Dalinghaus M, Knoester H, Gratama J W, Van der Meer J, Zijlstra W G, Kuipers J R
Beatrix Children's Hospital, Division of Pediatric Cardiology, Groningen, The Netherlands.
Am J Physiol. 1994 Aug;267(2 Pt 2):H471-6. doi: 10.1152/ajpheart.1994.267.2.H471.
In chronic hypoxemia blood flow and oxygen supply to vital organs are maintained, but to nonvital organs they are decreased. We measured organ blood flows (microspheres) and whole blood viscosity in 10 chronically hypoxemic lambs, with an atrial septal defect and pulmonary stenosis, and in 8 control lambs. Vascular hindrance (resistance/viscosity) was calculated to determine to what extent the effect of increased blood viscosity on organ blood flow was compensated for by a decrease in vascular tone. Arterial oxygen saturation was decreased (68 +/- 10 vs. 91 +/- 3%, P < 0.001), and both hemoglobin concentration (145 +/- 10 vs. 109 +/- 9 g/l, P < 0.05) and blood viscosity (4.4 +/- 0.6 vs. 3.6 +/- 0.6 mPa.s, P < 0.05) were increased in hypoxemic lambs. Systemic blood flow, oxygen supply, oxygen uptake, and blood pressures were not significantly different between hypoxemic and control lambs. Myocardial and cerebral blood flow was maintained in hypoxemic lambs, whereas renal, gastrointestinal, splenic, and thyroidal blood flows were at least 30% lower. Vascular hindrance was significantly decreased in the myocardium and tended to be lower in the brain of hypoxemic lambs, but in all other organs it was similar to that in control lambs. It is concluded that blood flow is redistributed in chronic hypoxemia in lambs; myocardial and cerebral blood flow is maintained, whereas blood flow to splanchnic organs, the kidneys, and the thyroids is decreased. The decreased blood flow to organs is a consequence of the increased whole blood viscosity.
在慢性低氧血症中，重要器官的血流和氧气供应得以维持，但非重要器官的则减少。我们测量了10只患有房间隔缺损和肺动脉狭窄的慢性低氧血症羔羊以及8只对照羔羊的器官血流（微球法）和全血黏度。计算血管阻力（阻力/黏度）以确定血管张力降低对增加的血液黏度影响器官血流的补偿程度。低氧血症羔羊的动脉血氧饱和度降低（68±10 vs. 91±3%，P<0.001），血红蛋白浓度（145±10 vs. 109±9 g/l，P<0.05）和血液黏度（4.4±0.6 vs. 3.6±0.6 mPa·s，P<0.05）均升高。低氧血症羔羊和对照羔羊之间的全身血流、氧气供应、氧气摄取和血压无显著差异。低氧血症羔羊的心肌和脑血流得以维持，而肾、胃肠、脾和甲状腺血流至少降低30%。低氧血症羔羊心肌的血管阻力显著降低，脑的血管阻力有降低趋势，但在所有其他器官中与对照羔羊相似。结论是，羔羊慢性低氧血症时血流重新分布；心肌和脑血流得以维持，而内脏器官、肾脏和甲状腺的血流减少。器官血流减少是全血黏度增加的结果。
