Background: Preliminary data on the perioperative use of dexmedetomidine in patients undergoing craniotomy for brain tumor under general anesthesia indicate that the intraoperative administration of dexmedetomidine is opioid-sparing, results in less need for antihypertensive medication, and may offer greater hemodynamic stability at incision and emergence. Dexmedetomidine, alpha 2 adrenoceptor agonist, is used as adjuvant to anesthetic agents. Relatively recent studies have shown that dexmedetomidine is able to decrease circulating plasma norepinephrine and epinephrine concentration in approximately 50%, decreases brain blood flow by directly acting on post-synaptic alpha 2 receptors, decreases CSF pressure without ischemic suffering and effectively decreases brain metabolism and intracranial pressure and also, able to decrease injury caused by focal ischemia.
Purpose: This prospective, randomized, double-blind study was designed to assess the perioperative effect of intraoperative infusion of dexmedetomidine in patients with supratentorial tumors undergoing craniotomy under general anesthesia.
Methods: Fourty patients with CT- scanning proof of supratentorial tumors were classified equally into 2 groups (twenty patients in each group). Group A:--Dexmedetomidine was given as a bolus dose of 1 microg/kg in 20 minutes before induction of anesthesia, followed by a maintenance infusion of 0.4 microg/kg/hr. The infusion was discontinued when surgery ended. Group B:--The patients received similar volumes of saline.
Results: Heart rate and mean arterial blood pressure, decreased significantly in patients of group A (dexmedetomidine group) compared to group B (placebo group) (p-value < 0.05). There was no significant statistical difference between the two groups regarding the central venous pressure and arterial partial pressure of carbon dioxide (p-value > 0.05). The intraoperative end-tidal sevoflurane (%) in patients of group A was less than in patients of group B (p-value < 0.05). The intracranial pressure decreased in patients of Group A more than group B (p-value < 0.05). The Glasgow coma scale (GCS) improved in patients of group A and deteriorated in patients of Group B with significant statistical difference between the two groups (p-value < 0.05). The total fentanyl requirements from induction to extubation of patients increased in patients of group B more than in patients of group A (p-value < 0.05). The total postoperative patients' requirements for antiemetic drugs within the 2 hours after extubation decreased in patients of group A more than group B (p-value < 0.05). The postoperative duration from the end of surgery to extubation decreased significantly in patients of group A more than group B (p-value < 0.05). The total urine output during the duration from drug administration to extubation of patients increased in patients of group A more than group B (p-value < 0.05).
Conclusion: Continuous intraoperative infusion of dexmedetomidine during craniotomy for supratentorial tumors under general anesthesia maintained the hemodynamic stability, reduced sevoflurane and fentanyl requirements, decreased intracranial pressure, and improved significantly the outcomes.