Cerebral vascular effects of loading dose of dexmedetomidine: A Transcranial Color Doppler study
Appavoo Arulvelan, Sethuraman Manikandan, Hari Venkat Easwer, Kesavapisharady Krishnakumar
Cerebral vascular resistance, dexmedetomidine, transcranial color Doppler
Citation Information :
Arulvelan A, Manikandan S, Easwer HV, Krishnakumar K. Cerebral vascular effects of loading dose of dexmedetomidine: A Transcranial Color Doppler study. Indian J Crit Care Med 2016; 20 (1):9-13.
Background: 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.
Methods: 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.
Results: 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.
Conclusion: 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.
Gerlach AT, Dasta JF. Dexmedetomidine: An updated review. Ann Pharmacother 2007;41:245-52.
Bekker A, Sturaitis MK. Dexmedetomidine for neurological surgery. Neurosurgery 2005;57 1 Suppl: 1-10.
van Beek AH, Claassen JA, Rikkert MG, Jansen RW. Cerebral autoregulation: An overview of current concepts and methodology with special focus on the elderly. J Cereb Blood Flow Metab 2008;28:1071-85.
Hancock SM, Mahajan RP, Athanassiou L. Noninvasive estimation of cerebral perfusion pressure and zero flow pressure in healthy volunteers: The effects of changes in end-tidal carbon dioxide. Anesth Analg 2003;96:847-51.
Wahl M, Schilling L. Regulation of cerebral blood flow - A brief review. Acta Neurochir Suppl (Wien) 1993;59:3-10.
Dagal A, Lam AM. Cerebral autoregulation and anesthesia. Curr Opin Anaesthesiol 2009;22:547-52.
Schlünzen L, Vafaee MS, Cold GE, Rasmussen M, Nielsen JF, Gjedde A. Effects of subanaesthetic and anaesthetic doses of sevoflurane on regional cerebral blood flow in healthy volunteers. A positron emission tomographic study. Acta Anaesthesiol Scand 2004;48:1268-76.
Endoh H, Honda T, Ohashi S, Hida S, Shibue C, Komura N. The influence of nicardipine-, nitroglycerin-, and prostaglandin E(1)-induced hypotension on cerebral pressure autoregulation in adult patients during propofol-fentanyl anesthesia. Anesth Analg 2002;94:169-73.
Moppett IK, Sherman RW, Wild MJ, Latter JA, Mahajan RP. Effects of norepinephrine and glyceryl trinitrate on cerebral haemodynamics: Transcranial Doppler study in healthy volunteers. Br J Anaesth 2008;100:240-4.
Ulrich PT, Becker T, Kempski OS. Correlation of cerebral blood flow and MCA flow velocity measured in healthy volunteers during acetazolamide and CO2 stimulation. J Neurol Sci 1995;129:120-30.
van der Linden J, Wesslén O, Ekroth R, Tydén H, von Ahn H. Transcranial Doppler-estimated versus thermodilution-estimated cerebral blood flow during cardiac operations. Influence of temperature and arterial carbon dioxide tension. J Thorac Cardiovasc Surg 1991;102:95-102.
Zornow MH, Maze M, Dyck JB, Shafer SL. Dexmedetomidine decreases cerebral blood flow velocity in humans. J Cereb Blood Flow Metab 1993;13:350-3.
Kontos HA. Validity of cerebral arterial blood flow calculations from velocity measurements. Stroke 1989;20:1-3.
Czosnyka M, Richards HK, Whitehouse HE, Pickard JD. Relationship between transcranial Doppler-determined pulsatility index and cerebrovascular resistance: An experimental study. J Neurosurg 1996;84:79-84.
Ishiyama T, Dohi S, Iida H. The vascular effects of topical and intravenous alpha2-adrenoceptor agonist clonidine on canine pial microcirculation. Anesth Analg 1998;86:766-72.
Ganjoo P, Farber NE, Hudetz A, Smith JJ, Samso E, Kampine JP, et al. In vivo effects of dexmedetomidine on laser-Doppler flow and pial arteriolar diameter. Anesthesiology 1998;88:429-39.
Asano Y, Koehler RC, Kawaguchi T, McPherson RW. Pial arteriolar constriction to alpha 2-adrenergic agonist dexmedetomidine in the rat. Am J Physiol 1997;272(6 Pt 2):H2547-56.
Zornow MH, Fleischer JE, Scheller MS, Nakakimura K, Drummond JC. Dexmedetomidine, an alpha 2-adrenergic agonist, decreases cerebral blood flow in the isoflurane-anesthetized dog. Anesth Analg 1990;70:624-30.
Fale A, Kirsch JR, McPherson RW. Alpha 2-adrenergic agonist effects on normocapnic and hypercapnic cerebral blood flow in the dog are anesthetic dependent. Anesth Analg 1994;79:892-8.
Schregel W, Bredenkötter U, Sihle-Wissel M, Cunitz G. Transcranial Doppler ultrasound: Effects of intravenous anesthetics in neurosurgical patients. Ultraschall Med 1995;16:60-4.
White H, Venkatesh B. Cerebral perfusion pressure in neurotrauma: A review. Anesth Analg 2008;107:979-88.
Weyland A, Buhre W, Grund S, Ludwig H, Kazmaier S, Weyland W, et al. Cerebrovascular tone rather than intracranial pressure determines the effective downstream pressure of the cerebral circulation in the absence of intracranial hypertension. J Neurosurg Anesthesiol 2000;12:210-6.
Ulrich K, Kuschinsky W. In vivo effects of alpha-adrenoceptor agonists and antagonists on pial veins of cats. Stroke 1985;16:880-4.