BACKGROUND This study compared ephedrine versus phenylephrine treatment on cerebral macro- and microcirculation, measured by cerebral blood flow, and capillary transit time heterogeneity, in anesthetized brain tumor patients. The hypothesis was that capillary transit time heterogeneity in selected brain regions is greater during phenylephrine than during ephedrine, thus reducing cerebral oxygen tension. METHODS In this single-center, double-blinded, randomized clinical trial, 24 anesthetized brain tumor patients were randomly assigned to ephedrine or phenylephrine. Magnetic resonance imaging of peritumoral and contralateral hemispheres was performed before and during vasopressor infusion. The primary endpoint was between-group difference in capillary transit time heterogeneity. Secondary endpoints included changes in cerebral blood flow, estimated oxygen extraction fraction, and brain tissue oxygen tension. RESULTS Data from 20 patients showed that mean (± SD) capillary transit time heterogeneity in the contralateral hemisphere increased during phenylephrine from 3.0 ± 0.5 to 3.2 ± 0.7 s and decreased during ephedrine from 3.1 ± 0.8 to 2.7 ± 0.7 s (difference phenylephrine versus difference ephedrine [95% CI], -0.6 [-0.9 to -0.2] s; P = 0.004). In the peritumoral region, the mean capillary transit time heterogeneity increased during phenylephrine from 4.1 ± 0.7 to 4.3 ± 0.8 s and decreased during ephedrine from 3.5 ± 0.9 to 3.3 ± 0.9 s (difference phenylephrine versus difference ephedrine [95%CI], -0.4[-0.9 to 0.1] s; P = 0.130). Cerebral blood flow (contralateral hemisphere ratio difference [95% CI], 0.3 [0.06 to 0.54]; P = 0.018; and peritumoral ratio difference [95% CI], 0.3 [0.06 to 0.54; P = 0.018) and estimated brain tissue oxygen tension (contralateral hemisphere ratio difference [95% CI], 0.34 [0.09 to 0.59]; P = 0.001; and peritumoral ratio difference [95% CI], 0.33 [0.09 to 0.57]; P = 0.010) were greater during ephedrine than phenylephrine in both regions. CONCLUSIONS Phenylephrine caused microcirculation in contralateral tissue, measured by the change in capillary transit time heterogeneity, to deteriorate compared with ephedrine, despite reaching similar mean arterial pressure endpoints. Ephedrine improved cerebral blood flow and tissue oxygenation in both brain regions and may be superior to phenylephrine in improving cerebral macro- and microscopic hemodynamics and oxygenation. EDITOR’S PERSPECTIVE

中文翻译：

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麻黄碱与去氧肾上腺素治疗麻醉脑肿瘤患者期间的脑大循环和微循环：使用磁共振成像的随机临床试验。

背景这项研究比较了麻黄碱与去氧肾上腺素治疗对脑大循环和微循环的影响，通过脑血流量和毛细血管通过时间异质性测量，在麻醉的脑肿瘤患者中。假设是，去氧肾上腺素期间所选大脑区域的毛细血管通过时间异质性大于麻黄碱期间，从而降低脑氧张力。方法 在这项单中心、双盲、随机临床试验中，24 名麻醉脑肿瘤患者被随机分配到麻黄碱或去氧肾上腺素组。在血管加压剂输注之前和期间进行肿瘤周围和对侧半球的磁共振成像。主要终点是毛细血管通过时间异质性的组间差异。次要终点包括脑血流量的变化，估计的氧气提取分数和脑组织氧张力。结果 来自 20 名患者的数据显示，在去氧肾上腺素期间，对侧半球的平均 (± SD) 毛细血管通过时间异质性从 3.0 ± 0.5 增加到 3.2 ± 0.7 s，在麻黄碱期间从 3.1 ± 0.8 降低到 2.7 ± 0.7 s（去氧肾上腺素差异与差异麻黄碱 [95% CI]，-0.6 [-0.9 至 -0.2] s；P = 0.004）。在瘤周区域，去氧肾上腺素期间的平均毛细血管通过时间异质性从 4.1 ± 0.7 增加到 4.3 ± 0.8 s，在麻黄碱期间从 3.5 ± 0.9 下降到 3.3 ± 0.9 s（去氧肾上腺素与麻黄碱差异 [95%CI]，-0.4 [-0.9 到 0.1] 秒；P = 0.130)。脑血流量（对侧半球比率差异 [95% CI]，0.3 [0.06 至 0.54]；P = 0.018；和瘤周比率差异 [95% CI]，0。3 [0.06 至 0.54; P = 0.018）和估计的脑组织氧分压（对侧半球比率差异 [95% CI]，0.34 [0.09 至 0.59]；P = 0.001；和瘤周比率差异 [95% CI]，0.33 [0.09 至 0.57]；P = 0.010）在麻黄碱期间比在两个地区的去氧肾上腺素期间更大。结论 去氧肾上腺素引起对侧组织的微循环（通过毛细血管通过时间异质性的变化来衡量）与麻黄碱相比恶化，尽管达到了相似的平均动脉压终点。麻黄碱改善了两个大脑区域的脑血流和组织氧合，在改善脑宏观和微观血流动力学和氧合方面可能优于苯肾上腺素。编辑观点 018）和估计的脑组织氧分压（对侧半球比率差异 [95% CI]，0.34 [0.09 至 0.59]；P = 0.001；和瘤周比率差异 [95% CI]，0.33 [0.09 至 0.57]；P = 0.010 ) 在麻黄碱期间比在两个地区的去氧肾上腺素期间更大。结论 去氧肾上腺素引起对侧组织的微循环（通过毛细血管通过时间异质性的变化来衡量）与麻黄碱相比恶化，尽管达到了相似的平均动脉压终点。麻黄碱改善了两个大脑区域的脑血流和组织氧合，在改善脑宏观和微观血流动力学和氧合方面可能优于苯肾上腺素。编辑观点 018）和估计的脑组织氧分压（对侧半球比率差异 [95% CI]，0.34 [0.09 至 0.59]；P = 0.001；和瘤周比率差异 [95% CI]，0.33 [0.09 至 0.57]；P = 0.010 ) 在麻黄碱期间比在两个地区的去氧肾上腺素期间更大。结论 去氧肾上腺素引起对侧组织的微循环（通过毛细血管通过时间异质性的变化来衡量）与麻黄碱相比恶化，尽管达到了相似的平均动脉压终点。麻黄碱改善了两个大脑区域的脑血流和组织氧合，在改善脑宏观和微观血流动力学和氧合方面可能优于苯肾上腺素。编辑观点 010) 在麻黄碱期间比在两个地区的去氧肾上腺素期间更大。结论 去氧肾上腺素引起对侧组织的微循环（通过毛细血管通过时间异质性的变化来衡量）与麻黄碱相比恶化，尽管达到了相似的平均动脉压终点。麻黄碱改善了两个大脑区域的脑血流和组织氧合，在改善脑宏观和微观血流动力学和氧合方面可能优于苯肾上腺素。编辑观点 010) 在麻黄碱期间比在两个地区的去氧肾上腺素期间更大。结论 去氧肾上腺素引起对侧组织的微循环（通过毛细血管通过时间异质性的变化来衡量）与麻黄碱相比恶化，尽管达到了相似的平均动脉压终点。麻黄碱改善了两个大脑区域的脑血流和组织氧合，在改善脑宏观和微观血流动力学和氧合方面可能优于苯肾上腺素。编辑观点 麻黄碱改善了两个大脑区域的脑血流和组织氧合，在改善脑宏观和微观血流动力学和氧合方面可能优于苯肾上腺素。编辑观点 麻黄碱改善了两个大脑区域的脑血流和组织氧合，在改善脑宏观和微观血流动力学和氧合方面可能优于苯肾上腺素。编辑观点