Arulvelan Appavoo, Manikandan Sethuraman, Easwer Hari Venkat, Krishnakumar Kesavapisharady
Department of Anesthesiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Ulloor, Trivandrum, Kerala, India.
Indian J Crit Care Med. 2016 Jan;20(1):9-13. doi: 10.4103/0972-5229.173680.
Dexmedetomidine has been widely used in critical care settings because of its property of maintaining stable hemodynamics and inducing conscious sedation. The use of dexmedetomidine is in increasing trend particularly in patients with neurological disorders. Very few studies have focused on the cerebral hemodynamic effects of dexmedetomidine. This study is aimed to address this issue.
Thirty patients without any intracranial pathology were included in this study. Middle cerebral artery flow velocity obtained from transcranial color Doppler was used to assess the cerebral hemodynamic indices. Mean flow velocity (mFV), pulsatility index (PI), cerebral vascular resistant index (CVRi), estimated cerebral perfusion pressure (eCPP), and zero flow pressure (ZFP) were calculated bilaterally at baseline and after infusion of injection Dexmedetomidine 1 mcg/Kg over 10 min.
Twenty-six patients completed the study protocol. After administration of loading dose of dexmedetomidine, mFV and eCPP values were significantly decreased in both hemispheres (P < 0.05); PI, CVRi, and ZFP values showed significant increase (P < 0.05) after dexmedetomidine infusion.
Increase in PI, CVRi, and ZFP suggests that there is a possibility of an increase in distal cerebral vascular resistance (CVR) with loading dose of dexmedetomidine. Decrease in mFV and eCPP along with an increase in CVR may lead to a decrease in cerebral perfusion. This effect can be exaggerated in patients with preexisting neurological illness. Further studies are needed to evaluate the effect of dexmedetomidine on various other pathological conditions involving brain like traumatic brain injury and vascular malformations.
右美托咪定因其维持血流动力学稳定和诱导清醒镇静的特性，已在重症监护环境中广泛应用。右美托咪定的使用呈上升趋势，尤其是在患有神经系统疾病的患者中。很少有研究关注右美托咪定对脑血流动力学的影响。本研究旨在解决这一问题。
本研究纳入了30例无任何颅内病变的患者。通过经颅彩色多普勒获得的大脑中动脉血流速度用于评估脑血流动力学指标。在基线时以及在10分钟内输注1μg/kg右美托咪定注射液后，双侧计算平均血流速度（mFV）、搏动指数（PI）、脑血管阻力指数（CVRi）、估计脑灌注压（eCPP）和零流压力（ZFP）。
26例患者完成了研究方案。给予负荷剂量的右美托咪定后，两个半球的mFV和eCPP值均显著降低（P<0.05）；右美托咪定输注后，PI、CVRi和ZFP值显著升高（P<0.05）。
PI、CVRi和ZFP的升高表明，负荷剂量的右美托咪定可能会增加远端脑血管阻力（CVR）。mFV和eCPP的降低以及CVR的增加可能导致脑灌注减少。在已有神经系统疾病的患者中，这种效应可能会更加明显。需要进一步研究来评估右美托咪定对其他各种涉及脑的病理状况（如创伤性脑损伤和血管畸形）的影响。
