Electron paramagnetic resonance assessment of brain tissue oxygen tension in anesthetized rats
Electron paramagnetic resonance assessment of brain tissue oxygen tension in anesthetized rats
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DOI：
10.1213/01.ane.0000055648.41152.63
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发表时间：
2003-05-01
影响因子：
5.7
通讯作者：
Swartz, HM
中科院分区：
文献类型：
--
作者：
Hou, HA;Grinberg, OY;Swartz, HM
脑组织氧合（PtO 2）的充分性是危重和麻醉患者的中心治疗终点。在临床上，PtO 2目前是间接测量的基础上，脑血管氧合测量使用近红外光谱和实验，使用正电子发射断层扫描。电子顺磁共振（EPR）血氧测定法的最新发展有助于准确、灵敏和重复测量PtO 2。EPR类似于核磁共振，但检测顺磁性物质。由于这些物种在体内的脑（或其他组织）中不丰富，因此植入大脑皮层的氧响应顺磁酞菁锂晶体用于测量氧。这些材料的EPR谱的线宽是PtO 2的线性函数。我们在麻醉大鼠中使用EPR血氧测定法来研究暴露于各种吸入和注射全身麻醉药以及不同水平的吸入氧期间PtO 2的模式。用2.0最小肺泡麻醉剂浓度异氟烷麻醉的大鼠保持最大PtO 2（38.0 +/- 4.5 mm Hg）。氯胺酮/甲苯噻嗪麻醉的大鼠在吸入氧分数（FIO 2）为0.21时具有最小的PtO 2（3.5 +/-0.3mmHg），P < 0.05。在氯胺酮/甲苯噻嗪麻醉下，FIO 2为1.0时达到的最大PtO 2为8.8 +/- 0.3 mm Hg，而在异氟烷麻醉期间，FIO 2为1.0时测量的PtO 2为56.3 +/- 1.7 mm Hg（P < 0.05）。这些数据突出了EPR在麻醉过程中测量PtO 2的实验效用，并作为进一步研究PtO 2对生理扰动和预防脑缺血的治疗干预的反应的基础。
The adequacy of cerebral tissue oxygenation (PtO2) is a central therapeutic end point in critically ill and anesthetized patients. Clinically, PtO2 is currently measured indirectly, based on measurements of cerebrovascular oxygenation using near infrared spectroscopy and experimentally, using positron emission tomographic scanning. Recent developments in electron paramagnetic resonance (EPR) oximetry facilitate accurate, sensitive, and repeated measurements of PtO2. EPR is similar to nuclear magnetic resonance but detects paramagnetic species. Because these species are not abundant in brain (or other tissues) in vivo, oxygen-responsive paramagnetic lithium phthalocyanine crystals implanted into the cerebral cortex are used for the measurement of oxygen. The line widths of the EPR spectra of these materials are linear functions of PtO2. We used EPR oximetry in anesthetized rats to study the patterns of PtO2 during exposure to various inhaled and injected general anesthetics and to varying levels of inspired oxygen. Rats anesthetized with 2.0 minimum alveolar anesthetic concentration isoflurane maintained the largest PtO2 (38.0 +/- 4.5 mm Hg). and rats anesthetized with ketamine/xylazine had the smallest PtO2 (3.5 +/- 0.3 mm Hg) at a fraction of inspired oxygen (FIO2) of 0.21, P < 0.05. The maximal PtO2 achieved under ketamine/xylazine anesthesia with FIO2 of 1.0 was 8.8 +/- 0.3 mm Hg, whereas PtO2 measured during isoflurane anesthesia with FIO2 of 1.0 was 56.3 +/- 1.7 mm Hg (P < 0.05). These data highlight the experimental utility of EPR in measuring PtO2 during anesthesia and serve as a foundation for further study of PtO2 in response to physiologic perturbations and therapeutic interventions directed at preventing cerebral ischemia.