Abstract
Ten studies were performed to examine the time course of arterial and venous thiopenlal concentrations following the administration of thiopental (4mg.kg-1 over 3 min) for cerebral protection during carotid occlusion in nine patients undergoing elective carotid endarterectomy; in five patients the time course of EEC change was also studied. The arterial and venous thiopental concentrations were similar with no evidence of a sustained arterial-venous gradient. The average arterial concentration was 20.1 μg.ml-1 ± 10 (SD) at 2 min after thiopental, and fell rapidly to 13.0 μg.ml-1 ± 3.2 at 5 min, 10.7 μg.ml-1 ± 4.4 at 10minand 6.2 μg-ml-1 at 30 min. After thiopental the EEG record showed an increase in delta activity and in four patients a burst suppression pattern was seen. The duration of burst suppression activity was variable (130 to 367 seconds) but in all instances cortical activity had returned to the pre-lhiopental level by five to ten minutes. Thus concentrations of thiopental of 10-30 μg.ml-1 were associated with EEG burst suppression and both were seen only within the first five minutes after drug administration. In contrast the carotid artery was occluded for considerably longer (26 ± 4) minutes.
We conclude that, since there was no sustained arterial-venous gradient, either arterial or venous concentrations are adequate for the study of thiopental pharmacokinetics. However, using burst suppression as an index of cerebral protection with thiopental it appears that the administration of thiopental (4mg.kg-1 over three minutes) before carotid occlusion is not adequate to protect for the duration of the carotid endarterectomy procedure.
Résumé
On a étudié à dix occasions chez neuf patients l’évolution des concentrations artérielles et veineuses de thiopental après son administration à une dose de 4mg.kg-1 donnée en trois minutes. Cette dose était donnée corrane protection cérébrale pendant l’occlusion de la carotide lors d’endartérectomie carotidienne. Chez cinq patients on a également étudié l’évolution de l’EEG. Les concentrations artérielles et veineuses de thiopental étaient similaires et il n’y eut pas lieu de penser qu’il existe un gradient artério-veineux. La moyenne des concentrations artérielles était de 20. J ± 10(DS)μg-ml-1 deux minutes après l’injection et diminuait rapidement à 13.0 ± 3.2 μg.ml-1 à cinq minutes, 10.7 ± 4.4 μg.ml-1 à dix minutes et à 6.2 μg.ml-1 à 30 minutes. Après le thiopental, l’EEG a montré une augmentation de l’activité delta et chez quatre patients une suppression des bouffées. La durée de la suppression des bouffées était variable (130 à 367 secondes) main dans tous tes cas l’activité corticale était revenue à son niveau pré-thio-pental après cinq à dix minutes. Des concentrations de thiopemal de 10 à 30 μg.ml-1 ont été associées avec la suppression des bouffées, conditions qui ne furent réalisées que dans les cinq minutes après l’administration du thiopental. Par contre la durée de l’occlusion de la carotide était beaucoup plus longue (26 ± 4 minutes). Nous concluons que, comme il n’y a pas de gradient artério-veineux, les mesures de la concentration artérielle ou veineuse sont adéquates pour l’étude de la pharmacocinétique du thiopental. Cependant, si on utilise la suppression des bouffées à l’EEG comme un index de protection cérébrale avec le thiopental, ilsemble que la dose de. 4 mg.kg-1 donnée en trois minutes avant l’occlusion de la carotide n’est pas adéquate pour toute la durée de l’endartérectomie.
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Moffat, J.A., McDougall, M.J., Brunet, D. et al. Thiopental bolus during carotid endar-terectomy-rational drug therapy?. Can Anaesth Soc J 30, 615–622 (1983). https://doi.org/10.1007/BF03015232
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DOI: https://doi.org/10.1007/BF03015232