Journal of Neuroanaesthesiology and Critical Care (Dec 2014)
To evaluate the effects of dexmedetomidine on intraocular pressure and haemodynamic changes in response to laryngoscopy and tracheal intubation
Abstract
Background: The most important prerequisites for neurosurgeries are brain relaxation, need of stable haemodynamics with less fluctuation in intracranial pressure and speedy recovery from anaesthesia. Endotracheal intubation is the major stressful stimuli that can elicit a marked pressor response. Various drugs have been used to attenuate these reflexes. Dexmedetomidine, a highly selective alpha 2-adrenoceptor agonist, have neuroprotective, cardioprotective, and sedative effects so it is potentially useful during neuroanaesthesia. This is a prospective randomised control trial carried out to see whether administration of Dexmedetomidine prior to intubation can attenuate the various haemodynamic responses, intraocular pressure (IOP) and the requirement of induction dose of propofol in control and study group. Materials and Methods: Fifty patients (ASA grade 1, 2) scheduled for intracranial tumour surgeries were divided into two groups (25 each). Group D received Dexmedetomidine 0.8 μg/kg i.v. over 10 mins and group C received 20 ml saline. Anaesthesia induced with Propofol, dose adjusted using bispectral index monitor. The groups were compared with IOP, Heart rate (HR), Mean arterial pressure (MAP), and dose of Propofol required for induction. Results: Groups were well matched for their demographic data and pre-operative. IOP in both the eyes decreases significantly after premedication and remained below baseline even after 10th min of intubation in group D while in Group C; it increased significantly after intubation and remained above baseline. The difference between groups was also statistically significant. HR and MAP decreased significantly in patients of group D compared to group C ( P< 0.05). Patients were more haemodynamicaly stable at all time points after premedication in group D ( P< 0.05). Propofol requirements for induction was lesser in group D (P < 0.05). Bradycardia and hypotension incidences were higher in group D. Conclusion: Dexmedetomidine premedication decreases the sympathoadrenal effect on IOP and haemodynamic parameters during laryngoscopy/intubation and decreases the requirement of propofol for induction of general anaesthesia.
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