一种将挥发性麻醉剂优先输送至原位山羊脑的方法。

A method for preferential delivery of volatile anesthetics to the in situ goat brain.

作者信息

Antognini J F, Kien N D

机构信息

Department of Anesthesiology, University of California at Davis 95616.

出版信息

Anesthesiology. 1994 May;80(5):1148-54. doi: 10.1097/00000542-199405000-00024.

DOI:10.1097/00000542-199405000-00024

PMID:8017652

Abstract

BACKGROUND

As part of studies aimed at better defining the effects of anesthetics at different anatomic sites, we have developed a model of preferentially delivering inhaled anesthetics to the in situ goat brain, using a bubble oxygenator and roller pump. We tested the hypotheses that (1) this model excludes the cerebral circulation from the body; (2) the concentration of halothane in the oxygenator exhaust correlates with the concentration of halothane in the oxygenator arterial blood.

METHODS

After ligation of the occipital arteries in six halothane-anesthetized goats, we used a bubble oxygenator to perfuse the brain preferentially (exclusive of the body) via a carotid artery, draining cranial venous blood back into the oxygenator via the isolated jugular veins. (In goats, the vertebral arteries do not directly contribute to the cerebral circulation, and internal jugular veins and extracranial internal carotid arteries are absent). The extent of isolation was determined with radioactive microspheres injected into the left atrium during the following periods: (1) baseline; (2) during bypass when the blood pressure in the head equalled that in the body; (3) during bypass when the blood pressure in the body exceeded that in the head by approximately 30-35 mmHg; (4) when the bypass roller pump was stopped. We also measured the concentration of halothane in the arterial blood of the bypass unit. In three animals, systemic metocurine was administered during bypass to detect the presence of venous contamination.

RESULTS

Baseline cerebral blood flow was 74 +/- 32 ml.100 g-1.min-1 (mean +/- SD). During bypass, cerebral blood flow originating from the systemic circulation was less than 1 ml.100 g-1.min-1, and isolation extended to the caudal medulla during periods 3 and 4, and to the first 1-cm segment of the spinal cord during period 2. The concentration of halothane in the oxygenator exhaust correlated reasonably well with the arterial halothane concentration (r = 0.82, P < 0.001). Systemic arterial metocurine concentrations peaked at 1 min (27 +/- 3.7 micrograms/ml) and decreased to 10.6 +/- 2.3 micrograms/ml at 10 min; head venous metocurine plasma concentrations gradually increased to 3.1 +/- 0.4 micrograms/ml at 10 min.

CONCLUSIONS

This technique permits selective perfusion and delivery of inhaled anesthetics to the in situ goat brain, but is not adequate for selective delivery of fixed intravenous anesthetics.

摘要

背景

作为旨在更好地确定麻醉剂在不同解剖部位作用的研究的一部分，我们开发了一种使用气泡氧合器和滚压泵将吸入麻醉剂优先输送至原位山羊脑的模型。我们检验了以下假设：（1）该模型使脑循环与身体其他部分分离；（2）氧合器排气中氟烷的浓度与氧合器动脉血中氟烷的浓度相关。

方法

在六只接受氟烷麻醉的山羊结扎枕动脉后，我们使用气泡氧合器通过颈动脉优先灌注脑（不包括身体其他部分），经分离的颈静脉将颅静脉血引流回氧合器。（在山羊中，椎动脉不直接参与脑循环，且不存在颈内静脉和颅外颈内动脉）。在以下时间段通过向左心房注射放射性微球来确定分离程度：（1）基线期；（2）体外循环期间，头部血压等于身体血压时；（3）体外循环期间，身体血压比头部血压高约30 - 35 mmHg时；（4）体外循环滚压泵停止时。我们还测量了体外循环装置动脉血中氟烷的浓度。在三只动物中，体外循环期间给予全身用美库氯铵以检测静脉污染的存在。

结果

基线脑血流量为74 ± 32 ml·100 g⁻¹·min⁻¹（平均值 ± 标准差）。体外循环期间，源自体循环的脑血流量小于1 ml·100 g⁻¹·min⁻¹，在第3和第4阶段分离范围扩展至延髓尾端，在第2阶段扩展至脊髓的首个1厘米节段。氧合器排气中氟烷的浓度与动脉氟烷浓度具有较好的相关性（r = 0.82，P < 0.001）。全身动脉美库氯铵浓度在1分钟时达到峰值（27 ± 3.7 μg/ml），并在10分钟时降至10.6 ± 2.3 μg/ml；头部静脉美库氯铵血浆浓度在10分钟时逐渐升至3.1 ± 0.4 μg/ml。