Pujol Jesus, Martínez-Vilavella Gerard, Gallart Lluís, Blanco-Hinojo Laura, Pacreu Susana, Bonhomme Vincent, Deus Joan, Pérez-Sola Víctor, Gambús Pedro L, Fernández-Candil Juan
MRI Research Unit, Department of Radiology, Hospital Del Mar, Barcelona, Spain; Centro Investigación Biomédica en Red de Salud Mental, CIBERSAM G21, Barcelona, Spain.
MRI Research Unit, Department of Radiology, Hospital Del Mar, Barcelona, Spain.
Br J Anaesth. 2023 Feb;130(2):e330-e338. doi: 10.1016/j.bja.2022.06.038. Epub 2022 Aug 13.
The safety of anaesthesia has improved as a result of better control of anaesthetic depth. However, conventional monitoring does not inform on the nature of nociceptive processes during unconsciousness. A means of inferring the quality of potentially painful experiences could derive from analysis of brain activity using neuroimaging. We have evaluated the dose effects of remifentanil on brain response to noxious stimuli during deep sedation and spontaneous breathing.
Optimal data were obtained in 26 healthy subjects. Pressure stimulation that proved to be moderately painful before the experiment was applied to the thumbnail. Functional MRI was acquired in 4-min periods at low (0.5 ng ml), medium (1 ng ml), and high (1.5 ng ml) target plasma concentrations of remifentanil at a stable background infusion of propofol adjusted to induce a state of light unconsciousness.
At low remifentanil doses, we observed partial activation in brain areas processing sensory-discriminative and emotional-affective aspects of pain. At medium doses, relevant changes were identified in structures highly sensitive to general brain arousal, including the brainstem, cerebellum, thalamus, auditory and visual cortices, and the frontal lobe. At high doses, no significant activation was observed.
The response to moderately intense focal pressure in pain-related brain networks is effectively eliminated with safe remifentanil doses. However, the safety margin in deep sedation-analgesia would be narrowed in minimising not only nociceptive responses, but also arousal-related biological stress.
由于对麻醉深度的控制得到改善，麻醉安全性有所提高。然而，传统监测无法提供无意识状态下伤害性刺激过程的性质信息。通过神经影像学分析大脑活动可能推断出潜在疼痛体验的质量。我们评估了瑞芬太尼在深度镇静和自主呼吸期间对大脑对有害刺激反应的剂量效应。
在26名健康受试者中获得了最佳数据。将实验前证明为中度疼痛的压力刺激施加于拇指指甲。在稳定输注丙泊酚以诱导轻度无意识状态的背景下，在瑞芬太尼低（0.5 ng/ml）、中（1 ng/ml）、高（1.5 ng/ml）目标血浆浓度下，以4分钟的时间段采集功能磁共振成像。
在低剂量瑞芬太尼时，我们观察到处理疼痛感觉辨别和情感方面的脑区部分激活。在中等剂量时，在对一般脑觉醒高度敏感的结构中发现了相关变化，包括脑干、小脑、丘脑、听觉和视觉皮层以及额叶。在高剂量时，未观察到明显激活。
安全剂量的瑞芬太尼可有效消除疼痛相关脑网络对中度强烈局部压力的反应。然而，在深度镇静镇痛中，安全范围不仅会因将伤害性反应降至最低，还会因将与觉醒相关的生物应激降至最低而变窄。
