Cerebral Microvascular Reactivity to Carbon Dioxide during Isoflurane Anesthesia as Assessed by Laser-Doppler Flowmetry

Isoflurane麻醉時腦部微循環對二氧化碳之反應

蔡玉娟(Yu-Chuan Tsai) ； 李淑娟(Shu-Chuan Lee) ； 張傳林(Chuan-Lin Chang)

《Acta Anaesthesiologica Sinica》 33卷2期 (1995/06) Pp. 101-106

摘要

Background: To determine the effects of carbon dioxide on the cerebral microcirculation during isoflurane anesthesia. Methods: We studied 10 rabbits using laser Doppler flowmetry on the parietal cortex. After surgical preparation, the end-tidal concentration of isoflurane was maintained at one MAC (2.05%). Mean arterial pressure, rectal temperature and hematocrit were kept constant. The arterial carbon dioxide tension (PaCO_2) was randomly adjusted to three levels: 20 - 25 mmHg (hypocapnia); 35-40 mmHg (normocapnia); and 45-50 mmHg (hypercapnia). Cerebral blood flow (CBF) was measured after target PaCO_2 had been achieved. Results: CBF at normocapnia was 27.4 ± 13.5 (mean ± SD) ml/100 gm/min, which increased to 42.4 ± 14.3 ml/100 g/min (p ＜ 0.01) and decreased to 15.3 ± 7.5 ml/100 g/min (p ＜ 0.05) at hypercapnia and hypocapnia respectively. The slopes of CBF versus PaCO_2 were 1.60 ± 0.63 ml/100 g/min/mmHg from normocapnia to hypercapnia and -0.79 ± 0.51 ml/100 g/min/mmHg from normocapnia to hypocapnia. The corresponding percentage of alteration in CBF on the respective change of PaCO_2 was 7.2 ± 5.1 and -3.0 ± 1.2%/mmHg. Conclusions: These data indicate that the changes of the cerebral microvascular blood flow reflect the CO_2 effects during isoflurane anesthesia.

關鍵字

Anesthetics, volatile: isoflurane ； Brain: blood flow ； Measurement techniques: Laser Doppler flowmeter ； Carbon dioxide

並列摘要

背景：探討isoflurane麻醉時腦部微循環對二氧化碳反應之影響。方法：方法選擇十隻健康兔子，以雷射都卜勒血流測定術（laser Doppler flowmetry）測定不同動脈血二氧化碳分壓（PaCO_2）改變下對腦微循環血流之影響。外科手術準備好動物後，以潮氣末isoflurane濃度2.05%（1 MAC）維持麻醉，並維持平均動脈壓，肛溫及血容比的恆定。以隨機次序調整PaCO_2至三個範圍20－25mmHg（hypercapnia）；35－40mmHg（normocapnia）和45－50mmHg（hypercapnia）。待PaCO_2達到設定之範圍後，記錄下腦血流。結果：在normocapnia時腦血流為27.4 ± 13.5（mean ± SD）ml/100g/min，在hypercapnia時增加至42.4 ± 14.3 mI/100g/min（p＜0.01），在hypocapnia時則減低至15.3 ± 7.5 ml/100g/min（p＜0.05）。從normocapnia至hypercapnia，多餘腦血流和PaCO_2的增加比值為1.60 ± 0.63 ml/100g/min/mmHg；從normocapnia至hypocapnia，其下降比值為0.79 ± 0.51 ml/100g/min/mmHg。相對百分比之變化為7.2 ± 5.1和3.0 ± 1.2%/ mmHg。結論：在isoflurane麻醉時，以雷射都卜勒血流測定術測得之腦部微循環血流可以反應CO_2的作用。

並列關鍵字

吸入性麻醉藥：isoflurane ； 腦血流 ； 雷射杜卜勒血流測定儀 ； 二氧化碳