Di Giantomasso David, Morimatsu Hiroshi, May Clive N, Bellomo Rinaldo
Department of Medicine, Melbourne University Austin & Repatriation Medical Centre, Heidelberg, Australia.
Crit Care Med. 2003 Oct;31(10):2509-13. doi: 10.1097/01.CCM.0000084842.66153.5A.
To measure changes in medullary and cortical renal blood flow during experimental hyperdynamic sepsis and the effect of subsequent norepinephrine infusion on such flows. DESIGN Experimental animal study.
Animal laboratory of university-affiliated physiology institute. SUBJECTS Eighteen anesthetized merino sheep.
A transit-time flow probe was placed around the left renal artery. Laser Doppler flow probes were inserted in the left renal medulla and cortex by micromanipulation to measure changes in regional intrarenal blood flow.
Systemic pressures, cardiac output, renal, and intrarenal blood flows were measured continuously. A bolus of Escherichia coli (7.5 x 10(9) colony forming units) was given intravenously to induce hyperdynamic sepsis. After the onset of hyperdynamic sepsis, all animals were randomly allocated to either norepinephrine (0.4 microg.kg-1.min-1 for 30 mins) or observation for 30 mins in random order. E. coli injection induced a significant decrease in mean arterial pressure (102.2 +/- 15.2 mm Hg to 74.3 +/- 16.1 mm Hg, p <.05) and an increase in mean cardiac output (4.60 +/- 1.62 L/min to 5.93 +/- 1.18 L/min, p <.05). However, renal blood flow did not change significantly (326.4 +/- 139.4 mL/min to 293.1 +/- 117.5 mL/min, not significant) despite a 30% increase in renal conductance (3.27 +/- 1.52 to 4.13 +/- 2.01 mL.min-1.mm Hg-1, p <.05). Cortical blood flow decreased by 15% (not significant) and medullary flow by 5% (not significant) during sepsis, but individual changes were unpredictable. On the other hand, norepinephrine infusion caused a significant improvement in mean arterial pressure (74.3 +/- 16.1 to 105.7 +/- 17.7 mm Hg, p <.05) and a further increase in cardiac output (5.93 +/- 1.18 to 7.13 +/- 1.52 L/min, p <.05). Mean renal blood flow also increased (293.1 +/- 117.5 to 384.5 +/- 168.1 mL/min, p <.05) despite decreased renal conductance (4.13 +/- 2.01 to 3.73 +/- 1.91 mL.min-1.mm Hg-1, p <.05). Infusion of norepinephrine significantly increased medullary blood flow by 35% compared with baseline (p <.05) and by 54% compared with untreated sepsis (p <.05), whereas the increases in cortical blood flow (16 and 53%, respectively) were not significant.
Hyperdynamic sepsis caused renal vasodilation but had limited effects on regional intrarenal blood flow. Norepinephrine infusion (0.4 microg.kg-1.min-1) during sepsis significantly increased global and medullary renal blood flow and restored renal vascular tone toward but not above normal.
测量实验性高动力型脓毒症期间肾髓质和皮质血流的变化，以及随后输注去甲肾上腺素对此类血流的影响。设计：实验性动物研究。
大学附属生理研究所的动物实验室。对象：18只麻醉的美利奴绵羊。
在左肾动脉周围放置一个渡越时间血流探头。通过显微操作将激光多普勒血流探头插入左肾髓质和皮质，以测量肾内局部血流的变化。
连续测量全身血压、心输出量、肾血流和肾内血流。静脉注射一剂大肠杆菌（7.5×10⁹菌落形成单位）以诱导高动力型脓毒症。高动力型脓毒症发作后，所有动物被随机分为两组，分别接受去甲肾上腺素（0.4μg·kg⁻¹·min⁻¹，持续30分钟）或观察30分钟，顺序随机。注射大肠杆菌导致平均动脉压显著降低（从102.2±15.2mmHg降至74.3±16.1mmHg，p<.05），平均心输出量增加（从4.60±1.62L/min增至5.93±1.18L/min，p<.05）。然而，尽管肾电导增加了30%（从3.27±1.52增至4.13±2.01mL·min⁻¹·mmHg⁻¹，p<.05），肾血流并未显著改变（从326.4±139.4mL/min降至293.1±117.5mL/min，无显著差异）。脓毒症期间皮质血流减少15%（无显著差异），髓质血流减少5%（无显著差异），但个体变化不可预测。另一方面，输注去甲肾上腺素使平均动脉压显著改善（从74.3±16.1升至105.7±17.7mmHg，p<.05），心输出量进一步增加（从5.93±1.18升至7.13±1.52L/min，p<.05）。尽管肾电导降低（从4.13±2.01降至3.73±1.91mL·min⁻¹·mmHg⁻¹，p<.05），平均肾血流仍增加（从293.1±117.5升至384.5±168.1mL/min，p<.05）。与基线相比，输注去甲肾上腺素使髓质血流显著增加35%（p<.05），与未治疗的脓毒症相比增加54%（p<.05），而皮质血流的增加（分别为16%和53%）不显著。
高动力型脓毒症导致肾血管舒张，但对肾内局部血流影响有限。脓毒症期间输注去甲肾上腺素（0.4μg·kg⁻¹·min⁻¹）显著增加了总体和肾髓质血流，并使肾血管张力恢复至接近正常但未超过正常水平。
