensible such that higher blood flow rates result in increased microvascular pressures. Hence, under conditions of increased pulmonary blood flow, such as occurs with left to right shunts, the tendency for edema formation will increase in newborn lungs even if left atrial pressure does not increase.