右美托咪定的临床麻醉应用进展

右美托咪定(dexmedetomidine,Dex)是高选择性α2-肾上腺素受体激动剂,具有镇静、镇痛、抑制交感神经活性、无呼吸抑制等药理性质。多项研究证实:围术期或ICUs住院期间给予患者右美托咪定,可以增加患者机械通气耐受力,减少机械通气时间,改善患者病情恢复,减少呼吸抑制,稳定血流动力学,减少麻醉剂用量及降低麻醉剂不良反应发生率,抑制应激反应,保护肺脏、神经功能、心脏功能,降低谵妄发生率,抗寒颤等作用特点。虽然右美托咪定存在心动过缓及低血压等不良反应,故应控制给药速度、剂量,合理用药在以便循环波动可控范围内。目前,右美托咪定可用于重症监护病房(ICUs)、全身麻醉、区域麻醉、小儿麻醉、日间手术及无痛检查等辅助用药。本文主要对右美托咪定的临床麻醉应用做以下介绍。     

Effect Of Different Doses Of Noradrenaline Against Ischemia-induced Ventricular Arrhythmias In Rat Heart In Vivo

Background

The present study was designed to evaluate the preconditioning effect of different doses of noradrenaline on ischemia-induced ventricular arrhythmias in open chest anesthetized rats.

Methods

The anaesthetized rats were subjected to 25 min of regional ischemia by left descending coronary artery (LAD) occlusion. In sham group, surgical procedures were done but ischemia was not applied. In control rats, saline was injected prior to ischemia. In noradrenaline groups, rats pretreated with three different doses of noradrenaline (respectively, 0.5, 1 and 2 μg/kg, IV).

Results

In control rats, induction of ischemia shortened the QTc (corrected QT) interval (ms) and led to occurrence of ventricular arrhythmias. Administration of low-dose of noradrenaline prevented shortening of the QTc interval during ischemia but could not significantly attenuate severity and incidences of arrhythmias. Injection of mid-dose of noradrenaline stabilized the QTc during ischemia and reduced severity of arrhythmias. Pretreatment with high-dose of noradrenaline significantly prolonged the QTc interval and declined severity and incidence of arrhythmias.

Conclusions

Noradrenaline dose-dependently attenuated ischemia-induced ventricular arrhythmias.     

The Specificity Of Processes Of Motivational Conditioning In The Human Mind

The methodological principle of the objectification of needs, which in activity theory explains the ontological development of motivation (Leont'ev, 1975), is in need of concrete psychological development to ascertain what influences and mental processes give rise to such objectification. In terms of biological motivation, this question is made easier by the existence of a detailed system of data, accumulated in conditioning studies, concerning the acquisition of the capacity to activate a person by neutral stimuli. A psychological interpretation of these data purports to explain the fact that the conditioned response phenomenon indicates not only a redirecting of unconditioned responses toward new stimuli but also the genesis, in response to this stimulus, of subjective relations orienting the person toward influences relevant to his needs. Such an interpretation therefore helps to concretize the concept of the objectification of biological needs (Vilyunas, 1986. Pp. 154-74).