From the Department of Anesthesiology, Section of Neuroanesthesia, Aarhus University, Aarhus, Denmark.
Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark.
Anesthesiology. 2021 Nov 1;135(5):788-803. doi: 10.1097/ALN.0000000000003877.
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.
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.
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.
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.
本研究比较了在麻醉脑瘤患者中，使用麻黄碱和去氧肾上腺素对脑血流和毛细血管转运时间异质性（通过测量脑血流来评估）的影响。研究假设在选定的脑区，去氧肾上腺素治疗时毛细血管转运时间异质性较麻黄碱治疗时更大，从而降低脑氧张力。
这是一项单中心、双盲、随机临床试验，24 名麻醉脑瘤患者被随机分为麻黄碱组或去氧肾上腺素组。在血管加压素输注前后，对肿瘤周围和对侧半球进行磁共振成像。主要终点是组间毛细血管转运时间异质性的差异。次要终点包括脑血流、估计氧提取分数和脑组织氧张力的变化。
20 名患者的数据显示，对侧半球毛细血管转运时间异质性在去氧肾上腺素治疗时从 3.0±0.5 增加到 3.2±0.7 s，而在麻黄碱治疗时从 3.1±0.8 减少到 2.7±0.7 s（去氧肾上腺素与麻黄碱的差异[95%CI]，-0.6[-0.9 至-0.2] s；P=0.004）。在肿瘤周围区域，毛细血管转运时间异质性在去氧肾上腺素治疗时从 4.1±0.7 增加到 4.3±0.8 s，而在麻黄碱治疗时从 3.5±0.9 减少到 3.3±0.9 s（去氧肾上腺素与麻黄碱的差异[95%CI]，-0.4[-0.9 至 0.1] s；P=0.130）。脑血流（对侧半球比值差异[95%CI]，0.3[0.06 至 0.54]；P=0.018；和肿瘤周围比值差异[95%CI]，0.3[0.06 至 0.54]；P=0.018）和估计的脑组织氧张力（对侧半球比值差异[95%CI]，0.34[0.09 至 0.59]；P=0.001；和肿瘤周围比值差异[95%CI]，0.33[0.09 至 0.57]；P=0.010）在两个区域中，麻黄碱治疗时均大于去氧肾上腺素治疗时。
与麻黄碱相比，去氧肾上腺素引起的毛细血管转运时间异质性恶化，表明其在对侧组织中的微循环恶化，尽管达到了相似的平均动脉压终点。麻黄碱改善了两个脑区的脑血流和组织氧合，在改善脑宏观和微观血液动力学和氧合方面可能优于去氧肾上腺素。
