Cerebral vascular effects of loading dose of dexmedetomidine: Transcranial colour Doppler study

Background: Dexmedetomidine has been widely used in critical care settings because of its property of maintaining stable haemodynamics and inducing conscious sedation. The use of dexmedetomidine is in increasing trend particularly in patients with neurological disorders. A very few studies have focused on the cerebral haemodynamic 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 (FV) obtained from transcranial colour Doppler was used to assess the cerebral haemodynamic indices. Mean FV (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 (LD) of dexmedetomidine, mFV and eCPP values were significantly decreased in both hemisphere (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 possibility of increase in distal CVR with LD of dexmedetomidine. Decrease in mFV and eCPP along with increase in CVR may lead to decrease in cerebral perfusion. This effect can be exaggerated in patients with pre-existing neurological illness. Further studies are needed to evaluate the effect of dexmedetomidine on various other pathological conditions involving brain such as traumatic brain injury and vascular malformations.

No conflict of interest has been declared by the author(s).